Design and optimization of high-efficiency resonant wireless power transfer system

Magnetic resonant coupling is widely considered a promising candidate for the midrange transfer of power because of its long range and compact dimensions. This paper reports the process of designing a high-efficiency resonant wireless power transfer (RWPT) system. It discusses the optimal parameters for maintaining high power transfer efficiency with respect to distance and load variations. The design method is based on circuit theory, analytical derivation, and the use of Matlab to find the relationships of the parameters and to simulate the overall system. The analytical derivation is used for determining the average values of voltage and power in the circuit. The proposed system consists of a class E amplifier with a 6.78 MHz resonant frequency, coupling coils, and a class E rectifier. With a mutual inductance coefficient of k = 0.2, the expected efficiency is 93% for a power of 5 W.