AN ENHANCED BIDIRECTIONAL LLC+C RESONANT CONVERTER WITH PARALLEL TRANSFORMERS FOR HIGH-EFFICIENCY EV CHARGING IN DC MICROGRIDS

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 power-handling capability. The inclusion of a hybrid LLC+C resonant tank allows zero-voltage 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 solar-charged electric vehicle powertrains and renewable energy-based charging infrastructures.