Sigma II User’s Manual
Chapter 6: Servo Adjustment
6-13
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 sup-
presses the occurrence of overshoot and undershoot as speed loop gain is increased.
Acceleration Used as Detection Point
If motor acceleration exceeds the value set in parameter Pn10E, the speed loop
switches to P control.
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 sup-
presses torque saturation and eliminates motor speed overshoot or undershoot.
Motor speed
Speed reference
Without mode switch
Long setting time
Increase speed loop gain.
Overshoot
Without mode switch
With mode switch
Setting time
Suppress overshooting
and undershooting.
Motor
speed
Motor
speed
Motor
speed
Undershoot
Time
Motor speed
Reference speed
Speed
Motor acceleration
+Pn10E
Acceleration 0
-Pn10E
PI control
PI control
PI control
P control
P control
Overshoot
Undershoot
Motor
speed
Time
Without mode switch
With mode switch
Motor
speed
Time
