Welding power supplies using the partial series resonant converter

Present technology in high frequency welding power supplies is mainly based on hard switching nonresonant power converters. Their disadvantages are high semiconductor and copper losses, complex short circuit protection, and a complex controller for shaping of the output load line. The partial series-resonant power converter, a new high frequency DC-to-DC power converter is applied to welding applications. It is based on the half-bridge version of the series resonant power converter, but the dynamic output voltage range is twice as large. Discrete energy pulses are transferred to the output every half switching cycle, permitting a simple variable frequency controller for controlling the output power. Therefore, a constant output power load line is simply achieved by keeping the switching frequency constant, which, in turn, provides excellent welding characteristics. The power converter features zero voltage turn-on, and snubbed turn-off at reduced current, making it suitable for IGBT switches operating well above 20 kHz