Live Calculation Method for the Mutual Capacitance in Capacitive Wireless Power Transfer Systems With Multiple Receivers

ABSTRACT Capacitive wireless power transfer shows promise for wireless energy delivery, utilizing capacitive coupling for transmission. Quantifying the coupling between individual transmitters and receivers is essential, as optimization techniques for optimal output impedance depend on accurate knowledge of the coupling coefficient. Because practical capacitive power transfer systems often experience variations in distance or alignment, impacting the coupling coefficient and consequently, the optimal output impedance, it is desired to constantly measure the coupling coefficient. However, existing methods for measuring mutual capacitance in CPT systems require specific conditions, making them unsuitable for live measurements. This paper introduces a method for live calculation of mutual capacitance in CPT systems, applicable during normal operation. We present a theoretical framework applicable to SIMO systems with an arbitrary number of receivers and validate our results experimentally for both SISO and SIMO systems using a 10‐W prototype operating at a frequency of MHz. Our method shows strong agreement with established techniques, especially for systems with identical receivers. This approach enables live mutual capacitance calculation based on voltages and currents available during normal system operation. It is effective for SISO and SIMO configurations, confirmed by simulations and experiments.