Design of a Bidirectional DC/DC Converter with Wide Input/Output Range for Flexible ESS Applications

Abstract

This paper proposes a bidirectional DC/DC converter with a wide input/output voltage range for integrated operation between energy storage systems (ESS) and various DC loads. The proposed converter employs a series-parallel configuration of two Dual Active Bridge (DAB) converters, enabling stable power conversion across a wide voltage range from 200 V to 1000 V. To achieve high efficiency and high power density under a 25 kW environment, a transformer optimized for thermal dissipation and vertical height, along with an inductor featuring a distributed gap structure, is designed. In addition, a switching module integrating thermal management and gate driver circuitry is implemented. Experimental results using the fabricated prototype verify that the bidirectional power flow is stably controlled under various voltage conditions, achieving a power conversion efficiency exceeding 97%.