Omnidirectional magnetic resonant coupling wireless power transfer system with a cubic spiral transmitter

Though impressive advances of the extension of effective working distance for magnetic resonant coupling wireless power transfer system have been made over past decades, their applications have been severely limited by the requirement of unidirectional coaxial distribution for the transmitter and receiver. In this paper, an omnidirectional magnetic resonant coupling wireless power transfer system is proposed. The cubic spiral transmitter requires only a single power source, and the receiver receives power in all directions. The power transfer efficiency of the system is derived through an equivalent circuit model. And an impedance matching circuit which includes a pair of parallel and series capacitors is proposed for better stability and higher efficiency. In addition, geometrical parameters of the single power driven spiral transmitter structure are optimized to improve distribution uniformity for different directions. Thus the power transfer efficiency of the system, which depends on the distance between the transmitter and the receiver, is almost the same for different receiving angles. Finally, the theoretical analysis is verified by practical experimental results, which shows the power transfer efficiency of 60% at 150 mm.