Continuously Adjustable Capacitor for Multiple-Pickup Wireless Power Transfer Under Single-Power-Induced Energy Field

This article proposes and implements a continuously adjustable capacitor for multiple-pickup wireless power transfer (WPT), aiming to enhance the energy security performance under single-power-induced energy field. With the accelerated development and commercialization of WPT, the energy security issue shows the increasing significance for multiple-pickup WPT systems, where the induced open radial electromagnetic field facilitates all involved pickup coils to access the wirelessly transferred energy. If utilizing no appropriate protection strategy, the energy privacy is inevitably jeopardized, especially for the single-power-induced energy field where the auxiliary technique, such as the radio-frequency identification, cannot identify the multiple pickups. Accordingly, this article proposes a continuously adjustable capacitor that enhances the security/transmission performance for multiple-pickup WPT systems. Differing from impedance adjusting schemes reported in previous studies, the continuously adjustable capacitor can continuously adjust the impedance to match the encrypted switching frequency dynamically and continuously. In such ways, it can effectively enhance the flexibility of the WPT hardware platform for the cryptographic algorithm, thus significantly reduce the possibility of power being hacked. Finally, the simulated and experimental results are provided to verify the feasibility of the proposed continuously adjustable capacitor for the energy encryption of multiple-pickup WPT systems.