A 3-Leg Inverter-Based High-Frequency Welding Power Supply Capable of AC 220 and 440-V Operation

In this article, a dc/dc topology is proposed for welding power supply that achieves a high conversion efficiency of over 94%, requiring ac 220 and 440 V operation. The secondary-side structure of the proposed topology is the same as that of conventional welding power supplies but the primary side consists of a three-leg inverter structure and a high-frequency transformer with two primary windings connected in series. Due to this structure, it is possible to operate in a wider input voltage range than conventional welding power supplies without significant loss of performance. In addition, it has the advantage of achieving high conversion efficiency over the entire input voltage range by reducing primary current stress and secondary rectifying voltage stress due to an increase in turn-ratio, and a reduction in circulating current. This advantage allows the use of mosfet s rather than insulated gate bipolar transistor (IGBTs) with low operating frequency, which are often used in conventional welding power supply applications. Using a mosfet reduces the size of the power-stage passive devices, thereby reducing the overall system size. The performance of the proposed topology is verified in prototypes with a switching frequency of 100 kHz, an input voltage of 311/622 V, an output of 50 V, and a 6.0 kW class specification.