Mitsubishi Electric FR-F800 Series Instruction Manual page 193

5.3.3 Troubleshooting in the speed control
PM PM PM
No. Condition
Motor does not run at the
correct speed.
1
(Command speed and
actual speed differ.)
The speed does not
2 accelerate to the
command speed.
3 Motor speed fluctuates.
Hunting (vibration or
4 acoustic noise) occurs in
the motor or the machine.
Acceleration/
5 deceleration time is
different from the setting.
Machine movement is
6
unstable.
Rotation ripple occurs
7 during the low-speed
operation.
Parameters referred to
Pr.3 Base frequency, Pr.19 Base frequency
Pr.72 PWM frequency
Pr.80 Motor capacity, Pr.81 Number of motor
Pr.125 Terminal 2 frequency setting gain frequency, Pr.126 Terminal 4 frequency setting gain
Pr.822 Speed setting filter
192
5. PARAMETERS
5.3 Speed control under PM motor control
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Possible cause
Speed command from the
controller is different from the
actual speed.
The speed command is
affected by noise.
The command speed and the
speed recognized by the
inverter are different.
Torque shortage.
Stall prevention function is
activated.
Only P (proportional) control is
performed.
Speed command varies.
Torque shortage.
Speed control gain is not
suitable for the machine.
(Resonance occurs.)
Speed control gain is too high. • Set Pr.820 lower and Pr.821 higher.
Torque control gain is too high.
Motor wiring is incorrect.
Torque shortage.
Load inertia is too high.
Speed control gain is not
suitable for the machine.
Response is slow because of
the inverter's acceleration/
deceleration time setting.
High carrier frequency is
affecting the motor rotation.
Speed control gain is too low.
voltagepage 552
selectionpage 218
polespage 177
1page 355
search engine
Countermeasure
• Check that the speed command sent from the controller is correct.
(Take EMC measures.)
• Set Pr.72 PWM frequency selection lower.
• Adjust the bias and gain of the speed command again in Pr.125,
Pr.126, C2 to C7, and C12 to C15.
• Raise the stall prevention operation level. (Refer to
• Increase the capacity.
• Speed deviation occurs under P (proportional) control when the load is
heavy. Select PI control.
• 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. (Refer to
• Raise the stall prevention operation level.
• (Refer to page 290.)
• Adjust Pr.820 Speed control P gain 1 and Pr.821 Speed control
integral time 1.
• Set Pr.824 Torque control P gain 1 (current loop proportional gain)
lower.
• Check the wiring.
• Raise the stall prevention operation level. (Refer to
• Set acceleration/deceleration time suitable for the load.
• Adjust Pr.820 and Pr.821.
• Set the optimum acceleration/deceleration time.
• Set Pr.72 lower.
• Set Pr.820 higher.
frequencypage 357
page 290.)
page 355.)
page 290.)