ADVANCED THREE-LEVEL CLLC RESONANT CONVERTER FOR HIGH-EFFICIENCY BIDIRECTIONAL EV CHARGING SYSTEMS

Abstract

This paper presents a High-Efficiency Bidirectional LLC+C Resonant Converter with Parallel Transformers designed for solar-charged electric vehicle (EV) applications. The proposed converter topology enables bidirectional power flow between the solar photovoltaic (PV) source, the battery storage system, and the EV drivetrain, ensuring optimal utilization of harvested solar energy. By integrating parallel-connected transformers, the system achieves reduced current stress, improved thermal performance, and enhanced powerhandling capability. The inclusion of a hybrid LLC+C resonant tank allows zerovoltage switching (ZVS) and zero-current switching (ZCS) over a wide load range, significantly improving conversion efficiency and minimizing switching losses. To further enhance system performance, an intelligent fuzzy logic controller (FLC) is employed for adaptive regulation of voltage and current, providing robust control under varying solar irradiation and load conditions. The proposed system is validated through simulation analysis, demonstrating superior efficiency, and stable bidirectional operation compared to conventional single-transformer LLC converters. The results confirm that the proposed design is a reliable, compact, and efficient solution for next-generation solarcharged electric vehicle powertrains and renewable energy-based charging infrastructures