YASKAWA SGD7S Product Manual page 348

8.13 Manual Tuning
8.13.1 Tuning the Servo Gains
Information
 Speed Loop Gain
This parameter determines the response characteristic of the speed loop. If the response char-
acteristic of the speed loop is low, it becomes a delay factor for the position loop located out-
side of the speed loop. This will result in overshooting and vibration in the speed reference.
Therefore, setting the speed loop gain as high as possible within the range that will not cause
the machine system to vibrate will produce a stable servo system with a good response char-
acteristic.
Pn100
Setting of Pn103 =
The default setting of Pn103 (Moment of Inertia Ratio) is 100. Before you tune the servo, calcu-
late the moment of inertia ratio with the above formula and set Pn103 to the calculation result.
Pn103
 Speed Loop Integral Time Constant
To enable response to even small inputs, the speed loop has an integral element. The integral
element becomes a delay factor in the servo system. If the time constant is set too high, over-
shooting will occur, positioning settling time will increase, and the response characteristic will
suffer.
Pn101
8-82
For machines for which a high position loop gain (Pn102) cannot be set, overflow alarms can
occur during high-speed operation. If that is the case, you can increase the setting of the fol-
lowing parameter to increase the level for alarm detection.
Use the following condition as a guideline for determining the setting.
Maximum feed speed [reference units/s]

Pn520
Pn102 ÷ 10 (1/s)
If you use a position reference filter, transient deviation will increase due to the filter time con-
stant. When you make the setting, consider deviation accumulation that may result from the
filter.
Position Deviation Overflow Alarm Level
Setting Range
Pn520
1 to
1,073,741,823
Speed Loop Gain
Setting Range Setting Unit
10 to 20,000
Load moment of inertia at motor shaft (J
Servomotor moment of inertia (L
Moment of Inertia Ratio
Setting Range Setting Unit
0 to 20,000
Speed Loop Integral Time Constant
Setting Range Setting Unit
15 to 51,200

2.0
Setting Unit Default Setting When Enabled Classification
1 reference
5,242,880
unit
Default Setting
0.1 Hz 400
)
L
)
M
Default Setting
1% 100
Default Setting
0.01 ms 2,000
Position
Immediately
Speed Position
When Enabled
Immediately
×100(%)
Speed Position
When Enabled
Immediately
Speed Position
When Enabled
Immediately
Setup
Torque
Classifica-
tion
Tuning
Torque
Classifica-
tion
Tuning
Classifica-
tion
Tuning