Multi-Functional Isolated Three-Port Bidirectional DC/DC Converter for Photovoltaic Systems

Abstract

This paper proposes a novel multi-function isolated three-port bidirectional DC–DC converter for a stand-alone photovoltaic (PV) system. The proposed topology was composed of a unidirectional step-up converter and a bidirectional step-up/step-down converter that only required one set of complementary PWM signals to control any operation mode and used multiple operating stages to improve the practicability of the converter. In addition, the proposed topology had the function of inductance energy leakage recovery to improve the conversion efficiency and used synchronous rectification technology to reduce the conduction losses from passive components. This paper implemented a 500 W converter to verify the feasibility of the proposed converter by theoretical analysis, simulation, and experiment results. The experimental results show the highest efficiency of 95.5% for the PV step-up to the DC bus, 97.8% for the PV step-down to the battery terminal, 94.5% for the battery terminal step-up to the DC bus, and 93.4% for the DC bus step-down to the battery terminal, respectively.