7-24
Oscillation and hunting occur in Open Loop Vector Control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting parameters C4-
02 (Torque Compensation Primary Delay time), n2-01 (Speed Feedback Detection Control (AFR) Gain), and
C3-02 (Slip Compensation Primary Delay Time) in order. Lower the gain setting and raise the primary delay
time setting.
Open Loop Vector Control will not operate the motor if Auto-Tuning has not yet been performed. Perform
Auto-Tuning, or calculate and set the motor parameters manually. Alternatively, change the Control Method
Selection to the V/f Control Method (A1-02 = 0).
Oscillation and hunting are occurring in V/f control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting parameters C4-
02 (Torque Compensation Primary Delay Time), C3-02 (Slip Compensation Primary Delay Time), and n1-02
(Hunting-Prevention Gain) in order. Lower the gain setting and raise the primary delay time setting.
Oscillation and hunting are occurring in Flux Vector Control.
The gain adjustment is insufficient. Adjust the various gains for speed control (ASR). If the oscillation points
overlap with those of the machine and cannot be eliminated, increase the primary delay time constant for
speed control (ASR) in C5-06 and then readjust the gains.
If Auto-Tuning is not performed, proper performance cannot be achieved for vector control. Perform Auto-
Tuning or set the motor parameters according to calculations.
Oscillation and hunting are occurring with PID control.
If there is oscillation or hunting during PID control, check the oscillation cycle and individually adjust P, I,
and D parameters. (Refer to page 6-98.)
Auto-Tuning has not been performed for Open Loop Vector Control.
Open Loop Vector Control will not operate the motor if Auto-Tuning has not yet been performed. Perform
Auto-Tuning, or calculate and set the motor parameters manually. Alternatively, change the Control Method
Selection to the V/f Control Method (A1-02 = 0).
Torque Generated for the Motor is Insufficient (Insufficient Power)
If Auto-Tuning has not yet been performed or the control method has been changed since the last time Auto-
Tuning was performed, then perform Auto-Tuning again. If the problem occurs after Stationary Auto-Tuning
is performed, perform Rotational Auto-Tuning.
Motor Rotates Even When MxC Output is Stopped
If the motor rotates even when the MxC output is stopped, the DC injection braking is insufficient. If the
motor continues operating at low speed, without completely stopping, and after a deceleration stop has been
executed, it means that the DC Injection Braking is not decelerating enough. Adjust DC Injection Braking as
follows:
• Increase the parameter b2-02 (DC Injection Braking Current) setting.
• Increase the parameter b2-04 (DC Injection Braking Time at Stop) setting.
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