Active Variable Reactance Rectifier – A New Approach to Compensating for Coupling Variations in Wireless Power Transfer Systems

This article introduces a new approach to compensate for coupling variations in wireless power transfer (WPT) systems by utilizing an active variable reactance (AVR) rectifier. The AVR rectifier operates at a fixed frequency and incorporates a power-splitting resonant network. By controlling the ratio of the split powers in its branches, the AVR rectifier continuously compensates for large misalignments and distance variations between couplers, while maintaining full power transfer. A comprehensive methodology is presented that maximizes the tolerable range of misalignments in an AVR-rectifier-enabled capacitive WPT system while meeting efficiency targets. The proposed approach is validated using a 13.56-MHz, 300-W, 12-cm nominal air-gap prototype capacitive WPT system, which incorporates an AVR rectifier and can be scaled up in power for dynamic electric vehicle (EV) charging applications. The prototype system maintains full power transfer for up to 45% lateral misalignment in the coupler and up to 45% increase in the vehicle’s road clearance. In a dynamic EV charging scenario, the AVR-rectifier-enabled system transfers 80% more energy during a single pass of the vehicle over the charging pad, as compared to a system without the AVR rectifier. The measured performance of the prototype system is in good agreement with predictions.