Functional Principle Of Medium-Frequency Welding; Fig. 2:Block Diagram Overview: Psi 6000 With Transformer; Fig. 3:Detailed Block Diagram Of A Medium-Frequency Inverter System - Bosch Rexroth PSI 6 Series Operating Instructions Manual

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5.2.2

Functional principle of medium-frequency welding

Mains
50/60 Hz
L1
L2
L3

Fig. 3:Detailed block diagram of a medium-frequency inverter system

PSI 6xxx
Weld timer

Fig. 2:Block diagram overview: PSI 6000 with transformer

The MF inverter integrated in the PSI controls the welding transformer
by a bipolar, rectangular voltage with a frequency of 1000 Hz. In order to
influence the resulting heat in the secondary circuit, the pulse width is
adjusted (refer to Fig. on following page).
Secondary rectification of the weld current is performed in the PSG.
6-pole bridge
rectifier
U1
V1
W1
Driver
Power
Controller
supply
to temperature
Weld timer
to constant-current
regulation in the PSI
Secondary vol­
tage tapping
*: depending on trans­
3~
1000
Hz
MF inverter
Direct current link circuit
Transistorized transformer-rectifier
U2
U
monitoring
*
*
former design
to electrode gun
PSI 6xxx | 1070080028 / 08
PSG
+
-
Transformer-
Welding
rectifier
equipment
PSI
V2
V
Welding
transformer
PSG
Rectifier