An Optimized Multiphase Bridgeless SEPIC Converter for High-Power Applications with Distributed Thermal Management and Enhanced Power Factor Correction

This paper presents the design and implementation of an optimized multiphase bridgeless SEPIC converter for high-power applications, such as fast-charging systems in electric vehicles (EVs), renewable energy interfaces, and industrial drives where the system operates under stable load conditions. An intra-phase interleaving technique is employed; wherein multiple switching legs are interconnected within the same phase to enhance thermal distribution and reduce component stress by equalizing current paths. This system combines a three-phase interleaved power factor correction (PFC) rectifier and a multiphase interleaved SEPIC converter, both controlled by PID controllers that contain signals with a 180-degree phase shift within each phase. High-fidelity simulation environment demonstrates low conduction ripple and a total harmonic distortion (THD) of less than 3%, as well as stable output voltage regulation of up to 800V at 5kW. The proposed design ensures thermal balance and a stable DC output under constant load, thereby improving system reliability and extending operational lifespan. These results provide a foundation for future investigations under dynamic load conditions.