Coupler Loss Analysis of Magnetically Coupled Resonant Wireless Power Transfer System

The demand for electric vehicles has increased over the past few years.Wireless power transfer for electric vehicles provides more flexibility than traditional plug-in charging technology.Charging couplers are critical components in wireless power transfer systems.The thermal effect produced by the magnetic coupler in work will cause the temperature of the device to rise rapidly,affecting the work efficiency,transfer power,operation reliability,and service life.This paper modeled and analyzed each component's temperature distribution characteristics and thermal behavior.Firstly,the magnetic coupler's mutual inductance and magnetic circuit model are established,and the thermal model of the magnetic coupler analyzes the heat generation process.The thermal models of the coupler under three different magnetic core distributions are established,and the temperature rise of each component is obtained.The temperature rise of different parts of the coupler is verified by the temperature rise test structure of the experiment.

Robust Beamforming for Secured Wireless Power Transfer in MIMO Magnetic Resonant Coupling System:A Probabilistic Approach

Wireless power transfer(WPT) to support mobile and portable devices is an emerging wireless technique.Among all kinds of approaches,magnetic resonance coupling(MRC) is an excellent one for mid-range WPT,which provides better mobility,flexibility,and convenience due to its simplicity in hardware implementation and longer transmission distances.In this paper,we consider an MRCWPT system with multiple power transmitters,one intended power receiver and multiple unintended power receivers.We investigate the probabilistic robust beamforming designs and provide efficient algorithms to achieve the local optimums under two different criteria,i.e.,total source power minimization problem and min-max unintended receiving power restriction problem.As the problems are quite typical in robust design situations,our proposed robust beamformers can be conveniently applied to other probabilistic robust design problems,thus reduce the complexity as well as improve the beamforming performance.Numerical results demonstrate that the proposed algorithms can significantly improve the performance as well as the robustness of the WPT system.

New Progress of Magnetically-coupled Resonant Wireless Power Transfer Technology

近些年,无线电能传输技术受到了越来越广泛的关注。作为一种中等距离无线电能传输技术,自从美国麻省理工学院于2007年发表其研究成果后,磁耦合谐振式无线电能传输技术就成为了研究热点问题。该文在对无线电能传输技术进行总体介绍的基础上,主要对磁耦合谐振式无线电能传输技术进行概括论述。首先分析了磁耦合谐振式无线电能传输技术的基本结构和工作原理,介绍了目前运用于分析该技术的主要理论;接着对该技术目前的传输水平和热点问题进行了分类阐释,主要分为传输特性、新材料的应用、干扰问题和实际应用,介绍了目前的研究现状;最后在当前研究热点问题的基础之上,对该技术有待研究的问题以及发展趋势进行了展望。

Numerical Analysis of Magnetic-Shielding Effectiveness for Magnetic Resonant Wireless Power Transfer System

Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer （MR-WPT） system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic performance in engineering. In this study, the shielding effectiveness of a two-coil MR-WPT system for different material shields is analyzed in theory using Moser＇s formula and Schelkunoff＇s formula. On this basis a candidate magnetic-shielding scheme with a double-layer structure is determined, which has better shielding effectiveness and coils coupling coefficient. Finally, some finite element simulation results validate the correctness of the theoretical analysis, and the shielding effectiveness with the double-layer shield in maximum is 30？dB larger than the one with the single-layer case.

Mid-Range Wireless Power Transfer and Its Application to Body Sensor Networks

It has been reported that, through the evanescent near fields, the strongly coupled magnetic resonance is able to achieve an efficient mid-range Wireless Power Transfer (WPT) beyond the characteristic size of the resonator. Recent studies on of the relay effect of the WPT allow more distant and flexible energy transmission. These new developments hold a promise to construct a fully wireless Body Sensor Network (wBSN) using the new mid-range WPT theory. In this paper, a general optimization strategy for a WPT network is presented by analysis and simulation using the coupled mode theory. Based on the results of theoretical and computational study, two types of thin-film resonators are designed and prototyped for the construction of wBSNs. These resonators and associated electronic components can be integrated into a WPT platform to permit wireless power delivery to multiple wearable sensors and medical implants on the surface and within the human body. Our experiments have demonstrated the feasibility of the WPT approach.

Resonant-Inductive Wireless Power Transfer for Autonomous Mobile Robots

Due to the increasing commercial interest in autonomy and sustainability,this paper reviews and presents a comprehensive summary of the resonant-inductive power transmission(RPT)technology for autonomous mobile robots.It outlines historic and recent research activities in wireless power transmission,covering the fundamental operation of microwave,capacitive and inductive power transfer technologies,state-of-the-art developments in RPT for high-power applications,current design and health standards,technological drawbacks,and possible future trends.In this paper,coupling-enhanced pad designs,adaptive tuning techniques,compensation network designs,and control techniques are explored.Major design issues such as coupling variation,frequency splitting,and bifurcation are reviewed.The difference between maximum power transfer and maximum energy efficiency is highlighted.Human exposure guidelines are summarized from documentations provided by the Institute of Electrical and Electronics Engineers(IEEE)and the International Commission on Non-ionizing Radiation Protection(ICNIRP).Other standards like WPC’s Qi and Airfuel design standards are also summarized.Finally,the possible trends of the relevant research and development,particularly dynamic charging,are discussed.The intention of this review is to encourage designs that will relieve robot operators of the burden of frequent manual recharging,and to reduce downtime and increase the productivity of autonomous mobile robots in industrial environments.

Cosmic Wireless Power Transfer System and the Equation for Everything E=mc^(2)=vc^(2)/60=a^(3)/T=G(M_(1)+M_(2))/4π^(2)=(KE+PE)/1.0E15=Q=PA|F=λ/hc=1/2q=VI=1/2LI^(2)=1/2CV=I^(2)R=…

By representing the Earth as a rotating spherical antenna several historic and scientific breakthroughs are achieved.Visualizing the Sun as a transmitter and the planets as receivers the solar system can be represented as a long wave radio system operating at Tremendously Low Frequency(TLF).Results again confirm that the“near-field”is Tesla’s“dynamic gravity”,better known to engineers as dynamic braking or to physicists as centripetal acceleration,or simply(g).Timewave theory is invented,and the relationship of reflected timewaves and time travel explored.A new law of the Sun is proposed as well as the merging of Einstein’s equation with acoustics and cosmic superstring theory.A new law of cosmic efficiency is also proposed that equates vibratory force and pressure with volume acceleration of the solar system.Lorentz force is broken down into centripetal and gravitational waves.Ten-dimensional cosmic superstring theory is espoused versus the aging three-dimensional Maxwellian model.Spherical antenna patterns for planets are presented and flux transfer frequency is calculated using distance to planets as wavelengths.The galactic grid operates at a Schumann Resonance of 7.83 Hz,which is derived from the science of dark energy and dark matter.The Sun and the planets are tuned to transmit and receive electrical power like resonating Tesla coils.The Earth’s stator winding has been modeled as a toroid tesla coil and the armature as a spherical armature.The equation for everything is born.

Advances in Inductively Coupled Power Transfer Technology for Rail Transit

Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.

Wireless Power Transmission into Metallic Tube Using Axial Slit for Infrastructure Diagnostics

Wireless power transfer (WPT) using a metallic tube with axial slits was attempted to demonstrate WPT using magnetic resonance coupling to the diagnostics infrastructure. The transmission efficiency was measured at various distances using the transmission and receiver resonator in the tube. Furthermore, the transmission and receiver resonator were set respectively outside and inside of the tube. Experiment results were assessed computationally using the finite-difference time-domain (FDTD) simulation. As a result, the transmission efficiency of the transmitter and receiver resonators in the metallic slit tube was higher than that of the case without a metallic tube in the range of the normalized transmission-distance of x/d > 0.4. In the simulation, the current density on the metallic tube around both transmitter and receiver coil were connected. These results reveal that the slit on the tube plays a role of the relay coil.

Finite Element Assisted Numerical Comparison of Single and Two Phase Inductively Coupled Power Transfer Systems

Inductively coupled power transfer systems (ICPT) are becoming ubiquitous in industry. Many such systems are excited with single or multi-phase input current. This leads to increased complexity in comparing such systems when solely using the magnetic frequency analysis. This paper utilizes modern finite element method analysis software to propose a novel software methodology for the numerical comparison of single and two phase ICPT systems as demonstrated on a three dimensional (3D) battery charging system. The sinusoidal magnetic frequency response of a single phase system is compared to the magnetic transient response of a multi-phase current system by use of a novel software methodology proposed in this paper. This consists of a transient response analysis to determine compute the resulting magnetic response over the duration of an input current period on the two phase system. The resulting non-sinusoidal response is then integrated over a whole period to extract the root-mean-square value for comparison with that of a single phase system across a 3D cubic power zone.

基于电场耦合的电能信号并行传输系统串扰抑制方法

针对较大功率电场耦合无线电能传输系统信号双向高速传输的需求,该文提出一种基于部分能量通道的电能与信号并行传输系统的串扰抑制方法。通过对所提出的系统拓扑进行分析,给出了电能传输增益表达式与电能串扰增益表达式,并分析了阻波电路参数变化对电能串扰增益的影响;基于交流阻抗法及香农定理分别给出了信号传输增益及信道容量表达式,分析了信号支路参数对信道容量的影响;在综合考虑信号传输增益、信道容量及阻波电路参数敏感性的情况下,给出系统信号支路参数的设计方法。该方法能保证系统在较大功率下降低电能串扰,保障信号稳定传输,实现信号的双向高速传输。通过仿真与实验验证了所提出的拓扑和参数设计方法的有效性。搭建的实验装置实现了传输530.4 W的电能,23.28 Mbit/s信号正向传输速度和24.2428 Mbit/s信号反向传输速度。

基于频率切换实现恒流/恒压输出的电场耦合无线电能传输系统

电场耦合无线电能传输(electric-field coupled wireless power transfer,EC-WPT)技术的实际应用中,有些用电设备需要系统具有不同的恒定输出特性(恒流/恒压),即系统输出电压或输出电流与负载解耦,此外,系统还需具备在恒流、恒压模式间按需切换的功能。针对该需求,基于LC-CLC谐振网络提出1种具有恒流/恒压输出特性的EC-WPT系统,分析LC-CLC谐振网络特性,推导恒流/恒压输出特性的实现条件以及恒流频率和恒压频率的计算方法,并给出系统参数设计方法,分析系统对工作频率的敏感性。最后通过仿真和实验验证所提出的EC-WPT系统恒流/恒压输出特性及其参数设计方法的正确性和有效性。实验结果表明所提出的系统在输入电压恒定的不同负载工况下分别实现2 A的恒流输出以及96 V的恒压输出,其最大传输效率分别为87.83%及88.17%。

双耦合SP-S补偿紧凑型抗偏移WPT系统

在无线电能传输(wireless power transfer,WPT)系统中,偏移是不可避免的,偏移会引起系统参数的变化从而影响系统的传输性能。基于S-S和P-S补偿拓扑,提出一种具有抗偏移特性的双耦合SP-S补偿的紧凑型WPT系统。该系统采用两个同轴布置、相互解耦的圆角方形线圈作为能量的发射线圈,其与单一方形接收线圈均有耦合,提升了X方向和Y方向的抗偏移容忍度。通过谐振参数配置使接收线圈在偏移的过程中,一个线圈回路的输出增加,另一个线圈回路输出减少,从而使系统输出随接收线圈位置偏移波动平缓。提出方形解耦线圈结构参数的设计方法,并分析发射端并联补偿电容对输出抗偏移性能的影响。最后,搭建实验平台验证该方法的有效性与系统的抗偏移能力。

电动汽车多车位WPT下沉式磁屏蔽系统研究

在电动汽车无线电能传输系统中,实现高效传输的同时减少磁泄漏一直是一个技术挑战。针对这一问题,本文提出了一种应用于多无线电能传输系统的下沉式屏蔽线圈结构,该结构在减小目标面漏磁的同时不会影响系统的传输效率。首先,提出了一种基于矢量磁位的矩形线圈磁场计算方法,通过此方法对系统目标面漏磁进行分析,为后续的磁泄漏优化提供了理论依据;其次,介绍了一种漏磁优化的方法,运用该方法得到满足要求的各线圈参数,为实现高效的无线电能传输提供了关键支持;最后,根据得到的线圈参数,研制了一套带磁屏蔽结构的双车位电动汽车无线充电系统,通过仿真和实验,让提出的屏蔽结构和方法的有效性得到了充分证实。结果显示,当系统输出功率恒定在4 kW时,所提出的屏蔽结构不仅使目标区域最大泄漏磁场降低了25%,且传输效率高达95%。

基于多频磁负超材料的心脏起搏器无线供能研究

针对植入式心脏起搏器无线供能系统频率变化发生共振失调导致传输效率低等问题,该文提出一种基于多频磁负超材料(MB-MNG)的心脏起搏器无线供能系统。首先,根据磁负超材料等效介质理论,推导了正八边形超材料设计的基本公式,建立了MB-MNG基元模型;其次,以S-S结构为例,通过仿真和实验研究了6.78 MHz、8.94 MHz和13.56 MHz频段下系统传输效率;再次,为了研究可靠性,讨论了系统与MB-MNG之间的错位情况;最后,为确保安全性,使用多物理场仿真软件研究系统的电磁安全特性,并进行温升实验。实验结果表明:在三工作频段下,基于MB-MNG的WPT系统的输出功率为3.29W、2.77W和2.87W,与传统WPT系统和加入铁氧体薄板WPT系统对比,传输效率提高了24.6%~36.5%。同时,在系统发生偏移时,仍能保持30.73%~48.41%的传输效率;60 min充电测试内组织SAR值及最大温升均符合安全标准。

基于等效阻抗的分数阶RLC_(α)串联谐振BD-WPT系统传输特性分析

针对谐振式无线电能传输系统中分数阶电感、电容元件的仿真实现困难的问题,采用等效阻抗实现分数阶电容的等效.基于分数阶电容的阻抗特性,给出了一种分数阶RLC_(α)串联谐振双向无线电能传输(bidirectional wireless power transfer,BD-WPT)系统结构,通过建立含分数阶电容的串联谐振式双向无线电能传输系统的电路模型,推导了其传输功率和效率关系.仿真实验结果表明,与整数阶串联谐振系统相比,系统的输出功率提升了7.82%,传输效率提升了0.58个百分点.

集成LCC-S拓扑的二维全向无线电能传输系统无盲区能量捕获方法研究

针对二维全向无线电能传输技术存在空间磁场完整度与电流控制策略复杂度的竞争问题,该文提出一种集成LCC-S拓扑的二维全向无线电能传输系统无盲区能量捕获方法。该系统以二维正交线圈为电磁耦合机构,并将其集成于LCC-S型补偿拓扑。同时提出一种自调整参数设计方法,实现系统在二维空间内产生时均旋转磁场以及系统的零相角输入。通过场-路耦合有限元模型分析系统在二维空间内磁场分布情况,随时间峰值磁场强度矢量轨迹为圆形。搭建集成型二维全向无线电能传输的实验样机,实验结果表明,该系统实现单一电源驱动下无盲区的二维全向电磁能量捕获。

基于磁耦合谐振的多自由度电机无线电能传输

针对多自由度电机无线电能传输中传输效率较低的问题,提出基于磁耦合谐振的多自由度电机无线电能传输方法。该方法根据共振原理构建磁耦合谐振式无线电能传输模型,通过反射系数描述阻抗匹配状态,获取最佳负载阻抗;采用混沌优化算法优化电机线圈损耗率,实现多自由度电机无线电能传输优化。实验结果表明,应用该方法后,多自由度电机的电能输出功率达到了893 W,传输效率提升了0.10以上,提高了电能输出功率和传输效率,方法有效,具备可行性。

面向无线传能的磁耦合通信射频链路解耦设计

针对磁耦合无线能量数据协同传输中传能链路与通信链路的解耦需求,在采用DD型通信线圈与传能线圈实现空域解耦的基础上,开展了滤波网络与线圈的协同设计,提升了通信链路通带阻抗匹配特性和带外抑制能力,并进一步引入带阻滤波网络,增强了与传能线圈的频域解耦。在耦合距离为30 mm时,搭建了与167 kHz无线传能天线共口径的磁耦合通信天线与滤波馈电网络硬件,在中心频率14.8 MHz实现了4 MHz的-3 dB通带带宽,该解耦天线系统相比DD线圈天线对传能信号提高了85 dB的抑制能力。

基于耦合谐振及新型空间全向耦合机构的无线电能传输系统

针对传统无线电能传输系统中发射机构和接收机构相对位置发生偏移时,传输功率和效率急剧下降的问题,提出了一种基于耦合谐振及新型空间全向耦合机构的无线电能传输系统。首先通过有限元仿真分析发射机构的磁场分布特性,设计了适应其磁场分布的接收机构;然后基于串串谐振补偿结构建立系统数学模型,分析系统传输特性;在此基础上提出了最优输出方式选择方法和传输特性优化方法。最后,通过试验验证了所提系统多自由度传输能量的可行性和有效性。试验结果表明,接收机构在多角度情况下的输出功率维持在35 W以上,传输效率稳定在60%~75%。