High efficiency wireless power transfer system design for circular magnetic structures

In this paper, a new approach is proposed to achieve maximum coupling coefficient for the windings in circular Wireless Power Transfer (WPT) systems. The designed magnetic structure has the maximum magnetic coupling coefficient in a specific air gap in order to maximize the system efficiency. Series resonant compensator network is analyzed in frequency domain and proper operating point is selected to achieve constant voltage gain in different loads. This system controls output voltage through a closed loop control via controlling inverter's duty cycle. The design procedure is explained for a 5 kW system. This system can transfer power from 100mm to 200mm air gap by resonant network and magnetic circular coupling that has a 480mm diameter. Efficiency results for output power in various air gaps are presented, where efficiency of the nominal load for 150mm air gap is 93%.