E-5

THEORY OF OPERATION

E-5

OUTPUT RECTIFICATION AND CONTROL

The AC output from the main transformer secondary

is rectified to a DC output and applied to the output

terminals. Output voltage and current feedback infor-

mation, which is fed to the control board, is sensed at

the output terminals and shunt. The control board

monitors the panel controls and remote control recep-

tacle and compares these commands to the feedback

information to determine how the output should be

controlled to optimized welding results. The control

board controls the IGBT switching through pulse width

modulation circuitry. See

IGBT Operation

Discussion

in this section.

FIGURE E.4 OUTPUT RECTIFICATION AND CONTROL

INVERTEC V250-S
INPUT
LINE
SWITCH
INPUT
RECTIFIER
R
E
C
O
N
N
E
C
T
S
W
I
T
C
H
AUXILIARY
TRANSFORMER
FAN
MOTORS
POWER BOARD MAIN
TRANSFORMER
SHUNT
POSITIVE
OUTPUT
TERMINAL
NEGATIVE
OUTPUT
TERMINAL
THERMAL
LIGHT
REMOTE
RECEPTACLE
OUTPUT
CONTROL STRIKE
CONTROL ARC
FORCE
CONTROL
MODE
SWITCH LOCAL/
REMOTE
SWITCH
RELAY
CAPACITOR
CAPACITOR
IGBT
IGBT
IGBT
IGBT
CURRENT
TRANSFORMER
18VAC
GATE SIGNALS
THERMOSTATS
O
V
E
R
V
O
L
T
A
G
E
PROTECTION SIGNAL
CR1 RELAY DRIVE SIGNAL
CR1
IGBT
CONTROL BOARD
A"
L
E
A
D
"
F
E
E
D
B
A
C
K
F
E
E
D
B
A
C
K

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

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