A Fast Self-positioning-based Optimal Frequency Control for Inductive Wireless Power Transfer Systems without Communication

A communication-free approach to achieve self-positioning optimal frequency control (SP-OFC) for a series-series-compensated wireless power transfer system is proposed in this article. Without any position sensor, the position of the receiver is located by only monitoring the winding current. The feasibility of optimal frequency control for achieving zero phase angle is elaborated based on the multiple transmitters charging condition. The proposed method involves no communication link with a small number of sensors, so the calculation effort in the controller is relieved. Hence, the control scheme can be fast, cost-efficient, and practically reliable. In addition, the technique allows random resonator parameters. Experimental results prove that the proposed SP-OFC process for high system efficiency at rated power level can be completed within 20 ms, and the phase difference can be controlled within 4.81° in the worst case. The system efficiency is proved to be improved by up to 14.3% by achieving optimal frequency. The interoperability of receivers with various coil shapes and positions is discussed in the form of the case study.