New Modelling and Control Techniques for Wireless Power Transfer (WPT) Systems

The operating conditions of WPT systems commonly result in coil misalignment and, thus reduce mutual inductance (M), between transmitting and receiving coils. As a consequence, the coil inductances and load impedance reflected to the primary side will be changed, detuning the resonant WPT system and limiting its power transfer capability, which in turn leads to excessive apparent power draw and low system efficiency. This paper presents the concepts of a new technique for modelling WPT systems that can be simply modified to investigate different types of compensation circuits. The concepts of an optimal control strategy are also presented that allows for regulated power transfer with impedance matching for maximum efficiency, regardless of large variations in M and load. The new modelling technique is used to investigate the performance of WPT systems implemented with two basic types of compensation circuit and an optimal control strategy. The results for a bi-directional WPT system demonstrate applicability of the proposed modelling and optimal control techniques.