YASKAWA Varispeed G7 Instruction Manual page 423

Vector control will not perform if autotuning has not been performed. Perform autotuning separately for the
motor, or set the motor constants through calculations. Alternatively, change the control method selection (A1-
02) to V/f control (0 or 1).
Oscillation and hunting are occurring with V/f control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting constants C4-02
(Torque Compensation Primary Delay Time Constant), N1-02 (Hunting Prevention Gain), and C3-02 (Slip
Compensation Primary Delay Time) in order. Lower the gain setting and raise the primary delay time setting.
Oscillation and hunting are occurring with V/f w/PG control.
The gain adjustment may be insufficient. Adjust the various types of speed control loop (ASR) gain.
If the oscillation cannot be eliminated in this way, set the hunting prevention selection (constant N1-01) to 0
(disabled) and then try adjusting the gain again.
Oscillation and hunting are occurring with open-loop vector 2 control.
Adjust the control constants with reference to Adjusted User Constants on page 18 in Chapter 4 Trial Opera-
tion. If autotuning has not been performed, or the control method has been changed since last performing auto-
tuning, perform autotuning. If the problem occurs after performing stationary autotuning, perform rotational
autotuning.
If oscillation and hunting occur under the following special conditions, perform the adjustments described
here.
Low-speed regenerative load (PRG: 102
If oscillation occurs during low-speed regeneration, increase the setting of N4-30 (low-speed regeneration
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stability coefficient 2). Increase the setting in intervals of approximately 0.2. The larger the setting, the
greater the ratio of the speed increase relative to the regenerative load will be.
Operating frequency between 6 and 10 Hz (PRG: 102
Accelerate the motor gradually, set N4-32 (speed estimator gain fluctuation frequency 1) to the lowest
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speed at which oscillation occurs and set N4-33 (speed estimator gain fluctuation frequency 2) to the high-
est. Then, reduce the setting of N4-34 (speed estimator gain fluctuation rate) until the oscillation stops.
Adjust N4-34 in intervals of approximately 5% in the range 50% to 100%.
Oscillation and hunting are occurring with 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 autotuning is not performed, proper performance cannot be achieved for vector control. Perform autotuning
or set the motor constants 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 constants. (Refer to page 6-110.)
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Troubleshooting
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