A small signal analysis of a dual half bridge isolated ZVS Bi-directional dc-dc converter for electrical vehicle applications

Due to its distinct operation characteristics, the recently proposed Dual Half Bridge (DHB) isolated ZVS bi-directional dc-dc converter achieves high power density, soft-switching and easy control at one package and thereby gains increasing interests in EV applications. These advantages are obtained at the expense of increasing the order of the system. In this paper, the small signal derivation and analysis of the new DHB converter is performed. Particularly, the small signal models and the corresponding equivalent circuits are developed to derive transfer functions at both voltage control mode and current programmed control (CPM) mode. The dynamic effects introduced by the phase-shift operation, capacitors and transformer leakage inductance have been modeled into the equivalent circuits. Model predictions are conformed by circuit measurements.