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THEORY OF OPERATION
E-6 E-6
INVERTEC STT
FIGURE E.6 – CONTROL BOARD, IGBT DRIVE AND MODULE
CONTROL BOARD, IGBT DRIVE
AND MODULE
The control board monitors the directives of the various
controls and compares these commands to the current
and voltage feedback information received from the
current sensor and voltage sensing receptacle. This
data is processed and the suitable PWM signal is sent
to the power board. (See Pulse Width Modulation
discussion).
The control board also determines when the IGBT
module should be switched OFF to reduce weld spat-
ter and fumes. The appropriate signal is sent to the
IGBT drive board which then applies, or removes, the
gate drive signal to the IGBT module. When the IGBT
module is in the OFF state, the welding current must
pass through the one ohm resistance. This reduces
the current and, subsequently, spatter and fumes.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
