Zero-voltage switching two-transformer full-bridge PWM lossless diode-clamp rectifier for PDP sustain power module (IECON ´04)

This paper presents a zero-voltage switching (ZVS) two-transformer full-bridge (TTFB) PWM converter with lossless diode-clamp rectifier for a plasma display panel (POP) sustaining power module (PSPM). The TTFB has series-connected two transformers which act as an output inductor as well as a main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the two-transformer make it easier to achieve the ZVS of the lagging leg switch along the wide load range, it instigates a serious voltage ringing across the output rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. 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 a half the output voltage (V₀/2) or the output voltage (V₀). Therefore, no dissipative snubber for the rectifier diodes is needed and a high efficiency as well as a low noise output voltage can be realized. In addition, the clamping capacitor of the LDCR can help to considerably reduce the primary circulating current. The operations, analysis and design consideration of proposed converter are presented. Also, a 425 W, 385-170 V dc prototype is constructed and experimental results verified the validity of the proposed converter.