A Comparison of EV Battery Charging Methods for Power Factor Corrected-LLC Converter

The Li-ion batteries are most suitable for electric vehicle(EV) application, it is due to its high energy and power density. An efficient charging method is required to improve the life cycle and state of health of the battery. In this paper, a comparison of constant voltage(CV), constant current(CC), CC-CV, and cascade mode of battery charging for power factor corrected(PFC) LLC converter is given. For the onboard charging system, a high efficiency converter is required. A complete design approach for the LLC converter is also presented for selecting the desired parameters. The PFC converter circuit is an essential block of the onboard charger. The PFC maintains desired DC input voltage for LLC converter and also for unity power factor on AC side. In this study, the PFC and half bridge LLC converter is used as charging for Li-ion battery. The simulation is carried out by using MATLAB/SIMULINK. A 56V, 30Ah Li-ion battery is used. For the experimental validation, GAN modules are used for the power switch for both the converters and RENESES controller is used for development of the controller. Both the simulation and experimental study is carried out for the rating of 350W, 40-65V DC battery charging and 400V DC input voltage which is obtained from PFC.