Multiport Soft-Switching Bidirectional DC-DC Converter for Hybrid Energy Storage Systems

This paper presents a bidirectional, soft-switching, multiport DC-DC converter, using a transformer isolated Dual-Active Bridge and a PWM boost configuration to interface two energy sources with a DC bus. The converter is intended for integration of battery and supercapacitor with a DC micro grid, which require the battery port to be interfaced in a current source manner. The converter topology and the operating principles are introduced. Suitable control strategy to regulate the DC link voltage along with current control of the battery port is proposed. Current source property along with soft switching at constant switching frequency makes this topology well suited for energy storage applications. Experimental results are given for a Multiport converter prototype operating over an output power range of 100 W to 1000 W while supplying a constant output DC link Voltage. The converter switching frequency is above the Audible frequency band to reduce switching noise. Using Silicon MOSFETs, the prototype achieves a peak efficiency of 98.5%, and maintains greater than 90% efficiency across the wide output power range.