Analysis of ZVS Series Resonant Converter with Two Transformers

Series resonant converter with two transformers and output voltage doubler is presented in this paper. Based on the resonant behavior of the resonant inductor and capacitor, the ZVS is achieved for all power switches and ZCS is realized for all rectifier diodes. For high power applications, the primary sides of two transformers are connected in series to reduce the voltage stress on primary windings. The secondary windings of two transformers are also connected in series to charge relative output capacitors. Since the voltage doubler rectifier is adopted in the secondary side, only one secondary winding per transformer is needed Thus, the transformer secondary winding can be reduced. Compared with the conventional series resonant converter with center-tapped rectifier, the voltage stress of rectifier diodes is clamped to output voltage instead of two times of output voltage. The low voltage drop schottky diodes can be adopted in the output side to reduce the conduction loss. The principle of operation, steady state analysis and design example of the proposed converter are provided and discussed in detail. The proposed converter is suitable for high efficiency applications such as industrial power supply unit, all-in-one power supply and LCD-TV power unit. The laboratory experiments with a 480W (24V/20A) prototype are provided to verify the effectiveness of the proposed converter. Copyright (C) 2010 Praise Worthy Prize S.r.l. - All rights reserved.