Lincoln Electric INVERTEC POWER WAVE 450 SVM112-B Service Manual page 49

Section E-1
Theory of Operation .............................................................................................................Section E
General Description ....................................................................................................................E-2
Input Voltage ...............................................................................................................................E-2
Precharge (Soft Start)..................................................................................................................E-3
Switch Boards.............................................................................................................................E-4
Main Transformer ........................................................................................................................E-5
Output Rectifier and Choke ........................................................................................................E-6
Control Board..............................................................................................................................E-7
Power Board ...............................................................................................................................E-8
Display Board..............................................................................................................................E-9
Thermal Protection....................................................................................................................E-10
Protective Circuits.....................................................................................................................E-10
Over Current Protection .....................................................................................................E-10
Over Voltage Protection......................................................................................................E-10
Field Effect Transistor (FET) Operation .....................................................................................E-11
Pulse Width Modulation............................................................................................................E-12
Minimum Output.................................................................................................................E-12
Maximum Output................................................................................................................E-12
THREE
PHASE
INPUT
POWER
INPUT
LINE
SWITCH
PROTECTION
BOARD
TABLE OF CONTENTS
-THEORY OF OPERATION-
FIGURE E.1 - POWER WAVE BLOCK LOGIC DIAGRAM
INPUT
RECTIFIER
INPUT AND
CONTACTOR RECONNECT
LEFT
SWITCH
BOARD
FET
ASSEMBLY
AUX.
TRANS
RIGHT
SWITCH
BOARD
FAN
FET
ASSEMBLY
POWER
BOARD
WATER
COOLER
PC
INTERFACE
POWER WAVE 450
MAIN
OUTPUT
TRAMSFORMER
RECTIFIER
CT
SNUBBER
SENSE LEADS
CONTROL
BOARD
LCD
DISPLAY
DISPLAY
BOARD
KEYPAD
OVERLAY
WF1 WF2
Section E-1
CHOKE POSITIVE
NEGATIVE
SHUNT
AND