A Three-Level Resonant DAB Converter Featuring Minimized Circulating Losses for EV Battery Charging

A three-level modified series-parallel bidirectional isolated dc-dc resonant converter (TL-MSPBRC) is proposed for electric vehicle (EV) battery charging. The converter's performance is enhanced for wide load conditions as the modified series-parallel resonant tank is formed by considering the parasitics in the transformer. The first-harmonic approximation (FHA) equivalent circuit model is employed to analyze the converter characteristics for the frequency modulation technique. This converter has high conversion efficiency in charging and discharging operations because of the soft-switching capability of the power switches in the primary and secondary bridges. In addition, low ON-state resistance switches in the three-level primary bridge minimize the conduction losses. A 3.3-kW converter prototype with a battery voltage range of 230-300-V is developed to validate the design method and the simulation results. The proposed converter has minimized circulating losses, good short-circuit protection, and excellent efficiency of 97.7% at the rated power level.

Automated summary

A three-level modified series-parallel bidirectional isolated dc-dc resonant converter (TL-MSPBRC) is proposed for EV battery charging. The converter's performance is enhanced by considering the parasitics in the transformer and using the first-harmonic approximation (FHA) equivalent circuit model. It has high efficiency, soft-switching capability, and minimized conduction losses. A 3.3-kW prototype with a battery voltage range of 230-300-V is developed to validate the design method and achieves an excellent efficiency of 97.7%.