Omron SYSDRIVE 3G3RV, User Manual

Page: 385 / 446

Troubleshooting
7-
23
n
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 parameters 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.
n
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 (parameter N1-01) to 0
(disabled)
and then try adjusting the gain again.
n
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 6-120.)
n
PID control diverges.
The
following causes are possible.
Feedback is not being input.
If
no feedback is being input and the detection value is zero, PID control will fail to function and the output
will
diverge. This will cause the motor speed to increase to the maximum frequency. Check for a break in the
feedback
signal or for an incorrect setting of either H3-09 (multi-function analog input terminal A2 function
selection)
= B or H6-01 (pulse train input function selection) = 1. Also check to make sure that the PID-related
parameters
are correct.
The target values and detection values do not agree.
PID
control brings the difference (error) between the target value and detection value to zero. Because of this,
it
is necessary to unify the input levels for the target value and detection value. Set the gain so that the level of
detection
coincides.
Example:
H3-10/H3-11 (gain (terminal A2)/bias (terminal A2)) or H6-03/H6-04 (pulse train input gain/pulse
train
input bias)
The Inverter output frequency and detection value relationship is reversed.
If
the Inverter is set so that the detection value decreases when the output frequency increases, the PID control
will
diverge. Correct this by switching the forward/reverse status of b5-09 (PID output characteristics selec-
tion).
For example, if 0 is being used, change it to 1.
n
Autotuning has not been performed with vector control.
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.
K K K K
If the Motor Rotates Even When Inverter Output Is Stopped
If
the motor rotates even when the Inverter 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