Single-Switch Wireless CC and CV Charger With Self-Sustained Battery Charging Profile and Theoretical Zero CV Output Deviation

In recent years, a wireless charging topology with inherent constant current (CC) and constant voltage (CV) output conversion through a clamp coil on the transmitting side has been proposed. Because it does not require auxiliary circuits such as load voltage sampling and wireless communication, it has received extensive attention and research. However, there are some issues with this topology. For example, there is cross-coupling between the transmitting coil and clamp coil, which causes a deviation in the CV output and easily causes overvoltage damage to the battery. Aiming at the above problem, this article proposes a single-switch wireless CC and CV charger with a self-sustaining battery charging profile and theoretical zero CV output deviation. On the transmitting side, a bipolar pad (BP) coil structure is used to eliminate the cross-coupling between the transmitting coil and clamp coil, and completely eliminates voltage deviation during CV output in theory. This article establishes the simplest equivalent model of the proposed circuit topology and calculates the mathematical expression of the equivalent input voltage in the time domain. And a method for automatically calculating the parameters of a single-switch circuit is designed. Finally, the superiority of the proposed circuit topology is verified through simulation and real lithium-ion battery charging experiments.