Digital servo control unit and laser machining apparatus

摘要

There is provided a digital servo control unit which uses a D/A converter, which suppresses the spike-like pulsation superimposed on a current error signal inside a current control circuit, and which has control performance not lower than that in the background art even when a low-voltage and low-price power supply circuit is used. The digital servo control unit has a first-order low pass filter acting on an analog signal output by the D/A converter, and a stabilizing compensation means for compensating a phase delay caused by the first-order low pass filter. An output signal of the first-order low pass filter is input to a current control circuit as a current command signal. The first-order low pass filter is formed as a low pass filter having a cut-off frequency which is lower than a sampling frequency. The first-order low pass filter may be replaced by a notch filter having a cut-off frequency which is equal to a sampling frequency or which is equal to an integer multiple of a Nyquist frequency.