Mitsubishi Electric FR-A820-00046 Instruction Manual page 284

Speed control under Real sensorless vector control, vector control, PM sensorless vector control
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 page 5-67.)
● Under Real sensorless vector control or vector control, adjust Pr. 820 "Speed control P gain 1" and
Pr. 824 "Torque control P gain 1 (current loop proportional gain)" to suit the motor, by referring to
the following methods.
● 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.
Rotation speed trackability is
2
poor.
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.
Tab. 5-37:
5 - 104
Adjustment method
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.
Also, for vector control, gain adjustment appropriate for the inertia can be easily
performed by using easy gain tuning (Pr. 819 = 1).
Set Pr. 820 "Speed control P gain 1" higher. Raise the setting by 10%s and set a
value that satisfies the following condition:
The setting immediately before vibration/noise starts occurring × 0.8 to 0.9.
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% s and set a value that satisfies the following condition:
The setting immediately before the condition improves × 0.8 to 0.9.
Adjustment method
Parameters