Power Driver _ Pcb3 / Pcb4 (0558038335) - ESAB Powercut 1600 Service Manual

SECTION 4 DESCRIPTION Of OPERATION
4.11

Power Driver _ PCb3 / PCb4 (0558038335)

The Power Driver circuit is used to drive the IGBTs to
produce a current output from the PC1600.
The power driver boards drive one half of each IGBT
per half cycle. The two input transformers on the
board are wired 180 degrees out of phase with each
other so that the IGBTs may conduct for a full 360 de-
grees of pulsed output. Each transformer drives one
of the two transistors on the IGBT for 180 degrees
of pulse conduction.. During the negative half of the
cycle, each driver circuit drives the gate of the IGBT
negative, forcing the IGBT off.
During the positive half of the cycle, the pulse travels
unaltered to the IGBT gate along the path of the solid
line. It passes a pair of diodes, D1 and D2, a one amp
fuse F1 and a surge diode D3. This is then sent to the
gate of the IGBT and the transistor conducts.
The negative half of the cycle follows a different path.
The negative portion of the pulse conducts through
Q1, Q2 and Q3, pulling the gate of the IGBT negative
and forcing the transistor off.
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