Using The Mode Switch (P/Pi Switching) - YASKAWA SGDH User Manual

9.4.5 Using the Mode Switch (P/PI Switching)

Use the mode switch (P/PI switching) function in the following cases:
• To suppress overshooting during acceleration or deceleration (for speed control)
• To suppress undershooting during positioning and reduce the settling time (for position control)
Speed
The mode switch function automatically switches the speed control mode from PI control mode to P control
mode based on a comparison between the servo's internal value and a user-set detection level.
1. The mode switch function is used in very high-speed positioning when it is necessary to use the
IMPORTANT
servodrive near the limits of its capabilities. The speed response waveform must be observed to adjust
the mode switch.
2. For normal use, the speed loop gain and position loop gain set by autotuning provide sufficient speed/
position control. Even if overshooting or undershooting occur, they can be suppressed by setting the host
controller's acceleration/deceleration time constant, the SERVOPACK's Soft Start Acceleration/Deceler-
ation Time (Pn305, Pn306), or Position Reference Acceleration/Deceleration Time Constant (Pn204).
(1) Selecting the Mode Switch Setting
The SERVOPACK provides the following four mode switch settings (0 to 3). Select the appropriate mode switch
setting with parameter Pn10B.0.
Parameter
Pn10B n.
n.
n.
n.
n.
Select a condition to execute the mode switch (P/PI switching). (Setting is validated immediately.)
1
From PI control to P control
TERMS
PI control means proportional/integral control and P control means proportional control. In short, switching "from PI
control to P control" reduces effective servo gain, making the SERVOPACK more stable.
Overshoot
Actual motor operation
Reference
Time
Undershoot
Settling time
Mode Switch Selection
0
Use a torque reference level for
detection point.
(Factory Setting)
1
Use a speed reference level for
detection point.
2
Use an acceleration level for detec-
tion point.
3
Use a position error pulse for detec-
tion point.
4
Do not use the mode switch function.
9-19
9.4 Servo Gain Adjustment Functions
Parameter
Containing
Setting Unit
Detection
Point Setting
Percentage to the rated torque
Pn10C
Servomotor speed: min
Pn10D
Servomotor acceleration: 10 min
Pn10E
Reference unit
Pn10F
− −
1
-1
9
-1
/s