YASKAWA SGM-A3 User Manual page 137

APPLICATIONS OF Σ-SERIES PRODUCTS
3.6.6 Using Mode Switch cont.
3
124
When Speed Reference Is Used as a Detection Point of Mode Switch
If a speed reference exceeds the value set in user
constant Cn-0D, the speed loop switches to P
control.
Example of Use:
The mode switch is used to reduce settling time.
Generally, speed loop gain must be increased to reduce settling time. Using the
mode switch suppresses the occurrence of overshoot and undershoot when
speed loop gain is increased.
Without mode switch
Speed reference Motor speed
Motor
speed
Settling time is long
When Acceleration Is Used as a Detection Point of Mode
Switch
If motor acceleration exceeds the value set in user
constant Cn-0E, the speed loop switches to P
control.
Example of Use:
If a mode switch is not used and PI control is always performed, torque may
enter a saturation state during acceleration or deceleration, causing the motor
speed to have overshoot or undershoot.
Using the mode switch suppresses torque saturation and prevents the motor
speed from having overshoot and undershoot.
Without mode switch
Overshoot
Motor
speed
Undershoot
Time
Speed
PI control
Increase speed loop gain
With mode switch
Motor
speed
Settling time
Speed
Acceleration
reference
Speed reference
P control PI control
Without mode switch
Overshoot
Motor
speed
Undershoot
Time
Suppress the occurrence
of overshoot and
undershoot.
Reference
speed
Motor speed
Motor
acceleration
PI control PI control PI control
P control P control
With mode switch
Motor
speed
Time
Motor
speed