Analysis and design of a wide range ZVS/ZCS push–pull DC/DC converter with voltage clamped

Abstract

A new isolated zero-voltage switching (ZVS)/zero-current switching (ZCS) push–pull (PP) DC/DC converter is presented. One auxiliary switch S3 and a clamping capacitor Cc are introduced at the primary of the conventional push–pull converter and a voltage doubler-rectifier is adopted on the secondary side. This proposed converter has the features: (1) Switching losses are reduced significantly owing to zero-voltage switching of primary switches and zero-current switching of secondary diodes over a wide load range variation. (2) The voltage spike across all of the power devices can be clamped that enable the use of low-voltage, low-performance, and lower-cost devices. (3) The energy stored in the transformer leakage inductance is used for the soft-switching action and no additional resonant inductor is required. (4) A voltage doubler-rectifier is employed to remove the problem of the diode reverse-recovery effect and reduce the duty cycle loss that provides a much higher voltage conversion ratio. These merits make this simple converter provide an attractive solution for a distributed power system, uninterruptible power system, or battery charge/discharge system. The detailed operation, analysis, design, comparative study, and experimental results for the proposed converter are presented and a 600 W prototype was developed to verify the discussed theoretical analysis.