Mitsubishi Electric 800 Series Instruction Manual page 109

 Adjustment procedure
1.
Change the Pr.820 setting while checking the conditions.
2.
If it cannot be adjusted well, change Pr.821 setting, and perform step
No. Movement / condition
1 Load inertia is too high.
Vibration or acoustic
2 noise are generated from
machines.
3 Response is slow.
Return time (response
4
time) is long.
Overshoots or unstable
5
movements occur.
NOTE
• Pr.830 Speed control P gain 2 and Pr.831 Speed control integral time 2 are valid when terminal RT is ON. In this case,
replace them for Pr.820 and Pr.821 in the description above.
 When using a multi-pole motor (8 poles or more)
• If the motor inertia is known, set Pr.707 Motor inertia (integer) and Pr.724 Motor inertia (exponent). (Refer to
• Under Real sensorless vector control, adjust Pr.820 Speed control P gain 1 and Pr.824 Torque control P gain 1
(current loop proportional gain) according to the motor as shown in the following table.
• Setting the parameter of Pr.820 Speed control P gain 1 higher speeds up the response, but setting this too high causes
vibration and acoustic noise.
• Setting the parameter of Pr.824 Torque control P gain 1 (current loop proportional gain) too low causes current ripple,
and a noise synchronous with this will be emitted from the motor.
• Adjustment method:
No. Movement / condition
Motor rotation speed in the low-
1
speed range is unstable.
2 Rotation speed trackability is poor. Set Pr.820 Speed control P gain 1 higher. Raise the setting by 10%s and set a
Large fluctuation of the rotation
3
speed relative to load fluctuation.
Torque shortage or motor
backlash occurs when starting or
4
passing a low-speed range under
Real sensorless vector control.
Unusual vibration, noise and
5 overcurrent of the motor or
machine occurs.
Overcurrent or overspeed (E.OS)
6 occurs when starting under Real
sensorless vector control.
108
5. Speed control
5.4 Performing high-accuracy, fast-response control (gain adjustment for Real sensorless vector control and PM sensorless vector control)
Set Pr.820 and Pr.821 higher.
If acceleration is slow, raise the setting by 10% and then set the value to 80% to 90% of the
Pr.820
setting immediately before vibration/noise starts occurring.
If overshoots occur, set about 80% to 90% of the maximum value without overshooting while
Pr.821
increasing the setting value by twice.
Set Pr.820 lower and Pr.821 higher.
Set about 80% to 90% of the maximum value without any vibration/noise while decreasing the
Pr.820
setting value by 10%.
If overshoots occur, set about 80% to 90% of the maximum value without overshooting while
Pr.821
increasing the setting value by twice.
Set Pr.820 higher.
If acceleration is slow, set about 80% to 90% of the maximum value without any vibration/
Pr.820
acoustic noise while increasing the setting value by 5%.
Set Pr.821 lower.
Set about 80% to 90% of the maximum value without overshooting or unstable movements while
decreasing the setting value of Pr.821 by half.
Set Pr.821 higher.
Set about 80% to 90% of the maximum value without overshooting or unstable movements while
increasing the setting value of Pr.821 by double.
Pr.820 Speed control P gain 1 must be set higher according to the motor inertia.
For multi-pole motors, because the inertia of the motor itself tends to be large, first
perform broad adjustment to improve the unstable movements, and then perform
fine adjustment by referring to the response level based on this setting.
value that approximately 80% to 90% of the setting right before vibration/noise
starts occurring. If it cannot be adjusted well, double Pr.821 Speed control integral
time 1 and perform the adjustment of Pr.820 again.
Set the speed control gain higher. (The same as No.1.) If this cannot be prevented
through gain adjustment, raise Pr.13 Starting frequency for a fault that occurs
when starting, or shorten the acceleration time and avoid continuous operation in a
low-speed range.
Set Pr.824 Torque control P gain 1 (current loop proportional gain) lower.
Lower the setting by 10% and set a value that is approximately 80% to 90% of the
setting immediately before the condition improves.
1
again.
Adjustment method
Adjustment method
page 299.)