A high performance dual output dc-dc converter combined the phase shift full bridge and LLC resonant half bridge with the shared lagging leg

A new dual output dc-dc converter is proposed in this paper. The first output works as a conventional full bridge converter; by connecting a LLC resonant tank to the lagging leg, a half bridge resonant converter is structured, and the second output is obtained. The first output is regulated by the phase shift and the second output by the switching frequency. Both of the outputs are fully regulated and independent. The narrow frequency variation of the LLC part makes the magnetic components easy to optimize. The ZVS of the leading leg is easy to achieve by the phase shift operation, the ZVS range of the lagging leg is extended down to empty load by the shared structure. Moreover, compared to the conventional full bridge phase shift converter, the shared lagging leg offers a loose dead-time limitation. Therefore the proposed converter is low cost, high reliability, high efficiency and high performance. A 300 V input, 36 V/10 A, 24 V/10 A outputs prototype is build to verify the design.