Totem-Pole PFC and LLC resonant converter based 6.6kW On-Board Charger for LEV Applications

As light electric vehicles (LEVs) gain popularity, the development of efficient and compact on-board chargers (OBCs) has become a critical area of focus in power electronics. Conventional AC-DC topologies often face challenges, including high inrush currents during startup, which can stress components and affect system reliability. Furthermore, DC-DC converters often have a limited soft-switching range under light load conditions, leading to increased switching losses and reduced efficiency. This paper proposes a novel 6.6 kW on-board charger architecture comprising a bridgeless totem-pole power factor correction (PFC) stage and an isolated LLC resonant DC-DC converter. The main contribution lies in the specific focus on enhancing startup behavior and switching performance. In PFC converters, limiting inrush current during startup is crucial, especially with fast-switching wide-bandgap devices like SiC or GaN. Conventional soft-start techniques fall short in of ensuring smooth voltage transitions. Moreover, maintaining stable operation across a universal input voltage range and achieving a high-power factor under light load conditions remain persistent challenges. Although resonant converters are widely used for their natural soft-switching ability, achieving zero voltage switching (ZVS) over a wide range of loads, especially at light load conditions, is still a technical challenge. Existing solutions rely on complex control strategies or hardware modifications, which increase cost and design complexity. The proposed architecture was modeled and simulated using MATLAB/Simscape to assess dynamic and steady-state behavior under a range of operating conditions. Results demonstrated high input power factor, line/load regulation, and switch-node waveforms to confirm ZVS operation. Additionally, the proposed charger exhibits low harmonic distortion, ensuring compliance with IEC 61000-3-2 power quality standards. These findings confirm the topology’s effectiveness for high-performance LEV charging and set a strong foundation for future experimental validation and hardware development.