Dynamic Adaptive Impedance Matching in Magnetic Coupling Resonant Wireless Power Transfer System

Abstract

The circuit and environment of Wireless Power Transfer (WPT) system are always complex, which makes it difficult to design the magnetic coupler and reduce the transmission efficiency. Recently, a few advanced matching strategies and structures have been able to improve transmission efficiency in the WPT system when the magnetic coupling system is detuning. But the current compensation and matching system suffers from difficulties in optimization and generalization. To address this issue, in the present work, an external coupling modeling and adaptive dynamic impedance matching method are applied to the energy transmission optimization for WPT system. Firstly, an external coupling network modeling method is designed in a four-coil magnetic coupling resonance system, and a scattering parameter expression method of T-type network transmission efficiency is defined. Secondly, we add frequency independent compensation reactance to the circuit, and use external coupling coefficient to match the impedance of the system to eliminate the detuning and improve the transmission efficiency. Tertiary, the frequency independent impedance is realized by using controllable capacitance, and the value range of compensation capacitance is determined. Finally, experiments and simulations show that the optimized system has good impedance matching and transmission efficiency.