Lincoln Electric COMMANDER SVM153-A Service Manual page 49

E-3
FIGURE E.3 - WELD WINDINGS, RECTIFIER, POWER MODULES AND FEEDBACK
COMMANDER 500
ENGINE
STARTER
ALTERNATOR
RUN/STOP
SWITCH
S
BATTERY
H
BOARD
U
I
T
D
D
L
O
120 10 E
W
VDC VDC
N R
BATTERY
SOL
PULL
COIL
TO WELD
BOARD CONTROL
SOL
BOARD
10
VDC
PERIPHERAL
BOARD
WELD WINDINGS, RECTIFIER,
POWER MODULES AND
FEEDBACK
The three-phase stator weld windings are connected to
a three-phase rectifier bridge. The resultant DC volt-
age is applied to four paralleled capacitors incorporat-
ed within each of the two power modules. There are
two capacitors in each module. These capacitors func-
tion as filters and also as power supplies for the IGBTs.
See IGBT Operation in this section. The IGBTs act as
high-speed switches operating at 20KHZ.
devices are switched on and off by the Weld Control
PC board through pulse width modulation circuitry.
See Pulse Width Modulation in this section. This
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
THEORY OF OPERATION
W
MECHANICAL
ROTATION
SLIP
RINGS
ENGINE
SENSORS
AUXILIARY
1/2
BATTERY
BD
These
COMMANDER 500
THREE-PHASE
RECTIFIER
+
80 VDC
W
I
D
N
L
D
E
I ANALOG
N
POWER SUPPLY
G
BOARD
TO
ROTOR
IDLE
HOLD
COIL
THERMAL
STATOR
LIGHT
42 VAC TO 14 PIN AMPHENOL
FOR WIRE FEEDER
WINDINGS
1
2
0
240VAC
V RECEPTACLE
A
C
120VAC
RECEPTACLES (2)
"chopped" DC output is applied through choke coils
and a shunt to the welding output terminals. The choke
functions as a current filter, and it helps to balance the
outputs of the two power modules.
diodes are incorporated in the power modules to pro-
vide a current path for the stored energy in the choke
when the IGBTs are turned off.
Technology in this section.
Output voltage and current feedback information is fed
to the Weld Control PC board. This information is
sensed from the output terminal circuits and the shunt.
WORK
TERMINAL
TO WELD
CONTROL
BOARD
POWER MODULES
(2) (2)
(2)
ELECTRODE
TERMINAL
IGBT
CHOKE
SHUNT
(2)
PWM
20 VDC
SIGNALS (2)
WELD
CONTROL
BOARD
VOLTMETER
AMMETER
ARC OUTPUT PROCESS/RANGE
CONTROL CONTROL SELECTOR
Free-wheeling
See Chopper
E-3
__ __
+
F
E
E
D
B
A
C
K