Contents

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.
Name
Factory
Setting
Change
during
Operation
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
C3-01 Slip compensation gain 1.0 Yes A A No
C3-02 Slip compensation delay time 2000 ms No A A No
C3-03 Slip compensation limit 200% No A A No
C3-04 Slip compensation during regeneration 0 No A A No
C3-05 Output voltage limit operation selection 0 No No A 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:
Rated motor speed (rpm) × Number of motor poles
slip (Hz) = Motor rated frequency (Hz) – ---------------------------------------------------------------------------------------------------------------------------
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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.
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