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.

Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System

Wireless power transfer via inductive link is becoming a popular choice as an alternate powering scheme for biomedical sensor electronics. Spiral printed circuit board (PCB) inductors are gaining attractions for wireless power transfer applications due to their various advantages over conventional inductors such as low-cost, batch fabrication, durability, manufacturability on flexible substrates, etc. In this work, design of a multi-spiral stacked solenoidal inductor for biomedical application in 13.56 MHz band is presented. Proposed stacking method enhances the inductance density of the inductor for a given area. This paper reports an optimization technique for design and implementation of the PCB inductors. The proposed scheme shows higher inductance and better figure-of-merit values compared to PCB inductors reported in literature, which are desirable for wireless power transfer system.

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.

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.

基于改进型ZVT Buck电路的IPT充电系统设计

为了避免在感应式无线电能传输系统的耦合机构中增加多余的开关器件以及额外的无源元件,同时减小系统工作在高频率、大功率时全控型开关器件存在的开关损耗,提出基于改进型ZVT Buck电路闭环控制的方法实现对电池的恒流、恒压充电,通过分析改进型ZVT Buck电路的工作模态以及对电路参数的设计,确保在整个充电过程中DC-DC变换器均工作在软开关状态,最后搭建充电电流为35 A、充电电压为370 V的实验平台验证该方法的可行性。结果表明:该方法控制简单,并且降低了系统电路结构的复杂度,传输效率相对较高,能够满足恒流恒压充电需求。

兼顾抗旋转偏移和中心磁场抑制的三相IPT系统设计与分析

与传统接触式充电方式相比,采用感应式电能传输IPT(inductive power transfer)系统给自主水下航行器AUVs(autonomous underwater vehicles)充电更加方便和安全。为了解决AUV船体中心磁场强和由波浪引起的旋转偏移导致传输功率剧烈波动的问题,提出1种具有新型耦合结构的三相IPT系统。耦合器由3个发射线圈和4个反向交替串联的接收线圈组成,该结构有利于抑制中心磁场并提高抗旋转偏移性能。Maxwell仿真结果表明,在船体旋转时,等效互感Meq波动小于2%,同时AUV中心磁场始终保持在较低水平。此外,为简化系统分析,采用1种无源元件解耦的方法对3个发射线圈进行解耦。搭建了1台基于LCC-S补偿拓扑的实验样机来验证系统的可行性,实验结果表明,当AUV旋转时,传输功率为536~595 W,最大波动率为9.91%,系统直-直最高效率为86.28%。

一种采用级联型多电平技术的IPT系统谐波消除与功率调节方法

传统的感应电能传输(inductive power transfer,IPT)系统采用单相全桥谐振逆变器,由于受到功率器件的容量限制,IPT系统的输出功率较低。为实现IPT系统大功率输出,构建了基于阶梯波移相合成方法的级联型多电平逆变器的IPT系统,并详细分析其工作原理和功率自平衡特性。在此基础上,建立谐波消除方程,得到移相角与脉宽的显式解,从而避免求解高次超越方程。在消除3次谐波的基础上,通过改变移相角与脉宽,不需增加DC-DC环节便能实现IPT系统输出功率的连续调节。仿真和实验验证了IPT系统的级联型逆变器输出功率为1.6 kW时,每个全桥单元的输出功率约为800 W,且级联逆变器的输出电压的3次谐波被完全消除,同时能连续调节IPT系统的功率。这种基于阶梯波移相合成方法的级联型多电平逆变器可望在大功率IPT系统中得到应用。

基于最小电流比值的IPT系统频率跟踪的动态调谐方法

在感应电能传输(IPT)系统中,含有磁心的电磁耦合机构的气隙间距变化会导致系统发送端与接收端自感及互感参数漂移,进而使得IPT系统处于失谐状态,增加了电源所需容量,降低了系统传输效率。针对该问题,提出一种基于最小电流比值的发送端频率跟踪的动态调谐方法。该方法通过实时测量发送线圈电流有效值与直流源输出电流平均值,在控制器中计算电流比值并根据最小电流比值原则,实时调节系统工作频率,使IPT系统恢复谐振状态,提高系统性能。最后,在不同气隙间距的情况下进行动态调谐实验验证。结果表明,当气隙间距变化时,所提方法有效实现了动态调谐,恢复了IPT系统谐振状态,达到减少电源所需容量、提高系统传输效率的目的,且最大效率提升幅度为1.64%。

基于变补偿参数的IPT恒流恒压电池充电研究

为了简化感应电能传输(inductive power transfer,IPT)电池充电系统原边与副边电路的设计和控制复杂性,该文提出通过在原边电路加入一个附加电容和一个半导体开关的方法实现对电池恒流恒压切换充电,无需调节逆变器直流输入电压、原边移相控制及副边加入调压电路。恒流模式时,配置的补偿电容完全补偿原边线圈;恒压模式时,只需一个开关切出或者切入附加电容。该方法只需简单的通信(用于充电模式切换),没有复杂的控制策略,结构简单,成本低。实验表明,所提出方法输出的恒流和恒压随着电池等效负载电阻改变而轻微变化,但结果仍然满足电池充电要求。

计及谐波和死区影响的IPT系统时域建模与软开关特性分析

LCC-S补偿感应电能传输(IPT)系统的原边逆变桥输出电流包含丰富的谐波分量,采用传统的基波分析法进行分析会带来较大的误差。针对该问题,文中考虑谐波和死区的影响,将谐波含量少的线圈支路用基波模型近似表示,保留富含谐波的输入脉冲激励电压,在基波模型基础上建立简化的时域分析模型。基于该时域模型,对系统参数进行优化,实现开关管的零电压开关(ZVS)。最后,搭建了1 kW实验样机,实验结果验证了所提模型的准确性,系统在宽工作范围内实现了ZVS软开关,当输出功率100 W以上时系统效率均高于90%,且最高效率达到95.6%。

IPT系统线性自抗扰恒压输出和最大效率跟踪复合控制方法

为实现感应电能传输(inductivepowertransfer,IPT)系统在负载变化下的恒定电压和高效电能输出,提出一种基于线性自抗扰控制(linear active disturbance rejection control,LADRC)的恒压输出和基于阻抗匹配技术的最大效率跟踪的复合控制方法。首先,分析LCC-S型IPT系统的参数与效率、输出功率的关系,通过参数优化设计使最优效率达到最大化;然后,在副边采用基于Buck-Boost电路的阻抗匹配技术以实现最大效率跟踪,同时在原边设计一阶LADRC对输出电压进行闭环控制,并给出控制器参数选取规则,所提复合控制方法保证效率和电压2个控制回路之间的解耦运行;最后,搭建实验平台对理论分析进行验证。实验结果表明,当负载电阻从满载到轻载变化时,所提系统可以实现恒压输出,整体效率保持在85.7%,与比例积分控制相比,LADRC对负载扰动和参考电压扰动具有更好的输出电压动态调节作用。

多负载IPT系统效率分析与控制

针对感应电能传输(inductive power transfer,IPT)系统多负载条件下能量传输效率问题研究频率与效率的关系,并从系统能量流动的角度解释效率特性。为了验证最大传输效率结论的正确性,采用双工作模式切换的电流调节方法和离散准滑模控制策略来维持原边谐振电流(激磁电流)的恒定。基于系统能量平衡函数关系,建立关于激磁电流峰值包络的系统离散变结构模型,构建具有重置积分环节的切换函数来改善系统的稳态响应。实验结果表明,当工作频率偏离副边固有谐振频率时,系统效率最大,合理的积分增益可以使系统具有较好的控制性能,对于负载大范围变化具有较强的鲁棒性,如当负载完全拿开时,控制器经过时长约为5 ms的调节,激磁电流最终稳定在参考值,表现出较好的抗扰动性,且系统效率均保持90%以上。

基于副边可变电容的IPT恒流恒压充电系统研究

为了减少基于感应电能传输技术的变补偿拓扑充电系统的开关器件和无源元件数量,同时保证系统恒压充电时有相对较高的效率,该文基于串/串并补偿拓扑,在副边电路增加一个交流开关和一个附加电容,通过切换开关的关断改变副边串联补偿电容,从而实现系统的恒流恒压切换。该方法无需原副边通信及复杂的控制电路,系统结构简单,所需元件较少。在恒流模式充电阶段系统输入阻抗呈感性,能实现零电压开关;在恒压模式充电阶段输入阻抗为纯阻性,几乎没有无功功率输入。实验结果表明,所提出方法的输出恒流和输出恒压在电池等效负载变化的同时有细微的波动,但实验结果仍然满足对电池充电的要求;此外,系统恒流时最高效率为92.2%,恒压时最高效率为94.2%。

基于辅助逆变器的IPT系统原边动态调谐方法研究

感应耦合电能传输(inductive power transfer,IPT)系统中,由于器件老化、升温、参数容差等原因会使系统原边回路失谐,导致逆变器开关损耗增大,发热增加,系统效率降低;为了保持IPT系统原边谐振,提出一种基于辅助逆变器的动态调谐方法。首先,主要针对系统原边呈容性的情况,详细分析串–串补偿型IPT系统的效率和原边失谐程度之间的关系;然后,分析调谐原理并提出调谐方案,通过检测主逆变器的输出电压和电流的相位差调节两个逆变器间驱动信号相位,来动态调节主逆变器的输出阻抗,达到调谐目的;最后,搭建实验平台,在原边回路不同失谐程度下进行动态调谐的实验。结果表明,该调谐装置可实现系统的动态调谐,并能有效提高系统效率。动态调谐系统能将15%容差时的系统效率由86.2%提高到92.8%,最大提高了6.6%,有效减少系统的发热。

基于DDQ线圈的双耦合LCL拓扑IPT系统及其抗偏移方法研究

基于传统LCL补偿拓扑IPT电路,该文将LCL拓扑中用于补偿的电感替换为一对耦合线圈,既可保证电路谐振,线圈间互感又为系统提供了一个新的能量传输通道,即一种双耦合LCL拓扑IPT系统。首先介绍了DDQ线圈结构与双耦合LCL拓扑电路的特点;理论结果表明,与传统单耦合LCL拓扑IPT系统的传输效率相比,所提出的双耦合LCL系统效率提升了0.8%。此外,该文还提出了一种将LCL拓扑切换为SS补偿拓扑的方法,有效提高系统在偏移时的功率输出能力。最后,通过实验验证了该系统的有效性与抗偏移能力:正对时两对耦合线圈传输功率分别为233W和392W,效率达95.5%;在偏移0～17cm范围内,输出功率始终高于500W,传输效率始终高于88.7%。

基于双螺旋正交线圈的强抗偏移IPT系统

为解决传统单拾取感应电能传输系统在横向大偏位下输出电压和系统效率骤降的问题,文中提出由方形正交子线圈与双螺旋子线圈组成的双螺旋正交线圈(double-solenoid quadrature pad,DSQP),该线圈结构与钳位电路相结合,可实现两种线圈之间自动切换,保证系统输出电压在较大的横向偏移范围内波动较小且效率较高。该方法无需原副边通讯,通过后级Buck实现输出电压的精准控制。文中解释DSQP偏移过程中如何利用纵向和横向磁通的变化实现强抗偏移性,同时给出利用有限元软件优化设计耦合机构的方法。最后搭建500W恒功率输出的实验样机验证所提出方法的正确性。原副边尺寸都为400mm×400mm,在X方向偏移±320mm(80%)范围内,等效互感波动仅为15%,输出电压一直稳定在72V,系统包括Buck变换器在内的直流到直流效率为87.4%~90.5%。

Achieving maximum power transfer of inductively coupled wireless power transfer system based on dynamic tuning control

As an emerging research field,inductively coupled wireless power transfer(ICWPT) technology has attracted wide spread attention recently.In this paper,the maximum power transfer performances of four basic topologies labeled as SS,SP,PS and PP are investigated.By modeling the equivalent circuits of these topologies in high frequency(HF),the primary resonance compensation capacitances for maximum power transfer capability are deduced.It is found that these capacitances fluctuate with load resistance change,which is disadvantageous to SP,PS and PP topologies and an obstacle to their practical applications as well.To solve this problem,a phase controlled inductor circuit is proposed.By adjusting the triggering angle,the real-time dynamic tuning control can be achieved to guarantee maximum power transfer.Finally,simulations and experiments show that the proposed method is of great effectiveness and reliability to solve the issue of resonance compensation capacitance fluctuation with load change and to guarantee the flexible applications of all topologies.

基于分离补偿网络的IPT系统功率扩容策略

将感应电能传输(IPT)系统的补偿网络分离并加入各并联逆变器中,用以解决功率扩容和环流问题.分析采用单逆变器拓扑和功率扩容拓扑的IPT系统数学模型.设计各并联逆变器的补偿网络参数,推导功率扩容系统的功率与效率表达式.分析各并联逆变器在驱动不同步时的环流回路,给出零电压开关(ZVS)控制策略.搭建1.2 kW基于分离补偿网络的IPT系统功率扩容装置,进行实验验证.实验结果表明,各并联逆变器的输出功率比约为1∶2,均实现了ZVS,功率扩容系统直流到直流的整体传输效率为92.53%,环流幅值为0.2 A,证明了所提功率扩容拓扑的实用性和有效性.

具有抗偏移特性的IPT与CPT结合的WPT系统

目前无线电能传输(WPT)技术正在迅速发展,并广泛运用于各种电子设备。由于耦合结构的偏移会导致系统输出发生较大的变化,为扩宽WPT技术的应用范围,高抗偏移性是WPT技术不可缺少的特性。为完善WPT技术的抗偏移特性,这里提出了一种基于感应式能量传输(IPT)技术与电容式能量传输(CPT)技术的串联系统,通过优化系统结构,利用IPT技术和CPT技术在耦合结构偏移时输出功率不同的变化趋势,将两者互补使得系统实现高抗偏移特性。最后,设计并实现了输出功率600 W,系统整体效率为89.2%的WPT系统,验证了该设计策略的可行性。

一种具有高抗偏移特性的通用复合式IPT耦合器

为实现高效高可靠的感应式无线电能传输(inductive power transfer,IPT),其耦合机构的原边和副边侧线圈应保持精准对齐,但在很多应用中线圈偏移不可避免。因此,文中提出一种具有高抗偏移特性通用复合式IPT耦合器,该复合式IPT耦合器通过结合一个4线圈的BP耦合器和一个高阶的PS-S或S-SP补偿网络,可有效实现高抗偏移能力,适用于任意补偿网络。同时,高阶网络的接入,使得BP耦合器原边或副边同一侧两个交叠的线圈可有效解耦,简化设计。另一侧两个交叠的线圈虽仍然相互耦合,但其参数设计只需考虑交叉耦合足够小即可,进一步简化BP耦合器的设计难度,无需迭代重复设计。最后,基于该复合式IPT耦合器构建一台3kW的抗偏移IPT系统,采用S-S补偿网络,输出不受负载和耦合变化影响的恒定电流,适合于电动汽车电池充电场合,实验结果验证了理论分析的正确性。