Mitsubishi Electric FR-A700 EC, Instruction Manual

Page: 272 / 826

Speed control by real sensorless vector control, vector control Parameter
6 - 92
Manual input speed control gain adjustment
Make adjustment when any of such phenomena as unusual machine vibration/noise, low
response level and overshoot has occurred.
●
Pr. 820 "Speed control P gain 1" = 60% (initial value) is equivalent to 120rad/s (speed
response of the motor alone). Increasing the setting value improves the response level, but
a too large gain will produce vibration and/or unusual noise.
●
Decreasing the Pr. 821 "Speed control integral time 1" shortens the return time taken at a
speed change. However, a too short time will generate an overshoot.
●
When there is load inertia, the actual speed gain is as given below.
Also, when there is load inertia, the actual speed gain decreases as indicated below.
JM: Inertia of the motor
JL: Motor shaft-equivalent load inertia
Fig. 6-16:
Setting of the proportional gain
I001483E
I001484E
Fig. 6-17: Speed characteristic at load fluctuation
Speed
response
200rad/s
120rad/s
60%
(Initial
gain)
100%
Pr. 820
Proportional
gain
Load
fluctuation
Speed
Decreasing the integral time shortens the return time taken.
Since increasing the proportional gain enhances the response
level and decreases the speed fluctuation.
Actual speed gain speed gain of motor without load
JM
JM JL +
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×
=