Lincoln Electric MULTI-WELD SVM151-A Service Manual page 31

Section E-1
- THEORY OF OPERATION SECTION -
General Description .......................................................................................................................E-2
Input Power Source, Contactor and DC Buss Power Supply Board ..........................................E-2
Power Modules and Feedback ...................................................................................................E-3
Analog Control Power Supply Board and Weld Control Board .................................................E-4
Mode Selector and Output Controls............................................................................................E-5
Protection Features.....................................................................................................................E-6
Insulated Gate Bipolar Transistor (IGBT) Operation...................................................................E-7
Pulse Width Modulation ..............................................................................................................E-8
Chopper Technology Fundamentals ...........................................................................................E-9
MULTI-WELD 350 BLOCK LOGIC DIAGRAM
INPUT
DIODES
ON/OFF
+
MODE
SWITCH
DC
(1/2)
POWER
SOURCE
(EXTERNAL)
_
FIGURE E.1 - MULTI-WELD 350 BLOCK LOGIC DIAGRAM
TABLE OF CONTENTS
INPUT
CONTACTOR
CR1
INPUT
CAPACITORS
20
VDC
x 2
ANALOG
DC
40
VDC
CONTROL
BUS
POWER
POWER
SUPPLY
SUPPLY
BOARD
BOARD
PERIPHERAL
MULTI-WELD 350
LEFT AND RIGHT
CHOPPER MODULES
IGBT
FREEWHEELING DIODE
CHOPPER MODULE
CHOKE
IGBT FREEWHEELING DIODE
CHOPPER MODULE
ON/OFF
VOLTS
MODE
SWITCH
(1/2)
GATE
SIGNALS
WELD
REGULATED CONTROL
VOLTAGES
BOARD
FAN
40 VDC
ARC
OUTPUT
15 VDC
FORCE
CONTROL
CONTROL
CR1
COIL
BOARD
INPUT
INDICATOR
LIGHT
Section E-1
TO ELECTRODE
CABLE
+
SHUNT
CURRENT FEEDBACK
TO WELD CONTROL BOARD
AMPS
REMOTE
RECEPTACLE
CC SLOPE
(STICK/GOUGE or PIPE)
HOT
THERMAL
START
LIGHT
-
WORK