A Multi-Cell SCC Capacitive Coupler with Strong Lateral, Longitudinal and Rotational Anti-offset Performance

The coupling structure of a capacitive power transfer (CPT) system eliminates the need for ferrite on the secondary side, resulting in a lighter, thinner, and more cost-effective design compared to an inductive power transfer (IPT) system, while still achieving high power transfer efficiency. This makes CPT a promising option for unmanned aerial vehicle (UAV) applications. However, existing researches cannot achieve efficient power transfer when lateral, longitudinal, and rotational offsets occur. This paper proposes a novel multi-cell single capacitance coupled (SCC) capacitive coupler with strong lateral, longitudinal, and rotational anti-offset performance at any position of the transmitter. The top and bottom plates of the transmitter consist of numerous interconnected rectangular cells. To avoid excessive mutual capacitance on the primary side and to enable effective coupling of the partial capacitance between the bottom plate of the transmitter and the top plate of the receiver, the rectangular cells of the transmitter's bottom and top plates are misaligned. When offset occurs, the top plate of the transmitter and the bottom plate of the receiver can maintain reliable contact, and the number of rectangular cells on the transmitter's bottom plate aligned with the receiver's top plate remains nearly constant, ensuring stable coupling capacitance and high power transfer efficiency, general design guidelines for the dimension of the small rectangular cells and the gap between the plates are also provided. Additionally, an LC-LC topology is designed to verify the anti-offset performance of the proposed coupler in CPT circuit system, and the designed circuit operates with constant current (CC), near zero-phase angle (ZPA) and zero voltage switching (ZVS) operations under any offset condition. Finally, an experimental prototype was built, demonstrating that the change in coupling capacitance is less than 4.2% under lateral, longitudinal, and rotational offsets, indicating excellent anti-offset performance. The system achieves a peak efficiency of 82.5% at 34.28 W.