Chengdu Huayuan Electric Equipment Co.,Ltd
LGK-40/63/100IGBT OPERATOR’S MANUAL
8
External Characteristic
◆
Work principles
The control circuit of cutting machine adopts advanced electronic part IGBT as the main inverter switch component. Three-phase
AC power is converted to 20KHz 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, then 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 figure 2.
Figure 2 Principle diagram
Common component list as diagram 1
No.
Symbol
Components
name
Model
Remark
1
V1
Three phase
rectifier
MDS35-14
LGK-40
、
63IGBT
MDS75-12
LGK-100IGBT
2
V2
～
V5
IGBT single
module
IKW25N120T2
LGK-40IGBT
IKW40N120T2
LGK-63IGBT
V2
、
V3
GD75HFV120C2S
LGK-100IGBT
I
270V
240V
40A
U
63A/105.2V
40A/96V
63A
296V
100A
100A/120V
Summary of Contents for LGK-63/100MA
Page 18: ......
