Mitsubishi Electric FR-F820-00046, Instruction Manual

Page: 228 / 940

Speed control under PM motor control Parameters
5 - 56
Adjusting the speed control gain manually
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The speed control gain can be adjusted for the conditions such as abnormal machine vibration,
acoustic noise, slow response, and overshoot.
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Pr. 820 "Speed control P gain 1" = "25 % (initial value)" is equivalent to 50 rad/s (speed response
of a single motor). (Equivalent to the half the rad/s value with the FR-F820-03160(75K) or higher
and FR-F840-01800(75K) or higher.) Setting this parameter higher speeds up the response, but
setting this too high causes vibration and acoustic noise.
●
Setting Pr. 821 "Speed control integral time 1" lower shortens the return time to the original speed
during speed fluctuation, but setting it too low causes overshoot.
The value in parentheses is applicable with the FR-F820-03160(75K) or higher and FR-F840-
01800(75K) or higher.
●
Actual speed gain is calculated as below when load inertia is applied.
JM: Motor inertia
JL: Load inertia converted as the motor axis inertia
Fig. 5-5:
Setting of the proportional gain
I001483E
I001484E
Fig. 5-6: Speed characteristic at load fluctuation
Actual speed gain = Speed gain of a single motor ×
JM
JM + JL
Proportional gain
200 (100) rad/s
50 (25) rad/s
25 %
(Initial value)
100 %
Pr. 820
Setting
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.