Gate buffers
Controller and
PWM
development
Set value
circuit
MMA ignition
Locking
MMA
dynamics
OCV
adjustment
AV~40
Fan control
Overheat
protection
Power supply
Control to IGBT
Net voltage
watch
Actual current value
Current information
to TIG
I2
U2
TIG/MMA
Current instruction
Control card A001 block diagram
The functions of power source´s control card A001 are built around the PWM-controller SG
3526.
Gate buffer
PWM-controller develops PWM-signals, that are amplified in the gate buffer and taken via a control transformer
to the IGBT-module´s gates.
Set value circuit
Set value circuit prepares the signal coming from the potentiometer suitable for the PWM-controller and protects
the electronics from potentiometer circuit´s insulation faults and possible overvoltages.
MMA ignition
The MMA ignition circuit develops an overcurrent spike to the set value current in order to ease the ignition.
MMA Dynamics
The dynamics circuit develops overcurrent spikes to the set value current during short circuits.
Locking
The locking circuit prevents the MMA ignition current and dynamics operation on TIG.
OCV controller
The OCV circuit controls the power stage during idling so that the power losses are minimized.
Shunt amplifier
Current signal amplifier amplifies the shunt voltage suitable for the PWM-controller.
Fan control
PWM-signal is used to control the fans on/off. During idling the PWMcontroller´s pulse ratio is so low , that the
fans are off. The fans start after 30 seconds from the start of welding, regardless of the welding current level. Post-
welding cooling is active for 5 minutes.
Overheat protection
Overheat protection is activated by PTC-resistors.
Power supply
The power supply section forms the auxiliary voltages needed by control card A001. The power supply section
also provides undervoltage watch.
Net voltage watch
Net voltage watch circuit stops the power stage, in case the net voltage rises above certain limit.
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