Soft-Switching PS-PWM DC-DC Converter for Full-Load Range Applications

An improved soft-switching full-bridge phase-shifted pulsewidth modulation converter using insulated-gate bipolar transistors with a special auxiliary transformer is presented in this paper. Zero-voltage switching for leading leg and zero-current switching for lagging leg switches in the converter are achieved for full-load range from no load to short circuit by adding an active energy recovery clamp and auxiliary circuits. The new significant feature of the converter consists in suppression of circulating current also in short-circuit conditions. The proposed converter is very attractive for applications where short circuit and no load are the normal states of the converter operation, e. g., arc welding. The principle of operation is explained and analyzed, and experimental results are presented on a 3-kW 50-kHz laboratory converter model.