Resonant Network Design of a Three-Phase Interleaved LLC Resonant Converter for Ultra-Fast Charging of Electric Vehicles with a Wide Output Voltage Range

As the demand for electric vehicles continues to rise, the development of a high-power ultra-fast charging system with a wide output voltage range is essential to reducing battery charging time and extending driving range. The single-phase LLC converter, which achieves zero voltage switching over the entire operating range, is widely used as a DC-DC converter in electric vehicle charging systems. However, in high-power applications, increased input and output current ripple leads to higher system losses and larger volume. To address these challenges, a three-phase interleaved LLC converter is proposed to reduce input and output current ripple while enhancing system efficiency and power density. This paper presents the resonant network design of a 30 kW three-phase interleaved LLC converter with a wide output voltage range, intended for ultra-fast EV charging applications. The performance of the proposed system is verified through a prototype, achieving a maximum efficiency of 98.24% and a power density of 3,086 W/L.