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THEORY OF OPERATION
E-4 E-4
INVERTEC® V155-S
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MAIN INVERTER BOARD
The Inverter Board includes the following circuits:
- Inverter Circuit: Through the use of Insulated Gate
Bipolar Transistors (IGBTʼs) the high voltage
(325VDC) input current is switched ON and OFF at a
frequency of 80KHz and fed to the primary of the
main transformer. The current is regulated via Pulse
Width Modulation (PWM). The width of each pulse is
determined by a ʻgateʼ signal from the Control Board.
(See IGBT Operation and Pulse Width Modulation
in this section).
- Main Transformer: The primary function of the main
transformer is to reduce the high voltge 80khz output
to the proper voltage for welding. It also serves to
insulate the operator from the input line. Additional
windings of the transformer provide both piamary and
secondary feeback signals to the PWM control circuit.
FIGURE E.4 — MAIN INVERTER BOARD
- Output Circuit: The output diodes and the output
choke rectify and filter the current from the secondary
of the main transformer to make it acceptable for
welding. The shunt provides the necessary current
feedback information to the Control Board.
Note: The shunt is shown off the board for clarity. It is
actually mounted on the Inverter Board.
CONTROL
BOARD
W
0
5
X
0
7
0
8
-
1
(
S
CHE
MA
T
IC: X
0
7
0
8
)
J
P1
I
N
P
U
T
B
OA
R
D
W
0
5
X
0
7
0
1
(
S
C
H
E
M
A
T
I
C
:
X
0
7
0
1
)
1
1
5
/
2
3
0
V
a
c
5
0
/6
0
Hz
ON
/
OFF
S
W
I
TC
H
5
2
N
L
G
W
IRE
T
IE
4
1
B
L
U
E
W
H
I
T
E
W
H
I
T
E
B
L
U
E
W
H
I
T
E
B
LA
C
K
A
C2
A
C
1
P
E
P
W
R
2
P
W
R
1
PW
R
4
P
W
R
3
D
C
+
R
ED
D
C
-
B
LA
C
K
P
C
B
C
ON
N
E
C
TOR
C
A
V
I
TY
N
U
M
B
E
R
I
N
G
S
E
QU
E
N
C
E
(
V
I
E
WE
D F
RO
M
CO
M
P
O
NE
NT
S
I
DE
O
F
P
.
C.
B
O
A
RD)
R
I
BBO
N
C
ABLE
T
WI
S
T
E
D
C
A
B
L
E
1
F
A
N
W
H
I
T
E
R
E
D
4
2
4
PIN
S
1
P
E
R
E
C
O
N
N
E
C
T
B
O
A
R
D
W
05X
0408
(
S
C
H
E
M
A
T
I
C
:
X
0
4
0
8
)
B
LA
C
K
J
P
4
B
L
U
E
1
6
1
6
PI
NS
15
JP
1
J
P1
D
C
+
R
ED
D
C
-
B
LA
C
K
Y
/G
P
E
I
N
V
E
R
T
E
R
B
O
A
R
D
W05X
0519
(
S
C
H
E
M
A
T
IC
:
X
0
5
1
9
)
BLAC
K
R
ED
J
P
2
W
HITE
WHITE
P
1
N1
BLACK
RED
S
H
U
N
T
-
+