Steady-State Analysis of a ZVS Bidirectional Isolated Three-Phase DC-DC Converter Using Dual Phase-Shift Control With Variable Duty Cycle

This study presents the steady-state analysis and experimental results on a soft-switching bidirectional isolated three-phase dc-dc converter using DPS control with variable duty cycle. The topology uses three single H-bridges in the primary side and a three-phase inverter in the secondary side. High-frequency isolation is ensured by using three single-phase transformers connected in open delta-wye configuration. The variation of both phase-shift angles between the H-bridge legs and/or primary and secondary sides allows controlling the power flow, while reduced reactive power flow is possible. The variable duty cycle is used to ensure a constant voltage bus and/or zero voltage switching operation. A detailed analysis is presented considering a model based on the fundamental components for the voltages and currents in the transformer. A comparison between the fundamental and the actual models is carried out to validate the proposed model. Experimental results on a 96 V/350-400 V, 3.5 kW prototype are presented and discussed to validate the proposed approach.