A Family of MI Enhancement Dual-Coupled WPT Systems With High-Misalignment Tolerance and Extensive Vertical Distance Adaptation

The transfer performance of wireless power transfer (WPT) systems is directly affected by the inevitable misalignment and vertical distance changes. The characteristic of the generalized dual-coupled WPT system with the positively and reversely connected coils is investigated. It is found that the enhanced stable equivalent mutual inductance (MI) can be flexibly designed, including its value and fluctuation by introducing MI adjustment factor. With the help of the factor, the relationship of the coil parameters, the compensation components, and the equivalent MI value is established. The MI variation characteristics of the circular dual-coupled coils are explored and the method to calculate the factor is given based on the slope of the MI function of the dual-coupled coils. Also, a set of design principles for the proposed systems with different coil connecting types and the coil position is provided, leading to a family of dual-coupled WPT systems with high-misalignment tolerance and extensive vertical distance adaptation. A 1-kW prototype is designed for validation. The result shows that the maximum fluctuation of the load current is 9.1% and 12.0% within the 100-mm misalignment and 70-130-mm vertical distance. The dc-dc efficiency of the system can reach 91.705%.