Lincoln Electric SVM150-A Manual Do Utilizador

Página de 134
WELD WINDINGS, RECTIFIER,
POWER MODULE AND FEEDBACK
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 power module.  These capacitors function as fil-
ters and also as power supplies for the IGBT.  See
IGBT Operation in this section.  The IGBT acts as a
high-speed switch operating at 20KHZ.  This device is
switched on and off by the control board through
pulsewidth modulation circuitry.  See Pulse Width
Modulation 
in this section. This “chopped” DC output 
is applied through a choke coil and shunt to the weld-
ing output terminals.  The choke functions as a current
filter.  Free-wheeling diodes are incorporated in the
power module to provide a current path for the stored
energy in the chokes when the IGBT is turned off.  See
Chopper Technology in this section.
Output voltage and current feedback information is fed
to the control board.  This information is sensed from
the output terminal circuits and the shunt.
THEORY OF OPERATION
E-3
E-3
RANGER 250
FIGURE E.3 – WELD WINDINGS, RECTIFIER, POWER MODULE AND FEEDBACK
NOTE:  Unshaded areas of Block Logic Diagram are the subject of discussion.
ENGINE
CONTROL
BOARD
ROTOR
STATOR
BATTERY
      BOARD
BATTERY
CHOKE
IGBT
MECHANICAL
ROTATION
STARTER
I
D
L
E
R
ARC
CONTROL
OUTPUT
CONTROL
MODE
SELECTOR
POWER MODULE
THREE-PHASE
RECTIFIER
WORK
TERMINAL
ELECTRODE
TERMINAL
+
120VAC
RECEPTACLE
240VAC
RECEPTACLE
SLIP
RINGS
TO 
CONTROL
BOARD
GAS
OIL 
PRESSURE
SWITCH
RUN/STOP
SWITCH
                 FLYWHEEL
                     ALTERNATOR
    
                            TO CONTROL
                             BOARD
              AMPHENOL
4
2
V
A
C
FIELD
WINDING
                                  AUXILIARY 
                                 WINDINGS
                          WIRE FEED
                          PWR WNDG
4
2
V
A
C
2
4
0
V
A
C
1
2
0
V
A
C
W
E
L
D
 
W
I
N
D
I
N
G
+
ANALOG
POWER
BOARD
2
0
V
D
C
4
0
TO
1
0
0
V
D
C
FROM
TOROID
CURRENT 
SENSOR
SHUNT
F
E
E
D
B
A
C
K
SOL
__
__
     REGULATED VOLTAGES
P
W
M
S
I
G
N
A
L
S