Thesis - UWSpace - University of Waterloo

Modeling and Simulation of
A Hybrid Electric Vehicle Using
MATLAB/Simulink and ADAMS
by
Brian Su-Ming Fan
A thesis
presented to the University of Waterloo
in fulfillment of the
thesis requirement for the degree of
Master of Applied Science
in
Mechanical Engineering
Waterloo, Ontario, Canada, 2007
© Brian Su-Ming Fan 2007
I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any
required final revisions, as accepted by my examiners.
I understand that my thesis may be electronically available to the public.
Signature
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Abstract
As the global economy strives towards clean energy in the face of climate change, the automotive
industry is researching into improving the efficiency of automobiles. Hybrid vehicle systems were
proposed and have demonstrated the capability of reducing fuel consumption while maintaining
vehicle performance. Various hybrid vehicles in the form of parallel and series hybrid have been
produced by difference vehicle manufacturers. The purpose of this thesis is to create a hybrid vehicle
model in MATLAB and ADAMS to demonstrate its fuel economy improvement over a conventional
vehicle system.
The hybrid vehicle model utilizes the Honda IMA (Integrated Motor Assist) architecture, where the
electric motor acts as a supplement to the engine torque. The motor unit also acts as a generator
during regenerative braking to recover the otherwise lost kinetic energy.
The powertrain
components power output calculation and the control logic were modeled in MATLAB/Simulink,
while the mechanical inertial components were modeled in ADAMS. The model utilizes a driver
input simulation, where the driver control module compares the actual and desired speeds, and applies
a throttle or a braking percent to the powertrain components, which in turns applies the driving or the
braking torque to the wheels. Communication between MATLAB and ADAMS was established by
ADAMS/Controls.
In order to evaluate the accuracy of the MATLAB/ADAMS hybrid vehicle model, simulation
results were compared to the published data of ADVISOR. The West Virginia University 5 Peaks
drive cycle was used to compare the two software models.
The results obtained from
MATLAB/ADAMS and ADVISOR for the engine and motor/generator correlated well.
Minor
discrepancies existed, but were deemed insignificant. This validates the MATLAB/ADAMS hybrid
vehicle model against the published results of ADVISOR.
Fuel economy of hybrid and conventional vehicle models were compared using the EPA New York
City Cycle (NYCC) and the Highway Fuel Economy Cycle (HWFET).
The hybrid vehicle
demonstrated 8.9% and 14.3% fuel economy improvement over the conventional vehicle model for
the NYCC and HWFET drive cycles, respectively. In addition, the motor consumed 83.6kJ of
electrical energy during the assist mode while regenerative braking recovered 105.5kJ of electrical
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energy during city driving. For the highway drive cycle, the motor consumed 213.6kJ of electrical
energy during the assist mode while the regenerative braking recovered 172.0kJ of energy.
The MATLAB/ADAMS vehicle model offers a simulation platform that is modular, flexible, and
can be conveniently modified to create different types of vehicle models. In addition, the simulation
results clearly demonstrated the fuel economy advantage of the hybrid vehicle over the conventional
vehicle model.
It is recommended that a more sophisticated power management algorithm be
implemented in the model to optimize the efficiencies of the engine and the motor/generator.
Furthermore, it is suggested that the ADAMS vehicle model be validated against an actual vehicle, in
order to fully utilize the multi-body vehicle dynamics capability which ADAMS has to offer.
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Acknowledgements
First and foremost, I would like to express my sincere gratitude to my thesis supervisors, Dr. Amir
Khajepour in the department of Mechanical and Mechatronics Engineering, and Dr. Mehrdad
Kazerani in the department of Electrical and Computer Engineering, for their guidance and patience
throughout the completion of my degree. This thesis was completed on a part-time basis, and would
have never materialized without their continuous understanding and support.
I would also like to express my thanks to my past and current supervisors at General Dynamics Land
Systems
Canada, Mr. Phong Vo and Mr. Zeljko Knezevic, for their advice and encouragement in
pursuing my academic degree throughout the course of my employment, and to allow time taken off
during the day to return to campus, and to stay numerous late nights and weekends at the office.
In addition, I would like to thank my thesis readers, Dr. John McPhee in the department of Systems
Design Engineering, and Dr. Madgy Salama in the department of Electrical and Computer
Engineering, for their thorough review and various suggestions to improve the quality of my thesis.
Last but not least, I would like to thank my family, my parents Ellen and K.C., and my sister Sharon.
No words can express my utmost appreciation for their unconditional support, inspiration, and
motivation over the years of pursuing this degree.
v
Table of Contents
Chapter 1 Introduction...................................................................................... 1
Chapter 2 Literature Review and Background .............................................. 4
2.1 Series Hybrid ................................................................................................................................4
2.2 Parallel Hybrid..............................................................................................................................5
2.3 Existing Design.............................................................................................................................6
2.3.1 Toyota ....................................................................................................................................6
2.3.2 Honda...................................................................................................................................11
2.3.3 Nissan...................................................................................................................................13
2.4 Summary.....................................................................................................................................16
Chapter 3 Hybrid Vehicle Modeling .............................................................. 17
3.1 Overall Structure.........................................................................................................................17
3.2 Powertrain Components..............................................................................................................19
3.2.1 Engine ..................................................................................................................................19
3.2.2 Motor/Generator ..................................................................................................................21
3.2.3 Battery System .....................................................................................................................24
3.2.4 Transmission ........................................................................................................................24
3.3 Controller Logic..........................................................................................................................25
3.3.1 Driver Logic.........................................................................................................................25
3.3.2 Power Management Logic ...................................................................................................26
3.3.3 Mechanical Brake Logic ......................................................................................................28
3.4 Mechanical Components.............................................................................................................28
3.4.1 Vehicle Body .......................................................................................................................29
3.4.2 Operating Environment........................................................................................................29
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Chapter 4 Software Structure......................................................................... 30
4.1 MATLAB/Simulink Model ........................................................................................................30
4.1.1 Drive Cycle ..........................................................................................................................31
4.1.2 Driver Control......................................................................................................................31
4.1.3 Power Management Controller ............................................................................................32
4.1.4 Engine ..................................................................................................................................34
4.1.5 Motor/Generator ..................................................................................................................34
4.1.6 Transmission ........................................................................................................................36
4.1.7 Mechanical Brake ................................................................................................................36
4.1.8 Battery System .....................................................................................................................37
4.1.9 ADAMS Subsystem.............................................................................................................38
4.2 ADAMS Model...........................................................................................................................39
4.2.1 Vehicle Chassis....................................................................................................................40
4.2.2 Suspension ...........................................................................................................................40
4.2.3 Driveline ..............................................................................................................................41
4.2.4 Steering System ...................................................................................................................41
4.2.5 Mechanical Brakes...............................................................................................................42
4.2.6 Tires and Road .....................................................................................................................43
4.3 Co-Simulation.............................................................................................................................44
4.3.1 ADAMS Plant Export ..........................................................................................................44
4.3.2 ADAMS/Control in MATLAB............................................................................................46
4.4 Model Validation with ADVISOR .............................................................................................47
4.4.1 Model Setup .........................................................................................................................48
4.4.2 Results Comparison .............................................................................................................50
Chapter 5 Simulation Results and Efficiency Comparison ......................... 56
5.1 New York City Cycle (NYCC)...................................................................................................58
5.1.1 Driving Behaviour ...............................................................................................................58
5.1.2 Efficiency Comparison ........................................................................................................60
5.2 Highway Fuel Economy Cycle (HWFET)..................................................................................64
5.2.1 Driving Behaviour ...............................................................................................................64
5.2.2 Efficiency Comparison ........................................................................................................66
vii
5.3 Summary.....................................................................................................................................69
Chapter 6 Conclusions and Recommendations............................................. 70
Bibliography ..................................................................................................... 72
Appendix A Engine Data................................................................................. 74
Appendix B Motor/Generator Data ............................................................... 76
Appendix C Mechanical Components Mass Properties............................... 78
Appendix D Steering System Controller ADAMS Definitions .................... 79
Appendix E Tire Property Definition File ..................................................... 82
Appendix F Road Property Definition File ................................................... 85
Appendix G ADAMS/Control Plant Definition ............................................ 86
Appendix H ADAMS/Control MATLAB .m File ......................................... 87
viii
List of Figures
Figure 2-1: Schematic of a Series Hybrid Electric Vehicle [1] ..............................................................4
Figure 2-2: Schematic of a Parallel Hybrid Electric Vehicle [1] ............................................................5
Figure 2-3: Toyota Power Management Principle [3] ............................................................................7
Figure 2-4: Toyota Hybrid System Schematic [3] ..................................................................................8
Figure 2-5: Toyota Hybrid System-CVT Schematic [3].........................................................................9
Figure 2-6: Toyota Hybrid System-Mild Schematic [3].......................................................................10
Figure 2-7: Honda IMA Schematic [1].................................................................................................11
Figure 2-8: Honda Civic Hybrid Schematic [1]....................................................................................12
Figure 2-9: Comparison of Engine and Motor Performance Efficiencies [7].......................................14
Figure 2-10: Nissan Tino Propulsion System Schematics [7] ..............................................................15
Figure 3-1: Honda's Integrated Motor Assist Powertrain Structure [1] ................................................17
Figure 3-2: Overall Structure of the Hybrid Vehicle Model.................................................................18
Figure 3-3: Maximum Engine Torque [10] ..........................................................................................19
Figure 3-4: Closed Throttle Torque [10] ..............................................................................................20
Figure 3-5: Engine Fuel Consumption Rate Data Map [10].................................................................21
Figure 3-6: Maximum Motor Torque [11]............................................................................................22
Figure 3-7: Maximum Generator Torque [11]......................................................................................22
Figure 3-8: Motor/Generator Efficiency Map [11] ...............................................................................23
Figure 3-9: Percent Throttle Closed-Loop Proportional Controller......................................................26
Figure 3-10: Percent Braking Closed-Loop Proportional Controller....................................................26
Figure 3-11: Control Logic for Activating Mechanical Brakes ............................................................28
Figure 4-1: Overall Model Structure in MATLAB/Simulink...............................................................30
Figure 4-2: Drive Cycle Subsystem......................................................................................................31
Figure 4-3: Driver Controller Subsystem .............................................................................................32
Figure 4-4: Power Management Subsystem .........................................................................................33
Figure 4-5: Engine Subsystem..............................................................................................................34
Figure 4-6: Motor/Generator Subsystem ..............................................................................................35
Figure 4-7: Transmission Subsystem....................................................................................................36
Figure 4-8: Mechanical Brake Subsystem ............................................................................................37
Figure 4-9: Battery Subsystem .............................................................................................................38
Figure 4-10: ADAMS Subsystem.........................................................................................................38
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Figure 4-11: Mechanical Components of the Vehicle Model in ADAMS/View..................................39
Figure 4-12: Close Up View of the Front Suspension, Driveline and Steering System .......................40
Figure 4-13: Closed Loop Steering Controller .....................................................................................41
Figure 4-14: Mechanical Brake Torque Element in ADAMS ..............................................................43
Figure 4-15: Defining Front Left Tire Element in ADAMS.................................................................44
Figure 4-16: Defining Plant Export for ADAMS/Control ....................................................................45
Figure 4-17: Simulation Parameters for ADAMS/Control in MATLAB/Simulink .............................47
Figure 4-18: ADVISOR 2002 Startup Window....................................................................................48
Figure 4-19: West Virginia University 5 Peaks Drive Cycle................................................................49
Figure 4-20: WVU 5 Peaks Drive Cycle Vehicle Speed Comparison..................................................50
Figure 4-21: WVU 5 Peaks Drive Cycle Engine Speed Comparison...................................................51
Figure 4-22: WVU 5 Peaks Drive Cycle Engine Torque Comparison .................................................52
Figure 4-23: WVU 5 Peaks Drive Cycle Motor/Generator Torque Comparison .................................53
Figure 4-24: WVU 5 Peaks Drive Cycle Fuel Rate Comparison .........................................................54
Figure 4-25: WVU 5 Peaks Drive Cycle State of Charge Comparison ................................................55
Figure 5-1: EPA New York City Cycle (NYCC) Standard Drive Cycle..............................................57
Figure 5-2: EPA Highway Fuel Economy (HWFET) Standard Drive Cycle .......................................57
Figure 5-3: NYCC Hybrid and Conventional Vehicle Speed Comparison ..........................................58
Figure 5-4: NYCC Hybrid and Conventional Vehicle Throttle Percent Comparison ..........................59
Figure 5-5: NYCC Hybrid and Conventional Vehicle Braking Percent Comparison ..........................60
Figure 5-6: NYCC Hybrid and Conventional Vehicle Fuel Consumption Comparison ......................61
Figure 5-7: NYCC Hybrid and Conventional Vehicle Battery State of Charge Comparison ..............62
Figure 5-8: HWFET Hybrid and Conventional Vehicle Speed Comparison........................................64
Figure 5-9: HWFET Hybrid and Conventional Vehicle Throttle Percent Comparison........................65
Figure 5-10: HWFET Hybrid and Conventional Vehicle Braking Percent Comparison......................66
Figure 5-11: HWFET Hybrid and Conventional Vehicle Fuel Consumption Comparison..................67
Figure 5-12: HWFET Hybrid and Conventional Vehicle Battery State of Charge Comparison..........68
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List of Tables
Table 2-1: Toyota Prius THS Specification [2] .................................... Error! Bookmark not defined.
Table 2-2: Toyota Estima THS-C Specification [2] ...............................................................................9
Table 2-3: Toyota Crown THS-M Specification [4].............................................................................10
Table 2-4: Honda Civic Hybrid Powertrain Specification [1] ..............................................................13
Table 2-5: Nissan Tino Powertrain Specification [7] ...........................................................................15
Table 3-1: Transmission Gear Ratio and Corresponding Vehicle Speed [12]......................................25
Table 3-2: Control Logic for Activating Motor Assist Mode...............................................................27
Table 3-3: Control Logic for Activating Regenerative Braking Mode. Error! Bookmark not defined.
Table 5-1: NYCC Fuel Consumption Summary of the Hybrid and the Conventional Vehicle Model 61
Table 5-2: NYCC Electrical Energy Consumption Summary of the Hybrid Vehicle ..........................63
Table 5-3: NYCC Fuel Economy Summary of the Hybrid and the Conventional Vehicle Model.......63
Table 5-4: HWFET Fuel Consumption Summary of the Hybrid and the Conventional Vehicle Model
......................................................................................................................................................67
Table 5-5: HWFET Electrical Energy Consumption Summary of the Hybrid Vehicle .......................68
Table 5-6: HWFET Fuel Economy Summary of the Hybrid and the Conventional Vehicle Model....69
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Nomenclature
Tout
Motor torque output [Nm]
Pdesired
Desire motor power [W]
engine
Engine speed [rad/s]
Consumed or generated by the motor/generator [J]
Pmogen
Power consumed or generated by the motor/generator [W]
Pmax
Maximum power output available from the engine and the motor combined [W]
%throttle
Throttle input percent by the driver [W]
Fd
Vehicle drag force [N]
CD
Drag coefficient of the Honda Insight
A
Frontal area of the Honda Insight [m2]
air
Density of air [kg/m3]
vact
Actual vehicle velocity [m/s]
steeringoutput
Steering controller output signal [mm]
steeringdesired
Desired vehicle steering path in Y-coordinate [mm]
steeringactual
Actual vehicle steering path in Y-coordinate [mm]
steeringgain
Proportional steering closed loop controller gain value
Fuelequiv
Equivalent fuel amount of the motor/generator s electrical energy [L]
elec
Electrical Energy of the motor/Generator [J]
fuel
Density of gasoline [g/L]
lhvfuel
Lower heating value (does not contain water vapour energy) of gasoline [J/g]
xii
Chapter 1
Introduction
As the global economy strives towards clean energy in the face of climate change, the industrial
world is researching into alternative sources of energy. Since automobiles are currently a major
source of air pollution, governments and major automotive companies are collaborating to provide a
solution that will result in the reduction of vehicle emissions, while reducing the consumption of
fossil fuel.
Various forms of fossil fuel reduction methods and alternative power sources are
currently researched by different manufacturers. The two notable categories in research are internal
combustion (IC) engine vehicles and electric vehicles. Fuels presently utilized in internal combustion
engine vehicle include turbo or supercharging gasoline, diesel, methanol, and natural gas. The energy
path of the IC engine is to transform the energy content of various fuel sources into kinetic energy
that propels the vehicle forward. This is accomplished by using the expansion of burning fuel in a
chamber to provide a translational motion to propel the wheels. The advantage of IC engine is that
fuels with high-energy content can be transported easily, while the disadvantage is that the burning of
fuels creates emissions that are hazardous to the environment. Alternatively, the electric vehicle uses
electric energy from a battery or fuel cell, and converts it into kinetic energy via electric motors. The
advantage of an electric vehicle is that zero emissions are produced when the electric energy is
converted into kinetic energy. Various methods of providing electric energy are currently being
explored.
Conventional battery is one method of storing electric energy, although current
technologies prevent a working solution with reasonable vehicle mileage. Hydrogen fuel cell is an
alternative method of storing electrical energy; however, current technologies have not matured yet to
provide a safe storage of hydrogen.
In search for a working solution, a hybrid vehicle system which combines the advantages of both
power sources (IC engine and battery), was proposed. By definition, a hybrid vehicle is one that
employs two or more power sources to improve the overall efficiency of the vehicle. By combining
an internal combustion engine with an electric battery-motor system, the goal of fuel portability can
be solved. In addition to achieving low emission and fuel consumption requirement, hybrid electric
1
2
vehicle can recapture the otherwise lost kinetic energy during the braking cycle, thus further
improving the efficiency of the vehicle system. Hybrid vehicle systems can also be utilized for
military application. By using the electric power source during vehicle idling, minimal thermal
signature is released, thus lowering the chances of enemy detection.
In order to increase the efficiency and accuracy of automotive design, Computer Aided
Engineering (CAE) has been playing an ever increasing role throughout the process of vehicle design.
With the increase of computing power, manufacturers are now able to perform design, testing, and
optimization of a vehicle through computer simulation, all prior to the actual manufacturing of a
vehicle. Similar to other areas of automotive research such as vehicle dynamics and crash worthiness,
numerous software packages were developed in order to evaluate the energy efficiencies of the hybrid
electric vehicle. One particular example is a software originally developed by the U.S. Department of
Energy (DOE) and the National Renewable Energy Laboratory (NREL) called ADVISOR (Advanced
Vehicle Simulator), which was later acquired by AVL Powertrain Engineering, Inc. ADVISOR is a
software based on MATLAB/Simulink that can be used to simulate and analyze light and heavy
vehicles, including hybrid and fuel cell vehicles, where it allows the user to customize the power
components such as internal combustion engines and electric motors to study the effect on fuel
efficiency and vehicle performance.
The purpose of this thesis is to create a MATLAB/ADAMS hybrid vehicle model that
demonstrates the fuel efficiency advantage of a hybrid vehicle. Current hybrid vehicle simulation
software such as ADVISOR can only simulate vehicle performances from an energy standpoint and
does not consider the complexity of multi-body dynamics of a vehicle system. Similarly, vehicle
dynamics simulation software tends to focus on the dynamic performance of a vehicle, and does not
consider the energy efficiency of the vehicle s powertrain components. The MATLAB/ADAMS
simulation platform of this thesis will combine the capabilities of both fields to allow the user to
perform powertrain design studies on a hybrid electric vehicle in a multi-body dynamic environment.
The MATLAB/ADAMS simulation platform of this thesis consists of a simple hybrid electric
vehicle system based on the mechanical and powertrain components of the Honda Insight using its
IMA (Integrated Motor Assist) architecture, where the electric motor will act as an assisting device to
complement the engine. The Honda IMA system was chosen since it was the least complex of all
3
hybrid systems. The mechanical components of the vehicle body were created in MSC ADAMS,
while the power components and the power management logic were modeled in MATLAB/Simulink.
Chapter 2 will further discuss various configurations of hybrid electric vehicles, and also provide an
overview of existing hybrid vehicle designs available on the market. Chapter 3 will present the
overall structure of the hybrid vehicle and its components in detail. Chapter 4 will discuss the
software structure of the simulation platform used to simulate the hybrid vehicle. Comparison of
simulation results obtained from the MATLAB/ADAMS simulation platform and ADVISOR will be
presented. Chapter 5 will contain comparative analysis of hybrid and conventional vehicle simulation
based on the ADAMS/MATLAB vehicle model. City and highway standard drive cycles will be used
to simulate the performance and the fuel efficiency of the hybrid and conventional vehicles. Finally,
Chapter 6 will conclude the modeling and simulation of the MATLAB/ADAMS hybrid vehicle
model, and provide recommendations for further improvement of the vehicle system.
Chapter 2
Literature Review and Background
The most successful hybrid configuration currently utilized by various vehicle manufacturers consists
of a diesel or gasoline engine, coupled with a motor and a generator linked with a battery system.
Although there are many different hybrid configurations currently proposed by vehicle
manufacturers, most configurations can be categorized into two hybrid systems: Series Hybrid and
Parallel Hybrid.
2.1 Series Hybrid
In the series hybrid system, the IC engine drives the generator, and electricity is supplied to the
battery. The electrical energy from the battery is then received by the motor, which in turns drives
the wheels to propel the vehicle. Figure 2-1 illustrates the system configuration of a series hybrid
electric vehicle. [1]
Figure 2-1: Schematic of a Series Hybrid Electric Vehicle [1]
The advantage of the series hybrid is that the engine runs at its best efficiency, thus generating the
maximum electrical energy to charge the battery. Since the engine is constantly operating at its
optimum efficiency, and the vehicle receives its power solely from the electric motor, this system is
4
5
most efficient during the stop and go of city driving. In addition, the internal combustion engine of
the series hybrid vehicle can be replaced by a fuel cell, thus converting it into a pure electric vehicle.
The disadvantage of a series hybrid vehicle is that the efficiency of the system is reduced during
highway driving cycles. During highway driving, the engine has to convert fuel energy to electrical
energy, which will be converted again to kinetic energy to drive the wheels. Energy loses during
conversion in addition to lower torque output of the electric motor at high rotational speeds
contributes to the overall lower efficiency of the system.
2.2 Parallel Hybrid
The parallel hybrid configuration switches between the two power sources, i.e., the internal
combustion engine and the electric motor drive, where the high efficiency range of each is selected
and utilized. Depending on the situation, both power sources can also be used simultaneously to
achieve the maximum power output. Figure 2-2 shows the system configuration of a parallel hybrid
electric vehicle. [1]
Figure 2-2: Schematic of a Parallel Hybrid Electric Vehicle [1]
The advantage of a parallel hybrid vehicle is that the system has the ability to offer higher
efficiency during highway driving condition. During highway driving, the vehicle speed does not
vary significantly and therefore it is more efficient to drive the wheels directly from the IC engine. In
addition, the electric motor can be used solely during city driving while the IC engine recharges the
battery, thus providing higher overall efficiency. In addition, both power sources can be utilized
simultaneously to provide maximum performance of the vehicle.
6
2.3 Existing Design
Various automakers have successfully introduced hybrid electric vehicles into the automobile market.
The following sections describe the system configuration of the most popular hybrid vehicles that are
currently on the market.
2.3.1 Toyota
Toyota launched the Prius, the world s first mass-produced hybrid vehicle in 1997, and introduced the
vehicle to the US and Europe in 2000. The Estima and the Crown Mild hybrid vehicle were placed in
the Japanese market following the Prius. Currently, Toyota has over 100,000 hybrid vehicles in the
automotive market. Toyota has developed three different Hybrid systems for the vehicles: THS
(Toyota Hybrid System) for the Prius, THS-C (Toyota Hybrid System
THS-M (Toyota Hybrid System
CVT) for the Estima, and
Mild) for the Crown. [2, 3, 4, 5]
Energy Management Principle
Figure 2-3 shows the energy management principle of the Toyota hybrid vehicles. Due to the fact
that the engine has different energy conversion efficiencies at different points in the operating range,
a battery is used to store or supply energy to ensure maximum efficiency is achieved during a typical
drive cycle. When the vehicle accelerates, the additional energy is supplied from the battery, while
the engine runs in the optimum efficiency range to supply the power required by the load. During
cruising of the vehicle, the engine is still operating in the maximum efficiency range, and depending
on the demand, excess energy is stored back in the battery. Energy can be supplied from the battery if
the vehicle needs to operate at a higher load. Finally, during deceleration, the engine is turned off,
and the braking energy is recovered by a generator and is returned to the battery. This state of
operation is often referred to as regenerative braking. Depending on the state of the charge of the
battery, the engine can remain on to charge the battery while still regenerative braking is performed.
[3]
7
Figure 2-3: Toyota Power Management Principle [3]
THS (Prius) System
The Toyota Prius is the hybrid vehicle marketed by Toyota in the compact sedan segment. Figure 2-4
illustrates the schematic diagram while Table 2-1 summarizes the specification of the Prius THS.
This system is a combination of parallel and series hybrid system, thus achieving the advantages of
both systems. A gasoline engine and an electric motor are utilized as the power sources, with the
gasoline engine remains as the main power source. The power produced by the gasoline engine is
distributed to drive the wheels as well as the generator via a set of planetary gears. Depending on the
mode of operation, the engine power can be used to solely drive the wheels, be distributed between
the wheels and the generator, or be used solely to power the generator. The engine can also be
completely shut off if the battery is fully charged. The generated electric power can be used to drive
the motor, or is converted into direct current and stored in a high voltage battery. [3, 5]
8
Figure 2-4: Toyota Hybrid System Schematic [3]
Table 2-1: Toyota Prius THS Specification [2]
Curb Weight
1,220kg
Battery
21kW, 274V, 6.5Ah
Motor Generator
33kW
Engine Max Power
53kW @ 4500rpm
Engine Max Torque
115Nm @ 4200rpm
THS-C (Estima) System
The Toyota Estima Hybrid is the hybrid vehicle marketed by Toyota in the mini-van segment in
Japan. Figure 2-5 depicts the configuration while Table 2-2 summarizes the specification of the
Estima THS-C. This system is based on the THS (Prius) system with the addition of an electric
motor to power the rear wheels, thus creating a rear drive unit that is mechanically separated from the
front system, eliminating the need for transfers or propeller shafts. The result is the construction of a
4WD system that satisfies the demands of a mini-van.
The transaxle of the front drive unit
incorporates a CVT (Continuous Variable Transmission) that achieves excellent driving comfort with
smooth speed change. [2, 3]
9
Figure 2-5: Toyota Hybrid System-CVT Schematic [3]
Table 2-2: Toyota Estima THS-C Specification [2]
Curb Weight
1,850kg
Battery
216V, 6.5Ah
Front Motor Generator
13kW
Engine Max Power
96kW @ 4500rpm
Engine Max Torque
190Nm @ 4200rpm
Rear Motor Generator
18kW
THS-M (Crown) System
The Crown mild hybrid is a luxury sedan introduced in the Japanese market. The mild hybrid differs
from previous systems in that the motor-generator is not used to drive the wheels. Instead it is used to
power the auxiliary devices such as air conditioner and power steering, and is used to recover the
otherwise lost energy during deceleration during braking. In addition, it is also used to start the
engine during the idle stop operation. In order to maximize the fuel economy of the system, the
engine is turned off when the vehicle is at a stop. When the vehicle starts moving, the motor will
instantly start the engine, thus allowing the vehicle to start instantly. Figure 2-6 shows the schematic
of the THS-M system. The motor-generator in this system is connected to the engine via the engine
belt. The motor-generator is connected to the inverter unit, which is then connected to the batteries.
10
The 42-V power supply system was selected due to the fact that it not only meets the high power
requirement unique to the hybrid vehicle, but also the increasing electrical loads of existing vehicles.
In addition, since international standardization of the 42-V power supply system has been publicized
as the next generation power supply system, it is cost-efficient to incorporate the new system into the
hybrid components. [3, 4] Table 2-3 summarizes the motor-generator specification utilized on the
Crown mild hybrid vehicle [4].
Figure 2-6: Toyota Hybrid System-Mild Schematic [3]
Table 2-3: Toyota Crown THS-M Specification [4]
Motor Type
AC Synchronous Motor
Rated Voltage
36V
Power Rating
Drive
3.0kW
Generation
3.5kW
Maximum Torque
56.0Nm (0-300rpm)
Permissible Max. Speed
15,000rpm
Cooling Method
Air Cooling
11
2.3.2 Honda
Currently, Honda has two hybrid electric vehicles on the market: the Insight and the Civic Hybrid.
The Insight is a two door coupe that was introduced in 1999, and is the first vehicle to contain the
Honda IMA (Integrated Motor Assist) system. The Civic Hybrid was made available in 2002, and
has a modified IMA system that is fitted to the Civic s 5-passenger 4-door sedan body. The Insight
achieved a fuel consumption rate of 3.4L/100km, while the Civic Hybrid with the manual
transmission attained 5.1L/100km and 4.6L/100km in the city and on the highway respectively. [1, 6]
Integrated Motor Assist (IMA) System
The IMA system schematic is shown in Figure 2-7. In this system, a permanent magnet DC brushless
motor is placed with direct crankshaft connection between the engine and the transmission. The IMA
system uses the engine as the main power source, while the motor acts as an auxiliary power source
when accelerating. By using the motor as an auxiliary power source, the overall system is simplified,
and it is possible to use compact and light-weight motor, battery, and power control unit, thus
reducing the overall weight of the vehicle. [1]
Figure 2-7: Honda IMA Schematic [1]
Figure 2-8 illustrates the vehicle layout of the Civic Hybrid vehicle. The powertrain which
includes the engine, motor, and the transmission, is placed in the front of the vehicle. The Intelligent
Power Unit (IPU) along with the Power Control Unit (PCU) that controls the motor and the battery is
placed in the rear of the vehicle.
12
Figure 2-8: Honda Civic Hybrid Schematic [1]
System Description
Three techniques were employed to increase the overall efficiency of the system: [1]
1. Deceleration Energy Regeneration and Acceleration Assist
2. Idle Engine Stop
3. Reduction in Engine Displacement
Conventionally, kinetic energy is lost by braking and engine friction during deceleration. By utilizing
the motor as a generator, the otherwise lost energy can be recovered into useful electric energy, and
can be used during acceleration, thus increasing the efficiency. Secondly, by shutting off the engine
during vehicle idling, fuel is not consumed, therefore reducing unnecessary fuel consumption.
Finally, by having a motor for auxiliary power, it is possible to achieve the required dynamic
performance through the combination of the engine and the motor. Therefore, it is possible to reduce
the engine displacement, which further reduces the fuel consumption. Table 2-4 summarizes the
powertrain specification of the Honda Civic Hybrid. [1]
13
Table 2-4: Honda Civic Hybrid Powertrain Specification [1]
Engine
Transmission
Motor (Assist)
Motor (Regeneration)
Battery
Inline 4-cylinder 1.3 liter i-DSI lean-burn SOHC engine
Max Power (kW/rpm): 63/5700
Max Torque (Nm/rpm): 119/3300
Continuous Variable Transmission (CVT) or Manual Transmission
(MT)
DC Brushless Motor
Max Power: 10kW
Max Torque: 62Nm (Starter); 103Nm
Max Power: 12.3kW (MT), 12.6kW(CVT)
Max Torque: 108Nm
Nickel Metal Hydride (Ni-MH)
2.3.3 Nissan
Nissan developed the Tino hybrid electric vehicle which was launched in Japan in March 2000. The
development goal of the Tino hybrid is to achieve a fuel economy twice as good as that of the
conventional vehicle. The following measures were used by Nissan to achieve the reduction in fuel
consumption: [7]
Recover braking energy to store in the battery
Eliminate idling
Enhance engine efficiency and increase the frequency driven under such efficiency range
Drive with motor-generated power in low engine load ranges using the power recovered from
deceleration energy or generated under high engine efficiency ranges
The comparison of efficiency between the motor and the engine utilized by the Tino Hybrid is
shown in Figure 2-9.
14
Figure 2-9: Comparison of Engine and Motor Performance Efficiencies [7]
The yellow coloured region shown in Figure 2-9 depicts the higher efficiency areas for both the
engine and the motor, while the red coloured areas indicate the low efficiency region of the
components. It is shown the motor shows higher efficiency in most areas, while the engine has
significantly lower efficiency at the low-load range.
Efficiency of the motor was derived by
multiplying the charging and the discharging efficiencies of the battery. In hybrid electric vehicles,
the power generated by the engine in the high-efficiency range is used to charge the battery, and used
to drive the motor at low speed. The efficiency by the motor-powered driving will exceed that of the
engine-powered driving, thus increasing the overall vehicle efficiency. [7]
System Specification
The major components of the Tino hybrid propulsion system include: [7]
1. Two power sources: a gasoline engine and a traction motor for propulsion and energy
regeneration
2. A Continuous Variable Transmission (CVT)
3. An electromagnetic clutch for transmitting power
15
4. A motor for generating power and starting the engine
5. Batteries
A schematic of the Tino hybrid propulsion system is shown in Figure 2-10.
Figure 2-10: Nissan Tino Propulsion System Schematics [7]
As shown in Figure 2-10, the engine and the traction motor are placed upstream of the CVT such
that both can transmit power to the wheels directly. An electromagnetic clutch is placed between the
traction motor and the engine in order for the engine to be turned on or off independently. Power can
then be generated regardless of the driving condition. The generator, which is placed in front of the
engine, generates electric power and starts the engine as well. A lithium-ion battery was selected due
to its high efficiency even with repeated charging and discharging at high power. The specifications
of each component are summarized in Table 2-5. [7]
Table 2-5: Nissan Tino Powertrain Specification [7]
4-cylinder DOHC, 1.8L, 73 kW
Engine (Gasoline)
Continuously variable intake valve timing
Electronically controlled throttle
Transmission
Motor-integrated belt CVT with motor-driven oil pump
Traction Motor
Permanent magnetic synchronous motor 17kW
Generator
Permanent magnetic synchronous motor 13kW
Clutch
Electromagnetic Clutch
Battery
Li-ion battery with Mn electrode
16
2.4 Summary
Presently, two types of hybrid configurations have been proposed and utilized by various
manufacturers: Series and Parallel Hybrid. The series hybrid consists of a fuel converter that drives
the generator, in which electricity is supplied to the battery and the motor, which subsequently drives
the wheels. The parallel hybrid, on the other hand, switches between the two power sources, i.e., the
fuel converter and the electric motor drive, where the high efficiency range of each is selected and
utilized.
Notable current hybrid vehicle manufacturers are Toyota, Honda, and Nissan. Toyota and Nissan
both utilize a combination of parallel and series hybrid architecture on their vehicles, where during
city driving the system acts as a series hybrid, and switches to parallel hybrid during highway driving
or under hard acceleration. Honda, on the other hand, implements the Integrated Motor Assist (IMA)
system, where the engine drives the wheels at all time, while the electric motor provides additional
torque when required. The disadvantage of such system is that higher fuel economy would be seen
during city driving. All systems however, utilize regenerative braking to recapture the otherwise lost
kinetic energy during the braking cycle, thus further improving the efficiency of the vehicle system.
Chapter 3
Hybrid Vehicle Modeling
As previously mentioned, the hybrid vehicle modeled in this project was based on the specifications
of the Honda Insight hybrid vehicle s Integrated Motor Assist (IMA) structure. Since the actual
engineering data of the Insight was not available directly from Honda, it was decided to use the test
data included in ADVISOR, which was provided by the Argonne National Laboratory (ANL) [8, 10,
11, 12, 13, 15]. This chapter describes the overall structure of the hybrid vehicle model and its
components in detail.
3.1 Overall Structure
The Honda IMA structure utilizes a DC brushless permanent magnet electric motor that is directly
coupled with the engine crankshaft, and is placed in between the engine and the transmission. Figure
3-1 depicts the powertrain configuration of the IMA structure. [1]
Figure 3-1: Honda's Integrated Motor Assist Powertrain Structure [1]
The battery provides electric power to the motor and stores the electrical energy released by the
motor during regenerative braking, and is electrically connected to the motor via a Power Control
unit. During vehicle acceleration, the motor assists the engine by providing additional torque into the
transmission, and electrical energy is supplied from the battery to the motor. During the vehicle
17
18
deceleration, the motor acts as a generator and provides a resistive torque to the transmission while
slowing the vehicle. During the braking process, kinetic energy of the vehicle is converted into
electrical energy, which is then used to charge the battery. This process is commonly referred to as
regenerative braking.
Since conventional vehicles depend solely on mechanical brakes during
deceleration, the stored kinetic energy is converted into heat and lost. On the contrary, regenerative
braking captures the energy that would otherwise be lost, leading to an increase in the overall
efficiency of the vehicle. Hybrid vehicles however, are still equipped with mechanical brakes in the
case when higher braking torque is required.
The hybrid vehicle model in this project utilizes two softwares: MSC ADAMS and
MATLAB/Simulink. The mechanical components of the vehicle body are created in MSC ADAMS,
while powertrain components and power management logic are modeled in MATLAB/Simulink.
Figure 3-2 depicts the overall schematic of the system.
Figure 3-2: Overall Structure of the Hybrid Vehicle Model
19
The MATLAB/ADAMS hybrid vehicle model utilizes a driver input simulation, where the driver
control module compares the actual and the desired speed, and applies a throttle or a braking percent
to the powertrain components, which in turns applies the driving or the braking torque to the wheels.
Chapter 4 will discuss the software structure in further details.
3.2 Powertrain Components
3.2.1 Engine
The engine utilized in this model is the Honda Insight 1.0L VTEC-E SI Engine.
Several
characteristics such as Maximum Torque, Closed Throttle Torque, and Fuel Consumption Rate are
modeled in the engine as lookup tables [10]. Throttle percent and engine speed are inputs to the
engine model, which are used to calculate the corresponding output torque and fuel consumption rate.
Figure 3-3 and Figure 3-4 depict the maximum throttle torque and closed throttle torque, respectively.
100% Throttle Engine Torque
68
Engine Torque [lb-ft]
66
64
62
60
58
56
0
1000
2000
3000
4000
5000
Engine Speed [RPM]
Figure 3-3: Maximum Engine Torque [10]
6000
7000
20
Closed Throttle Torque
0
0
1000
2000
3000
4000
5000
6000
7000
-10
Engine Torque [lb-ft]
-20
-30
-40
-50
-60
-70
Engine Speed [RPM]
Figure 3-4: Closed Throttle Torque [10]
Maximum engine torque is the maximum amount of torque available when the throttle is wide open
at 100%, while the closed throttle torque is the engine resistive torque when the throttle is completely
closed. Closed throttle torque is the braking torque felt by the driver from the engine when the gas
pedal is completely released while the vehicle is coasting. The relationship between the throttle
percent and the maximum engine torque is assumed to be linear; thus, the actual output torque from
the engine is calculated by scaling the maximum engine torque at any given engine speed with the
throttle percent. The fuel consumption rate of the engine is subsequently calculated by interpolating
the fuel rate data map, using the current engine speed and the output engine torque. Figure 3-5
illustrates the fuel consumption rate data map indexed by the engine speed and the engine torque.
The engine data is included in Appendix A.
21
Engine Fuel Consumption Rate
4.5
4
3.5
3
2.5
Fuel Rate [g/s]
2
1.5
1
55.8
0.5
39.1
5527
4582
3636
22.3
2691
1745
800
0
5.6
Engine Torque [lb-ft]
Engine Speed [RPM]
Figure 3-5: Engine Fuel Consumption Rate Data Map [10]
3.2.2 Motor/Generator
The electric motor utilized in this project is a 10-kW DC brushless permanent magnet motor. The
unit also functions as a generator during regenerative braking mode. Similar to the engine, the
motor/generator is modeled using lookup tables, where the maximum torque of the motor/generator is
indexed by the shaft speed. In addition, the efficiency map of the motor/generator is modeled as a
three dimensional lookup up table indexed by the torque range and the shaft speed [11]. Since the
motor/generator shaft is coupled directly to the engine crankshaft, the speeds of the motor and engine
are equal at any given time. Figure 3-6 and Figure 3-7 depict maximum torques of the motor and
generator, respectively.
22
Maximum Motor Torque
50
45
40
Motor Torque [Nm]
35
30
25
20
15
10
5
0
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
8000
9000
Shaft Speed [RPM]
Figure 3-6: Maximum Motor Torque [11]
Maximum Generator Torque
0
0
1000
2000
3000
4000
5000
6000
7000
-5
Generator Torque [Nm]
-10
-15
-20
-25
-30
-35
-40
-45
-50
Shaft Speed [RPM]
Figure 3-7: Maximum Generator Torque [11]
It should be noted that the positive and negative signs of the motor/generator torque depict the
direction of the torque, where positive sign describes torque applied to the transmission from the
motor/generator, whereas negative torque signals the transmission is applying torque to the
23
motor/generator. During vehicle acceleration, the output torque of the motor is calculated based on
the desired power determined by the power management control and the current shaft speed, up to the
maximum available motor torque at the current speed. The output torque is calculated by the
following equation.
T
P
desired
(3.1)
out
engine
During regenerative braking mode, output torque is calculated based on the maximum generator
torque scaled by the brake percent received from the driver control logic.
As described earlier, the efficiency map is modeled as a look-up table indexed by the torque range
and shaft speed.
The power consumed and generated by the motor/generator is calculated by
multiplying the current torque and speed and scaling by the corresponding efficiency. The output
power value is then used to calculate the energy level of the battery system. Figure 3-8 illustrates the
efficiency map of the motor/generator. The motor/generator data are included in Appendix B.
Motor/Generator Efficiency Map
100
90
80
70
60
Efficiency [% ]
50
40
30
6000
4000
2000
43.5
0
Motor/Generator Torque [Nm]
28
16
0
-12
-24
-36
10
0
8000
20
Figure 3-8: Motor/Generator Efficiency Map [11]
Shaft Speed
[RPM]
24
3.2.3 Battery System
The battery of this vehicle system is modeled using simple energy calculations. At each time step, the
energy consumed or generated is governed by the following equation:
Pmogen dt
where
(3.2)
= Energy consumed or generated
Pmogen = Power consumed or generated
The energy consumed or generated by the motor/generator is calculated at each time step, and
would be added to or subtracted from the available energy in the previous time step. The new energy
value would then be stored in memory to be used for the next time step. The battery state of charge
(SOC) is calculated by dividing the current energy value by the maximum energy capacity of the
battery. An initial state of charge of the battery must be specified at the start of the simulation.
Several important assumptions were made to simplify the modeling of the battery. First, it was
assumed that the no-load voltage of the battery at various states of charge was constant. This
eliminates the need for look-up tables and simplifies the energy calculation. Second, it was assumed
that the internal resistance of the battery was zero, and the no-load voltage was equal to the rated
voltage. In reality, the internal resistance of the battery would be different during the charge and the
discharge cycle, and again varies depending on the state of charge of the battery. At this stage, a
simple energy storage system would suit the need of the battery system, and can be further refined if
necessary. The maximum energy capacity of the battery is calculated by multiplying the rated
capacity (6.5 Ah) and the rated voltage (144V) of the Insight s battery.
3.2.4 Transmission
This model is assumed to have a five-speed manual transmission, and is modeled using a look-up
table that defines the gear ratio based on the current vehicle speed. The overall ratio is the sum of the
transmission s gear ratio and the final drive ratio. The final drive ratio is a further gear reduction ratio
between the transmission and the wheels. Table 3-1 summarizes the transmission s gear ratio and the
corresponding vehicle speed. [12]
25
Table 3-1: Transmission Gear Ratio and Corresponding Vehicle Speed [12]
Gear Number
Gear Ratio
Vehicle Speed [km/h]
1
3.46
0 - 24
2
1.75
24 - 40
3
1.1
40 - 64
4
0.86
64 - 75
5
0.71
75+
Final Drive
3.21
The input torque to the transmission is the sum of the engine and the motor/generator torque, and
the output torque is applied to the wheels. The output torque is calculated by multiplying the input
torque and the overall ratio. The output shaft speed of the transmission will also be multiplied by the
overall ratio to calculate the input shaft s speed, which will be used as the speed of the engine and the
motor/generator.
3.3 Controller Logic
As previously mentioned, both driver logic and power management algorithms are modeled in
MATLAB/Simulink. This section describes the controller logic in details.
3.3.1 Driver Logic
The goal of the driver controller is to create a module that mimics the response of a real-life driver.
On real road, the driver decides the intended speed of the vehicle, and controls the throttle and the
brakes accordingly. If the driver wishes to accelerate the vehicle, one will press on the gas pedal as
hard or as light as is one s desire for acceleration. Similarly, one will press the brake pedal according
to how quickly or slowly one likes to decelerate. To model such behaviour, the driver controller
monitors the differences between the desired and the actual vehicle speeds, and the error value is fed
into a proportional controller. Two proportional controllers are used to generate the percent throttle
and the percent braking, as illustrated in Figure 3-9 and Figure 3-10, respectively.
26
Figure 3-9: Percent Throttle Closed-Loop Proportional Controller
Figure 3-10: Percent Braking Closed-Loop Proportional Controller
It should be noted that during vehicle braking, the desired vehicle speed will be lower than the
actual vehicle speed, and therefore it is necessary to negate the error signal in order to generate a
positive braking percent. Percent throttle is then used by the engine to output engine torque, and by
the power management controller to activate motor assist mode. Similarly, the percent braking is
outputted to the mechanical brake controller to activate the mechanical brakes, and to the power
management controller to activate the regenerative braking mode.
The benefit of modeling the driver controller logic as a separate module is that if desired,
hardware-in-the-loop interface can replace the proportional controller allowing the user to control the
throttle and braking directly in real time. For the scope of this project, the proportional controllers
will be used to model the driver s input.
3.3.2 Power Management Logic
The goal of the Power Management Controller is to control the power components to achieve the
desired vehicle power while increasing the vehicle s overall efficiency. Since the objective of the
software model is to provide an overall structure of a hybrid vehicle simulation platform, a simple
power management logic will satisfy the purpose of this project at the present time.
The simple power management logic deploys an intuitive approach where the desired power is in
direct relation with the driver s throttle input.
The desired power equals the maximum power
available multiplied by the percent throttle, where the maximum power available is assumed to be the
sum of the maximum power available from the engine and the electric motor. Thus at each time step:
Pdesired
Pmax %throttle
(3.3)
27
The purpose of the coupled motor/generator unit of this system is to provide motor assist during
acceleration and regenerative braking during deceleration. Therefore, it is desired that the motor
assists the acceleration when the total desired power is greater than the maximum power available
from the engine. It is arbitrarily assigned that the motor assist mode is activated when the percent
throttle is greater than 50%, while the regenerative braking mode is activated while the percent
braking is greater than 5%. Additionally, it was observed from testing that in ADVISOR, the motor
assist occurs only in second gear and above, and regenerative braking is activated only if the vehicle
speed is greater than 16 km/h (10mph). The control logics of the motor assist and regenerative
braking modes are summarized in Table 3-2 and Table 3-3 respectively.
Table 3-2: Control Logic for Activating Motor Assist Mode
Motor Assist Mode
Desired Power > Maximum Engine Power Available
Desired Speed > Actual Speed
Percent Throttle > 50%
Transmission Gear > 1
Table 3-3: Control Logic for Activating Regenerative Braking Mode
Regenerative Braking Mode
Desired Power < Maximum Engine Power Available
Desired Speed < Actual Speed
Percent Throttle = 0%
Percent Braking > 5%
Vehicle Speed > 16 km/h
The power management logic employed in this system is a simple and straight forward logic that
activates the motor assist mode during acceleration, and regenerative braking during deceleration.
Optimization of the power management logic is recommended for future work to improve the overall
vehicle efficiency.
28
3.3.3 Mechanical Brake Logic
As mentioned in the previous section, regenerative braking occurs only when the vehicle speed is
greater than 16 km/h. Therefore for vehicle speeds less than 16km/h, braking of the vehicle is solely
based on the mechanical brakes. In addition, to increase the amount of kinetic energy recovered
during regenerative braking, it is desired that the generator provides the majority of the braking
torque prior to the mechanical braking. It is therefore defined that the mechanical brakes are only
activated when the percent braking is greater than 90%. Figure 3-11 illustrates the control logic of
the mechanical brakes.
Figure 3-11: Control Logic for Activating Mechanical Brakes
The brake constant for this model is arbitrarily set as 200Nm, and can be modified if additional test
data are available. Modeling the mechanical brake interface with the wheels will be further discussed
in Chapter 4.
3.4 Mechanical Components
The mechanical components of the vehicle system are modeled in MSC ADAMS, where it performs
the vehicle dynamics analysis simulation.
This section will present a brief overview of the
mechanical components of the vehicle system, and detailed modeling description of the components
will be discussed in Chapter 4.
29
3.4.1 Vehicle Body
The vehicle body utilized in this model is a simple 4x2 Front Wheel Drive (FWD) vehicle with
McPherson suspensions for both front and rear axles. The vehicle assumes the characteristic of an
open differential, where the input torque to the differential is split equally between the left and the
right wheels. Drive torque and regenerative torque from the powertrain are applied to the input of the
differential, while mechanical braking torque is applied to the wheels individually. The speed of each
wheel is equal to the input speed to the differential. A simple rack and pinion steering system is used
to steer the front wheels, where a simple closed loop proportional controller maintains the vehicle in a
straight line. P165/65 R14 tires are used for both front and rear axles. [13]
3.4.2 Operating Environment
In reality, various factors of the environment such as road grade, surface condition, and wind forces
would affect the vehicle s overall operating efficiency. For the sake of simplicity and consistency in
order to study the efficiency of the hybrid vehicle, the vehicle is assumed to be operating in a perfect
environment, where the road is assumed to be perfectly flat with a friction coefficient of 1. In
addition, it is assumed that there is no additional wind force affecting the vehicle except for the drag
force due to the velocity of the vehicle. The drag force equation is given by equation 3.4. [14]
Fd
1
CD A
2
v
air act
2
(3.4)
The drag coefficient of the vehicle is assumed to be 0.25, and the frontal area of the vehicle is
assumed to be 1.9m2 [15].
Chapter 4
Software Structure
The hybrid vehicle model utilizes two simulation software packages: MATLAB/Simulink and MSC
ADAMS. As previously mentioned, the powertrain components and the control logics are modeled in
MATLAB/Simulink,
and
the
mechanical
components
are
modeled
in
MSC ADAMS.
ADAMS/Control module is used to provide the communication link for data transfer between the two
softwares. This Chapter will describe the software modeling in detail, and provide validation results
of the MATLAB/ADAMS model against the ADVISOR simulation data.
4.1 MATLAB/Simulink Model
The powertrain components and control logics are modeled in MATLAB/Simulink R2006a operating
on Windows XP Professional SP2.
Figure 4-1 depicts the overall structure of the
MATLAB/Simulink model.
Figure 4-1: Overall Model Structure in MATLAB/Simulink
30
31
The MATLAB model components are setup in the chronological order of data flow starting from
the left with the drive cycle data, ending to the right with the ADAMS model subsystem. Input data
ports of each component block are on the left hand side of the block, while the output data ports are
placed on the right of each block. The output data ports are then connected to the input ports of the
appropriate component block. This section will present each of the data blocks in details.
4.1.1 Drive Cycle
The drive cycle subsystem contains the time history data for the desired vehicle speed, where several
standard drive cycles are modeled as look-up tables. The block outputs the desired vehicle speed
based on the current simulation time. Figure 4-2 depicts the drive cycle subsystem.
Figure 4-2: Drive Cycle Subsystem
Details of the standard drive cycles used to perform simulations will be discussed in the results
section.
4.1.2 Driver Control
The purpose of the driver control subsystem is to mimic the driver s response in controlling the
vehicle. As mentioned in the previous Chapter, a simple closed-loop proportional controller is used
32
to simulate the percent throttle and the percent braking to the vehicle system. Figure 4-3 illustrates
the driver controller subsystem.
Figure 4-3: Driver Controller Subsystem
The input to the driver controller subsystem is the desired drive cycle speed and the actual vehicle
speed. The outputs of the subsystem are percent throttle, percent braking, and the velocity difference.
For modeling purposes, the vehicle is allowed to settle for two seconds prior to any throttle or braking
calculation. This is to allow the dynamic model in ADAMS to settle to its zero velocity state prior to
the actual driving of the vehicle.
In addition, the desired vehicle acceleration and speed are
monitored via two switches to ensure that the throttle output is zero when the vehicle slows down and
when it is stationary. Finally, the braking and throttle percent are both limited between zero and a
hundred percent via saturation function blocks.
4.1.3 Power Management Controller
The purpose of the power management controller subsystem is to implement the power management
logic discussed in section 3.3.2, and to turn the engine off when the vehicle is stationary. The
subsystem also calculates the net power requirement to the motor/generator, where a positive power
33
output value implies additional power is requested for the motor assist mode. Figure 4-4 depicts the
power management subsystem.
Figure 4-4: Power Management Subsystem
The desired power of the vehicle at any simulation time is the product of the maximum power
available and the percent throttle. The maximum power is modeled as a constant, and calculated by
summing the peak power output of the engine and the electric motor. The Boolean function blocks
perform the logic calculations for the motor and the generator as described in section 3.3.2, and
activates the motor and generator modes accordingly. If all Boolean logic is satisfied for the motor or
the generator, the AND gate outputs value 1 to activate the operating mode, and returns to zero to turn
the motor or the generator mode off. Finally, the engine switch monitors the drive cycle speed, and
switches the engine off if the vehicle is to be stationary.
34
4.1.4 Engine
The main function of the engine subsystem is to perform the engine output torque calculations based
on the current throttle percent and the engine speed. Open and closed throttle torque is modeled using
look-up tables indexed by the current engine speed. Figure 4-5 illustrates the engine subsystem
block.
Figure 4-5: Engine Subsystem
In addition to outputting the engine torque, the engine subsystem also calculates the maximum
engine power available and the engine s fuel consumption. The maximum engine power available is
the product of the current engine speed and the maximum engine torque.
The engine fuel
consumption rate is modeled using a look-up table indexed by the current engine speed and torque.
The fuel consumption rate is then integrated to calculate the total fuel consumed.
4.1.5 Motor/Generator
Similar to the engine model, the motor/generator output torque is modeled using look-up tables
indexed by the shaft speed. Since the motor/generator shaft is directly coupled with the engine shaft,
35
the shaft speed of the motor/generator equals that of the engine.
Figure 4-6 illustrates the
motor/generator subsystem block.
Figure 4-6: Motor/Generator Subsystem
The power management controller decides whether the motor/generator subsystem performs as a
motor or as a generator. During motor assist mode, the motor mode signal becomes 1. The power
output of the motor is decided by the required power calculation which is performed by the power
management controller. In the case where the required power exceeds the maximum power available
from the motor, the maximum power available is outputted from the motor. During the regenerative
braking mode, the braking torque is the product of the maximum available braking torque of the
generator and the percent braking from the driver. Finally, similar to the engine fuel consumption
calculation, the motor efficiency is modeled using a look-up table indexed by the shaft speed and
torque. The consumed or generated power is subsequently outputted to the battery to perform energy
calculations.
36
4.1.6 Transmission
The transmission utilized in this model is a five-speed manual transmission. A simple logic is used
for gear shifting, where the gear ratio is determined by the actual vehicle speed. Figure 4-7 depicts
the transmission subsystem.
Figure 4-7: Transmission Subsystem
A look-up table is used to output gear ratio indexed by the vehicle speed, and is multiplied with the
sum of engine and motor/generator torque to calculate the final driveshaft torque to ADAMS.
Similarly, the driveshaft speed from ADAMS is multiplied by the gear ratio to determine the engine
speed. Finally, the engine idle speed is defined as a constant at 900 RPM, where the driveshaft would
be decoupled from the engine if the driveshaft speed falls below the engine idle speed. Similarly, the
transmission would be disconnected from the engine if the engine is turned off.
4.1.7 Mechanical Brake
As mentioned in section 3.3.3, the mechanical brakes supply the entire vehicle braking torque when
the vehicle speed is less than 16 km/h, while acting as supplementary braking torque to the
regenerative braking when the vehicle speed is higher than 16km/h.
mechanical brakes subsystem.
Figure 4-8 illustrates the
37
Figure 4-8: Mechanical Brake Subsystem
A switch is used to activate the mechanical brake torque, which is determined by the mechanical
brake logic. Once active, the actual mechanical braking output torque is the product of the maximum
braking torque and the percent braking. The maximum braking torque currently is arbitrarily set to
200Nm, and can be further modified if test data is available.
4.1.8 Battery System
The battery system in this model utilized a simple energy calculation, where the generated or
consumed power is integrated over time to calculate the energy level in the battery. The initial energy
level and State of Charge (SOC) of the battery is defined at the beginning of the simulation and
subsequently updated based on the power consumption or generation of the motor/generator
throughout the simulation. Figure 4-9 depicts the battery subsystem in the MATLAB/Simulink
model.
38
Figure 4-9: Battery Subsystem
4.1.9 ADAMS Subsystem
The ADAMS subsystem block is the standard ADAMS/Control subsystem that is required for
MATLAB/Simulink to communicate with ADAMS. The input and output variables of the ADAMS
subsystem are defined within ADAMS, and will be further discussed in detail later in the chapter.
Figure 4-10 illustrates the ADAMS subsystem block.
Figure 4-10: ADAMS Subsystem
39
4.2 ADAMS Model
The mechanical components of the hybrid vehicle system are modeled in MSC ADAMS/View 2005a
operating on Windows XP SP2. The vehicle model includes vehicle chassis, suspension, driveline,
steering linkages and control, brakes, and tires. The mechanical components are assumed to be rigid
bodies, with the exception of the suspension and tires. Figure 4-11 shows an isometric view of the
vehicle model in ADAMS/View.
Figure 4-11: Mechanical Components of the Vehicle Model in ADAMS/View
As shown in the diagram, the global sign convention used in this model assumes that positive x
points rearwards of the vehicle, positive y points towards the right, and positive z points upwards. As
a result, gravity defaults to the negative z-direction. The mass and the inertia properties of the
mechanical components are summarized in Appendix C. The following sections will discuss the
aforementioned components in detail.
40
4.2.1 Vehicle Chassis
The vehicle body is modeled using a simple rigid body mass, connects to the suspension at the control
arms (A-Frame) via revolute joints, and to the upper struts through spherical joints. The driveshaft
connects to the vehicle chassis via a revolute joint, while the steering rack connects to the chassis via
a translational joint. Details of the vehicle mechanical subsystem will be further discussed in the
subsequent sections. Figure 4-12 depicts the front suspension, the driveline, and the steering system
in ADAMS.
Suspension
Driveline
Steering
Figure 4-12: Close Up View of the Front Suspension, Driveline and Steering System
A single component force is used to model the drag force due to vehicle velocity as depicted by
equation (3.4), and is applied opposite to the vehicle velocity at the vehicle s center of gravity.
4.2.2 Suspension
The suspension utilized in this model is a simple McPherson suspension, which includes a control
arm, a lower strut, and an upper strut. As mentioned earlier, the control arm and the upper strut are
connected to the vehicle body via a revolute joint and a spherical joint, respectively. The lower strut
is connected to the control arm through a spherical joint, and connected to the upper strut via a
41
translational joint. Finally, the tire is connected to the lower strut through a revolute joint. For
steering purposes, spherical joints at the upper_strut-chassis and the lower_strut-control_arm
locations allow rotation of the struts about the z-axis. The steering motion of the suspension is
controlled via the tie rod, where it is connected to the lower strut via a spherical joint. The rear
suspension is essentially the same as the front suspension, with the only difference being a revolute
joint used at the upper strut-chassis location to restrict the rotational movement about the z axis.
4.2.3 Driveline
A simple driveline system is created to drive the front wheels. As depicted in Figure 4-12, a
driveshaft is created and attached to the vehicle body via a revolute joint. A set of couplers are
created that constrains the rotation of the wheels to the rotation of the driveshaft. This is achieved by
creating a coupler constraint that linked the revolute joint of the driveshaft and the tires together.
Since the final drive ratio is modeled in the transmission model in MATLAB/Simulink, the ratio of
the couplers is assumed to be 1. A single component torque is created at the driveshaft, where the
action body is the driveshaft, and the reaction body is the vehicle body. The magnitude of the drive
torque is the state variable drive_torque , which is used to receive the driveline torque value from
MATLAB.
4.2.4 Steering System
A rack and pinion steering system is utilized in the vehicle model. However, due to the requirement
of this project, the steering wheel and the subsequent pinion gears are not actually modeled. It is
sufficient at this stage to only model the actual movement of the steering rack and tie rods. As
mentioned earlier, the steering rack is connected to the vehicle chassis to allow the rack to move in
the y-direction with respect to the chassis. A set of tie rods are connected to either end of the rack via
spherical joints. To steer the vehicle, a closed loop position controller is used to control the lateral
movement of the steering rack, which in turn steers the wheels accordingly. Figure 4-13 illustrates
the simple closed loop controller of the steering system.
Figure 4-13: Closed Loop Steering Controller
42
The closed loop position controller is created using ADAMS built-in controls toolkit, where the
input and the output variables are defined. For the purpose of this project, it is only required for the
vehicle to maintain a straight path along the x-axis, thus the desired vehicle coordinate is set to y = 0.
The following equation defines the steering input and output of the steering controller.
Steeringouptut
( Steeringdesired
Steeringactual ) Steering gain
(4.1)
To control the movement of the steering rack, a general motion is applied to constrain the steering
rack in the local y-direction with respect to the vehicle chassis, where the actual value of the general
motion is defined by the steering output variable. The variables of the steering controller used in the
ADAMS controls toolkit as well as the general motion definition are included in Appendix D.
4.2.5 Mechanical Brakes
The mechanical brakes are defined as a single-component torque element applied at each wheel. It is
assumed that the actual torque values of each wheel are equal, and are received from the
MATLAB/Simulink s mechanical brake logic via ADAMS/Control.
Detailed description of
ADAMS/Control will be discussed later in the chapter, and the mechanical brake torque element in
ADAMS is illustrated in Figure 4-14.
43
Figure 4-14: Mechanical Brake Torque Element in ADAMS
4.2.6 Tires and Road
Various tire modules are available in ADAMS, where different tire modules can be used for different
purposes, such as handling, durability, two dimensional, or three dimensional roads.
More
information of the different tire modules available in ADAMS can be found in the ADAMS/Tire
documentation [9]. For the purpose of this model, where the vehicle travels straight on a flat ground,
it is decided the durability tire model on a 2D road will satisfy the purpose of this vehicle model. A
Pacejka 94 tire model is used to simulate the P165/65 R14 tire utilized by the Honda Insight. The tire
and road interface is created through the ADAMS tire element as shown in Figure 4-15.
44
Figure 4-15: Defining Front Left Tire Element in ADAMS
To define all four tires, it is necessary to create the tire elements at each of the four tire locations
while referencing the same tire and road property file. The tire and road property files are attached in
Appendix E and Appendix F, respectively.
4.3 Co-Simulation
In order to interface ADAMS and MATLAB via ADAMS/Control, a series of steps are necessary to
invoke ADAMS/Controls and to ensure a proper co-simulation between the two softwares.
ADAMS/Control is accessed through ADAMS/View, where a set of files are generated for
communicating with MATLAB. To perform a simulation, the files created by ADAMS must first be
called in MATLAB.
Once the simulation command is executed in MATLAB or Simulink,
ADAMS/Control will then activate ADAMS/Solver to perform the co-simulation.
4.3.1 ADAMS Plant Export
To perform an ADAMS/Controls Simulation, the ADAMS model that contain a set of state variables,
which specifies the input and the output parameters from MATLAB, must first be created. To invoke
ADAMS/Controls, the controls plug-in must be loaded in ADAMS in order to export the plant
45
systems to MATLAB. Plant input and output variables are created where plant input specifies the
input state variables of the system, while the plant output variable specifies the output variable, or the
sensor variable that will be monitored in MATLAB. Figure 4-16 illustrates the plant export window
for ADAMS/Control.
Figure 4-16: Defining Plant Export for ADAMS/Control
Plant input defines the input variables into the ADAMS model from MATLAB, and vice versa for
plant output definition. For the hybrid vehicle model, the MATLAB control logic computes the
driveshaft torque and the mechanical brake torque for the vehicle; therefore, the driveshaft torque and
the mechanical brake torques are defined as plant input variables in ADAMS/Control. Similarly,
ADAMS outputs the vehicle s current state for MATLAB to perform control logic calculation; thus,
the vehicle speed and the driveshaft speed are defined as plant output variables in ADAMS/Control.
The plant input and output definitions are attached in Appendix G.
Once the plant input and output variables have been specified, exporting the plant will generate .m,
.adm, and .cmd files. The .m file is the initialization file that must be executed in MATLAB, where
the ADAMS setup parameter would be read into the MATLAB workspace memory. The .adm file is
the ADAMS solver dataset file used by the solver when performing simulations in the ADAMS
46
solver mode, while the .cmd is the command file that would be used to solve the model in the
interactive mode. The difference between the two modes is that the solver mode performs the
simulation without updating the graphical interface at each time step, while the interactive mode
provides the user a visual update at each time step.
To save time and computing power, the
simulations for the hybrid vehicle model are executed in the solver mode.
4.3.2 ADAMS/Control in MATLAB
Once the input and output plants have been exported, the next step is to call the .m file in MATLAB,
which will define the necessary variables in order to execute the ADAMS solver. The .m file for the
hybrid vehicle model is attached in Appendix H. Once the .m file is executed in MATLAB, a
subsystem named ADAMS_sys will be created, and will contain a subsystem block as described in
section. 4.1.9, which is needed to establish the connectivity between the MATLAB/Simulink model
and ADAMS vehicle model. Figure 4-17 depicts the simulation parameters for ADAMS/Control in
MATLAB/Simulink.
47
Figure 4-17: Simulation Parameters for ADAMS/Control in MATLAB/Simulink
To perform an analysis, simulation command is executed in Simulink, in which ADAMS/Controls
will invoke the ADAMS/Solver to perform co-simulation with MATLAB, completing the process.
4.4 Model Validation with ADVISOR
ADVISOR (ADvanced VehIcle SimulatOR), a software originally developed by the U.S. Department
of Energy (DOE) and the National Renewable Energy Laboratory (NREL), is based on
MATLAB/Simulink that can be used to simulate and analyse light and heavy vehicles, including
hybrid and fuel cell vehicles, where it allows the user to perform rapid analysis of the performance
and fuel economy of conventional, electric, and hybrid vehicles [8].
Initially developed as a
48
shareware, where it allowed free download for industries, it has since been commercialized by AVL
Powertrain Engineering, Inc., in 2003. The ADVISOR version used for comparison purpose in this
thesis was ADVISOR 2002, which is the shareware version prior to its commercialization by AVL.
ADVISOR was initially developed as an analysis tool, rather than a detailed design tool. Its
components are created as a quasi-static model; therefore, it cannot be used to perform dynamic
analysis. ADVISOR utilizes a backwards facing vehicle simulation architecture, where it uses the
required/desired speeds as inputs, and determines what drivetrain torque, speed, and power would be
required to meet that vehicle speed. For more information on ADVISOR, refer to the documentation
help file of the software. [8] Figure 4-18 depicts the startup window of the ADVISOR 2002 in
MATLAB/Simulink.
Figure 4-18: ADVISOR 2002 Startup Window
This section will provide a result comparison between the MATLAB/ADAMS hybrid vehicle
model and ADVISOR. A standard drive cycle and common powertrain components will be used for
the two models, and the simulation results of various components will be presented.
4.4.1 Model Setup
As mentioned previously, the major difference between ADVISOR and the MATLAB/ADAMS
model is that ADVISOR utilizes backwards-facing vehicle simulation architecture, while the
49
MATLAB/ADAMS model performs a forwards-facing vehicle simulation. For comparative purpose,
common drive cycle and component characteristic are used for the ADVISOR and the
MATLAB/ADAMS models.
The standard drive cycle used for the simulation is the West Virginia University (WVU) Five
Peaks drive cycle, where the vehicle is accelerated to a constant speed from standstill, and decelerated
back to stationary.
The cycle is repeated five times at increasing constant speed.
The
MATLAB/ADAMS hybrid vehicle model utilizes the power management control logic where the
motor assist is active when the throttle percent is over 50%, and the regenerative braking occurs when
the braking percent is 5% and over. Figure 4-19 illustrates the time history of the WVU 5 Peaks drive
cycle.
West Virginia University 5 Peaks Drive Cycle
45
40
Vehicle Speed [MPH]
35
30
25
20
15
10
5
0
0
100
200
300
400
500
600
700
800
Time [sec]
Figure 4-19: West Virginia University 5 Peaks Drive Cycle
900
50
4.4.2 Results Comparison
The MATLAB/ADAMS hybrid vehicle model simulation was performed for 850 seconds over the
West Virginia University 5 Peaks drive cycle, and the results are as follows.
Vehicle Speed
The actual vehicle speeds of both models are presented in Figure 4-20. There is a close match
between the results, as expected.
Vehicle Speed Comparison - WVU 5 Peaks Drive Cycle
MATLAB/ADAMS (50%-5%)
Advisor
70
60
Speed [km/h]
50
40
30
20
10
0
0
100
200
300
400
500
600
700
800
900
Time [sec]
Figure 4-20: WVU 5 Peaks Drive Cycle Vehicle Speed Comparison
Engine Speed
Figure 4-21 depicts the engine speed of the two models. The overall results match very closely. Since
both vehicles have manual transmission, and the vehicle speeds of the two models match, it should be
expected for the engine speed to correlate well. However, it is observed that during the acceleration
phase, the engine speeds of the two models differ. The main difference is due to the transmission
modeling. MATLAB/ADAMS utilizes a simple gear change logic and the gear number is dependent
51
on the vehicle speed. However, in ADVISOR, a clutch logic is implemented and it seems that during
every up-shift, the engine is accelerated to an unusually high speed. This does not seem to be
reasonable, and therefore is disregarded in validating the MATLAB/ADAMS vehicle model.
Engine Speed Comparison - WVU 5 Peaks Drive Cycle
7000
MATLAB/ADAMS (50%-5%)
Advisor
Engine Speed [RPM]
6000
5000
4000
3000
2000
1000
0
0
100
200
300
400
500
600
700
800
900
Time [sec]
Figure 4-21: WVU 5 Peaks Drive Cycle Engine Speed Comparison
Engine Torque
Figure 4-22 depicts the engine torque comparison of the two models and, as seen, the trends match
very closely. However, it is noted that there are several differences between the magnitudes of the
engine torque, specifically during the closed throttle (negative) torque region. During deceleration,
both models calculate the negative torque from the engine due to the closed throttle characteristic of
the engine. However, it is noted that when the vehicle is stationary, the engine model in ADVISOR
still exhibits a negative engine torque value, while the engine torque of the MATLAB/ADAMS
model returns to zero. Since both models turn the engine off when the vehicle is stationary, such that
there is no engine idling when the vehicle is stopped, it is not possible for the engine to output any
torque values. It seems that in ADVISOR, when the vehicle is stopped and the engine is shut off, the
52
engine still outputs a closed throttle torque at the engine idle speed. It is concluded that this might be
due to a modeling glitch in ADVISOR, and thus, can be disregarded in the validation of the
MATLAB/ADAMS model.
Engine Torque Comparison - WVU 5 Peaks Drive Cycle
100
MATLAB/ADAMS (50%-5%)
Advisor
80
Torque [Nm]
60
40
20
0
0
100
200
300
400
500
600
700
-20
Time [sec]
Figure 4-22: WVU 5 Peaks Drive Cycle Engine Torque Comparison
800
900
53
Motor/Generator Torque
The motor/generator torques of ADVISOR and MATLAB/ADAMS vehicle models are included in
Figure 4-23. The torque results from the two models matched reasonably well. However, the
ADVISOR model exhibited some motor torque spikes just when the vehicle comes to a rest,
especially around 453 seconds.
Again, this is disregarded when compared with the
MATLAB/ADAMS vehicle model.
Motor/Generator Torque Comparison - WVU 5 Peaks Drive Cycle
60
40
Torque [Nm]
20
0
0
100
200
300
400
500
600
700
800
900
-20
-40
MATLAB/ADAMS (50%-5%)
-60
Time [sec]
Advisor
Figure 4-23: WVU 5 Peaks Drive Cycle Motor/Generator Torque Comparison
Fuel Consumption Rate
Figure 4-24 depicts a comparison of the engine fuel consumptions of the two models. Similar to the
engine speed curve in Figure 4-21, ADVISOR exhibits values higher than that of MATLAB/ADAMS
model at the beginning of each acceleration cycle. Such phenomenon is again due to the high engine
speed during the clutch logic of ADVISOR, and therefore can be disregarded. Other than the initial
spikes, the fuel rate results for the two models matched reasonably well.
54
Fuel Rate Comparison - WVU 5 Peaks Drive Cycle
MATLAB/ADAMS (50%-5%)
4
Advisor
3.5
Fuel Rate [g/s]
3
2.5
2
1.5
1
0.5
0
0
100
200
300
400
500
600
700
800
900
Time [sec]
Figure 4-24: WVU 5 Peaks Drive Cycle Fuel Rate Comparison
Battery State of Charge (SOC)
Figure 4-25 illustrates the state of charge (SOC) of the battery system of the two models. The overall
trend of the energy consumption and generation of the two models matches reasonably well.
However, since the battery model used in the MATLAB/ADAMS model utilizes a simple energy
calculation for the battery, some discrepancies existed between the magnitudes of the results.
However, since the magnitude differences are within 2% of the overall SOC, the MATLAB/ADAMS
battery model is considered satisfactory for the purpose of this thesis. Detailed battery modeling can
be further implemented should the user require it.
55
State of Charge Comparison - WVU 5 Peaks Drive Cycle
70
69
68
67
SOC [%]
66
65
64
63
MATLAB/ADAMS (50%-5%)
62
Advisor
61
60
0
100
200
300
400
500
600
700
800
900
Time [sec]
Figure 4-25: WVU 5 Peaks Drive Cycle State of Charge Comparison
Results Conclusion
It is concluded that the MATLAB/ADAMS hybrid vehicle results matched very well with the
ADVISOR data. The overall torque values of the engine and the motor/generator system correlated
well between the two models, for the exception of a few torque spikes from the ADVISOR motor
torque and the negative engine torque while the vehicle is stationary. The vehicle speeds and the
engine speeds of the two models also compared well, with the exception that ADVISOR implemented
a clutch logic causing the engine speed to increase to an unusually high value, in turn causing the fuel
consumption rate to increase. The negative torque during engine shut off and the high engine speed
during acceleration of the ADVISOR model both seem unreasonable, and are therefore disregarded
for the purpose of comparative evaluation of the MATLAB/ADAMS model. Finally, since the
battery model utilized in the MATLAB/ADAMS model is based on a simple energy calculation, it is
recommended that further work be performed to increase the accuracy of the battery model should the
user require it.
Chapter 5
Simulation Results and Efficiency Comparison
The purpose of a hybrid vehicle is to provide better fuel efficiency over a conventional vehicle. As
shown in the previous chapter, the MATLAB/ADAMS hybrid vehicle model provided results that
correlated well with the published ADVISOR simulation data. Using a validated vehicle model, it is
essential to show that the hybrid vehicle model indeed provides better fuel efficiency over a
conventional vehicle. The purpose of this chapter is to provide an efficiency performance comparison
of the MATLAB/ADAMS hybrid vehicle over a conventional vehicle.
The conventional vehicle model will be based on the same hybrid vehicle model developed for this
thesis, but without the motor assist and the regenerative braking.
It is also assumed that the
conventional vehicle is 100kg1 less than the hybrid vehicle. The vehicle performance of the hybrid
and the conventional vehicle models will be compared over the same standard drive cycles. Two
standard U.S. EPA (Environmental Protection Agency) drive cycles will be used to simulate city and
highway driving. The EPA NYCC (New York City Cycle) will be used to simulate the city driving,
while the EPA HWFET (Highway Fuel Economy Cycle) will be used to determine the highway fuel
economy. Figure 5-1 and Figure 5-2 depict the NYCC and the HWFET standard drive cycles.
1
Assumed mass of the motor/generator and batteries, based on the mass difference of the conventional and
hybrid model of the Honda Civic [17, 18]
56
57
EPA New York City Cycle
50
45
Vehicle Speed [km/h]
40
35
30
25
20
15
10
5
0
0
100
200
300
400
500
600
Time [sec]
Figure 5-1: EPA New York City Cycle (NYCC) Standard Drive Cycle
EPA Highway Fuel Economy Cycle
120
Vehicle Speed [km/h]
100
80
60
40
20
0
0
100
200
300
400
500
600
700
Time [sec]
Figure 5-2: EPA Highway Fuel Economy (HWFET) Standard Drive Cycle
800
58
5.1 New York City Cycle (NYCC)
As previously mentioned, the New York City Cycle is used to simulate city driving. Figure 5-3
depicts the results of comparison between the hybrid and the conventional vehicle models.
Actual Vehicle Speeds
Conventional Vehicle
Hybrid Vehicle
50
NYCC Drive Cycle
45
40
Vehicle Speed [km/h]
35
30
25
20
15
10
5
0
0
100
200
300
400
500
600
-5
Tim e [sec]
Figure 5-3: NYCC Hybrid and Conventional Vehicle Speed Comparison
It can be seen that both the hybrid and the conventional vehicle model followed the desired drive
cycle speed very well. The actual driving behaviour of the vehicle and the efficiency comparison will
be presented in the subsequent sections.
5.1.1 Driving Behaviour
In order for the vehicle to achieve the desired speed profile, the driver control logic applies the
appropriate percent throttle and braking accordingly. Since the conventional vehicle model does not
utilizes motor assist and regenerative braking, only the engine torque and the mechanical brakes are
available throughout the drive cycle. Figure 5-4 and Figure 5-5 depict, respectively, the throttle and
braking percent comparison throughout the New York City Cycle.
59
Throttle %
Conventional
Hybrid
100
90
80
70
Percent
60
50
40
30
20
10
0
0
100
200
300
400
500
600
Tim e [sec]
Figure 5-4: NYCC Hybrid and Conventional Vehicle Throttle Percent Comparison
As illustrated in Figure 5-4, the conventional vehicle model applied more throttle than the hybrid
vehicle model, which is logical since the conventional vehicle does not have the additional motor
torque of the hybrid vehicle, and thus additional engine torque is required for the vehicle to achieve
the desired speed.
Figure 5-5 depicts the braking percent of the hybrid and the conventional vehicle models
throughout the NYC cycle. Similar to the throttle percent, the conventional vehicle model applied
more braking percent than the hybrid vehicle model. Since the conventional vehicle does not have
regenerative braking available, higher braking percent is required from the mechanical brakes to
decelerate the vehicle.
60
Braking %
Conventional
Hybrid
100
90
80
70
Percent
60
50
40
30
20
10
0
0
100
200
300
400
500
600
Tim e [sec]
Figure 5-5: NYCC Hybrid and Conventional Vehicle Braking Percent Comparison
5.1.2 Efficiency Comparison
To demonstrate the advantages of a hybrid vehicle over a conventional vehicle, it is essential to
analyze the energy consumptions of the vehicle. The fuel and the electrical energy consumption of
the hybrid and the conventional vehicles will be presented in this section.
Figure 5-6 depicts the fuel consumptions of the hybrid and the conventional vehicle models over
the NYC cycle. As expected, the total amount of fuel consumed by the conventional vehicle is higher
than that of the hybrid vehicle.
61
Fuel Consumption
0.16
0.14
0.12
Volume [L]
0.1
0.08
0.06
Conventional
Hybrid
0.04
0.02
0
0
100
200
300
400
500
600
Tim e [sec]
Figure 5-6: NYCC Hybrid and Conventional Vehicle Fuel Consumption Comparison
Table 5-1 summarizes the actual fuel consumption comparison of the conventional and the hybrid
vehicle models.
Table 5-1: NYCC Fuel Consumption Summary of the Hybrid and the Conventional Vehicle
Model
Vehicle Model
Fuel Consumption [L]
Distance Traveled [km]
Conventional
0.13609
1.89
Hybrid
0.12464
1.89
62
Figure 5-7 illustrates the battery state of charge of the hybrid vehicle throughout the drive cycle.
Due to the stop and go nature of city driving, the regenerative braking of the hybrid vehicle was able
to recover the kinetic energy, which would otherwise be lost to the mechanical brakes, back into
electrical energy to recharge the battery. The recovered electrical energy can then be used to provide
additional power to the motor during the assist mode, and further reduce the amount of fuel
consumed. The process of recovering lost kinetic energy into electrical energy for later use is
essentially the major advantage of a hybrid vehicle over a conventional vehicle.
Battery SOC
70.6
70.4
State of Charge [%]
70.2
70
69.8
69.6
69.4
Hybrid
69.2
-100
0
100
200
300
400
500
600
700
Tim e [sec]
Figure 5-7: NYCC Hybrid and Conventional Vehicle Battery State of Charge Comparison
To understand the amount of energy savings provided by the hybrid vehicle model from a different
perspective, the energy consumed or generated can be used to calculate an equivalent fuel amount
using the following equation.
63
Fuelequiv
elec
fuel
where
Fuelequiv
(5.1)
lhv fuel
= Equivalent fuel of the motor/generator s electrical energy [L]
= Electrical energy of the motor/generator [J]
elec
fuel
lhv fuel
= Density of gasoline [g/L]
= Lower heating value (does not contain water vapour energy) of
gasoline [J/g]
The following table summarizes the electrical energy consumption and its equivalent fuel amount
for the hybrid vehicle.
Table 5-2: NYCC Electrical Energy Consumption Summary of the Hybrid Vehicle
Electrical Energy [kJ]
Equivalent Fuel [L]
Energy Consumed
83.61
2.620e-3
Energy Generated
105.49
3.306e-3
By combining the equivalent fuel consumption of the motor/generator with the actual fuel usage of
the hybrid vehicle as indicated in Table 5-1, the overall fuel economy of the hybrid vehicle can be
calculated. The following table summarizes the fuel economy of the conventional and the hybrid
vehicle over the NYCC drive cycle.
Table 5-3: NYCC Fuel Economy Summary of the Hybrid and the Conventional Vehicle Model
Vehicle Model
Fuel Consumption [L]
Distance Traveled [km]
Fuel Economy [L/100km]
Conventional
0.1361
1.89
7.20
Hybrid
0.1246
1.89
6.56
% Difference
-8.92%
-8.92%
It should be noted that since the actual ADAMS vehicle model and the power management logic of
the MATLAB/ADAMS hybrid vehicle model are not validated against the Honda Insight, the fuel
64
economy stated in Table 5-3 may differ from the published value of 3.9L/100km [16] from the
manufacturer.
5.2 Highway Fuel Economy Cycle (HWFET)
The Highway Fuel Economy Cycle as previously mentioned is used to simulate highway driving.
Figure 5-8 depicts the comparison results between the hybrid and the conventional vehicle model.
Actual Vehicle Speeds
Conventional Vehicle
Hybrid Vehicle
100
HWFET Drive Cycle
90
80
Vehicle Speed [km/h]
70
60
50
40
30
20
10
0
0
100
200
300
400
500
600
700
800
Tim e [sec]
Figure 5-8: HWFET Hybrid and Conventional Vehicle Speed Comparison
Similar to the city driving of the NYCC, it can be seen that both the hybrid and the conventional
vehicle model followed the desired drive cycle speed very well. The actual driving behaviour of the
vehicle and the efficiency comparison will be presented in the subsequent sections.
5.2.1 Driving Behaviour
Similar to section 5.1.1, Figure 5-9 and Figure 5-10 depict, respectively, the throttle and brake percent
comparisons throughout the highway fuel economy cycle.
65
Throttle %
Conventional
Hybrid
100
90
80
70
Percent
60
50
40
30
20
10
0
0
100
200
300
400
500
600
700
800
Tim e [sec]
Figure 5-9: HWFET Hybrid and Conventional Vehicle Throttle Percent Comparison
As illustrated in Figure 5-9, it is shown that the conventional vehicle model applied significantly
more throttle than the hybrid vehicle model, especially past the 50% throttle threshold. Since the
power management logic of the hybrid vehicle depicts the motor to assist the engine when the throttle
percent is over 50%, it is not surprising that the hybrid vehicle s throttle percent is maintained around
50% during highway cruising.
However, due to the lack of additional motor torque in the
conventional vehicle, a higher throttle percent is needed to output the required engine torque in order
to maintain the highway cruising speed.
Figure 5-10 depicts the braking percent of the hybrid and the conventional vehicle models
throughout the highway drive cycle.
Again, since the conventional vehicle does not have
regenerative braking available, higher brake percent is required from the mechanical brakes to output
the same amount of braking torque. However, due to the nature of highway driving, the brakes were
not engaged as frequently as in the case of the New York City Cycle.
66
Braking %
Conventional
Hybrid
100
90
80
70
Percent
60
50
40
30
20
10
0
0
100
200
300
400
500
600
700
800
Tim e [sec]
Figure 5-10: HWFET Hybrid and Conventional Vehicle Braking Percent Comparison
5.2.2 Efficiency Comparison
Similar to the city driving results comparison, the fuel and the electrical energy consumption of the
hybrid and the conventional vehicles will be presented in this section.
Figure 5-11 depicts the fuel consumption of the hybrid and the conventional vehicle models over
the highway fuel economy drive cycle. As expected, the total amount of fuel consumed by the
conventional vehicle is higher than that of the hybrid vehicle.
67
Fuel Consumption
0.5
0.45
0.4
0.35
Volume [L]
0.3
0.25
0.2
0.15
0.1
Conventional
0.05
Hybrid
0
0
100
200
300
400
500
600
700
800
Tim e [sec]
Figure 5-11: HWFET Hybrid and Conventional Vehicle Fuel Consumption Comparison
Table 5-4 summarizes the actual fuel consumption comparison of the conventional and the hybrid
vehicle models.
Table 5-4: HWFET Fuel Consumption Summary of the Hybrid and the Conventional Vehicle
Model
Vehicle Model
Fuel Consumption [L]
Distance Traveled [km]
Conventional
0.4423
16.45
Hybrid
0.3779
16.45
Figure 5-12 illustrates the battery state of charge of the hybrid vehicle throughout the drive cycle.
As discussed in section 5.2.1, due to the nature of highway driving, the brakes were not engaged as
frequently as in city driving, and therefore less electrical energy was recovered. As a result of the
68
motor assisting the engine primarily to maintain highway cruising speed, a higher net energy was
consumed in the highway driving when compared to the city driving cycle.
Battery SOC
71.5
71
70.5
Available Energy [kJ]
70
69.5
69
68.5
68
67.5
67
Hybrid
66.5
0
100
200
300
400
500
600
700
800
Tim e [sec]
Figure 5-12: HWFET Hybrid and Conventional Vehicle Battery State of Charge Comparison
Using equation (5.1), Table 5-5 summarizes the electrical energy consumption and its equivalent
fuel amount of the hybrid vehicle.
Table 5-5: HWFET Electrical Energy Consumption Summary of the Hybrid Vehicle
Electrical Energy [kJ]
Equivalent Fuel [L]
Energy Consumed
213.56
6.69e-3
Energy Generated
171.99
5.39e-3
Again, by combining the equivalent fuel consumption of the motor/generator with the actual fuel
usage of the hybrid vehicle as indicated in Table 5-4, the overall fuel economy of the hybrid vehicle
can be calculated. The following table summarizes the fuel economy of the conventional and the
hybrid vehicle over the HWFET drive cycle.
69
Table 5-6: HWFET Fuel Economy Summary of the Hybrid and the Conventional Vehicle
Model
Vehicle Model
Fuel Consumption [L]
Distance Traveled [km]
Fuel Economy [L/100km]
Conventional
0.4423
16.45
2.69
Hybrid
0.3792
16.45
2.31
% Difference
-14.27%
-14.27%
Again, it should be noted that since the ADAMS vehicle model and the power management logic
of the MATLAB/ADAMS hybrid vehicle model are not validated against the Honda Insight;
therefore, the fuel economy stated in Table 5-6 differs from the published value of 3.2L/100km [16]
from the manufacturer.
5.3 Summary
It is shown that simulations of the hybrid and the conventional vehicles are successfully performed
over the EPA New York City Cycle (NYCC) and the Highway Fuel Economy Cycle (HWFET). It is
found that the hybrid vehicle model demonstrated 8.92% and 14.27% fuel economy improvement
over the conventional vehicle model for the NYCC and HWFET drive cycles, respectively. Due to
the stop and go nature of the city driving, it is demonstrated that the regenerative braking recovered
sufficient kinetic energy to recharge the battery for motor assist. The motor assist consumed 83.61kJ
while the regenerative braking recovered 105.49kJ of electrical energy during the city driving. On the
other hand, less energy is recovered during the highway driving due to the less frequent braking
throughout the drive cycle. The motor assist consumed 213.56kJ while the regenerative braking
recovered 171.99kJ of electrical energy throughout the highway drive cycle.
Chapter 6
Conclusions and Recommendations
The MATLAB/ADAMS hybrid vehicle model was successfully created based on the Honda
Integrated Motor Assist (IMA) architecture. The energy components and the vehicle controllers were
created in MATLAB/Simulink, while the vehicle body and its inertial components were created in
MSC ADAMS. The powertrain components utilized in the hybrid vehicle model were based on the
Honda Insight s 1.0L VTEC-SI engine and the 10kW DC brushless permanent magnet motor. Test
data of both the engine and the motor/generator were published by the Argonne National Laboratory
(ANL), and were used in the MATLAB/ADAMS hybrid vehicle model.
The hybrid vehicle model utilized a driver input architecture, where a driver controller compares
the desired and actual vehicle speeds, and outputs throttle or braking percent to the powertrain, which
in turn provides a drive torque to the vehicle driveshaft. Communication between the powertrain and
the mechanical components was established by ADAMS/Control. To evaluate the accuracy of the
MATLAB/ADAMS hybrid vehicle model against the published ADVISOR results, the West Virginia
University (WVU) 5 Peaks drive cycle was used.
There was a close match between the
MATLAB/ADAMS and the ADVISOR vehicle models for the engine and the motor/generator.
Minor discrepancies existed where the engine speed of ADVISOR reached an unusually high value
during each gear change, and thus directly affected the fuel consumption rate of the engine. In
addition, the magnitude of the battery state of charge (SOC) comparison curve exhibited some
differences due to the fact that the MATLAB/ADAMS model was based on a simple energy
calculation. However, since the trend of the battery SOC curve matched very well, and that the
magnitude difference was relatively small, it was concluded that the MATLAB/ADAMS hybrid
vehicle model correlated well with the published results of ADVISOR.
In order to demonstrate the fuel efficiency advantages of the hybrid vehicle over the conventional
vehicle, a comparison study was performed over standard city and highway drive cycles. The EPA
standard New York City Cycle (NYCC) and the Highway Fuel Efficiency Cycle (HWFET)
simulations were performed on both the hybrid and the conventional vehicle models. The hybrid
vehicle model demonstrated 8.9% and 14.3% fuel economy improvement over the conventional
70
71
vehicle model for the NYCC and HWFET drive cycles, respectively. Since the Honda Insight is a
form of parallel hybrid vehicle, the result is consistent with the consensus that parallel hybrid vehicles
are more energy efficient during highway driving than city driving over series hybrid vehicles. In
addition, due to the stop and go nature of the city driving, it was demonstrated that the regenerative
braking recovered sufficient kinetic energy to recharge the battery for motor assist. The motor assist
consumed 83.6kJ while the regenerative braking recovered 105.5kJ of electrical energy during the
city driving. On the other hand, less energy was recovered during the highway driving due to the less
frequent braking throughout the drive cycle.
The motor assist consumed 213.6kJ while the
regenerative braking recovered 172.0kJ of electrical energy throughout the highway drive cycle.
The MATLAB/ADAMS hybrid vehicle model offers a simulation platform that is modular,
flexible, and can be easily modified for different types of vehicle model. In addition, the simulation
results clearly demonstrated the fuel economy advantage of the hybrid vehicle over the conventional
vehicle. However, additional work is recommended to further optimize the efficiency of the power
management controller. Since the current power management controller utilizes a simple motor assist
and regenerative braking logic, it is recommended that a more sophisticated power management
controller be implemented to optimize the efficiencies of the engine and the motor/generator.
Furthermore, it is recommended that the mechanical portion of the vehicle system be validated
against an actual vehicle, in order to fully utilize the multi-body vehicle dynamics that the ADAMS
has to offer.
Bibliography
[1]
H. Ogawa, M. Matsuki, and T. Eguchi: Development of a Power Train for the Hybrid
Automobile
[2]
The Civic Hybrid , SAE Paper, No. 2003-01-0083
T. Ozeki and M. Umeyama: Development of Toyota s Transaxle for Mini-van Hybrid
Vehicles , SAE Paper, No. 2002-01-0931
[3]
M. Takimoto: Experience and Perspective of Hybrids , SAE Paper, No. 2002-21-0068
[4]
K. Itagaki, T. Teratani, Kuramochi, S. Nakanura, T. Tachibana, H. Nakao, and Y. Kamijo:
Development of the Toyota Mild-Hybrid System (THS-M) , SAE Paper, No. 2002-01-0990
[5]
T. Inoue, M. Kusada, H. Kanai, S. Hino, and Y. Hyodo: Improvement of a Highly Efficient
Hybrid Vehicle and Integrating Super Low Emissions , SAE Paper, No. 2000-01-2930
[6]
K. Aoki, S. Kuroda, S. Kajiwara, H. Sao, and Y. Yamamoto: Development of Integrated
Motor Assist Hybrid System: Development of the Insight , a personal Hybrid Coupe , SAE
Paper, No. 2000-01-2216
[7]
I. Matsuo, T. Miyamoto, and H. Maeda: The Nissan Hybrid Vehicle , SAE Paper, No. 200001-1568
[8]
A. Brooker, K. Haraldsson, T. Hendricks, V. Johnson, K. Kelly, B. Kramer, T. Markel, M.
O Keefe, S. Sprik, K. Wipke, M. Zolot: ADVISOR Documentation , National Renewable
Energy Laboratory, install_dir\ADVISOR2002\documentation\advisor_doc.htm
[9]
MSC Software Corporation: ADAMS/Tire Help Documentation , MSC Software Corporation,
install_dir\MSC.Software\MSC.ADAMS\2005\help\tire\tire_home.htm
[10] K. Kelly: ADVISOR Data File: FC_INSIGHT.m , National Renewable Energy Laboratory,
install_dir\ADVISOR2002\data\fuel_converter\FC_INSIGHT.m
[11] K. Kelly: ADVISOR Data File: MC_INSIGHT_draft% , National Renewable Energy
Laboratory, install_dir\ADVISOR2002\data\motor\MC_INSIGHT_draft.m
72
73
[12] M. Cuddy: ADVISOR Data File: TC_INSIGHT.m , National Renewable Energy Laboratory,
install_dir\ADVISOR2002\data\transmission\TC_INSIGHT.m
[13] K. Kelly: ADVISOR Data File: WH_INSIGHT.m , National Renewable Energy Laboratory,
install_dir\ADVISOR2002\data\wheel\WH_INSIGHT.m
[14] B. Munson, D. Young, T. Okiishi, 1998: Fundamentals of Fluid Mechanics. 3rd ed , John
Wiley & Sons, INC.
[15] K. Kelly: ADVISOR Data File: VEH_INSIGHT.m , National Renewable Energy Laboratory,
install_dir\ADVISOR2002\data\vehicle\VEH_INSIGHT.m
[16] Honda Insight Specification, www.canadiandriver.com
2001 Honda Insight Test Drive
http://www.canadiandriver.com/testdrives/01insight.htm
[17] Honda Civic Hybrid Specification, www.honda.ca
2007 Honda Civic Hybrid Specification
http://www.honda.ca/HondaCA2006/Models/CivicHybrid/2007/Specs?L=E
[18] Honda Civic Sedan Specification, www.honda.ca
2007 Honda Civic Sedan Specification
http://www.honda.ca/HondaCA2006/Models/CivicSedan/2007/Specs?L=E
Appendix A
Engine Data
Maximum Engine Torque
Engine Speed [RPM]
800
1273
1745
2218
2691
3164
3636
4109
4582
5055
5527
6000
100% Throttle Engine Torque [lb-ft]
56.9
58.2
59.5
60.7
62
63.2
64.5
65.7
67
64.3
61.5
58.6
Closed Throttle Engine Torque
Engine Speed [RPM]
800
1273
1745
2218
2691
3164
3636
4109
4582
5055
5527
6000
100% Throttle Engine Torque [lb-ft]
-5.15
-8.58
-12.29
-16.28
-20.57
-25.13
-29.97
-35.11
-40.52
-46.23
-52.2
-58.47
74
75
Fuel Consumption Rate [g/s] Data Map
Engine Torque [lbs]
5.6
11.2
16.8
22.3
27.9
33.5
39.1
44.7
50.3
55.8
61.4
67
800
0.0962
0.142
0.1871
0.2371
0.2953
0.3656
0.4521
0.5591
0.7038
0.868
1.0663
1.3032
1273
0.1269
0.1909
0.2541
0.3223
0.3987
0.4871
0.5918
0.7169
0.8993
1.0863
1.3087
1.5709
1745
0.1576
0.2398
0.3212
0.4075
0.502
0.6086
0.7314
0.8747
1.1014
1.3123
1.5596
1.8484
2218
0.1883
0.2887
0.3882
0.4927
0.6053
0.7301
0.8711
1.0325
1.3102
1.5458
1.8193
2.1357
Engine Speed [RPM]
2691
3164
3636
4109
0.2191 0.2498 0.2805 0.3112
0.3375 0.3864 0.4353 0.4842
0.4552 0.5223 0.5893 0.6563
0.5779 0.663 0.7482 0.8334
0.7087 0.812 0.9154 1.0187
0.8516 0.9731 1.0946 1.216
1.0107 1.1504
1.29
1.4297
1.1903 1.3481 1.5059 1.6637
1.5255 1.7475 1.976 2.2112
1.7869 2.0356 2.2919 2.5558
2.0877 2.3647 2.6504 2.9448
2.433 2.7402 3.0572 3.3841
4582
0.361
0.5584
0.7533
0.9524
1.1591
1.3777
1.6124
2.0304
2.453
2.8272
3.2479
3.7208
5055
0.4566
0.7129
0.9683
1.2297
1.5012
1.7875
2.0936
2.4249
2.7014
3.1063
3.5596
4.0675
5527
0.4641
0.7383
1.0215
1.3207
1.6278
1.9363
2.2647
2.6182
2.9563
3.393
3.8801
4.2459
6000
0.4641
0.7383
1.0215
1.3207
1.6399
1.9839
2.3577
2.7666
3.2156
3.5433
3.883
4.2459
Appendix B
Motor/Generator Data
Maximum Motor and Generator Torque
Shaft Speed [RPM]
0
500
1000
1500
2000
2500
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
Maximum Motor Torque [Nm]
46.5
46.5
46.5
46.5
46.5
38.2
27.3
23.9
21.2
19.1
17.4
15.9
14.7
13.6
12.7
11.9
11.2
76
Maximum Generator Torque [Nm]
-46.5
-46.5
-46.5
-46.5
-46.5
-38.2
-27.3
-23.9
-21.2
-19.1
-17.4
-15.9
-14.7
-13.6
-12.7
-11.9
-11.2
77
Motor/Generator Efficiency [%] Map
Motor/Generator Torque [Nm]
-4
0
4
8
16
Speed [RPM]
-36
-32
-28
-24
-20
-16
-12
-8
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
54.17
56.09
59.74
62.16
64.71
64.88
66.49
68.3
63.07
63.07
87.76
84.71
79.49
54.17
56.09
59.74
62.16
64.71
64.88
66.49
68.3
63.07
63.07
87.76
84.71
70
71.77
75.2
78.37
80.62
82.73
84.62
85.31
80.23
80.23
85.98
86.96
79.08
80.25
82.73
84.76
86.91
87.56
87.27
87.2
80.24
80.24
87.45
83.36
84.27
86.74
88.36
89.34
90.2
90.39
89.14
81.05
81.05
86.38
87.62
88.89
90.36
90.71
91.07
91.08
89.2
83.52
83.52
90.83
90.83
91.04
91.41
92.6
91.95
92.22
90.68
84.9
92.78
92.78
92.78
92.78
93.06
93.1
92.21
91.79
84.92
93.49
93.49
93.49
93.49
93.49
93.74
93.45
91.19
86.24
94.37
94.37
94.37
94.37
94.37
94.24
93.97
91.8
85.7
95.03
95.03
95.03
95.03
95.03
94.26
94.29
91.51
94.75
94.75
94.75
94.75
94.75
94.75
93.06
94.07
94.07
94.07
94.07
94.07
94.07
93.27
93.84
93.84
93.84
93.84
93.84
93.84
93.05
93.05
93.05
93.05
93.05
93.05
92.12
92.12
92.12
92.12
92.12
92.12
91.27
91.27
91.27
91.27
91.27
91.27
90.47
90.47
90.47
90.47
90.47
90.47
20
24
28
78.1
76.56
75.09
79.49
78.1
76.56
87.34
86.64
85.45
88.53
89.23
89.37
90.54
90.31
90.33
88.41
91.83
91.51
84.9
90.61
91.38
84.92
90.37
92.79
86.24
93.14
85.7
90.78
82.22
82.22
90.49
81.37
89.98
80.69
92.95
89.38
93.05
89.16
92.12
91.27
90.47
87.8
32
36
43.5
46.5
73.9
71.33
63.88
59.75
75.09
73.9
71.33
63.88
59.75
84.73
84.03
83.26
80.81
77.35
88.36
88.08
87.98
87.33
85.65
82.47
90.42
90.38
90.13
89.86
89.38
87.95
87.25
91.56
91.43
91.28
91.02
91.23
90.67
90.67
92.36
92.29
92.35
92.16
92.12
93.52
93.61
93.61
93.59
94.31
94.42
94.68
95.24
95.42
95.42
95.42
94.56
95.69
95.67
96.02
96.07
95.88
95.88
95.88
95.88
93.73
96
96.13
96.39
96.23
96.23
96.23
96.23
96.23
89.23
93
95.29
96.05
96.05
96.05
96.05
96.05
96.05
96.05
81.37
87.75
92.89
95.47
95.83
95.83
95.83
95.83
95.83
95.83
95.83
80.69
86.69
92.47
95.18
95.4
95.4
95.4
95.4
95.4
95.4
95.4
79.83
79.83
86
92.05
95.06
95.48
95.48
95.48
95.48
95.48
95.48
95.48
78.99
78.99
85
91.13
94.5
94.7
94.7
94.7
94.7
94.7
94.7
94.7
88.9
77.41
77.41
84.26
90.75
94.21
94.21
94.21
94.21
94.21
94.21
94.21
94.21
88.14
76.08
76.08
82.89
90.31
93.49
93.49
93.49
93.49
93.49
93.49
93.49
93.49
75.97
75.97
82.22
89.96
93.17
93.17
93.17
93.17
93.17
93.17
93.17
93.17
Appendix C
Mechanical Components Mass Properties
Component
Mass [kg]
Ixx [kg-mm]
Iyy [kg-mm]
Izz [kg-mm]
Vehicle System
1498.89
2.95815E+009
9.15079E+009
7.25796E+009
Vehicle Chassis
1143
2.83059E+009
7.71304E+009
5.77436E+009
20
1.43460E+007
2.30495E+008
2.40485E+008
Control Arm (each)
18.72
4.17384E+006
1.29802E+007
1.30713E+007
Upper Strut (each)
6.62
4.96956E+006
6.93284E+006
5.68370E+006
Lower Strut (each)
18.58
9.02080E+006
1.26049E+007
1.58652E+007
Steering Rack
9.08
1.30545E+006
2.10352E+006
1.43088E+006
Tie Rod (each)
1.54
4.41253E+005
4.57350E+005
5.61937E+005
Hybrid Components2
100
n/a
n/a
n/a
Tire (each)
X-direction: towards the rear of the vehicle
Y-direction: towards the passenger side of the vehicle
Z-direction: upwards of the vehicle (opposite of gravity)
2
Assumed mass of the motor/generator and batteries, based on the mass difference of the conventional and
hybrid model of the Honda Civic [17, 18]
78
Appendix D
Steering System Controller ADAMS Definitions
Steering Rack General Motion
Object Name
Object Type
Parent Type
Location
Orientation
: .vehicle_new.general_motion_3
: general_motion
: Model
: 0.0, 0.0, 0.0 mm, mm, mm
: 0.0, 0.0, 0.0 deg
General Parameters:
i_marker
(MARKER_195 (MARKER_195))
j_marker
(MARKER_196 (MARKER_196))
constraint
(JOINT_24 (JOINT_24))
t1_type
(0)
t2_type
(0)
t3_type
(1)
r1_type
(0)
r2_type
(0)
r3_type
(0)
t1_func
(0 * time)
t2_func
(0 * time)
t3_func
(step(time, 1, 0, 2, .vehicle_new.steering_gain.steering_gain))
r1_func
(0 * time)
r2_func
(0 * time)
r3_func
(0 * time)
t1_ic_disp
(0.0)
t2_ic_disp
(0.0)
t3_ic_disp
(0.0)
r1_ic_disp
(0.0)
r2_ic_disp
(0.0)
r3_ic_disp
(0.0)
t1_ic_velo
(0.0)
79
80
t2_ic_velo
t3_ic_velo
r1_ic_velo
r2_ic_velo
r3_ic_velo
(0.0)
(0.0)
(0.0)
(0.0)
(0.0)
Input Parameters: None
Output Parameters: None
Steering Desired Variable
Object Name : .vehicle_new.steering_d.steering_d_input
Object Type
: ADAMS_Variable
Parent Type
: controls_input
Adams ID
: 129
Active
: NO_OPINION
Initial Condition : 0.0
Function
:0
Steering Actual Variable
Object Name : .vehicle_new.steering_a.steering_a_input
Object Type
: ADAMS_Variable
Parent Type
: controls_input
Adams ID
: 131
Active
: NO_OPINION
Initial Condition : 0.0
Function
: DY(mar1)
81
Steering Difference Variable
Object Name
Object Type
Parent Type
Location
Orientation
: .vehicle_new.steering_diff
: controls_sum
: Model
: 0.0, 0.0, 0.0 mm, mm, mm
: 0.0, 0.0, 0.0 deg
General Parameters:
input_obj
(.vehicle_new.steering_d, .vehicle_new.steering_a)
gain1 (1.0)
gain2 (1.0)
Input Parameters: None
Output Parameters: None
Steering Gain Variable
Object Name : .vehicle_new.steering_gain.steering_gain_input
Object Type
: ADAMS_Variable
Parent Type
: controls_gain
Adams ID
: 136
Active
: NO_OPINION
Initial Condition : 0.0
Function
: steering_diff.steering_diff
Appendix E
Tire Property Definition File
!:FILE_TYPE:
tir
!:FILE_VERSION: 2
!:TIRE_VERSION: PAC94
!:COMMENT:
New File Format v2.1
!:FILE_FORMAT: ASCII
!:TIMESTAMP:
1996/02/15,13:22:12
!:USER:
ncos
$--------------------------------------------------------------------------units
[UNITS]
LENGTH
= 'inch'
FORCE
= 'pound_force'
ANGLE
= 'radians'
MASS
= 'pound_mass'
TIME
= 'second'
$-------------------------------------------------------------------------model
[MODEL]
!
use mode 1
2
3
4
!
------------------------------------------!
smoothing
X
X
!
combined
X
X
!
! USER_SUB_ID = 903
PROPERTY_FILE_FORMAT = 'PAC94'
FUNCTION_NAME
= 'TYR903'
USE_MODE
=4
$--------------------------------------------------------------------dimensions
[DIMENSION]
UNLOADED_RADIUS
= 11.222 !Honda Insight tire radius used by Advisor. Wheel dia: 570.1mm
WIDTH
= 10.0
ASPECT_RATIO
= 0.30
$---------------------------------------------------------------------parameter
[PARAMETER]
VERTICAL_STIFFNESS
= 2500
VERTICAL_DAMPING
= 250.0
LATERAL_STIFFNESS
= 1210.0
ROLLING_RESISTANCE
= 0.0054
$-----------------------------------------------------------------------scaling
[SCALING_COEFFICIENTS]
DLAT = 0.10000E+01
DLON = 0.10000E+01
BCDLAT = 0.10000E+01
BCDLON = 0.10000E+01
82
83
$-----------------------------------------------------------------------lateral
[LATERAL_COEFFICIENTS]
A0 = 1.5535430E+00
A1 = -1.2854474E+01
A2 = -1.1133711E+03
A3 = -4.4104698E+03
A4 = -1.2518279E+01
A5 = -2.4000120E-03
A6 = 6.5642332E-02
A7 = 2.0865589E-01
A8 = -1.5717978E-02
A9 = 5.8287762E-02
A10 = -9.2761963E-02
A11 = 1.8649096E+01
A12 = -1.8642199E+02
A13 = 1.3462023E+00
A14 = -2.0845180E-01
A15 = 2.3183540E-03
A16 = 6.6483573E-01
A17 = 3.5017404E-01
$----------------------------------------------------------------longitudinal
[LONGITUDINAL_COEFFICIENTS]
B0 = 1.4900000E+00
B1 = -2.8808998E+01
B2 = -1.4016957E+03
B3 = 1.0133759E+02
B4 = -1.7259867E+02
B5 = -6.1757933E-02
B6 = 1.5667623E-02
B7 = 1.8554619E-01
B8 = 1.0000000E+00
B9 = 0.0000000E+00
B10 = 0.0000000E+00
B11 = 0.0000000E+00
B12 = 0.0000000E+00
B13 = 0.0000000E+00
$---------------------------------------------------------------------aligning
[ALIGNING_COEFFICIENTS]
C0 = 2.2300000E+00
C1 = 3.1552342E+00
C2 = -7.1338826E-01
C3 = 8.7134880E+00
C4 = 1.3411892E+01
C5 = -1.0375348E-01
C6 = -5.0880786E-03
C7 = -1.3726071E-02
C8 = -1.0000000E-01
C9 = -6.1144302E-01
C10 = 3.6187314E-02
C11 = -2.3679781E-03
C12 = 1.7324400E-01
C13 = -1.7680388E-02
C14 = -3.4007351E-01
C15 = -1.6418691E+00
C16 = 4.1322424E-01
84
C17 = -2.3573702E-01
C18 = 6.0754417E-03
C19 = -4.2525059E-01
C20 = -2.1503067E-01
$--------------------------------------------------------------------------shape
[SHAPE]
{radial width}
1.0 0.0
1.0 0.2
1.0 0.4
1.0 0.5
1.0 0.6
1.0 0.7
1.0 0.8
1.0 0.85
1.0 0.9
0.9 1.0
Appendix F
Road Property Definition File
$---------------------------------------------------------------------MDI_HEADER
[MDI_HEADER]
FILE_TYPE = 'rdf'
FILE_VERSION = 5.00
FILE_FORMAT = 'ASCII'
(COMMENTS)
{comment_string}
'flat 2d contact road for testing purposes'
$--------------------------------------------------------------------------UNITS
[UNITS]
LENGTH
= 'mm'
FORCE
= 'newton'
ANGLE
= 'radians'
MASS
= 'kg'
TIME
= 'sec'
$--------------------------------------------------------------------------MODEL
[MODEL]
METHOD
= '2D'
FUNCTION_NAME
= 'ARC901'
ROAD_TYPE
= 'flat'
$-----------------------------------------------------------------------GRAPHICS
[GRAPHICS]
LENGTH
= 160000.0
WIDTH
= 80000.0
NUM_LENGTH_GRIDS = 16
NUM_WIDTH_GRIDS = 8
LENGTH_SHIFT
= 10000.0
WIDTH_SHIFT
= 0.0
$---------------------------------------------------------------------PARAMETERS
[PARAMETERS]
MU
= 1.0
85
Appendix G
ADAMS/Control Plant Definition
PINPUT_1
Object Name
Object Type
Parent Type
Adams ID
Active
Variables
: .vehicle_new.PINPUT_1
: Plant_Input
: Model
:1
: NO_OPINION
: brake_torque, drive_torque
POUTPUT_1
Object Name
Object Type
Parent Type
Adams ID
Active
Variables
: .vehicle_new.POUTPUT_1
: Plant_Output
: Model
:1
: NO_OPINION
: driveshaft_speed, vehicle_speed
86
Appendix H
ADAMS/Control MATLAB .m File
% ADAMS / MATLAB Interface - Release 2005.0.0
machine=computer;
if strcmp(machine, 'SOL2')
arch = 'ultra';
elseif strcmp(machine, 'SGI')
arch = 'irix32';
elseif strcmp(machine, 'GLNX86')
arch = 'rh_linux';
elseif strcmp(machine, 'HPUX')
arch = 'hpux11';
elseif strcmp(machine, 'IBM_RS')
arch = 'ibmrs';
else
arch = 'win32';
end
[flag, topdir]=dos('adams05 -top');
if flag == 0
temp_str=strcat(topdir, arch);
addpath(temp_str)
temp_str=strcat(topdir, '/controls/', arch);
addpath(temp_str)
temp_str=strcat(topdir, '/controls/', 'matlab');
addpath(temp_str)
ADAMS_sysdir = strcat(topdir, '');
else
addpath( 'install_dir\MSC~1.SOF\MSC~1.ADA\2005\win32' ) ;
addpath( 'install_dir\MSC~1.SOF\MSC~1.ADA\2005\controls/win32' ) ;
addpath( 'install_dir\MSC~1.SOF\MSC~1.ADA\2005\controls/matlab' ) ;
ADAMS_sysdir = 'install_dir\MSC~1.SOF\MSC~1.ADA\2005\' ;
end
ADAMS_exec = '' ;
ADAMS_host = 'host' ;
ADAMS_cwd ='My Documents\thesis\model latest' ;
ADAMS_prefix = 'vehicle' ;
87
88
ADAMS_static = 'yes' ;
ADAMS_solver_type = 'Fortran' ;
if exist([ADAMS_prefix,'.adm']) == 0
disp( ' ' ) ;
disp( '%%% Warning : missing ADAMS plant model file !!!' ) ;
disp( ' ' ) ;
end
ADAMS_init = '' ;
ADAMS_inputs = 'brake_torque!drive_torque' ;
ADAMS_outputs = 'driveshaft_speed!vehicle_speed' ;
ADAMS_pinput = '.vehicle_new.PINPUT_1';
ADAMS_poutput = '.vehicle_new.POUTPUT_1';
ADAMS_uy_ids = [
137
125
127
126
] ;
ADAMS_mode
= 'non-linear' ;
tmp_in = decode( ADAMS_inputs ) ;
tmp_out = decode( ADAMS_outputs ) ;
disp( ' ' ) ;
disp( '%%% INFO : ADAMS plant actuators names :' ) ;
disp( [int2str([1:size(tmp_in,1)]'),blanks(size(tmp_in,1))',tmp_in] ) ;
disp( '%%% INFO : ADAMS plant sensors
names :' ) ;
disp( [int2str([1:size(tmp_out,1)]'),blanks(size(tmp_out,1))',tmp_out] ) ;
disp( ' ' ) ;
clear tmp_in tmp_out ;
% ADAMS / MATLAB Interface - Release 2005.0.0