Improving the Efficiency of an Isolated Bidirectional Dual Active Bridge DC–DC Converter Using Variable Frequency

Abstract

This article presents a control method for an isolated bidirectional dual active bridge DC–DC converter (IBDC) where single phase shift (SPS) and variable frequency (VF) modulations are combined simultaneously with the purpose of improving the efficiency of the converter applied to the bidirectional charging of electric vehicles batteries. A complete power characterization of the dual active bridge (DAB) converter is carried out. The combined control achieves lossless turn-on and turn-off on the primary bridge for a wide range of output powers. A comparative study of power losses between the traditional SPS control and the combined method proposed here was also carried out. A prototype with an output power of 10 kW was built based on Silicon Carbide (SiC) Metal Oxide Semiconductor Field-Effect Transistors (MOSFET), with which a peak efficiency close to 99% was obtained, thus verifying the viability of the method.