Specifications

49
Constant Descriptions
5. Adjust Motor Torque
Compensate for Torque at Start/Low-
speed Operation
Torque compensation gain C4-01
Torque compensation is a function to detect the increase of
the motor load and increase output torque.
If control method selection (A1-02) is set to 0 (V/f control
without PG) or 1 (V/f control with PG), this function
compensates for insufficient torque at start or low-speed
operation using the entire area full-automatic torque boost
function according to output voltage.
When control method selection (A1-02) is set to 2 (open-
loop vector control), motor torque is automatically
controlled according to the load by calculating motor
primary current to compensate for undertorque.
Automatic torque offset gain normally does not need
adjustment. The factory setting is C4-01 = 1.0
Make necessary adjustments when the wiring distance
between the inverter and motor is long, or when the motor
vibrates excessively.
The motor torque can be increased by increasing the
torque offset gain, but may also cause the following
failures.
・
Excessive motor current may cause failure of the inverter.
・The motor may heat or vibrate excessively.
Increase the torque offset gain little by little, while
observing the motor current.
Limit Motor Torque
Forward torque limit L7-01
Reverse torque limit L7-02
Forward regenerative torque limit L7-03
Reverse regenerative torque limit L7-04
The motor torque limit function is enabled at vector control
with PG and open-loop vector control.
Since torque that is output from the motor is calculated
internally in the vector control with PG and the open-loop
vector control mode, torque limit can be applied with any
value. This function is effective when torque exceeding a
certain amount is not to be applied to the load or when the
regenerative value is not to be generated at a certain
amount or more.
Set the torque limit value in the ％ for the motor rated
torque.
It can be set individually in each quadrant.
Torque Reference
Positive
Negative
Forward Regenerative Torque Limit
L7-03
Reverse Regenerative Torque Limit
L7-04
Forward
Motor Rotation
Reverse
Reverse Torque Limit
L7-02
Forward Torque Limit
L7-01
Notes:・Since torque control has a priority when the torque limit function
operates, the motor revolution control or compensation will be
disabled. Therefore, accel/decel time may increase or the motor
revolutions may reduce.
Notes:・When torque limit is used for lifting load applications, set such a
torque limit value that the load may not drop or slip.
Notes:・To increase the torque limit value, the inverter capacity may have
to be increased.