A Novel Anti-Offset Interdigital Electrode Capacitive Coupler for Mobile Desktop Charging

This article proposes a novel antioffset interdigital electrode capacitive wireless power transfer system for mobile desktop applications. The coupler consists of two pairs of series connected interdigital electrodes at transmitter side and two copper plates at receiver side, and a detailed generalized design methodology is provided. To realize antioffset at transverse direction, switch array is adopted at series connected interdigital electrodes side, and coupling coefficient can be kept stable at any misalignment distance. When misalignment occurs, changes of switch array are decided by voltage and current phase angle detection at transmitter side, and the system resonance frequency does not need to be tuned with the changes of misalignment distance. No additional position detection sensors are required, which simplifies the system and reduces the production cost. System energy transfer efficiency can be kept stable between 81.18% and 86.77% at any misalignment distance. When rotational misalignment occurs, the receiver can maintain voltage gain of more than 1.95 with stable 5 W output at -45°∼45° offset. Experimental results at 2.28 MHz show great agreement with theoretical analysis.