Three-Phase Current-Fed Isolated DC-DC Converter With Zero-Current Switching

A new current-fed zero-current switching (ZCS) three-phase dc-dc converter topology is proposed in this paper. The converter architecture consists of a current-fed three-phase three-leg IGBT bridge, three single-phase high-frequency transformers with star-connected primary, and three single-phase rectifier bridges. Each secondary winding of the high-frequency transformer forms the input for single-phase rectifier bridges at the output. The parallel-connected outputs of these bridges supply the desired load. The three-leg IGBT-based primary bridge is modulated with constant frequency phase-shift pulse width modulation technique. ZCS for all the primary IGBTs is achieved with the aid of transformer leakage inductance, small auxiliary ac capacitors connected in parallel to secondary side of single-phase transformers and modulation scheme. Detailed operation with converter design and analysis are discussed. Digital simulation and experimental test results on a laboratory prototype are presented to investigate the converter design and operation.