Working Principle; Volt-Ampere Characteristic - Matco Tools MM200 LCD Operator's Manual

§2.2 Working Principle
The working principle of MM SERIES arc welding machine is shown as the following figure. Single-phase
110V/220V work frequency AC is rectified into DC, then is converted to medium frequency AC by inverter
device (IGBT), after reducing voltage by medium transformer (the main transformer) and rectifying by medium
frequency rectifier (fast recovery diodes), and is outputted by inductance filtering. The circuit adopts current
feedback control technology to insure current output stably when MMA or TIG. And adopts voltage feedback
control technology to insure voltage output stably when MIG. Meanwhile, the welding current parameter can
be adjusted continuously and infinitely to meet with the requirements of welding craft.
Single-phase
110V 50/60Hz
Single-phase AC
Rectifier
220V 50Hz
Single-phase
220V 50/60Hz
§2.3 Volt-Ampere Characteristic
MM SERIES welding machine has an excellent volt-ampere characteristic, whose graph is shown as the
following figure. The relation between the rated loading voltage U
U =14+0.05I (V)
2 2
DC
AC
Inverter
CPU control
（V）
U
o

Volt-ampere characteristic

Working point
44
14
0
AC
Transformer
Current
Feedback
control
Welding current
PWM signal
regulate
(Wire feed speed)
The relation between the rated loading
voltage and welding current
600
- Ⅳ -
DC
Current sensor
Rectifier Hall
Voltage
Feedback
control
Wire feeder
motor
and welding current I
2
（A）
I
o
DC
is as follows:
2