High-Performance Multi-MHz Dynamic Capacitive Wireless Power Transfer System Using Asymmetric Couplers

The paper presents a high-power density multi-MHz dynamic capacitive wireless power transfer (WPT) system for wireless charging of mobile robots that leverages asymmetric couplers to achieve an improved misalignment tolerance. A methodology to design such couplers is presented. Furthermore, the impact of varying the physical parameters of the proposed asymmetric couplers is studied. Two 6.78-MHz 3-cm air-gap 2-kW capacitive WPT prototypes (one using conventional couplers and the other using the proposed asymmetric couplers) are designed and built to validate the proposed methodology. The developed prototype leveraging asymmetric couplers exhibit a significant improvement in misalignment tolerance i.e., 100% nominal output power delivery at ± 50% misalignment, with 85% peak experimental efficiency, as compared to the conventional prototype that can only deliver 35% nominal output power at ± 50% misalignment. Moreover, the proposed use of asymmetric couplers on the secondary-side offers a simple, efficient, and cost-effective alternative to active compensation techniques.