Design and Performance Analysis of a High-Efficiency Bidirectional DC-DC Converter for Electric Vehicle Battery Systems

This preprint presents the design and simulated performance analysis of a high-efficiency bidirectional DC-DC converter for electric vehicle (EV) battery systems. A non-isolated, two-phase interleaved synchronous buck-boost topology built with SiC MOSFETs is proposed to interface a 300–400 V lithium-ion battery pack with a 400 V DC traction bus, supporting bidirectional power flow between motoring (boost mode) and regenerative braking (buck mode). Analytical design procedures are presented for the power inductor, DC-link capacitors, and semiconductor devices, along with a dual-loop PI control strategy with automatic buck/boost mode arbitration. A loss model incorporating conduction, switching, and inductor losses is used to predict converter efficiency across the operating range. Simulated results show a peak efficiency of approximately 97.4%, inductor current ripple below 20% of rated current, DC bus voltage ripple under 1.5%, and a regenerative-braking mode-transition settling time of approximately 1.1 ms. These results are based on analytical loss modeling and average state-space simulation rather than hardware validation; switching-cycle-accurate simulation and hardware prototyping are proposed as future work.