A Hybrid Charger of Conductive and Inductive Modes for Electric Vehicles

Electric vehicles (EVs) are gaining more and more user acceptances due to their clean, efficient, and environmentally friendly nature. Currently, most commercial EVs use conductive charging for their batteries. Inductive charging, which is an alternative charging technology, has recently received a great deal of attention because of its increased user convenience and safety. It is forecast that the two charging technologies will be implemented in future charging infrastructures globally. Consequently, future EVs need to be capable of dealing with both charging methods. So far, there have only been a very few charging topologies reported in the literature that describe both charging methods in the same vehicle. However, solutions that have been proposed do not show a significant component reduction. In this article, we propose a hybrid charger system where the high-frequency transformer of an onboard dc-dc converter becomes the coupling point between the conductive and inductive charging. Using this coupling point, the circuit utilizes the same components for conductive and for inductive charging. This results in the reduction of component count and, therefore, an improved integration. The proposed system is verified by both simulation and experiment. For the experiment, a 3-kW prototype has been built and tested. The maximum efficiency of 97.4% and 93.6% was achieved in the conductive and inductive mode, respectively.