A Series of Hybrid WPT Systems With Automatic Switching Between Constant-Current and Constant-Voltage Modes on the Secondary Side

Abstract

In battery charging applications, wireless power transfer (WPT) technology has unique advantages over wired power transmission. For stationary charging cars, it is necessary to overcome the system performance changes caused by coil misalignment, and the constant-current (CC) mode must be quickly and stably switched to constant-voltage (CV) mode to ensure battery safety. Based on a T-type network, this article presents the basic characteristics of a series of hybrid structures with high misalignment tolerance. Additionally, based on these structures, a series of methods to automatically and quickly switch from CC to CV by changing the resonance compensation structure on the secondary side is proposed without communication or complicated control methods. To verify the performance of the proposed structure, this article presents a reconfigurable system based on a hybrid structure and builds a set of experimental equipment with the power of 200 W. In the CC/CV mode, the misalignment tolerance in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -axis can reach 50%, in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -axis can reach 33.33%, and the output current/voltage fluctuation range is less than 5%. In addition, the switching process is stable enough to satisfy charging requirements.