Design of High-Efficiency Isolated Bidirectional DC/DC Converter with Single-Input Multiple-Outputs

Abstract

This study mainly develops a high-efficiency isolated bidirectional DC/DC converter (HEIBDC) with a single input and multiple outputs. For the requirement of multiple output voltages with only one single input source, the proposed HEIBDC can achieve the objectives of high-efficiency power conversion and bidirectional power flow. The proposed HEIBDC can be operated at two modes, including the step-down mode and the step-up mode. At the step-down mode, the high-voltage DC bus transmits extra energy to charge the bidirectional input power source. At the step-up mode, it can transmit the energy from the input power source to the high-voltage DC bus for the possible utilization of a later DC/AC inverter, and from the auxiliary source (e.g., a battery module) to supply power for peripheral devices. The proposed HEIBDC uses a coupled inductor to increase the step-up/step-down voltage ratio and adopts an auxiliary inductor to indirectly adjust the voltage of the auxiliary output terminal. Moreover, the utilization of voltage clamping and soft switching in the proposed HEIBDC is helpful for accomplishing the goal of high-efficiency power conversion. In addition, the effectiveness of the proposed HEIBDC is verified by experimental results of a 600W prototype in practical applications. The experimental results reveal that the maximum power conversion efficiency at the step-up mode or the step-down mode is measured to exceed 96%.