Supply of electric vehicles via magnetically coupled air coils

The paper describes the contactless electrical energy transfer system (CEETS), by which electrical energy may be transmitted, without electrical connection or physical contact, through the large air gap. In this case energy is transmitted via coreless transformer. Coupling between the coils changes and depend on dimension of air gap. The efficiency of CEETS is mainly depended on the transmission frequency. Additionally large leakage inductances may be compensated also in resonance condition by adding capacitors to the coils. The article presents theoretical analyses and simulation results of transformer equivalent circuit with capacitors. Theoretical developments are compared with practical measurements from a prototype contactless system.