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Servo Adjustment
6.2.5 Using Mode Switch
6 -12
Speed reference
Speed
Pn10D
Motor speed
Time
P control
PI
control
PI 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 overshooting and undershooting when speed loop gain is increased.
Motor speed
Speed reference
Without mode switch
Long setting time
Increase speed loop gain.
Overshooting
Without mode switch
With mode switch
Setting time
Suppress overshooting
and undershooting.
Motor
speed
Motor
speed
Motor
speed
Under-
shooting
Time
Acceleration Used as Detection Point
If motor acceleration exceeds the value set in user constant Pn10E, the speed loop switches to
P control.
Motor speed
Reference speed
Speed
Motor acceleration
+Pn10E
Acceleration 0
--Pn10E
PI control
PI control
PI control
P control
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 accelera-
tionordecelerationofthemotor. Themode switchfunction suppressestorque saturationand
eliminates the overshooting or undershooting of the motor speed.
Overshooting
Under-
shooting
Motor
speed
Time
Without mode switch
With mode switch
Motor
speed
Time
6
A
EXAMPLE
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A
EXAMPLE
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