Linlin Tan

A Promoted Design for Primary Coil in Roadway-Powered System

As technology advances, electric vehicle (EV) dynamic charging utilizing wireless power transfer (WPT) becomes prevalent. This new power supply mode allows running cars to be charged with electricity at any time on the road. Unlike traditional tramcars, the EVs can be free from rail limitation, and WPT technology provides maximal charging flexibility. This paper studies a WPT charging system, which uses a series of sectional primary coils. The relationship between primary coil size and transfer efficiency is fully explored. On the basis of sectional wireless power supply, the lateral movement of transfer coils is reported, and a promoted design for the primary coil that provides power for a two-lane road simultaneously is proposed.

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.

Design and Implementation of High Frequency Weakly-Radiative Wireless Power Charging System

As the rapid development of electrical equipment, more and more mobile portable devices rely on battery power supply. If the energy can be provided wirelessly, the device can greatly reduce the dependence on the battery. In this paper, mutual inductance theory was used to analyze the system and a wireless charging system was designed which can achieve maximum 300W power transmission and the efficiency is up to 80% at the distance of 50cm. Finally we proposed a method based on adjusting the duty cycle of the DC/DC switch tubes to achieve stable voltage output of the system which can solve the issue that output voltage is sensitive to transmission distance. Theoretical and experimental results show that the system has good transmission characteristics and output voltage stability, suitable for resistive and battery load.

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.

Design and magnetic properties of electric vehicle wireless charging system

With energy issue gradually going prominent, new power sources has been increasingly focused . Under the circumstance that it is an inexorable trend of electric vehicles scale development, much attention has always been paid to the issue of battery . However, electric vehicle utilizing wireless charging can tackle this issue with the merits of accessibility of power supply, security, reliability and small cubage . In this paper, A wireless power transfer system via magnetic resonance coupled is designed . In addition, the influence, exerted by battery load access, on the system is analyzed and a scheme which can control and optimize the system power and solve the key issue of battery load access through the adjustment of duty ratio in voltage regulation circuit of the pick-up side is proposed . Moreover, the electromagnetic issue of the charging system, concerned by the public, is researched with the establishment of magnetic simulation model .

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.

Study on transmission characteristics of resonant coupling wireless power transfer system with double receivers

Wireless power transfer system with single transmitter and double receivers are introduced and modeled. By comparing single receiving coil with double receiving coils (each receiver of double receivers is the same parameters as the singleload receiver) when the transmitter is the same one, transmission characteristics of system are analyzed with the method of equivalent mutual inductance circuits. As the requirement of the size of the receiver is not strict, calculated by the Matlab, output power and transmission efficiency of double receivers in the best power receiving position are much higher than that of single-load receiver when the power supply voltage is constant. Finally, contrast experiments are carried out to verify the correctness of theoretical analysis.

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.