Adjusting The Speed Control Gain Manually - Mitsubishi Electric FR-F800 Instruction Manual

Adjusting the speed control gain manually
• The speed control gain can be adjusted for the conditions such as abnormal machine vibration, acoustic noise, slow
response, and overshoot.
• 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.
Proportional gain
∗1
200 (100)rad/s
∗1
50 (25)rad/s
25%
(initial value)

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.
Load
fluctuation
Speed
Actual speed gain = Speed gain of a single motor 
• Adjust in the following procedure:
1) Change the Pr.820 setting while checking the conditions.
2) If it cannot be adjusted well, change Pr.821 setting, and perform 1) again.
Movement  condition
No.
1 Load inertia is high.
Vibration or acoustic noise
2 are generated from
machines.
3 Response is slow.
Return time (response time)
4
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.
Pr.820
Setting
100%
Since increasing the proportional gain enhances the
response level and decreases the speed fluctuation.
Decreasing the integral time shortens the return time taken.
JM + JL
Set Pr.820 and Pr.821 higher.
If acceleration is slow, raise the setting by 10%s and then set the value to 0.8 to 0.9 
Pr.820
the setting immediately before vibration/noise starts occurring.
If overshoots occur, raise the setting by double the setting and then set the value to 0.8
Pr.821
to 0.9  the setting where overshoots stop occurring.
Set Pr.820 lower and Pr.821 higher.
Lower the setting by 10%s and then set the value to 0.8 to 0.9  the setting
Pr.820
immediately before vibration/noise starts occurring.
If overshoots occur, raise the setting by double the setting and then set the value to 0.8
Pr.821
to 0.9  the setting where overshoots stop occurring.
Set Pr.820 higher.
If acceleration is slow, raise the setting by 5%s and then set the value to 0.8 to 0.9 
Pr.820
the setting immediately before vibration/noise starts occurring.
Set Pr.821 lower.
Lower Pr.821 by half the current setting and then set the value to 0.8 to 0.9  the setting
immediately before overshoots or unstable movements stop occurring.
Set Pr.821 higher.
Raise Pr.821 by double the current setting and then set the value to 0.8 to 0.9  the setting
immediately before overshoots or unstable movements stop occurring.
Speed control under PM motor control
JM JM: Motor inertia
JL: Load inertia converted as the motor axis inertia
Adjustment method
155
PARAMETERS
5