YASKAWA SGMAH, User Manual

Page: 246 / 488

Sigma II User’s Manual Chapter 6: Servo Adjustment
6 - 18
Operating Example
If the system is always in PI control without using the mode switch function, the
speed of the motor may overshoot or undershoot due to torque saturation at the time
of the acceleration or deceleration of the motor. The mode switch function
suppresses torque saturation and eliminates motor speed overshoot or undershoot.
Error Pulse Used as a Detection Point
This setting is enabled for position control operation only.
If an error pulse exceeds the value set in parameter Pn10F, the speed loop switches to
P control.
Operating Example
In this example, the mode switch is used to reduce setting time. Generally, speed
loop gain must be increased to reduce setting time. Using the mode switch
suppresses the occurrence of overshoot and undershoot when speed loop gain is
increased.
Overshoot
Undershoot
Motor
speed
Time
Without mode switch
With mode switch
Motor
speed
Time
Motor speed
Reference
Speed
Pn10F
Deviation
Pulse
Time
P control PI control PI control
Motor speed
Speed reference
Without mode switch
Long setting time
Increase speed loop gain.
Overshoot
Without mode switch
With mode switch function
Setting time
Motor
speed
Motor
speed
Motor
speed
Under
shooting
Time
Suppress overshoot
and undershoot