Mitsubishi Electric FR-F820-00046, Instruction Manual

Page: 230 / 940

Speed control under PM motor control Parameters
5 - 58
5.3.3 Troubleshooting in the speed control
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, C2 to C7, C12 to C15)
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 5-180.)
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 "PWM frequency selection" lower.
Set Pr. 822 "Speed setting filter 1" higher (page 5-264).
Torque shortage.
Raise the stall prevention operation level.
(Refer to page 5-180.)
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 "Speed control P gain 1" lower and Pr. 821 "Speed
control integral time 1" 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 5-180.)
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 "PWM frequency selection" lower.
Speed control gain is too
low.
Set Pr. 820 "Speed control P gain 1" higher.
Tab. 5-24: Troubleshooting
Parameters referred to
Pr. 3 Base frequency => page 5-537
Pr. 19 Base frequency voltage => page 5-537
Pr. 72 PWM frequency selection => page 5-88
Pr. 80 Motor capacity => page 5-41
Pr. 81 Number of motor poles => page 5-41
Pr. 125 Terminal 2 frequency setting gain frequency => page 5-266
Pr. 126 Terminal 4 frequency setting gain frequency => page 5-266
Pr. 822 Speed setting filter 1 => page 5-264
PM PM PM