Mitsubishi FR-A800

Speed control under Real sensorless vector control, vector control, PM sensorless vector
control
PARAMETERS
195
5
Adjusting the speed control gain manually (Pr.819 = "0" No easy gain
tuning)
• 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="60% (initial value)" is equivalent to 120 rad/s (speed response of a single motor).
(Equivalent to the half the rad/s value during Real sensorless vector control or with the FR-A820-03800(75K) or higher and
FR-A840-02160(75K) or higher during vector control.) 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 during Real sensorless vector control or with the FR-A820-03800(75K) or higher and FR-A840-
02160(75K) or higher during vector control.
 Performing PM parameter initialization changes the settings. (Refer to page 173.)
• Actual speed gain is calculated as below when load inertia is applied.
• 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.
Actual speed gain = Speed gain of a single motor 
JM JM: Motor inertia
JL: Load inertia converted as the motor axis inertia
JM + JL
No. Movement  condition Adjustment method
1 Load inertia is high.
Set Pr.820 and Pr.821 higher.
Pr.820
If acceleration is slow, raise the setting by 10%s and then set the value to 0.8 to 0.9 
the setting immediately before vibration/noise starts occurring.
Pr.821
If overshoots occur, raise the setting by double the setting and then set the value to 0.8
to 0.9  the setting where overshoots stop occurring.
2
Vibration or acoustic noise
are generated from
machines.
Set Pr.820 lower and Pr.821 higher.
Pr.820
Lower the setting by 10%s and then set the value to 0.8 to 0.9  the setting
immediately before vibration/noise starts occurring.
Pr.821
If overshoots occur, raise the setting by double the setting and then set the value to 0.8
to 0.9  the setting where overshoots stop occurring.
3 Response is slow.
Set Pr.820 higher.
Pr.820
If acceleration is slow, raise the setting by 5%s and then set the value to 0.8 to 0.9 
the setting immediately before vibration/noise starts occurring.
4
Return time (response time)
is long.
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.
5
Overshoots or unstable
movements occur.
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.
Pr.820
Setting
100%
60%
(initial value
)
Proportional gain
200 (100)rad/s
120 (60)rad/s
∗1
∗1
∗2
Since increasing the proportional gain enhances the
response level and decreases the speed fluctuation.
Load
fluctuation
Speed
Decreasing the integral time shortens the return time taken.