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ANALYSIS OF THE BLOCK DIAGRAM
Block 1
Block 2
Block 4
Block 5
Block 6
Block 7
NOTE: Unless indicated otherwise, it should be assumed that
the components are assembled on thewelding machine.
Consisting of: C3, C8, C9, L1
.
Prevents noise from the machine from being transmitted along
the main power line and vice versa.
Consisting of: D3, D5
.
Converts the mains alternating voltage into continuous pulsed
voltage.
Consisting of: C2, C4, C5, C6, C7
.
Converts the pulsed voltage from the rectifier bridge into
continuous voltage.
Consisting of: Q1, Q2
.
Converts the continuous voltage from the filter into a high
frequency square wave capable of piloting the power
transformer.
Regulates the power according to the required welding
current/voltage.
Consisting of:T2.
The C.T. is used to measure the current circulating in the power
transformer primary and transmit the information to block 14
(primary current reader and limiter).
Consisting of:T1
.
Adjusts the voltage and current to values required for the
welding procedure. Also forms galvanic separation of the
primary from the secondary (welding circuit from the power
supply line).
EMC Filter
Rectifier bridge
Filter
Chopper
Current transformer
Power transformer
(primary board)
(primary board)
Consisting of: K1, K2, R1 (primary board).
Prevents the formation of high transient currents that could
damage the main switch, the rectifier bridge and the
electrolytic capacitors.
When the power source is switched on relays K1 and K2 are
de-energised, capacitors C2, C4, C5, C6, C7 are therefore
charged via R1. When the capacitors are charged the relays
will be energised.
(primary board)
(primary board)
(primary board)
Consisting of: D1, D2, D3, D4, D5, D6, D7, D8, D9, D10
(secondary board)
D1, D2 convert the current circulating in the positive OUT of
the power transformer to a single direction, preventing
saturation of the nucleus.
D3, D4, D5 recirculate the inductance output current (block 9)
during the time when the IGBT's are not conducting,
bypassing the power transformer (block 7).
Block 3
Block 8
Pre-charge
Secondary diodes
Positive polarity diodes in the circuit:
Negative polarity diodes in the circuit:
D9, D10 convert the current circulating in the negative OUT of
the power transformer to a single direction, preventing
saturation of the nucleus.
D6, D7, D8 recirculate the inductance output current (block 9)
during the time when the IGBT's are not conducting, bypassing
the power transformer (block 7).
The positive polarity diodes in the circuit are
involved.
The positive and negative polarity diodes in the
circuit are involved alternately.
Consisting of: SCR (secondary board)
The SCR module is piloted by block 18 (microcontroller) and
block 27 (SCR driver), transforming the secondary output
current from DC to AC when TIG AC welding is required.
Consisting of: L1, R2, (secondary board)
The inductance levels the output current from the secondary
board diodes making it practically direct. The shunt detects
the current circulating in the secondary and sends a voltage
signal to block 25 (shunt amplifier), which will process it.
(primary board)
(primary board)
Consisting of: D16, R81, R82, R83, R84, R85 (control board).
Detects and limits the signal from block 6 (current transformer)
and, via trimmer R85, adjusts the maximum allowable primary
current. The signal is also redimensioned so that it can be
processed and compared in block 16 (duty cycle maker).
Consisting of: U14 (control board).
Processes the information arriving from block 17 (adder) and
block 15 (primary current reader and limiter), producing a
square wave with variable duty cycle, limiting in any case the
primary current to a maximum preset value.
DC Operation:
AC Operation
Block 9
Block 10
Block 15
Block 16
Primary current reader and limiter
Duty cycle maker
AC/DC current converter
Inductance and Shunt
Secondary EMC Filter
HF Transformer
Flyback power supply
IGBT Driver
Block 11
Block 12
Block 13
Block 14
Consisting of: CY1.
Prevents noise from the power source from being transmitted
through the welding cables and vice versa.
Consisting of:T2.
The HF transformer boosts the signal from block 34 (hf power
source), raising the voltage impulse in the secondary at the
instant when arc strike is generated.
It also isolates the welding circuit from the primary circuit
Consisting of:T2, U2
.
Uses switching methods to transform and stabilise the voltage
obtained from block 4 (filter) and supplies auxiliary voltage to
power block 14 (driver) and the control board correctly.
Consisting of: ISO1, ISO2
..
Takes the signal from block 13 (flyback power supply) and,
controlled by block 16 (duty cycle maker), makes the signal
suitable for piloting block 6 (chopper).
TECHNOLOGY TIG 172 AC/DC
