Overshoot Damping and Dynamics Improvement in Wireless Power Transfer Systems Via Receiver-Side Controller Design

Abstract

Buck converters have been extensively used for output regulation in the receiver of series-series compensated wireless power transfer (WPT) systems. Nonetheless, there are two major challenges in the controller design of this class of WPT systems. First, due to the current-source nature and finite dc-link capacitance, a right-half-plane (RHP) zero exists in the WPT receiver, reducing its stability margin and causing limited system dynamics. Second, this RHP zero can cause an overshoot issue in the WPT system. Without proper treatment, this overshoot may largely increase the voltage/current stress of the system and even cause catastrophic failure. However, existing solutions to the above two issues suffer from long communication delays or significantly compromised output regulation, degrading system performance. In this article, the slow dynamics and the overshoot issue of the WPT system are elaborated in theory and a solution is proposed by adding a feedforward path of the dc-link voltage in the receiver's controller. No communication is involved in the proposed control method, and only trivial computation is added to the controller. The proposed method is examined on a WPT prototype. The experimental results show that the two issues of the WPT system can be simultaneously solved by the proposed method while the output regulation of the system is not compromised.