Theory Of Operation - Lincoln Electric VANTAGE SVM178-B Service Manual

E-3
FIGURE E.3 - WELD WINDINGS, RECTIFIER, POWER MODULES AND FEEDBACK
ENGINE
ALTERNATOR
+12 VDC
STARTER
RUN
OIL
RUN/STOP
PRESSURE
SWITCH
ON
ENGINE
SENSORS
START
BUTTON
+12 VDC
RUN
+
BATTERY
PERIPHERAL
PCB
PULL
COIL
PCB
PULL PULL
IDLER FUEL
SOLENOID SOLENOID
WELD WINDINGS, RECTIFIER,
POWER MODULES AND
FEEDBACK
The three-phase stator weld windings are connected to a
three-phase rectifier bridge. The resultant DC voltage is
applied to four paralleled capacitors incorporated within each
of the two power modules. There are two capacitors in each
module. 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. These devices are switched on and off by the Weld
Control PC board through pulse width modulation circuitry.
See Pulse Width Modulation discussion in this section.

THEORY OF OPERATION

D
L
E
W
MECHANICAL
25•
(COLD)
ROTATION
SLIP
RINGS
STATOR
WATER
TEMP.
AUXILIARY
160VDC
FLASHING
120VAC
RECEPTACLES
(Not on EURO Machnes)
LOW IDLER SIGNAL (TO SUPPLY PULL VOLTS)
HOLD VOLTS FROM CONTROL PCB
* On some codes the Peripheral Board, Pull Coil Board, Idler Solenoid & Fuel Solenoid are
replaced by an Electronic Governor Control module and components. See Wiring Diagram.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
VANTAGE® 500
RECTIFIER
THREE-PHASE
+ +
_ _
W
I
N
D
I
+12VDC
G
RUN
ROTOR
AUX. POWER
USE SENSING
42 VAC and 120VAC
to 14 Pin Amphenol
for Wire Feeder
(No 120 VAC on EURO Models)
WINDINGS
AC RECEPTACLES
Various combinations of
1Ø and 3Ø Outputs.
See Techincal Specs.
120 VAC
This 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. Free-wheeling diodes are incorporated
in the power modules to provide a current path for the stored
energy in the choke when the IGBTs are turned off. See the
Chopper Technology discussion in this section.
Output voltage feedback from the output terminals and current
feedback from the shunt is fed to the Weld Control PC board
as a means of controlling the output.
+ +
SHUNT
TO WELD
CONTROL
BOARD TO
CONTROL
PCB
IGBT
IGBT
CHOKE
__ __
R4-50•
2-POWER MODULES
PWM PWM
SIGNAL SIGNAL
WELD
CONTROL
BOARD VOLTMETER
AMMETER
ARC OUTPUT MODE
CONTROL
CONTROL SELECT
SWITCH
E-3