Robust Control of Wireless Power Transfer Despite Load and Data Communications Uncertainties

This article focuses on the robust control of wireless power transfer (WPT) systems, to work satisfactorily around the desired resonant frequency in the presence of load and data communications uncertainties. The proposed robust control system is based on the quantitative feedback theory (QFT), consisting of a feedback compensator and a prefilter, which are designed by shaping the system's frequency responses, to satisfy the design constraints defined in terms of stability, tracking, and other desired requirements. A feature of QFT is to provide the designer with interactive graphical tools for the design and tuning of the feedback compensator and prefilter. Without loss of generality, this article elaborates the design of the QFT-based robust control for a WPT system with a full-bridge inverter and series-series capacitor-based compensation circuits and uncertain direct-current (dc) load. The data communications uncertainties are also addressed in the design. The effectiveness of the proposed QFT-based robust control methodology is evaluated through simulations and practical experiments and compared with H
_∞
and Skogestad internal model control (SIMC) design methods. Since QFT is a model-based approach, this article also elaborates on small-signal transfer function modeling of WPT systems.