Mitsubishi Electric FR-A700 Instruction Manual page 155

Basic settings
Manual input speed control gain adjustment
Make adjustment when any of such phenomena as unusual machine vibration/noise, low re-
sponse 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.
response
200rad/s
120rad/s
● 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.
Fig. 5-15: Speed characteristic at load fluctuation
Also, when there is load inertia, the actual speed gain decreases as indicated below.
Actual speed gain
JM: Inertia of the motor
JL: Motor shaft-equivalent load inertia
FR-A700 EC
Speed
60% 100%
(Initial
gain)
Load
fluctuation
Speed
= speed gain of motor without load
Fig. 5-14:
Setting of the proportional gain
Pr. 820
Proportional
gain
Since increasing the proportional gain enhances the response
level and decreases the speed fluctuation.
Decreasing the integral time shortens the return time taken.
JM
×
--------------------
JM + JL
Simple mode parameter list
I001483E
I001484E
5 - 35