Jinpeng Guo

Power Stabilization Based on Efficiency Optimization for WPT Systems With Single Relay by Frequency Configuration and Distribution Design of Receivers

The operation of wireless power transfer systems (WPT) with a single relay, which could charge one or multiple receivers simultaneously, is investigated. Besides, a new method for ensuring the optimized transfer efficiency and the output power by configuring the operating frequency is presented, even when the coupling coefficients between all the coils are very small. An issue of concern is that the couplings between receivers cannot be ignored due to limited operating space, which adds to the complexity of both the system design and the control method. The contribution of the research presented here is to propose an optimized strategy which can charge each receiver with identical power and simplify the coupling complexity thereof. Specifically, the efficiencies and outputs of the introduced WPT systems are discussed. In addition, the distribution design according to different numbers of receivers is proposed to guarantee that both the system operating frequency and the output power remain stable. The theoretical analysis is confirmed by both simulation and experimental results.

Stabilization Control of Output Power in Double-Source Wireless Power Transfer Systems Without Direct Output Feedback

Output power of a wireless power transfer (WPT) system based on magnetic resonant coupling is required to be stable for powering mobile devices. Thus accurate measurement of transmitting distance or mutual inductance, which has a significant impact on output power, is of great necessity. In this letter, a wireless power transfer system with double sources is proposed to broaden the stable region of output power. In addition, detection of mutual inductances between coils placed in arbitrary positions is presented based on measurements of input voltages and currents without any direct output feedback. By using detected mutual inductances, this letter puts forward a coordinated control strategy of double sources to meet the load power demand. Experiments are finally conducted to verify the feasibility and correctness of the mutual inductance detection method as well as the stable power control strategy.

Dynamic Wireless Charging for Inspection Robots Based on Decentralized Energy Pickup Structure

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. First, the dynamic wireless charging systems based on centralized energy pickup 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.

Effect of metal shielding on a wireless power transfer system

In this paper, the effect of non-ferromagnetic metal shielding (NFMS) material on the resonator of wireless power transfer (WPT) is studied by modeling, simulation and experimental analysis. And, the effect of NFMS material on the power transfer efficiency (PTE) of WPT systems is investigated by circuit model. Meanwhile, the effect of ferromagnetic metal shielding material on the PTE of WPT systems is analyzed through simulation. A double layer metal shield structure is designed. Experimental results demonstrate that by applying the novel double layer metal shielding method, the system PTE increases significantly while the electromagnetic field of WPT systems declines dramatically.

Coordinated Source Control for Output Power Stabilization and Efficiency Optimization in WPT Systems

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.

Efficiency optimization of on-road charging for electrical vehicles

The paper introduces an on-road charging system for several electrical vehicles (EV) at the same time based on magnetic resonant coupled wireless power transfer (WPT). To analyze the proposed system, an equivalent circuit model of the system with single longer transmitting coil and several shorter receiving coils is presented. System efficiency is of particular interest and is found to be determined by power loss factor, coupling coefficient, resonator quality factors, load amounts and load resistances through analysis. Efficiency optimization by adjusting load resistances in according to load amount variations is derived. For the verification of theoretical analysis, an experimental prototype is implemented. It is shown that with the proposed strategy, a 90% maximum efficiency can be achieved regardless of the variations of load amounts.

Moving impedance matching analysis for three-coil wireless power transfer system in mid-range

There is a bottleneck for traditional two-coil wireless power transfer (2C-WPT) system for short transfer distance and low efficiency. In this paper, a novel three-coil WPT(3C-WPT) system based on moving impedance matching window is proposed to increase transfer distance to mid-range. System efficiency is further promoted by optimizing relay coil. Acting as a moving impedance matching window, relay coil improves the flexibility of selecting proper reflection impedance. Once the overall optimization goal is set up, best parameters of the impedance matching can be determined with the given optimization design procedure. Derived conclusions undoubtedly play an instructive role in the design and application of proposed three-coil structure WPT system.

A Topological Transformation and Hierarchical Compensation Capacitor Control in Segmented On-road Charging System for Electrical Vehicles

Experiencing power declines when the secondary coil is at the middle position between two primary coils is a serious problem in segmented on-road charging systems with a single energized segmented primary coil. In this paper, the topological transformation of a primary circuit and a hierarchical compensation capacitor control are proposed. Firstly, the corresponding compensation capacitors and receiving powers of different primary structures are deduced under the condition of a fixed frequency. Then the receiving power characteristics as a function of the position variations in systems with a single energized segmented primary coil and those with double segmented primary coils are analyzed comparatively. A topological transformation of the primary circuit and hierarchical compensation capacitor control are further introduced to solve the foregoing problem. Finally, an experimental prototype with the proposed topological transformation and hierarchical compensation capacitor control is carried out. Measured results show that the receiving power is a lot more stable in the movement of the secondary coil. It is a remarkable fact that the receiving power rises from 10.8W to 19.2W at the middle position between the two primary coils. The experimental are in agreement with the theoretical analysis.