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.

This paper presents the framework for the applications of double-source wireless systems in charging for movable electronic devices. To acquire the real-time mutual inductances between the receiving coil and the transmitting coils, a detection strategy on the basis of primary parameters (currents and voltages) is introduced, which can replace the wireless communications between the receiving side and the transmitting side. Coordinated control of two source voltages is employed to deal with the power fluctuation of load, which is caused by load position variations. In specific, the constraint of two source voltages, which can maintain the output power stable, is derived. Based on these feasible combinations of source voltages, numerical calculations are further carried out to identify the optimized voltage combination, which can achieve high power transfer efficiency. Finally, an experimental prototype is built up and the results show that the proposed coordinated control strategy can minimize power fluctuation and maintain relative high efficiency at the same time.

In a wireless charging system, non-alignment has been a big problem that affects the transmission efficiency. The uniform magnetic field can ensure the charging power stability and extension of battery life in a multi-load wireless charging system, which also expands the free charging area of the loads. In this article, the array circular coils of wireless power transfer (WPT) with a compensation structure have been proposed, which can be obtained by analyzing the magnetic field trajectory of the elementary unit of the array coils. Larger scale of the uniform magnetic field could be expended by the joint of several elementary units. The correctness and validity of the structure are verified by theoretical derivation and finite element simulation. Besides, the compensation method could be used for any forms of array coils.

Mg-Sr alloy is considered as a promising biodegradable bone repair material. However, its poor corrosion resistance limits its clinical application. In this study, the corrosion rate of Mg-Sr alloy was greatly improved through the heat treatment. Both in vitro and in vivo corrosion tests (immersion and electrochemical test) showed that corrosion resistance of Mg-Sr alloy was enhanced. In the animal test (New Zealand rabbit), both micro-CT analysis and Van Gieson staining demonstrated that the treated Mg-Sr alloy implant exhibited better osteogenesis and osteointegration ability, which accelerate the healing of bone defect. The results indicate that the treated Mg-Sr alloy has great possibility and potential for application as a new bone repair material.

The electric vehicles (EVs) have played an important role in people's travelling due to the clean energy and environment-friendly. Considering the endurance issue of EVs, wireless charging is regarded as a convenient and effective solution. However, the charging power and the efficiency would be greatly affected when the transmitting coil (TC) and the receiving coils (RC) are non-aligned. This paper presents a flexible and high-accuracy positioning device based on electromagnetic balance, which could automatically achieve wireless charging and two-level positioning without communication between TC and EVs during location. Besides, a six-coils cross-coupled circuit model has been built to optimize key parameters that affect the positioning accuracy. Theoretical analysis and experimental results show that the proposed structures and location method have certain advantages in positioning accuracy, operation complexity and practicability. Within the range of first level positioning, the accuracy could achieve 1 cm. There is a high fitting performance between the simulation and experimental results, which verify the correctness of the theoretical analysis and the validity of the structures. Moreover, an additional comparative experiment has been designed to verify the correctness of the proposed method used in the wireless charging positioning system with ferrite cores and a magnetic shielding layer.