6
6
rectified into DC (about 380V) with PFC, then is converted to medium frequency AC (about
50
KHz) by inverter device (IGBT module), after reducing voltage by medium transformer (the
main transformer) and rectifying by medium frequency rectifier (fast recovery diodes), and is
output by inductance filtering. The circuit adopts current feedback control technology to insure
current output stably. Meanwhile, the welding current parameter can be adjusted continuously and
steplessly to meet with the requirements of welding craft.
PFC
Inverter
Medium
frequency
transformer
Medium
frequency
rectify
Hall device
Current positive-
feedback control
Single-phase AC
DC
AC
DC
AC220V&AC110V
AC
DC
Rectify
Fig 2.1 working principle diagram
§2.3 Volt-Ampere Characteristic
GT- series welding machine has an excellent volt-ampere characteristic, whose graph is
shown as the following figure. The relation between the conventional rated loading voltage U
2
and
the conventional welding current I
2
is as follows:
When I
2
≤
600A
，
U
2
=10+0.04I
2
(V); When I
2
＞
600A,U
2
=34(V).
Fig2.2 output characteristic of GT-series
63
34
10
U
2
（
V
）
Working
point
Volt-ampere characteristic
The relation between the
conventional loading
voltage and welding current
