High-Order Network Based General Modeling Method for Improved Transfer Performance of the WPT System

In wireless power transfer system, zero phase angle (ZPA), zero voltage switching (ZVS), load-independent output voltage, and current are key to improve transfer performance, like efficiency and output power over load change. More concerned, it is hard to realize those expected electrical characteristics in a topology simultaneously. To solve the issue, this article proposes a general modeling method based on the high-order resonant network. The equivalent impedance of passive components in each circuit branch is replaced by jX and then, according to the analysis of Kirchhoff principle, the conditions to realize load-independent output and simplified calculation of input impedance are given out. Hence, the proper passive components can be chosen to get expected electrical characteristics. A specific prototype, using the proposed modeling method for parameter design, is implemented to verify the validity of proposed modeling method. In the prototype, load-independent constant voltage and constant current modes can be switched by restructuring the passive network; meanwhile, ZPA or ZVS could also be realized by regulating only one component. The experimental results fit well with the theoretical analysis.