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Sigma II User's Manual
6.2.5
Using Mode Switch
Use the mode switch function for the following purposes.
•
To suppress overshoot during acceleration or deceleration (for speed control).
•
To suppress undershoot during positioning and to shorten the setting time (for
position control).
No mode switch function
Motor
speed
The mode switch function makes it possible to automatically switch the servo ampli-
fier's internal speed control mode from PI to P control mode and vice versa when
specified conditions are satisfied.
Definition:PI control means proportional/integral control, and P control means proportional control. In
effect, switching "from PI control to P control" reduces effective servo gain, thereby making the
servo system more stable.
• The mode switch is used to fully utilize performance of a servodrive to achieve very high-speed positioning.
The speed response waveform must be observed to adjust the mode switch.
• For normal use, the speed loop gain and position loop gain set by auto-tuning provide sufficient speed/posi-
tion control. Even if overshoot or undershoot occurs, it can be suppressed by setting either:
•The acceleration/deceleration time constant for the host device.
•The soft start time constants (Pn305, Pn306)
•The position reference acceleration/deceleration constant (Pn204) for the servo amplifier.
n
Selecting Mode Switch Setting
The servo amplifier incorporates four mode switch settings (0 to 3). Select a mode
switch with the following parameter (Pn10B.0).
Pn10B.0
Setting
Uses torque reference as the detection point.
0
(Standard setting)
1
Uses speed reference input as the detection point.
2
Uses acceleration as the detection point.
Overshoot
Undershoot
Time
IMPORTANT
Description
With mode switch function
Motor
speed
Parameter
Used to Set
Detection Point
Pn10C
Pn10D
Pn10E
6-11
Chapter 6: Servo Adjustment
Time
Setting Unit
Percentage of rated
torque (%)
Motor Speed (rpm)
× 10rpm/s
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