GaN-Based Bi-Directional 7.2kW OBC with 10kW/L Power Density and High Efficiency

Abstract:
This paper presents the design and control of a high-power-density bidirectional on-board charger (OBC) with a 7.2kW power rating. The proposed OBC comprises an interleaved Power Factor Correction (PFC) circuit for the AC/DC stage and a Dual Active Bridge (DAB) for the isolated DC/DC stage. Gallium Nitride (GaN) technology is employed to achieve higher switching frequencies, leading to more compact passive component solutions. An advanced control structure for the overall OBC, utilizing two interconnected microcontroller boards, is proposed. The 7.2 kW OBC prototype has been experimentally verified, demonstrating an outstanding power density of 10 kW/L and a peak efficiency of 97.8% (3X more compact and 30% less overall losses than the state-of-the-art reference designs). Experimental results show a power factor exceeding 0.99 and Total Harmonic Distortion (THD) below 4% across a wide power range.