Cebora SYNSTAR 200 M Manual De Servicio página 18

On power board (45) are mounted, in a non-removable
way, two boards that contain the control circuits of the
boost converter and inverter.
In particular:
− the board welded on J5 connector of the power board
(45) contains the control circuit of the boost converter
(hereinafter will be called PFC board);
− the board welded on J4 connector of the power board
(45) contains the inverter control circuit (hereinafter
will be called INV board).
Each board contains a microprocessor which manages its
EN
own converter.
The PFC board starts running automatically as soon as
the power source is powered and sends to the INV board
information on the mains voltage status, on the boost con-
verter operating status (running or stopped) and on the
boost converter igbt temperature.
This information is sent, to the INV board, with a coded
signal through the OP2 optocoupler, on power board (45).
The INV board communicates with the panel board (48)
via RS232 serial line. Receives the start and set point com-
mands for the inverter management and sends information
on inverter and boost converter operating status.
Given the particular type of installation (direct soldering to
connectors J4 and J5 on power board (45)), in this manual
the two boards PFC and INV are considered integral parts
of the power board (45).
The input rectifier bridge is equipped with a DC-capacitors
pre-charge circuit, made up of the PTC (PTC1) and relay
RL1, controlled by PFC board.
The boost converter, connected downstream the input
rectifier, contributes to optimize the "Power Factor" and
to reduce the harmonic distortion of the current absorbed
from the line.
Connected directly to the DC-capacitors, a flyback con-
verter, present on power board (45), generates the supply
18
NOTE
Fig. 2.3.1
voltages for all power source circuits.
These voltages are measurable on the connectors J2, J3
and on the test points J1, TP11, TP12, TP13 on power
board (45), as indicated in Fig. 2.3.2.
THE CIRCUITS OF THE FLYBACK PRIMARY SIDE
(SEE J1, TP11, TP12, TP13) ARE DIRECTLY CON-
NECTED TO THE MAINS POTENTIAL AND THERE-
FORE DANGEROUS.
The flyback converter starts running automatically when
the voltage on the DC-capacitors becomes higher than 100
Vdc approximately.
The inverter is made up of two igbt connected in a "for-
ward" configuration, driven by the driver circuits located
in proximity of the igbt and directly controlled by the INV
board.
The task of the inverter is to generate the square-wave
alternating voltage for TF5 power transformer. Welding
current is adjusted by modulating this voltage appropri-
ately.
On the power board (45) is installed a TA, TF4, inserted
on the TF5 power transformer primary circuit, that pro-
vides the current feedback signal used for the welding cur-
rent regulation.
The TF5 power transformer secondary circuit is connected
to the secondary diodes group, present on power board
(45), which rectifies the alternating current generated
by the inverter, making it available at the power source
output.
The secondary diodes group is made up of 8 diodes
connected to a shared cathode on L7 inductor terminal,
used for welding current levelling and provides, on this
terminal, a positive output voltage with respect to the TF5
power transformer terminal, connected to VITE1 terminal
of power board (45).
From power board (45) VITE1 and VITE2 output
terminals, is picked up, through the inductors L6 and L4,
WARNING
3302316/A