Development of Bi-Directional Isolated DC-DC Converter for Battery Test Equipment

摘要

A resonant CLLLC converter is developed and tested to prove the feasibility of replacing the bulky grid side ac transformer with the high frequency bi-directional converter to develop a compact test equipment for battery aging and formation test. This topology can provide ZVS for primary side swathes and ZCS for the secondary side switches independent of the power flow direction. Achieving soft switching in all MOSFETs not only reduces the losses and increases the efficiency but also makes reaching higher switching frequencies feasible. Higher switching frequencies would increase the power density of the converter. In this paper first, brief literature review is done on available topologies, then steady state analysis and design procedure of the CLLLC converter is described. Finally, prototype is built and tested in lab. Input voltage of the converter is in the range of 650-750 V, output voltage should be regulated between 350-450 V and output current should be in the range of ±30 A. the resonant frequency of the converter is designed to be around 300 kHz. The converter could achieve peak efficiency of over 98%.