Battery Management Systems for Electric and Plug

Battery Management Systems for Electric and Plug

Battery Management Systems for

Electric and Plug-in Hybrid Electric

Vehicles

Chris Mi, Ph.D, Fellow IEEE

Professor, Department of Electrical and Computer Engineering

Director, DOE GATE Center for Electric Drive Transportation

San Diego State University

5500 Campanile Drive, San Diego, CA 92182 USA,

Tel: (619)594-3741; email: [email protected]

First Prepared on Jan 2009. Last Revised on October 20, 2015

OEM and Suppliers are committed to the electrification of the Automobile

EVs provide opportunity for fuel savings and GHG emissions.

Range, cost, charging time is of major concerns, and……………….…..

1

A after market conversion of a Prius has caught fire in June 2008

Before

After

Saturday, June 7, 2008

Fire Damaged PHEV, conversion by a Colorado company

Chevy Volt Battery Fires Threaten All

Electric Vehicle Makers, Not Just GM, by Forbes

Statement of the National Highway Traffic Safety Administration On Formal Safety

Defect Investigation of Post-Crash Fire Risk in Chevy Volts

http://www.nhtsa.gov/PR/Volt

GM Announces Fix for

Chevrolet Volt Fire Risk: http://www.foxnews.com/leisure/2012/

01/05/gm-announces-fix-forchevrolet-volt-firerisk/#ixzz20QrKboWQ http://www.forbes.com/sites/jimhenry/2011/12/12/chevy-volt-battery-fires-threaten-all-electric-ve/

2

BYD e6 taxi catches fire in China after crash caused by drunk Nissan GT-R driver

http://www.shenzhenparty.com/byd-electric-taxi-explosion-fire

http://green.autoblog.com/2012/05/28/byd-e6-taxi-catches-fire-inchina-after-crash-caused-by-drunk-ni/

http://www.nytimes.com/2012/05/30/business/global/byd-releasesdetails-about-electric-taxi-fire.html

Tutorial Outline

1. Introduction to energy storage systems

2. Functions of battery management systems

3. Current, voltage, and temperature monitoring

4. State of charge (SOC) calculation

5. Battery cell balancing

6. Thermal Management

7. State of health (SOH)

9. High Voltage System Safety

10. Battery Modeling

3

1. Introduction to Energy Storage

Systems for EV, HEV, and PHEV

Energy Storage Options

Batteries

Flywheels

Ultracapacitors

Compressed air

Hydraulic energy storage

Superconducting magnetic energy storage

Integrated energy storage using lithium ion battery and ultracapacitor

Lithium ion battery is considered the only viable energy storage solution for EV and PHEV at the present time

4

Battery Types, History, and

Evolvement

Primary Battery- non-rechargeable battery

Cannot be recharged. Designed for a single use

Secondary Battery – rechargeable battery

Lead-acid (Pb-acid)

Nickel-cadmium (NiCd)

Nickel-metal-hydride (NiMH)

Lithium-ion (Li-ion)

Lithium-polymer (Li-poly)

Sodium-sulfur

- Zinc-air (Zn-Air)

Secondary batteries are still evolving

Some metal-air batteries are under development, high energy density

(500+Wh/kg+, but low cycle life (25+)

1946 Neumann: sealed NiCd

1960 Alkaline, rechargeable NiCd

1970 Lithium, sealed lead acid

1990 Nickel metal hydride (NiMH)

1991 Lithium ion

1992 Rechargeable alkaline

1999 Lithium ion polymer

5

Battery Power and Energy

Specific Energy

Energy Density

SE

Discharge Energy

Total Battery Mass

E

M

B

(units: Wh/kg)

SP

P

M

B

Specific Power

Power Density

Discharge Energy

Total Battery Volume

E

V

(units: Wh/m 3 )

Power Density

(units: W/kg)

Power Density

P

V

(units: W/m 3 )

Lithium Battery Schematics

6

Advantages of Li-Ion Batteries

Lithium battery are considered the only viable solution for PHEV

Li ion batteries offer high energy density:

1.5 times NiMH; 3 times lead acid

High power density model 18650, energy

3.2V*1.5Ah=4.8Wh;

Long life cycles Lithium:

1000 vs. 300 lead acid;

228Wh/L;

Low memory effect; deep discharge cycles

120-200Wh/kg

Lead Acid:

High cell voltage (3.2V vs. 1.2V)

85Wh/L; 39Wh/kg

Low self discharge, long shelf life – only 5% discharge loss per month; 10% for NiMH, 20% for NiCd

Disadvantages of Li-Ion

Expensive -- 40% more than NiCd.

Delicate -- battery temp must be monitored from within (which raises the price), and sealed particularly well.

Regulations -- when shipping Li-Ion batteries in bulk (which also raises the price).

Class 9 miscellaneous hazardous material

7

Major Lithium Ion Battery Players

Company

Toyota

Panasonic

JCS

Hitachi

AESC

Sanyo

GS Yuasa

A123

LG Chem

Samsung

SK

Toshba

AltairNano

BYD

Electrovaya

Valence

Cathode

NCA

NMC

NCA

LMO/NMC

LMO/NMC

LMO//NMC

LMO/NMC

LFP

LMO

LMO/NMC

LMO

LMO

LMO

LFP

LMP

LFP

Anode

Graphite

Blend

Graphite

Hard Carbon

Electrolyte

Liquid

Liquid

Liquid

Liquid

Hard Carbon

Blend

Hard Carbon

Graphite

Liquid

Liquid

Liquid

Liquid

Brend Carbob Gel

Graphite Liquid

Graphite Liquid

LTO

LTO

NA

Liquid

Liquid

Liquid

NA

NA

NA

Polymer

Packaging

Metal

Metal

Metal

Metal

Pouch

Metal

Metal

Metal

Pouch

Metal

Pouch

Pouch/metal

Pouch

Metal

NA pouch

Stacked

Spiral

Spiral

Spiral

Stacked

Spiral

NA

Stacked

Structure

Spiral

Spiral

Spiral

Spiral

Stacked

Spiral

Spiral

Spiral

Shape

Elliptic

Elliptic

Cylindrical

Cylindrical/Elli ptic

Prismatic

Cylindrical

Elliptic

Cylindrical/Elli ptic

Prismatic

Cylindrical

Prismatic

Prismatic

Prismatic

Cylindrical/Elli ptic

NA

Prismatic

Major Collaborations

Sanyo

Panasoni c

NEC

Ford Toyota Honda GM Mercede s

X X X X

Nissa n

VW

Develo p

JV

Mitsubis hi

Hyunda i

Bosc h

Continenta l

JV

X JC-Saft

Bak-A123 X

X A123-

Cobsys

MRI

LG

GYS

X

JV

X

JV

X

Samsung

Enax

JV

JV

8

Ultra-Capacitors

Electrochemical energy storage systems

Devices that store energy as an electrostatic charge

Higher specific energy and power versions of electrolytic capacitors

Stores energy in polarized liquid layer at the interface between ionically conducting electrolyte and electrode

Energy

1

2

CV

2

Current aim is to develop ultra capacitors with capabilities of 4000 W/kg and

15Whr/kg.

Functions of Capacitors

Energy Storage: for smoothing the DC bus voltage, absorbing surge

Snubber circuits to limit voltages applied to devices during turn off transients (usually use in combination with resistance); limit currents during turn-on transients; as well as limit di/dt and dv/dt values

This is what ultracapacitors do though

9

Flywheels

Electromechanical energy storage device

Stores kinetic energy in a rapidly spinning wheel-like rotor or disk

Has potential to store energies comparable to batteries

All IC Engine vehicles use flywheels to deliver smooth power from power pulses of the engine

J v

,

Modern flywheels use highstrength composite rotor that rotates in vacuum

Vehicle wheel

Energy

1

2

J

2

Converter /

Inverter

Motor

Generator

Motion transfer direction

Generator

Motor

Flywheel

J

FW

, ω

FW

Gasoline, diesel etc.

Hydraulic Energy Storage

IC Engine

Hydraulic pump

Reservoir with fluid at high pressure

Compressible fluid for energy storage

Reservoir with fluid at low pressure

Hydraulic motor

Mechanical load

10

Superconducting magnetic energy storage

Energy Storage Efficiency

Energy Storage Options

Battery ultracapacitor

Flywheel

Compressed air

Hydraulic

Hydrogen

Super Conducting Magnetic

Efficiency

60% - 80%

90% - 98%

80%-90%

75% - 85%

70% - 85%

60% - 85%

98%

11

Hybridization of Energy Storage

Use multiple sources of storage

Tackle high demand and rapid charging capability

One typical example is to combine battery and ultracap in parallel

High power demand

High specific

Energy storage

Power converter

High specific power storage

Low power demand

High specific energy storage

High specific power storage

Negative power

High specific

Energy storage

High specific power storage

(a)

(b)

(c)

Fig. 10.18

Power converter

Power converter

Load

Load

Load

Primary power flow

Secondary power flow

Topologies of Hybridization

Direct parallel connection - passive

Or through two quadrant chopper for better power management – semi-active or active

PEMFC

Ultracapacitor

Buck or Boost

DC-DC

Converter

DC

Link

Battery

Load

Buck –Boost

Bidirectional

DC-DC

Converter

Longer service life due to peaks are only from ultracap

Smaller size, volume, and weight possible

More fuel savings due to increased regen capture

Better performance due to power capabilities

-

+

12

Hybrid Energy Storage Example

For PHEV 40 miles

60kW power requirement,

Battery 11kWh; at 2C discharge gives 22kW, so 38kW from ultra cap discharging

C/2 charging (braking) battery is 5.5kW; at 60kW will need ultracap to absorb 54.5kW

At 4.3kW/kg, need minimum 54.5/4.3=13kg

At 13kg, energy is 13kg*(4.3Wh/kg)= 54Wh

54Wh/54.5kW=10 seconds

Battery 11kWh, 110kg, 5.5kW (CC), 22kW (2C, DC)

Ultracap: 54Wh, 13kg, 55 kW (CC), 55kW (DC)

Total: 11kWh, 123kg, 60kW CC and DC

2. Functions of Battery

Management Systems (BMS)

13

Functions of BMS

Cell monitoring

Voltage, current, temperature, state of charge (SOC), SOH

Cell protection and safety

Avoid over charge or over discharge and over temperature

Cell balancing

Dynamic balancing

Charge balancing

Thermal management

Charge control

Safety, life and capacity of lithium batteries can be effectively addressed by a battery management system

Protect the cells from damage, and prolong the life

3. Current, Voltage, and

Temperature Monitoring

14

LEM Current Measurement

DHAB S/25 Dual Channel

200A for discharge measurement, 25A for charging measurement, 5V supply

V=constant * I

15

Current Measurement Circuit

Channel 1: 10mV/A, offset 2.5V with 5V supply

-200A  0.5V; 0A  2.5V; 200A  4.5V

Channel 2: 80mV/A, offset 2.5V with 5V supply

-25A  0.5V; 0A  2.5V; 25A  4.5V

Vo

5V

2.5V

-250A 0 250A

I

Isolated High Voltage Sensor

LEM AV 100: The linearity errors are within 0.1 % while the overall accuracy is 1.7 % of VPN between –40 and 85 °C.

Range 50V to 1500V, for pack voltage measurement

Configuration with single power supply http://www.lem.com/images/stories/files/Products/1-3_applications/CH24101.pdf

16

HV Measurement and Floating

Ground

Op-amp is able to handle 2000V ESD

The up and bottom 12M separates the op-amp from HV

1% resistors provide accurate measurement

Careful about band width

Bypass cap necessary

C=2200pF

I bat

12

Meg

V bat

12

Meg

V bat

24

Meg

;

V

V

1

2

V bat

V

 relative to battery negativeterminal

bat

1

240

V bat

V

; relative to analog ground

V

0

V

100

k

I bat

;

so V o

V

I bat

*100

k

V bat

120

Floating ground is generated at Vbat/2; this is relative to the analog ground (the op-amp ground)

Current from battery + go through R8 to analog ground

Current of R9 goes through 12Meg to battery negative

If Vbat = 400V

Vo = 3.33V

LTC6803-2

Cell voltages, maximum 5V per cell, resolution near

1mV (12-bit ADC), measurement error < 0.25%

Cell or module temperature (2 temperature sensors per module)

Low standby mode supply current (12uA)

SPI communication with Packet Error Checking

A 48-cell monitoring and management unit

Proprietary, Gannon Motors and Controls, LLC

17

Temperature Monitoring

Thermal couples or thermistors can be directly connected to

MCU A/D channel; or through a op-amp follower to the A/D

Channel

A table is needed inside the MCU to look up the temperature

RTDs

A platinum resistance temperature detector

(RTD) is a device with a typical resistance of

100 Ω at 0C. It consists of a thin film of platinum on a plastic film. Its resistance varies with temperature and it can typically measure temperatures up to 850 C. The relationship between resistance and temperature is relatively linear.

http://www.omega.com/rtd.html

18

Thermistors

• Thermistors are made from certain metal oxides whose resistance decreases with increasing temperature. Because the resistance characteristic falls off with increasing temperature

• They are called negative temperature coefficient (NTC) sensors.

• Popular for Battery temperature measurement http://www.omega.com

Thermocouples

Thermocouples are based on the effect that the junction between two different metals produces a voltage which increases with temperature.

Compared with resistance thermometers they offer the clear advantage of a higher upper temperature limit, up to several thousand degrees Celsius.

Their long-term stability is somewhat worse (a few degrees after one year), the measuring accuracy is slightly poorer

Has polarity in wiring

19

4. Calculation of State of Charge

Integration of Current

If the battery original SOC is given, then the new

SOC is

( )

( )

s

(

Ah

)

total

SOC is in percentage

Ts is the sampling time

Therefore, initial SOC or (Ah) of the battery needs to be known

Sampling frequency needs to be accurate

20

Self Discharge

Self discharge inside the battery can not be counted for by the BMS for SOC calculations

Small current draw from the HV when vehicle is at rest (BMS sleeping mode) can also be monitored by the BMS

Therefore, initial calibration is also important during vehicle start up

Impact of Current Harmonics

Modern electric machines and power electronics operating from the battery generates harmonics. Therefore it is difficult to measure accurately the current

21

Measurement Error and Process

Noise

Current sensor has certain error (resolution, accuracy, etc.)

Timing may cause error too

Noise in the measurement loop and in the amplification circuits

Capacity fade over time

Internal loss due to internal impedance

Different at different discharge rate

Aging of Battery etc.

Aging of battery will alter the base of nominal capacity hence cause error in the calculated percentage SOC

In consistency (could be small) but can cause error over time in the accumulated SOC calculations

Furthermore, initial SOC may not be known or may not be accurate

Temperature can cause nominal capacity to change

22

5. Cell Balancing

Batteries without Charge Balancing

A balanced system can be charged without cell monitoring

Battery cells deteriorate differently

Chemistry

Temperature

Once the highest cell is charged, continued charge will cause potential damage and hazard due to over charge of some cells potential damage

23

9

10

11

12

7

8

5

6

13

14

15

ID

1

2

3

4

Batteries without Management

3.30

3.34

3.33

3.32

3.34

3.32

3.33

3.34

V1

3.67

3.31

3.34

3.31

3.33

3.32

3.66

3.28

3.30

3.31

3.30

3.32

3.30

3.31

3.32

V2

3.64

3.29

3.31

3.29

3.31

3.29

3.64

3.30

3.35

3.33

3.32

3.34

3.33

3.34

3.35

V3

3.68

3.31

3.34

3.32

3.33

3.32

3.64

3.32

3.35

3.35

3.34

3.35

3.35

3.35

3.36

V4

3.69

3.33

3.36

3.33

3.35

3.33

3.67

28

27

28

27

27

26

27

25

27

28

28

T1

26

26

27

26

T2

27

26

26

27

26

26

27 27

26

27

23

Prius PHEV

28 27

28

27

28

28

28

28

28

27

28

28

T3

27

9

27

26

28

27

Unmanaged system start to deteriorate over time

26

27

28

27

0

26

27

27

29

28

31

T4

28

23

26

27

V

14.69

13.23

13.35

13.26

13.20

13.34

13.32

13.27

13.36

13.31

13.34

13.36

13.32

13.26

14.62

Passive Resistor Balancing

Energy of high cells is consumed by resistors

Loss of energy due to balance

Hard to manage heat

N. H. Kutkut, “Life cycle testing of series battery strings with individual battery equalizers,” white paper,

Power Designers, Inc., 2000. Available: http://t2rerc.buffalo.edu/products/2003_powercheq%20testing.pdf

24

Capacitive Balancing

Slow speed balancing: up to 20 hours

Large size Capacitor

Lack of enable/disable feature

P. T. Krein, R. Balog, “Life Extension Through Charge Equalization of Lead-Acid Batteries,” ITELEC02,

2002

Inductive Balancing

Large size transformer

Difficult to package

Werner Rößler, Boost battery performance with active charge-balancing, Infineon, EE Times India, 2008. http://www.powerdesignindia.co.in/STATIC/PDF/200807/PDIOL_2008JUL24_PMNG_TA_01.pdf?SOURC

ES=DOWNLOAD

25

Dynamic Balance

6+

The lowest row/cell is charged by the DC-DC converter using the pack voltage

The highest cell is discharged to the whole pack

Difficulty is the small duty ratio for large packs

Rows are divided into groups

Balance within and between groups

5+

4+

3+

2+

1+

6-

5-

4-

3-

2-

1-

Bidirectional

DC-DC

Converter

Ziling Nie, and Chunting Mi, “Ziling Nie, and Chunting Mi, “Fast Battery Equalization with Isolated

Bidirectional DC-DC Converter for PHEV Applications,” the Fifth IEEE International Vehicle Power and

Propulsion Conference (VPPC), Dearborn, Michigan, USA, September 7-11, 2009.

Advanced Active Balancing Technology

Multi-winding transformer, one per cell

Balance up to 4 A

Efficiency up to 94%

One control signal for all switches (on and off at the same time)

Soft switching

26

Balancing Example

 http://files.evbatteryforum.com/battery2/2_12Adam%20Opel_Horst%20Mettlach_Cell%20Balanci ng%20Techniques%20Using%20The%20Example%20Of%20The%20Li-

Chevy Volt Battery Pack ion%20Battery%20System%20For%20The%20Opel%20Ampera.pdf

Resistive passive balancing; at very low current

Accumulated balancing duration over 10 month

On average, the balancing resistors are switched on in only 0.55% of time

Balancing Algorithms

Based on when to balance

Balance during charging

Balance during discharging

Balance during idle

Based on balance current

Fast balancing (> 4A)

Slow balancing (< 1A)

Based on balance activation

Voltage based – most popular

SOC based – very difficult due to the need of SOC of individual cells

27

6. Battery Thermal Management

Battery Cooling

Measurement of individual cell temperature

Max (T)

Ambient temperature

Ta

Fun turn on when T>Tset

Fan speed (if possible) proportional to (T-Ta)

Typical lithium ion battery temperature

0 to 60 o C (high self discharge at high T)

28

Battery Heating

Battery does not perform very well below 0 o C

A heater may be added and controlled by BMS

Thermally insulated pack may help the battery to stay warm

Cycling the battery at very low charge/discharge rate may also help to keep the battery warm

Heating the battery while also heat up the catalyst; start engine after the catalyst is hot can help reduce cold emissions.

7. Battery State of Health (SOH)

29

What Parameters in SOH

Internal impedance

Increase over time and aging of battery

Individual cell voltage

Become too high too quickly during charge

Become too low too quickly during discharge

Individual cell temperature

Hotter that other cells during charge/discharge

Cell capacity

Needed to be balanced first during charge or discharge (repeatedly)

Cell Impedance Measurement

Cell impedance can be measured by impose a

AC excitation and measure the response.

Measure DC voltage and current during charge or discharge to estimate the DC resistance of the battery

R=(Vo-VB)/IB, where Vo is open circuit voltage, and VB is the battery voltage during discharge at rate IB

30

Measured DC Resistance and

Cell Capacity

Compare the internal resistance to determine whether the battery has deteriorated.

If monitored charge or discharge capacity has dropped, then the health condition has deteriorated

Health Condition

Nominal

C urrent

Resistance

100 %

Resistance

Health Condition

Available Capacity

100 %

Nominal Capacity

10. Battery Modeling

It is extremely difficult, if not impossible, to follow all the complex interactions of individual cell phenomena in an electrochemical system that is on the order of the size of a human hair using a strictly experimental approach.

Modeling supports battery research efforts

Interpreting experimental results

Identifying performance limiting phenomena

Predicting the impact of new materials and components

Assisting in cost and performance optimization

Suggesting advanced designs for specialized applications

Modeling methods

Electrochemical Modeling

Equivalent circuit

Thermal modeling

Reference: http://www.transportation.anl.gov/batteries/modeling_batteries.html

31

Electrochemical Modeling

Utilizes a set of coupled non-linear differential equations to describe the pertinent transport, thermodynamic, and kinetic phenomena occurring in the cell

Reference: http://www.transportation.anl.gov/batteries/modeling_batteries.html

Equivalent Circuit

Use an equivalent circuit to represent the characteristics of the battery

One example is shown below

4.2

OCV at charge process

Average value

OCV at discharge process

4

3.8

3.6

3.4

0 0.2

0.4

Battery SOC

0.6

0.8

1

_ _

i

v

1

R

1

C

1

dv

1

v

2

dt R

2

C

2

dv

2

dt v o

E o

  

IR o

+ +

32

Thermal Modeling

At pack level and cell level

5

Gradients' in a pack or within a cell

10

Group

1

15

Cooling air

20 25

Group

2

30 35 40

5

6

7

8

3

4

1

2

11

12

9

10

We conduct research to help improve performance and safety of PHEVs

33

Advanced Battery Management System Incorporating Real-Time Diagnosis and

Data-Driven Prognostic Health Management with Joint SOC, SOH and Parameter

Estimation

Contributors: Yuhong Fu, Le Yi Wang, Chris Mi, Zhimin Xi et al

Technology Summary

Real-time battery diagnosis with joint SOC and parameter estimation and large deviation principles

Prognostic health management of battery systems through data-driven algorithms

Technology Impact

Increase effectiveness of fault diagnostics

Increase accuracy of residual life predictions

Reduce sensor count by incorporating advanced algorithms

Preventing catastrophic failures through fast, real time, and accurate battery cell parameter estimations

Proposed Targets

Metric

Diag response time

Prog response time

Accuracy

Real time

Need of sensor

State of the Art

Seconds minutes

90%

No

Large number

Proposed

Milliseconds

3 seconds

99%

Yes

Reduced count

Joint parameter estimation with error less than 1%

Gannon

BMS

Patent pending

Life prediction with high accuracy

Funding Agency/Collaborations: DOE, Chrysler, Ford, ARPA-e

Integrated Battery Management System Incorporating Modular, Reconfigurable

Charger, Active Balancer, PFC and Sensorless Voltage Monitoring

Contributor: Siqi Li, Chris Mi, et al

Patent Pending

Technology Summary

Modular,, high efficiency, and low cost charger with integrated active balance and power factor correction (PFC)

High efficiency, low cost active cell balancing

Sensorless cell parameter monitoring

Gannon

BMS

Technology Impact

Modular design reduce BMS/Charger/Balancer cost by 80%

Increase charge efficiency by 3~5%

Increase balance efficiency by 5~10%

Modular concept to reduce cost and increase efficiency

 

Module #1 

Module #2 

Module #n 

Charger 

Balancer 

Monitoring 

Novel 

Packaging 

Concepts 

Proposed Targets

State of the Art Metric

6kW PHEV

Charger

Active cell balancer

Sensorless monitoring

O

<90%; cost>$1000

O

<70%;cost>$10/cell max 2A/cell

Proposed

O

>96%; cost<$200

O

>93%;cost<$0.15/c ell; max 8A/cell

PFC Separate circuit

Part of charger/balancer

Individual cell based charger/bala ncer/PFC

Funding Agency/Collaborations: DOE, GATE, ARPA-e, Chrysler

34

A High Efficiency Active Battery Balancing Circuit

Using Multi-Winding Transformer

Conventional balancer using multi-winding transformer

Disadvantages:

1. Two stage Energy Transfer:

a. Energy flows out of all cells b. Energy distribute to different cells

2. Diode voltage drop effect:

a. Inconsistency b. energy loss c. Temperature dependent

Hard to achieve good balance results

Low efficiency : ~ 75% by simulation

Advanced balancer using multi-winding transformer

Advantages:

1. Direct energy transfer:

High efficiency

2. No Diode voltage drop involved:

Ideal balance & high efficiency

3. Simple control:

Only one MOSFET signal needed

4. Low cost:

All low voltage components

Final Results:

Up to 93% energy transfer efficiency

Prototype test

Soft-switching waveforms

Test platform

(4-cell version)

Dimension: 10cm x 9.5cm

Support 12 cells per board

Maximum current :1.5A

V V

Efficiency vs. voltage difference

Funding Agency/Collaborations: DOE, Chrysler

Bi-directional PFC converter with reduced passive components size and low electro-magnetic interference for electric vehicle on-board charger

Contributors: Siqi Li, Chris Mi, et al

Patent Pending

Technology Summary

High order input filter for low weight and compact size

Model based control method for good dynamic characteristics

Bi-directional capability for future V2G technology

Technology Impact

Compared with traditional bridgeless PFC:

1/10 of the input inductor value with same current ripple

Total size and weight reduced by 20%~40%

Total cost almost the same

No EMI issue

Bi-directional capability and good dynamic characteristics, get ready for V2G

Proposed bi-directional PFC topology

1200

1000

800

600

400

200

0

Traditional PFC

Proposed PFC

Volume Price

Passive components size and cost comparison

Model base control schematic

Input AC current

450

Output DC voltage

50

0

-50

50

400

350

100 150 200 250 t / ms

300 350 400

300

50 100 150 200 250 t / ms

300

Step response from no load to full load

350 400

Funding Agency/Collaborations: DOE, Chrysler

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Wireless Charging of EV

Wireless changing is different from inductive charging, and information transmission, such as radio signal

Wireless means transferring power and energy in a great distance.

It is typically done through electromagnetic resonance

MIT, KIAST, and University of Tokyo, some of the leaders in this area.

MIT Lab

University of Tokyo

US DOE

Funding Agency/Collaborations: Chrysler, DENSO, Oakridge National Laboratory

High Efficiency Lithium-Ion Battery Charger for Plug-in Hybrid Electric Vehicle

Contributors: Sideng Hu, Junjun Deng, Chris Mi, et al

Technology Summary

Bridgeless PFC boost converter performs the front end AC-

DC conversion with high efficiency by eliminating the input rectifier diodes

Full bridge multi-resonant LLC converter offers very high efficiency and low EMI at high power by providing ZVS of

MOSFETs and ZCS of output diodes

Technology Impact

Increase power rating for different P-HEV application

Increase efficiency by soft-switching technology

Increase power factor by advanced algorithms

Fig.1 System Diagram Overview

Proposed Targets

Metric

Power rating

EMI/noise

Power factor

Efficiency

Cost

State of the Art Proposed

3.3kW

6kW fair medium fair medium good high good low

Funding Agency/Collaborations: Chrysler, DOE

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