Power Stabilization Based on Efficiency Optimization for WPT Systems With Single Relay by Frequency Configuration and Distribution Design of Receivers

The operation of wireless power transfer systems (WPT) with a single relay, which could charge one or multiple receivers simultaneously, is investigated. Besides, a new method for ensuring the optimized transfer efficiency and the output power by configuring the operating frequency is presented, even when the coupling coefficients between all the coils are very small. An issue of concern is that the couplings between receivers cannot be ignored due to limited operating space, which adds to the complexity of both the system design and the control method. The contribution of the research presented here is to propose an optimized strategy which can charge each receiver with identical power and simplify the coupling complexity thereof. Specifically, the efficiencies and outputs of the introduced WPT systems are discussed. In addition, the distribution design according to different numbers of receivers is proposed to guarantee that both the system operating frequency and the output power remain stable. The theoretical analysis is confirmed by both simulation and experimental results.