Mitsubishi Electric 800 Series Instruction Manual page 157

• 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.
No. Movement / condition
1 Load inertia is high.
2 Vibration or acoustic noise
are generated from
machines.
3 Response is slow.
4 Return time (response time)
is long.
5 Overshoots or unstable
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.
 Gain adjustment of current controllers for the d axis and the q axis
• Use Pr.824 Torque control P gain 1 (current loop proportional gain) to adjust the proportional gain of current
controllers for the d axis and the q axis. The 100% gain is equivalent to 1000 rad/s. Setting this parameter higher improves
the trackability for current command changes. It also reduces the current fluctuation caused by external disturbances.
• Use Pr.825 Torque control integral time 1 (current loop integral time) to set the integral time of current controllers for
the d axis and the q axis. If the setting value is small, it produces current fluctuation against external disturbances,
decreasing time until it returns to original current value.
NOTE
• Pr.834 Torque control P gain 2 (current loop proportional gain) and Pr.835 Torque control integral time 2 (current
loop integral time) are valid when terminal RT is ON. In this case, replace them for Pr.824 and Pr.825 in the description
above.
156
5. PARAMETERS
5.3 Speed control under PM motor control
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
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.
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.
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 immediately
Pr.820
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.
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.
JM: Motor inertia
JL: Load inertia converted as the motor axis inertia
Adjustment method