Zero-Voltage Switching Two-Transformer Full-Bridge PWM Converter With Lossless Diode-Clamp Rectifier for PDP Sustain Power Module

This paper presents a zero-voltage switching (ZVS) two-transformer full-bridge (TTFB) pulsewidth modulation (PWM) converter with lossless diode-clamp rectifier for a plasma display panel sustaining power module (PSPM). The TTFB converter has series-connected two transformers which act as an output inductor as well as a main transformer. Although the naturally doubled leakage inductor due to the series-connected two transformers contributes to achieve the ZVS of the lagging leg, it creates a serious voltage ringing across the output rectifier diodes. This results in the heavy voltage stresses across the rectifier diodes. Thus the dissipative snubber circuits are required in spite of the severe power dissipation. To overcome these problems, a new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped at one half the output voltage (V_o/2) or a full output voltage (V_o). Therefore, no dissipative snubber circuits for the rectifier diodes are needed and a high efficiency as well as a low noise output voltage can be realized. In addition, the clamping capacitors of the LDCR can help considerably to reduce the primary circulating current. The operations, analysis, and design consideration of proposed converter are presented. Also, a 425-W, 385-Vdc input, 170-Vdc output prototype is constructed and experimental results show the validity of the proposed converter