Adaptative Resonant Tank of Bidirectional CLLC Resonant Converters for Electric Vehicle Charging Applications

This paper focuses on optimizing the design of CLLC converters for asymmetric bidirectional operation, a critical requirement in electric vehicle (EV) charging systems. Previous research has shown that CLLC converters are effective due to their soft-switching characteristic, achieving high performance in terms of efficiency and power density. However, challenges remain in optimizing their operation for bidirectional power flow, particularly for wide voltage and load applications such as vehicle-to-grid (V2G). To address this, we evaluate a novel approach that adds a parallel inductor to the primary side of the resonant tank in reverse operation to improve the gain characteristics and efficiency. The research uses theoretical analysis and simulations. The results show a resonant converter capable of meeting the requirements of a wide voltage and load range application without compromising the performance of the main operating mode, all while keeping the magnetizing/leakage inductance relation within the design criteria for integrated transformers.