HUAYUAN LGK-240P, Инструкция по эксплуатации, Страница: 39 / 49

7
The control circuit of cutting machine adopts advanced electronic part IGBT as the
main inverter switch component. Three-phase AC power is converted to 40 kHz
high-frequency DC current after being rectified by three phase rectifier. Then under
the function of IGBT inverter the DC current is inverted to AC high frequency
current, which is inverted to DC current after experiencing voltage reduction in
high frequency transformer, current rectifying in fast recovery diode. This DC
current is filtered through reactor, and the output cutting current is obtained.
Control circuit can control output current by controlling driven pulse width. The
real time cutting current, which is obtained through current sensor connected to
output terminal in series, is used as negative feedback control signal. After
comparing with current adjusting signal, the negative control signal is sent to PWM
adjusting integrated circuit, a controlled driving pulse is output to control IGBT.
Thereby a constant output current can be maintained, and a steep dropping &
constant current external characteristic is obtained. Striking arc adopts
high-frequency striking model. The main circuit refers to appendix figure1
，
and
principle diagram of control circuit is shown as drawing:
Working Principle