Design and Optimization of an Asymmetric CLLC Resonant Converter with Interleaved Totem-Pole Front-End for Wide Voltage Range Single-Stage EV Charging

The increasing adoption of 800 V-class electric vehicles has created strong demand for single-stage onboard chargers capable of operating over a wide output voltage range while maintaining high efficiency and power density. This paper presents the design and multi-objective optimization of a single-stage bidirectional AC-DC converter that integrates a three-phase interleaved totem-pole front-end with an asymmetric CLLC resonant converter. The proposed topology eliminates large electrolytic DC-bus capacitors by using only small film capacitors and enables seamless operation across an ultra-wide battery voltage range of 100–850 V. The asymmetric CLLC parameters were optimized using a combination of fundamental harmonic approximation (FHA), time-domain analysis (TDA), and multi-objective particle swarm optimization (PSO) to achieve high voltage gain, wide zero-voltage switching (ZVS), and high efficiency. Simulations show a peak efficiency of 97.1%, an input-current THD of 2.8%, primary ZVS down to about 18% load, and bidirectional (V2G) operation. The design is a candidate for 800 V-class onboard chargers that must cover 100–850 V.