
4. SERVO FUNCTION DETAILS B-65150E/04
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4.5.7 Current Loop 1/2PI Function
(1) Overview
To improve servo performance in high-speed high-precision machining,
high-speed positioning, ultrahigh-precision positioning, and so forth, a
velocity loop gain as high as possible needs to be set stably.
To set a high velocity loop gain stably, the response of the current loop
needs to be improved.
The current loop 1/2PI function enables the response of the current
loop to be improved.
(2) Series and editions of applicable servo software
Series 9080/K(11) and subsequent editions (Series 15-B, 16-C, 18-C)
Series 9090/C(03) and subsequent editions (Series 15i, 16i, 18i, 21i,
Power Mate i)
Series 90A0/A(01) and subsequent editions (Series 15i, 16i, 18i, 21i,
Power Mate i)
(3) Control method
As shown in Fig. 4.5.7, in the area where a small current flows, a
current loop calculation is based on PI control rather than on the
conventional IP control method. When a large current flows, the
control method returns to IP control to suppress a current overshoot.
Fig. 4.5.7 Block diagram of current loop 1/2PI control
p
PK1/s
PK2
+
−
The proportional from the command is added to PWM calculation.
Torque command
Switching to the
intermediate state of PI
control and I-P control
PWM command