157
5. PARAMETERS
5.3 Speed control under PM motor control
3
4
5
5
5
6
7
8
9
10
5.3.3 Troubleshooting in the speed control
Pr.3 Base frequency, Pr.19 Base frequency voltage page 539
Pr.72 PWM frequency selection page 179
Pr.80 Motor capacity, Pr.81 Number of motor poles page 145
Pr.125 Terminal 2 frequency setting gain frequency, Pr.126 Terminal 4 frequency setting gain frequency page 328
Pr.822 Speed setting filter 1 page 326
No. Condition Cause Countermeasure
1 Motor does not run at
the correct speed.
(Command speed and
actual speed differ.)
Speed command from the
controller is different from
the actual speed.
The speed command is
affected by noise.
• Check that the speed command sent from the controller is correct. (Take
EMC measures.)
•Set Pr.72 PWM frequency selection lower.
The command speed and
the speed recognized by the
inverter are different.
• Adjust the bias and gain (Pr.125, Pr.126, Pr.902 to Pr.905, Pr.917,
Pr.918) of the speed command again.
2 The speed does not
accelerate to the
command speed.
Torque shortage.
The stall prevention
operation level is operating.
• Raise the stall prevention operation level.
• (Refer to page 257.)
• Increase the capacity.
Only P (proportional) control
is performed.
• Speed deviation occurs under P (proportional) control when the load is
heavy. Select PI control.
3 Motor speed
fluctuates.
Speed command varies. • Check that the speed command sent from the controller is correct. (Take
EMC measures.)
•Set Pr.72 lower.
•Set Pr.822 Speed setting filter 1 higher. (page 326)
Torque shortage. • Raise the stall prevention operation level.
• (Refer to page 257.)
Speed control gain is not
suitable for the machine.
(Resonance occurs.)
• Adjust Pr.820 Speed control P gain 1 and Pr.821 Speed control integral
time 1.
4 Hunting (vibration or
acoustic noise) occurs
in the motor or the
machine.
Speed control gain is too
high.
•Set Pr.820 lower and Pr.821 higher.
Torque control gain is too
high.
•Set Pr.824 Torque control P gain 1 (current loop proportional gain)
lower.
Motor wiring is incorrect. • Check the wiring.
5 Acceleration/
deceleration time is
different from the
setting.
Torque shortage. • Raise the stall prevention operation level.
• (Refer to page 257.)
Load inertia is too high. • Set acceleration/deceleration time suitable for the load.
6 Machine movement is
unstable.
Speed control gain is not
suitable for the machine.
• Adjust Pr.820 and Pr.821.
Response is slow because
of the inverter's
acceleration/deceleration
time setting.
• Set the optimum acceleration/deceleration time.
7 Rotation ripple occurs
during the low-
speed
operation.
High carrier frequency is
affecting the motor rotation.
•Set Pr.72 lower.
Speed control gain is too
low.
•Set Pr.820 higher.
Parametersreferredto
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