Efficiency optimization and power distribution design of a megahertz multi-receiver wireless power transfer system

It is attractive to achieve multi-receiver wireless power transfer (WPT) through a megahertz operating frequency. However, the power distribution among receivers can be a difficult task due to the different load characteristics, i.e., power requirement, receiver size, and coupling coefficient. This paper proposes a general design methodology of efficiency optimization and power distribution of a MHz multi-receiver WPT System. A Class E rectifier is introduced in the MHz multi-receiver WPT system to provide the design freedom for the power distribution and efficiency optimization. Based on the fundamental analysis and analytical derivations of the Class E rectifier and coupling coils, a numerical optimization problem is formulated to achieve the power distribution and maximized efficiency simultaneously. Finally, an example 6.78-MHz three-receiver WPT system is built to verify the proposed design methodology. The experimental results show that the proposed design can meet the power requirement of loads within 5% error and achieve system efficiency of 90% at a power level of 25W.