Soft Switching PWM Full Bridge Three-Level DC-DC Converters

A novel soft switching PWM full bridge threelevel (TL) dc-dc converter is proposed. Eight power switches in the presented circuit are directly clamped by the input capacitors, and no auxiliary primary clamping devices are required. Thus, the proposed converter has simple and compact primary circuit structure compared to other full bridge (FB) TL dc-dc converters. Phase shift (PS) modulation strategy can be used to achieve wide output range, which means most commercial PS PWM controllers can be directly utilized. The total VA rating of the two transformers in the proposed converter is identical to that of other FB TL dc-dc converters with single transformer. The main issues about basic operation principle, integrated transformer method, soft switching characteristics, ZVZCS solution, and output characteristics are discussed. Prototypes are built and experimental results are provided and analyzed to validate the proposed converter.