5.3 Description of Function Codes 5.3.1 F codes (Fundamental functions)
F42 = 2: V/f control with slip compensation
Applying any load to an induction motor causes a rotational slip due to the motor characteristics, decreasing the
motor rotation. The inverter’s slip compensation function first presumes the slip value of the motor based on the
motor torque generated and raises the output frequency to compensate for the decrease in motor rotation. This
prevents the motor from decreasing the rotation due to the slip.
That is, this function is effective for improving the motor speed control accuracy.
Specify the motor rated slip.
Slip compensation gain
(for drive)
Adjust the slip compensation for driving.
Slip compensation amount when driving = Rated slip x Slip
compensation gain (when driving)
Slip compensation gain
(braking)
Adjust the slip compensation amount when braking.
Slip compensation amount when braking = Rated slip x Slip
compensation gain (when braking)
Slip compensation
response time
Set the slip compensation response time. Basically, there is no need
to modify the setting.
To improve the accuracy of slip compensation, perform auto-tuning.
H68 enables or disables the slip compensation function 1 according to the motor driving conditions.
Motor driving frequency zone
F42 = 1: Dynamic torque vector control
To get the maximal torque out of a motor, this control calculates the motor torque matched to the load applied and
uses it to optimize the voltage and current vector output. Specify motor constants, or perform auto tuning.
When the vector control without speed sensor (dynamic torque vector) is selected, automatically auto torque boost
and slip compensation become enabled. This control is effective for improving the system response to external
disturbances such as load fluctuations, and the motor speed control accuracy.
Note that the inverter may not respond to a rapid load fluctuation.
F42 = 3: V/f control with speed sensor
Applying any load to an induction motor causes a rotational slip due to the motor characteristics, decreasing the
motor rotation. Under V/f control with speed sensor, the inverter detects the motor rotation using the encoder
mounted on the motor shaft and compensates for the decrease in slip frequency by the PI control to match the
motor rotation with the reference speed. This improves the motor speed control accuracy.
Speed detection is performed, but the motor starts based on the H09: Auto search mode setting. The
motor starts from the speed detection value only if auto search is enabled with function code H09 set to
1 or 2. If H09 = 0 (factory default), the speed detection value is ignored, and the motor starts from the
starting frequency.
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