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.

Overhead high voltage power line (HVPL) online monitoring equipment is playing an increasingly important role in smart grids, but the power supply is an obstacle to such systems’ stable and safe operation, so in this work a hybrid wireless power supply system, integrated with inductive energy harvesting and wireless power transmitting, is proposed. The energy harvesting device extracts energy from the HVPL and transfers that from the power line to monitoring equipment on transmission towers by transmitting and receiving coils, which are in a magnetically coupled resonant configuration. In this paper, the optimization design of online energy harvesting devices is analyzed emphatically by taking both HVPL insulation distance and wireless power supply efficiency into account. It is found that essential parameters contributing to more extracted energy include large core inner radius, core radial thickness, core height and small core gap within the threshold constraints. In addition, there is an optimal secondary coil turn that can maximize extracted energy when other parameters remain fixed. A simple and flexible control strategy is then introduced to limit power fluctuations caused by current variations. The optimization methods are finally verified experimentally.

In order to solve the problem of the electric vehicle (EV) charging amount fluctuation caused by the variation of driving speed during dynamic wireless charging, this paper proposes an EV dynamic wireless charging control method adapting to speed change. Firstly, a dynamic wireless charging model based on a long-track transmitting coil is established, and the expression of the charging power of each load under multi-load situation is obtained. Secondly, the influence of the EV charging number and maximum driving speed on the range of system parameters is studied. Subsequently, the method for determining the load resistance value according to the driving speed under a multi-EV charging condition is further discussed. Afterwards, a charging power control method adapting to the speed variation by load adjustment is proposed. By adjusting the equivalent load of the variable-speed charging EV, its speed variation range can reach 20~60 km/h, while the remaining EVs’ charging power fluctuation range can be kept within 10%~15%. Finally, the experimental prototype is built to verify the above-mentioned control method.

In order to promote the driving range of the electric vehicles (EVs), decrease the demand for large capacity battery and create more charging opportunities for the EVs, the static-dynamic hybrid wireless charging system is presented to utilize waiting time of traffic lights at intersections to replenish electricity in this paper. Firstly, the topology and principle of the proposed static-dynamic hybrid wireless charging system with short-segmented coils at traffic lights are introduced. Secondly, the general circuit model of the static-dynamic hybrid wireless charging system with multi-coupling between the primary and secondary sides is developed. The design method of the compensation circuit in primary side based on the number and the positions of the energized primary coils is investigated. After analyzing the characteristics of the system varying with the position of the single load, the control conceptions of the energizing mode alternating in primary side and the combination of the primary compensation capacitors are put forward. Then the power stabilization control strategy of the static-dynamic hybrid wireless charging system with multi short-segmented coils and multi loads is proposed. Finally, the theoretical analyses are verified with the experiments.

On-road charging systems for electric vehicles (EVs) have shown revolutionary potential in extending driving range and reducing battery capacities. The optimal equivalent load resistances to maximize receiving power of each EV according to different EV amounts are investigated. This paper introduces a typical on-road charging system with a single transmitting coil and multiple receiving coils. The equivalent circuit models according to different numbers of EVs are built. Power control strategies with regard to a varying number of EVs are then presented. Specifically, self-adaptive source voltage based on primary current detection is utilized to charge EVs, while the source can support enough EVs by providing the rated power. Otherwise, the source voltage is regulated to its maximum value and the charging energy of each EV is suggested to be controlled by adjusting the individual driving speed. A remarkable feature of the power control strategies is that the charging power for each EV is stable and can compensate for energy losses efficiently. As for urgent power demand from a particular EV with a low battery capacity, the adjustment of the corresponding load resistance is applied to alter the power distribution. The proposed technique has been verified in an experimental prototype.

An opportunity wireless charging system for electric vehicles when they stop and wait at traffic lights is proposed in this paper. In order to solve the serious power fluctuation caused by random access loads, this study presents a power stabilization strategy based on counting the number of electric vehicles in a designated area, including counting method, power source voltage adjustment strategy and choice of counting points. Firstly, the circuit model of a wireless power system with multi-loads is built and the equation of each load is obtained. Secondly, after the counting method of electric vehicles is stated, the voltage adjustment strategy, based on the number of electric vehicles when the system is at a steady state, is set out. Then, the counting points are chosen according to power curves when the voltage adjustment strategy is adopted. Finally, an experimental prototype is implemented to verify the power stabilization strategy. The experimental results show that, with the application of this strategy, the charging power is stabilized with the fluctuation of no more than 5% when loads access randomly.