5
-26
Improving the Operation Performance
Reducing the Motor Speed Fluctuation (Slip Compensation Function)
When the load is large, the motor slip also grows and the motor speed decreases. The slip compensation function keeps the motor speed constant, regardless of changes in load. When the motor is operating at the rated load, parameter E2-02 (Motor Rated Slip)
× the slip compensation gain value in parameter C3-01 is added to the output frequency. The function can be used in V/f control or Open Loop Vector control.
Related Parameters
Parameter
No.
C3-01
C3-02
C3-03
C3-04
C3-05
Name
Slip compensation gain
Slip compensation delay time
Slip compensation limit
Slip compensation during regeneration
Output voltage limit operation selection
Factory
Setting
1.0
2000 ms
200%
0
0
Change during
Operation
Yes
No
No
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
A A No
A
A
A
A
No
No
A
No
A
A
No
A
Adjusting Slip Compensation Gain (C3-01)
The set value of C3-01 depends on the control method. The factory settings are:
•
Open Loop Vector control: 1.0
•
Closed Loop Vector control: 1.0
Set C3-01 to 1.0 to compensate the slip depending on the actual torque output status using the rated slip
(E2-02) as reference.
Adjust the slip compensation gain using the following procedure.
1. With Open Loop Vector control set E2-02 (Motor Rated Slip) and E2-03 (Motor No-load Current). The motor rated slip can be calculated using the values on the motor nameplate and the following formula: slip (Hz) = –
120
The motor data can be set automatically using the autotuning function.
2. With V/f control set C3-01 to 1.0.
3. Apply a load and compare the speed reference and the actual motor speed during run with constant speed.
Adjust the slip compensation gain by 0.1 at a time. If the speed is less than the target value, increase the slip compensation gain, and if the speed is higher than the target value, reduce the slip compensation gain.
4. Setting C3-01 to 0.0 disables the slip compensation function.
Adjusting Slip Compensation Primary Delay Time Constant (C3-02)
The slip compensation delay time constant is set in ms. The setting value of C3-02 is 2000ms. Normally, there is no need to change these settings. When the slip compensation response is low, lower the set value. When the speed is unstable, increase the set value.
Improving the Operation Performance
Adjusting Slip Compensation Limit (C3-03)
Using parameter C3-03 the upper limit for the slip compensation can be set as a percentage, taking the motor rated slip as 100%.
If the speed is lower than the target value but does not change even after adjusting the slip compensation gain, the slip compensation limit may have been reached. Increase the limit, and check the speed again. Always make sure that the value of the slip compensation limit and reference frequency does not exceed the tolerance of the machine.
The following diagram shows the slip compensation limit for the constant torque range and fixed output range.
Slip compensation limit
Output frequency
E1-06: Base frequency
E1-04: Maximum output frequency
Fig 5.39 Slip Compensation Limit
Selecting Slip Compensation Function During Regeneration (C3-04)
Enables or disables the slip compensation function during regeneration. The factory setting is enabled.
Operation Selection when Output Voltage Saturated (C3-05)
Generally the Inverter cannot output a voltage that is higher than the input voltage. If the output voltage reference for the motor (monitor parameter U1-06) exceeds the input voltage in the high-speed range, the output voltage becomes saturated, and inverter cannot respond to speed or load changes. This function automatically reduces the output voltage to avoid voltage saturation.
Thereby the speed control accuracy can be maintained even at high speeds (around the rated speed of the motor). By the lowered voltage the current can be around 10% higher compared to the operation without voltage limiter.
5
Torque Compensation Function Adjustments
The torque compensation function detects a rising motor load, and increases the output torque.
In V/f control the inverter calculates the motor primary loss voltage using the terminal resistance value (E2-
05) and adjusts the output voltage (V) to compensate insufficient torque at startup and during low-speed operation.
The compensation voltage is calculated by the calculated Motor primary voltage loss
× parameter C4-01.
In Open Loop Vector control the motor excitation current and the torque producing current are calculated and controlled separately. The torque compensation affects the torque producing current only.
The torque producing current is calculated by the calculated torque reference
× C4-01.
5-
27
5-
28
Related Parameters
Parameter
No.
C4-01
C4-02
C4-03
C4-04
C4-05
Name
Torque compensation gain
Torque compensation delay time constant
Starting torque compensation value (forward direction)
Starting torque compensation value (reverse direction)
Starting torque compensation time constant
Factory
Setting
Change during
Operation
1.00
2000 ms
0.0
0.0
1 ms
Yes
No
No
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
A A No
A
No
A
A
No
No
No
No
A
A
No
No
Adjusting Torque Compensation Gain (C4-01)
Normally, there is no need to change this setting. If adjustments are necessary do the following:
Open Loop Vector control
•
If the torque response is slow increase the setting value.
•
If vibrations occur decrease the setting value.
V/f control
•
If the cable is very long, increase the set value.
•
•
If the motor capacity is smaller than the Inverter capacity (max. applicable motor capacity), increase the set value.
If the motor is vibrating, reduce the set value.
Setting precautions
•
Adjust this parameter so that the output current during low-speed rotation does not exceed the Inverter rated output current range.
•
Adjust the value in steps of 0.05 only.
Adjusting the Torque Compensation Delay Time Constant (C4-02)
The factory setting depends on the control mode. The factory settings are:
•
V/f control: 200 ms
•
Open loop vector control: 20 ms
Normally, there is no need to change this setting. If adjustments are necessary do the following:
•
If the motor is vibrating or if overshooting occurs, increase the set value.
•
If the torque response is slow, decrease the set value.
Improving the Operation Performance
Starting Torque Compensation Function (C4-03 to C4-05)
A starting torque compensation can be applied to speed up the torque establishment at start in Open Loop Vector control.
It works like shown in the following diagram.
Forward (Reverse) Run command
ON
OFF
Time constant: C4-02
Time constant: C4-05
C4-03 (forward)
C4-04 (reverse, negative polarity)
Torque compensation volume
C4-05 x 4
E1-09
Output frequency
E1-09
Fig 5.40 Time Chart for Starting Torque Frequency
When this function is used, the following should be considered:
•
Both values, C4-03 and C4-04 have to be set.
•
•
•
The compensation works for motoring operation only. It can not be used for regenerative operation.
If the starting torque compensation is used and a large shock is generated at the start, increase the starting torque compensation time constant (C4-05)
The function can be not be used unrestricted for elevators, since the load is not know before the start.
5
Automatic Speed Regulator (ASR) (Closed Loop Vector only)
In Closed Loop Vector control the automatic speed regulator (ASR) adjusts the torque reference in order to eliminate the deviation between the speed reference and the measured speed (PG feedback).
Fig 5.1
shows the
ASR structure.
Frequency
Reference
Motor
Speed
+
-
C5-01/03/09
P
I
C5-02/04/10
C5-08
I-Limit
+
+
Delay
Timer
C5-06
Torque
Limits
Torque
Reference
Fig 5.1 ASR Structure Block Diagram
Related Parameters
Parameter
No.
C5-01
C5-02
C5-03
C5-04
C5-06
C5-08
C5-09
C5-10
Name
ASR proportional (P) gain 1
ASR integral (I) time 1
ASR proportional (P) gain 2
ASR integral (I) time 2
ASR delay time
ASR integral limit
ASR proportional (P) gain 3
ASR integral (I) time 3
Factory
Setting
Change during
Operation
40.00
0.500 s
20.00
0.500 s
0.004 s
400%
40.00
0.500 s
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Control Methods
V/f
Open
Loop
Vector
Closed
Loop
Vector
No No A
No
No
No
A
A
A
No
No
No
No
A
A
A
A
5-
29
5-
30
ASR Gain and Integral Time Adjustments
There are three sets of ASR gain and bias, one for the maximum speed (C5-01/02), one the minimum speed for acceleration (C5-03/04) and one for the minimum speed for deceleration (C5-09/10) (see the figure
ASR P,I
ASR P,I
C5-01 ASR Gain 1
C5-02 ASR I Time 1
C5-09 ASR Gain 3
C5-10 ASR I Time 3
C5-03 ASR Gain2
C5-04 ASR I time 2
C5-03 ASR Gain2
C5-04 ASR I time 2
0Hz
C5-07 E1-04
Speed(Hz)
During Acceleration
0Hz
C5-07 E1-04
Speed(Hz)
During Deceleration
below).
Adjusting ASR Proportional Gains (C5-01/03/09)
This gain adjusts the responsiveness of the speed control (ASR). The responsiveness of the ASR is increased when this setting is increased. Oscillation will occur if this setting is increased too much.
•
•
•
Increase C5-01 if the ASR is too slow at start or very low frequencies, decrease it if vibrations occur.
Increase C5-03 if the ASR is too slow at high speed or if overshooting occurs at speed changes in the high speed area, decrease it if vibrations occur
Increase C5-09 if ASR is slow in the low speed area or if undershooting occurs at leveling speed. If vibrations occur in the low speed area during deceleration decrease the value.
Adjusting ASR Integral Times (C5-02/04/10)
This parameter sets the speed control (ASR) integral time. Lengthening the integral time lowers the responsiveness and the speed accuracy when the load changes suddenly. Oscillation and overshooting can occur if this setting value is too low.
•
•
•
Decrease C5-02 if a speed deviation is compensated too slow at start or at very low frequencies, increase it if vibrations occur.
Decrease C5-04 if a speed deviation is compensated too slow at high speeds or if overshooting occurs at speed changes in the high speed area, increase it if vibrations occur.
Decrease C5-10 if a speed deviation is compensated too slow in the low speed area or if undershooting occurs at leveling speed. If vibrations occur in the low speed area during deceleration increase the value.
Improving the Operation Performance
Stabilizing Speed (Automatic Frequency Regulator) (Open Loop Vector)
The speed feedback detection control (AFR) function controls the stability of the speed when a load is suddenly applied or removed. It calculates the amount of speed fluctuation using the torque current (Iq) feedback value and compensates the output frequency with the amount of fluctuation. f ref f out
I q
Fig 5.41 AFR Control Loop
Related Parameters
Parameter
No.
N2-01
N2-02
Name
Speed feedback detection control (AFR) gain
Speed feedback detection control (AFR) time constant
Factory
Setting
Change during
Operation
1.00
50 ms
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
No A No
No A No
Setting the AFR Gain (N2-01)
Normally there is no need to change this setting. If adjustments are necessary do the following:
If hunting occurs increase N2-01.
If the response is too low, decrease N2-01.
Adjust the setting by 0.05 at a time while checking the response.
Inertia Compensation (Closed Loop Vector Only)
The Feed Forward Control is used to eliminate the speed overshoot or undershoot.
The function can be enabled using parameter n5-01.
Related Parameters
Parameter
No.
n5-01 n5-02 n5-03
Name
Feed forward control selection
Motor acceleration time
Feed forward proportional gain
Factory setting
Change during operation
0:disabled No kVA dependent
1.0
No
No
V/f
No
No
No
Open
Loop
Vector
No
No
No
Closed
Loop
Vector
A
A
A
5
5-
31
5-
32
Adjustments
Motor acceleration time (n5-02)
The motor acceleration time n5-02 the time which is needed to accelerate the to the rated speed with the rated torque of the motor. The time can be estimated like follows:
•
•
Make the general setup (V/f pattern, Motor Setup, etc.)
Balance the elevator (car in middle position, Car weight = Counter weight)
•
•
•
•
Set the torque limits to 100% using the L7- parameters.
Set the acceleration time very short (the inverter must reach the torque limit very fast).
Start in any direction and measure the time from zero speed to top speed.
Set this time in n5-02.
Feed Forward Gain (n5-03)
This value usually has not to be changed.
•
Increase the time to improve the response to the speed reference
•
Decrease the time if vibrations occur
Improving the Leveling Accuracy by Slip compensation
This function can be used in V/f and Open Loop Vector control to compensate the motor slip influence at low speed under different load conditions. Thereby the leveling accuracy can be improved.
The inverter measures the current level or torque reference 1.0 sec after speed-agree condition (acceleration finished) for 0.5 sec and calculates the average value to estimate the load. This value is used for the calculation of slip which is added to the speed reference at leveling speed (see
Fig 5.42
).
measure apply
Fig 5.42 Slip Compensation Working Principle
Related Parameters
Parameter
No.
S2-01
S2-02
S2-03
S2-07
Name
Motor Rated rpm
Slip Compensation Gain at Motoring
Slip Compensation Gain at Regenerating
Slip Compensation primary Delay Time
Factory setting
1380rpm
0.7
1.0
200ms
Change during operation
No
No
No
No
V/f
A
A
A
No
Open
Loop
Vector
No
A
A
A
Closed
Loop
Vector
No
No
No
No
Improving the Operation Performance
Adjustments
The Slip compensation values can be set separately for motoring and regenerative operation. Before adjusting this function the general setup should have been done (Motor Setup, V/f pattern, Speeds, ASR settings etc.).
To adjust the Slip compensation function do the following in motoring and regenerative mode:
•
•
Set the motor speed in S2-01 if V/f control is used.
Try to measure the actual motor speed during leveling.
•
•
If the motor speed is lower than the leveling speed reference increase S2-02 in motoring mode or decrease
S2-03 in regenerative mode.
If the motor speed is higher than the leveling speed reference decrease S2-02 in motoring mode or increase
S2-03 in regenerative mode.
Field Forcing
The field forcing function controls the motor flux and compensates the flux establishment delay of the motor.
Thereby it improves the motor responsiveness on changes in the speed reference or the load.
Field forcing is applied during all operation conditions except DC Injection.
Using parameter d6-06 a field forcing limit can be applied. A setting of 100% is equal to the no-load current set in parameter E2-03.
Related Parameters
Parameter
No.
d6-03 d6-06
Field forcing selection
Field forcing limit
Name
Factory
Setting
Change during
Operation
0
400%
No
No
Control Methods
V/f
Open
Loop
Vector
Closed
Loop
Vector
No No A
No A A
5
Adjusting DC injection current level
When Open Loop Vector control mode is used, the DC injection current level at stop for motoring and regenerative operation can be adjusted individually. The motor condition (Regenerative or motoring) is detected when the inverter is running at another speed than leveling speed.
The function can be used to improve the stopping behavior.
Related Parameters
Parameter
No.
S1-17
S1-18
Name
DC injection current regenerative
DC injection current motoring
Factory
Setting
Change during
Operation
100%
20%
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
No A No
No A No
5-
33
