To deal with the problems of charging for inspection robots in substations such as frequent charging, complex mechanical interface and insufficient battery capacity, a dynamic wireless charging system is proposed. The structure design of energy pickup device and the indispensable positioning strategy is presented in this paper. Firstly the dynamic wireless charging systems based on centralized energy pickup (CEP) and decentralized energy pickup (DEP) are investigated and the unified circuit model is built for two kinds of systems simultaneously. Based on the comparison of working performances, the DEP structure is selected as the pickup device in this paper. Then the positioning scheme is realized based on imitative relaying coil structure including the DEP device and the additional sensor coil. A switching control strategy of the segmented transmitting coils is proposed further to implement the dynamic wireless charging for inspection robots. The theoretical analyses are validated by the relevant experiments.

Wireless charging technology greatly improves the flexibility and convenience of electric vehicles (EVs) charging. The alignment of coils directly affects the performance of the wireless charging system. For the above problems, we proposed a mesh-based accurate positioning strategy for EV wireless charging coils. The strategy takes the center of primary coil as the origin and divides the meshed reference points in the plane of secondary coil. It is based on voltage induced by detection coils installed on the secondary coil. The centimeter-level positioning of the secondary coil is realized in the X and Y directions of the horizontal plane. The effectiveness of the proposed strategy is verified by simulations and experiments. Without considering the rotation, the maximum error is within 3cm in 5cm mesh width. The positioning strategy helps to align coils and improves transmission performance. It is also helpful for automatic parking, unmanned vehicle, and other industrial applications.

Recently, most wireless power transmission (WPT) systems have used a "one-to-one" charging method of one receiving coil to one transmitting coil. However, when the receiving coil is offset in this way, the mutual inductance between the transmitting and receiving coils will be weakened, and the flexibility of the WPT system application will also be reduced. Therefore, how to realize the "one-to-many" transmission mode of one transmitting coil to multiple receiving coils and ensure the power stability of multiple loads is an urgent problem to be solved. In order to solve the above problems, the LCC-S topology is combined with the three-phase circuit, and a three-phase omnidirectional WPT system coil scheme is proposed based on the power characteristics of the three-phase LCC-S topology in this paper. Firstly, the influence of the resonance compensation topology on power characteristics is analyzed through circuit theory and a more suitable LCC-S topology is chosen. Then, the optimal coil scheme of the three-phase omnidirectional WPT system is proposed based on the law of mutual inductance. Compared with the original scheme, the theoretical calculation results show that the power fluctuation of the system is reduced by 75.13%. Finally, a set of three-phase WPT system model and test systems similar to the theory are established, which effectively verify the improvement of the proposed scheme, and verify the correctness and feasibility of the scheme.

The equivalent resistance of the battery will change during charging in practical applications, so it is difficult to design a wireless power transfer (WPT) system with accurate constant current (CC) and constant voltage (CV) output characteristics. In addition, the WPT system efficiency is also affected by the change of equivalent resistance. Therefore, this paper studies the charging control and efficiency optimization strategy for the WPT system with dynamic loads. The WPT system with a structure of double-sided LCC compensation topology and containing controllable rectifier circuit at the secondary side is established, and the working process of full-bridge controllable rectifier circuit is analyzed. Then the output characteristics of the WPT system are analyzed. The expressions of the optimal transmission efficiency and the optimal equivalent impedance of the full-bridge rectifier are derived. The relationships between the equivalent impedance of the capacitor-filtered full-bridge controllable rectifier circuit and the phase shift angle, the charging current and the phase shift angle are also obtained. In this paper, the CC and CV charging strategies based on phase shift control of controllable rectifier circuit and efficiency optimization strategy based on dynamic equivalent impedance matching are proposed, which can improve the WPT system transmission efficiency while realizing CC and CV charging. Finally, the effectiveness of the proposed control strategy is verified by simulation and experiment. The WPT system realizes CC charging mode and CV charging mode in turn when the load resistance changes from $5~\Omega $ to $30~\Omega $ , and the overall efficiency is up to 90.71% at the transmission distance of 15cm.

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.

Wireless power transfer (WPT) is greatly affected when the transmission channel is surrounded by non-ferromagnetic metallic objects and the alternating magnetic field interacts with the metal conductor, which is more of an issue in wirelessly charged electric vehicle (EV) applications. This paper analyses the performances of a WPT system in an environment with a non-ferromagnetic metal plate. The impedance model of the WPT system in the metal environment is established. Moreover the variation law of a coil’s equivalent inductance and resistance is deduced when the coil is surrounded by the non-ferromagnetic metal plate. Meanwhile, simulations, theory and experiments all confirm that the model is correct. Finally, since the system performance of a wireless charging system is influenced by non-ferromagnetic metals, this paper puts forward a method to improve the performance, that is, to place ferrite cores between the receiving coil and a metal plate. Experiments are carried out to verify the method, and the desired results are achieved.