This paper proposes a ground-side power transmitting coil parameter design method that takes the length of the transmitting coil as an optimization target, which takes into account the driving speed of EV (Electrical Vehicle), the EV's power consumption per kilometer, the coil energy loss and the system charging efficiency. The system uses a long-track transmitting coil, rectangular receiving coil, and LCC-S resonance compensation topology. First, the charging power and energy transmission efficiency are calculated. Based on the condition that the dynamic wireless charging power within 1km is not less than the EV's power consumption per kilometer, the lower limit of the charging power is determined. Secondly, the minimum value of transmitting coil current is inferred from the peak value of the charging power, the corresponding compensation inductance and transmitting coil wire diameter are further obtained, then the relationship between the system efficiency, the load resistance and the transmitting coil length is calculated. Under the condition that the charging efficiency is not less than 80%, the selection range of the transmitting coil's length and the load resistance value is initially determined, which further refined by combining the curve of the charging power with the load resistance value and “2 second principle”. Finally, aiming at segmenting a road section of 1 km in integers with the least number of transmitting coil segments, the number of transmitting coil segments and coil length that simultaneously meet the economic requirements for coil laying and system efficiency are determined. Finally, the feasibility of the above transmitting coil parameter design method is verified through experiment. The parameter design and optimization method of ground-side power transmitting coil of EV DWPT charging system proposed in this paper provides a reference for the design of the power transmitting coil length of EV DWPT charging system in the high-speed driving scene.

The application of wireless power transfer (WPT) technology in power replenishment for drones can help to solve problems such as the frequent manual plugging and unplugging of cables. A wireless power replenishment system for drones based on the transmitter design with multiple annular-sector-shaped coils is proposed in this paper, which improves the misalignment tolerance of couplers, enlarges the drone landing area, and reduces the control requirements of drone landing accuracy further. The general analysis model of the proposed transmitter and the numerical calculation method for mutual inductance between energy transceivers are established. Then, the effect of multiple parameters of the proposed transmitter on the variation in mutual inductance is studied. The misalignment tolerance improvement strategy based on the optimization of multiple parameters of the transmitter is investigated. Finally, an experimental prototype of a wireless power replenishment system for drones based on LCC-S compensation topology is designed to validate the theoretical research. Under the same maximum outer radius of 0.20 m and the same mutual inductance fluctuation rate of 5%, compared to single circular transmitter mode, the maximum offset distance of all directions (360 degrees) in the x-y plane is increased from 0.08 m to 0.12 m. As the receiving side position changes, the maximum receiving power and efficiency are 141.07 W and 93.79%, respectively. At the maximum offset position of 0.12 m, the received power and efficiency are still 132.13 W and 91.25%, respectively.

The wireless power transfer (WPT) system will usually contact with the metal environment in military applications. Adjacent large metal plates will result in severe deviation of system parameters and degradation of system performance. Therefore, in order to solve the above problems, an optimization method of additional ferrite is proposed in this paper based on the magnetic field aggregation to decrease the influence of metal plates. First, the characteristic of influence caused by metal plates is analyzed through circuit theory and the optimization goal is pointed out. Then, the influence characteristic of the typical metal surface plate and the curved plate is obtained by the FEM simulation. Subsequently, the optimization scheme is investigated based on magnetic field aggregation. By analyzing the adjustment rules of multiple design parameters, the optimization scheme is formed ultimately. Based on the optimization scheme, the maximum 33% deviation of the system parameter is completely corrected and the transmission performance index parameter is improved according to the simulation. In addition, an improved strategy is proposed to reduce the system eddy current loss. Finally, the influences of metal plates and the beneficial effect of the optimization scheme are verified by the experiment. The effectiveness of the improved scheme for eddy current loss is also verified. The experiment results demonstrate that the deviation of system parameters is completely corrected and the transmission performance index parameter is improved by 5.54%.

In the existing pieces of literature about the three-coil wireless power transfer (WPT) system, a three-coil structure is proposed to increase the efficiency compared to the two-coil WPT system. The cross-coupling among three coils, compensation capacitor of the repeating coil (RPC) and the rectified load are considered incompletely. The circuit model of a three-coil WPT system with rectified load is developed by taking the cross-coupling of all coils and the compensation capacitor of RPC into consideration in this paper. The relationship among system efficiency, compensation level, and rectifier load is deduced. The detailed mathematical analysis and compensation capacitor selection of RPC are investigated to improve the system efficiency. An experimental study demonstrates that the selected compensation capacitor of RPC achieves a higher efficiency than resonant compensation in a three-coil WPT system with different cross-coupling conditions and rectifier load conditions. System efficiency is promoted from 73.9% (resonant compensation capacitor for RPC) to 84.2% (selected compensation capacitor for RPC).