Abstract: A welding machine with a power source and an inverter. The inverter has at least one switching leg, made up of switches in series, and an output terminal. The power source has a circuit for controlling the switches by delivering an on-signal or and off-signal. The power source also has a transformer linked to a rectifier. The power source also has a circuit for detecting the voltage that the terminals of each switch of the inverter. A pilot circuit is also present for receiving control and voltage signals. The pilot circuit then sends a pilot circuit to each of the switches. The pilot signal corresponds to an on-command when the control signal corresponds to an on-signal and when the voltage between the power electrodes is very close to zero.

Abstract: An apparatus for arc welding using a quasi-resonant, soft-switching type inverter. The inverter is connected to an electrical energy power source at a point between a power supply terminal and a reference terminal. The inverter has at least one quasi-resonant type switching leg. The leg is made of an even number of switches, arranged in series, and an output terminal located between the two central switches. The inverter is connected to a circuit for controlling the switches and also has a transformer. The primary element of the transformer is linked to the output terminals of the switching legs, while the secondary element of the transformer is linked to a rectifier which supplies a DC output voltage. The inverter also has a intermediate power supply terminal located between the power supply and the reference terminal. The output terminal of each switching leg is linked to the intermediate power supply terminal by an inductive element.

Abstract: A welding machine with a power source and an inverter. The inverter has at least one switching leg, made up of switches in series, and an output terminal. The power source has a circuit for controlling the switches by delivering an on-signal or and off-signal. The power source also has a transformer linked to a rectifier. The power source also has a circuit for detecting the voltage that the terminals of each switch of the inverter. A pilot circuit is also present for receiving control and voltage signals. The pilot circuit then sends a pilot circuit to each of the switches. The pilot signal corresponds to an on-command when the control signal corresponds to an on-signal and when the voltage between the power electrodes is very close to zero.