Mitsubishi Electric FR-D720-0.2K-G Instruction Manual page 83

Test operation and gain adjustment of the PM sensorless vector control
· Adjust in the following procedure:
1) Change the Pr. 820 setting while checking the conditions.
2) If it cannot be adjusted well, change Pr. 821 setting, and perform 1) again.
No. Movement/condition
1
Load inertia is too high.
Vibration or acoustic noise is
2
generated from machines.
3
Response is slow.
Return time (response time)
4
is long.
Overshoots or unstable
5
movements occur.
(2) Troubleshooting
Condition
Motor does not run at the correct
speed.
1
(Command speed and actual
speed differ.)
The speed does not accelerate to
2
the command speed.
3 Motor speed fluctuates.
Hunting (vibration or acoustic
4 noise) occurs in the motor or the
machine.
80
Set Pr. 820 and Pr. 821 higher.
If acceleration is slow, raise the setting by 10%s and set a value that
Pr. 820 satisfies the following condition: The setting immediately before vibration/
noise starts occurring  0.8 to 0.9
If overshoots occur, raise the setting by double the setting and set a value
Pr. 821 that satisfies the following condition: The setting where overshoots stop
occurring  0.8 to 0.9
Set Pr. 820 lower and Pr. 821 higher.
Lower the setting by 10%s and set a value that satisfies the following
condition: The setting immediately before vibration/noise starts occurring 
Pr. 820
0.8 to 0.9
If overshoots occur, raise the setting by double the setting and set a value
Pr. 821 that satisfies the following condition: The setting where overshoots stop
occurring  0.8 to 0.9
Set Pr. 820 higher.
If acceleration is slow, raise the setting by 5%s and set a value that satisfies
Pr. 820 the following condition: The setting immediately before vibration/noise starts
occurring  0.8 to 0.9
Set Pr. 821 lower.
Lower Pr. 821 by half the current setting and set a value that satisfies the following
condition: The setting immediately before overshoots or unstable movements stop
occurring  0.8 to 0.9
Set Pr. 821 higher.
Raise Pr. 821 by double the current setting and set a value that satisfies the following
condition: The setting immediately before overshoots or unstable movements stop
occurring  0.8 to 0.9
Possible Cause
(1) Speed command from the
controller is different from
the actual speed.
The speed command is
affected by noise.
(2) The command speed and
the speed recognized by
the drive unit are different.
(1) Torque shortage
Stall prevention operation
is activated.
(2) Only P (proportion) control
is performed.
(1) Speed command varies.
(2) Torque shortage
(3) Speed control gain is not
suitable for the machine.
(Resonance occurs.)
(1) Speed control gain is too
high.
(2) Motor wiring is incorrect.
Adjustment Method
Countermeasure
(1) Check that the speed command sent from the
controller is correct. (Take EMC measures.)
(2) Adjust bias and gain (Pr. 125, Pr. 126, C2 to C7) of the
speed command again.
(1) -1 Raise the stall prevention operation level. (
.)
page 83
(1) -2 Capacity shortage
(2) Speed deviation occurs under P (proportional)
control when the load is heavy. Select PI control.
(1) Check that the speed command sent from the
controller is correct. (Take EMC measures.)
(2) Raise the stall prevention operation level. (Refer to
page 83.)
(3) Adjust Pr. 820 and Pr. 821 (
(1) Set Pr. 820 lower and Pr. 821 higher.
(2) Check the wiring.
Refer to
.)
Refer to page 79