Analysis of the coreless transformer in wireless battery vehicle charger

This paper mainly concentrates on development of fundamental theory associated to wireless power transfer application, specifically the wireless battery charger of electric vehicles. The primary core of the coreless transformer is integrated in the charger unit and the secondary core in the electric vehicle. In order to reach efficient power transfer through a large air gap between the windings of the wireless power transfer transformer, the principle of coupling magnetic resonance is used. Analysis of wireless charger battery coreless transformer of electric vehicle is performed through several simple and accurate expressions linked to the electric modeling. A capacitive compensation in primary and secondary winding is added to enhance the power transfer capability offering four topology cases (Parallel-Parallel, Series-Series, Series-Parallel, and Parallel-Series). Simulation results are performed for each case to compare their performances. The study shows the dominance of the Series-Parallel topology in energy efficiency point of view and thus the transmitted power yield over the same distance.