Mitsubishi Electric FR-A820-00046 Instruction Manual page 288

Speed control under Real sensorless vector control, vector control, PM sensorless vector control
No. Condition
Motor speed
4
fluctuates.
Hunting (vibration
or acoustic noise)
5
occurs in the motor
or the machine.
Acceleration/
deceleration time is
6
different from the
setting.
Machine movement
7
is unstable.
Rotation ripple
occurs during the
8
low-speed
operation.
Tab. 5-39:
Parameters referred to
Pr. 3
Pr. 19
Pr. 72
Pr. 80
Pr. 81
Pr. 125
Pr. 126
Pr. 359
Pr. 369
Pr. 822
Pr. 824
Pr. 851
Pr. 852
5 - 108
Cause
Speed command varies.
Torque shortage.
Speed control gain is not
suitable for the machine.
(Resonance occurs.)
Speed control gain is too
high.
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.
Troubleshooting (2)
Base frequency
Base frequency voltage
PWM frequency selection
Motor capacity
Number of motor poles
Terminal 2 frequency setting gain frequency
Terminal 4 frequency setting gain frequency
Encoder rotation direction
Number of encoder pulses
Speed setting filter 1
Torque control P gain 1 (current loop proportional gain)
Control terminal option-Number of encoder pulses
Control terminal option-Encoder rotation direction
Countermeasure
Check that the speed command sent from the controller is
correct. (Take EMC measures.)
Set Pr. 72 "PWM frequency selection" lower.
Set Pr. 822 "Speed setting filter 1" higher (page 5-399).
Raise the torque limit.
(Refer to the torque limit for speed control on page 5-84.)
Perform speed feed forward control.
Perform easy gain tuning.
Adjust Pr. 820 "Speed control P gain 1" and Pr. 821 "Speed
control integral time 1".
Perform speed feed forward control or model adaptive speed
control.
Perform easy gain tuning.
Set Pr. 820 "Speed control P gain 1" lower and Pr. 821 "Speed
control integral time 1" higher.
Perform speed feed forward control or model adaptive speed
control.
Set Pr. 824 "Torque control P gain 1 (current loop proportional
gain)" lower.
Check the wiring.
Raise the torque limit.
(Refer to the torque limit for speed control on page 5-84.)
Perform speed feed forward control.
Set acceleration/deceleration time suitable for the load.
Perform easy gain tuning.
Adjust Pr. 820 and Pr. 821.
Perform speed feed forward control or model adaptive speed
control.
Set the optimum acceleration/deceleration time.
Set Pr. 72 "PWM frequency selection" lower.
Set Pr. 820 "Speed control P gain 1" higher.
Parameters
=> page 5-654
=> page 5-654
=> page 5-219
=> page 5-56
=> page 5-56
=> page 5-401
=> page 5-401
=> page 2-73
=> page 2-73
=> page 5-399
=> page 5-144
=> page 2-73
=> page 2-73