Analysis and Design of ZVZCS Full-Bridge Converter with Reduced Components for Input-Series-Output-Parallel Application

Different from the conventional performance improvement of a single phase-shift full-bridge (PSFB) converter by adding auxiliary components, this paper utilizes the intrinsic advantage of multi-module in the input-series-output-parallel (ISOP) application to achieve zero-voltage and zero-current switching (ZVZCS) operation of switches and reduce the duty-cycle loss and conduction loss in two PSFB converters through their interaction. The interaction is established by sharing the secondary rectifier diodes, and hence the number of components used in the proposed converter is reduced compared with the ISOP PSFB converter. Moreover, the voltage stress of the shared diodes is reduced. As a consequence, lower cost is achieved along with the improved performance. In this paper, operational principle and relevant analysis of the proposed ZVZCS PSFB converter with reduced components are presented in detail to obtain a comprehensive understanding. Besides, its small-signal model is gained and a closed-loop control scheme is accordingly designed to improve the dynamic performance. Finally, the favorable advantages of the proposed converter are experimentally verified in a prototype circuit with 400 V input and 120 V/500 W output.