Generator for arc welder with high power factor

A generator for arc welder of the type composed of a rectifier stage supplied by the mains, followed by a PFC stage and by an inverter stage, both of the high-frequency type, the latter supplying an output stage for supplying power to a welding arc, wherein:

• said PFC stage is composed of:
• two inductors, which are mutually magnetically coupled and are arranged each one in series with an output of the rectifier stage;
• two first high-frequency controlled switches, which are connected between a common node and two nodes respectively at the outputs of the two inductors;
• two diodes with opposite conduction directions, which are respectively connected to the nodes between the switches and mutual inductors;
• two leveling capacitors, which are connected to the output nodes of said diodes and the common node of said first switches;
• means being further provided for controlling the succession of the on and off switchings of said two first switches, so as to shape the current absorbed by the rectifier stage, correlating it to the waveform of the line voltage;
• said inverter stage, supplied between the common node of said first high-frequency switches and the common node between said capacitors, comprises four triads, each composed of a second controlled switch, a diode and a capacitor, connected so as to form five nodes, respectively a central node, two intermediate nodes and two external nodes, said external nodes being connected to the nodes between said first switches and the respective diodes, said intermediate nodes being connected to the common node of said two first electronic switches with the interposition of a diode respectively, a capacitor being connected between said intermediate nodes, a control device being further provided for the four second switches, the current for the output stage that supplies the welding arc being drawn between the common of the two first switches and the central node of said four triads of second controlled switches, diodes and capacitors.