Lincoln Electric COMMANDER SVM145-B Service Manual page 51

E-3
FIGURE E.3 – WELD WINDINGS, RECTIFIER, POWER MODULES AND FEEDBACK
ENGINE
STARTER
ALTERNATOR
ENGINE
SENSORS
BATTERY
ENGINE
PROTECTION
WELD WINDINGS, RECTIFIER,
POWER MODULES AND FEED-
BACK
The three-phase stator weld windings are connected to
a three-phase rectifier bridge. The resultant DC volt-
age is applied to parallel capacitors incorporated with-
in the two power modules. These capacitors function
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 control board
through pulse width modulation circuitry. See Pulse
Width Modulation in this section. This "chopped" DC
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
THEORY OF OPERATION
D
L
E
W
MECHANICAL
ROTATION
SLIP
RINGS
STATOR
AUXILIARY
SOL
1
1
I
5
D
SOL
V
L
S A
E
H C
R
U
T
D
O
W
N
CONTROL
TRANSFORMER
These
COMMANDER 300
TO
CONTROL
BOARD
THREE-PHASE
RECTIFIER
W
I
N
D
I
N
G
CONTROL
BOARD
ROTOR
ARC OUTPUT
CONTROL CONTROL
WINDINGS
230VAC
RECEPTACLE
115VAC
RECEPTACLE
42VAC
30VAC
30VAC
output is applied through choke coils to the welding out-
put terminals. The chokes function as current filters
and also help to balance the outputs of the two power
modules. Free-wheeling diodes are incorporated in the
power modules to provide a current path for the stored
energy in the chokes when the IGBTs are turned off.
See Chopper Technology in this section.
Output voltage and current feedback information is fed
to the control board. This information is sensed at the
output terminals and the shunt.
E-3
WORK
TERMINAL
__
SHUNT
TO
CONTROL
BOARD
POWER MODULES
(TWO)
ELECTRODE
IGBT
TERMINAL
CHOKE
+
IGBT
MODE
SELECTOR