Small-Signal Modeling and Decoupling Control Method of Modular WPT Systems

Modularization is an effective way to realize high-power wireless power transfer (WPT). A modular WPT system can be adaptive to multiple power levels by simply modifying the number of its modules. However, the cross couplings among different modules form complicated power transfer paths in the system and, consequently, the output of one module will be affected by the inputs of the other modules, and thereby it is difficult to achieve stable output regulation for each module by using the conventional negative-feedback control method. In this article, a decoupling control method is proposed to compensate for the adverse effect of the cross couplings among the modules, and, thereby, individual output control for each module can be realized. The small-signal model of the modular WPT system is derived to analyze the stability of the proposed decoupling control method. A 7-kW two-module WPT prototype is built for experimental verification.