The magnetic field's compactness can better increase energy's transmission distance in a near-filed wireless power transfer (WPT) system. This paper proposes a non-centrosymmetric excitation unit (NEU) design method for the WPT system with a matrix coupling mechanism to improve the magnetic flux density in the central region. The proposed method enhances the magnetic focusing performance with a flat two-dimensional structure while maintaining its misalignment tolerance without any other auxiliary coil or circuit. The self-inductance value of the transmitting coil in this design method is even smaller than that of the conventional design method under the same size and number of turns. In addition, the proposed method is applicable to all regular matrix coils. Then, a detailed design method of the coupler is given based on the circuit analysis. Finally, taking the LCL-LCC compensation WPT system as an example, the feasibility of the proposed design method is verified. Compared to traditional design methods, the proposed design method can increase the induced voltage by 24.7% at the optimal position.

The current mobile robot UAV (unmanned aerial vehicle)/AGV (automated guided vehicle) plays an important role in industrial inspection, office logistics, agricultural and forestry plant protection, and military reconnaissance and surveillance fields. A multi-level, multi-modal power supply demonstration application has been designed in intelligent parks and industrial inspections to achieve charging docking between unmanned devices. However, most power supply methods are fixed-point charging, which is complicated in the energy transmission process and faces energy loss problems. In special charging environments such as wilderness and underwater, if there is no suitable parking charging platform condition, UAV hovering charging technology has become the most necessary and perfect charging solution, and it is also the key to building wireless power transmission network environments. Based on the well-established technology of fixed-point hovering and hovering following for unmanned inspection equipment in the air-to-air, ground-to-ground, and air-to-ground scenarios, hovering and alignment energy replenishment is undoubtedly a highly efficient and cutting-edge design concept applied to unmanned inspection equipment. Nowadays, to further enhance the flexibility and reliability of wireless charging systems, more and more wireless charging systems are designed based on matrix coils. The matrix-based multi-excitation wireless charging system has gained more favor in charging applications due to its reconstruction mechanism of the magnetic field at the transmitting end and strong tolerance for voltage and current stress.

In summary, a matrix coil design method based on non-centrosymmetric excitation units is proposed, combined with an evaluation of the system's spatial field transmission capability to improve the optimization design steps and the focusing ability of the magnetic field. This design method, which has a two-dimensional planar structure, enhances the magnetic flux density at the center position without any auxiliary coils or circuits, avoiding the offset tolerance weakening of the matrix coil itself as much as possible. It reduces the self-inductance of the coil unit to improve mutual inductance utilization.