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.

Power transfer efficiency in an air-breathing radio frequency ion thruster

Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit missions due to its high specific impulse and efficiency. In this paper, the power transfer efficiency of the radio frequency ion thruster with different gas compositions is studied experimentally, which is obtained by measuring the radio frequency power and current of the antenna coil with and without discharge operation. The results show that increasing the turns of antenna coils can effectively improve the radio frequency power transfer efficiency, which is due to the improvement of Q factor. In pure N_2 discharge,with the increase of radio frequency power, the radio frequency power transfer efficiency first rises rapidly and then exhibits a less steep increasing trend. The radio frequency power transfer efficiency increases with the increase of gas pressure at relatively high power, while declines rapidly at relatively low power. In N_(2)/O_(2) discharge, increasing the N_(2) content at high power can improve the radio frequency power transfer efficiency, but the opposite was observed at low power. In order to give a better understanding of these trends, an analytic solution in limit cases is utilized, and a Langmuir probe was employed to measure the electron density. It is found that the evolution of radio frequency power transfer efficiency can be well explained by the variation of plasma resistance, which is related to the electron density and the effective electron collision frequency.

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.

LCL-S型注入信号式能量与信号共享通道ICPT系统研究

针对感应耦合电能传输(Inductive Coupled Power Transfer,ICPT)系统应用场景中的信号反向传输需求,提出了一种基于LCL-S谐振拓扑的注入信号式ICPT电能信号共享通道系统。运用交流阻抗法对所提出的系统的电能通道与信号通道分别进行了理论分析,建立了数学模型。以负载得到的电压恒定为前提,兼顾信号调制解调结构的影响,分析计算了系统参数,并搭建了MATLAB/Simulink验证模型。仿真结果表明,信号传递电路引入后,负载可以实现恒压,系统能量传输正常,在保证能量传输的情况下,可以实现信号的反向传输。最后按照仿真模型搭建了实际电路,验证了所提出的系统的可行性。

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.

Design and analysis of an underwater inductive coupling power transfer system for autonomous underwater vehicle docking applications

We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.

多方位无线电能传输耦合机构设计与分析

针对传统的多方位无线电能传输耦合机构常采用xyz正交圆线圈结构,需要3个电源且充电区域受线圈结构限制的问题,提出1种新型多方位无线电能传输耦合机构,该机构由2组8字型线圈和1组圆形线圈组合而成,整体呈现5个不同方位的圆环状,仅需单电源供电。对基于S-S型发射端拓扑进行了改进,通过对电路的操控改变线圈磁场分布,实现了线圈的内、外部电能传输,拓宽了充电区域。基于线圈结构,建立了该耦合机构的数学模型,推导出任意空间位置的互感和效率计算式。通过仿真和试验确定了该耦合机构的最佳工作区域。

电压型ICPT系统功率传输特性的分析与优化

针对感应耦合电能传输(ICPT)系统功率传输能力和效率优化问题,对电压型ICPT的功率传输特性进行了分析。通常认为提高系统的谐振频率能提高系统的功率传输能力,但通过本文的研究发现,对于采用SS拓扑的ICPT系统,谐振频率的选取存在一个优化的取值,而对于采用SP拓扑结构的ICPT系统,在一定的频率带上,谐振频率的增加对系统的传输特性基本没有影响。另外,对电压型ICPT系统副边线圈匝数进行了优化设计。最后,通过实验验证了理论分析的正确性。

变负载ICPT系统电能与信号反向同步传输方法

为满足感应耦合电能传输(inductively coupled power transfer,ICPT)系统在实现电能正向无线传输的同时,对副边电路状态信息的采集与反向传输,基于ICPT系统电能耦合传输通道,提出了一种在负载变化情况下,电能与信号反向同步传输ICPT系统,并对其控制方法进行了深入研究。该系统在副边增加信号调制电容,检测负载大小以确定具体的信号调制方案,通过切入与切出该调制电容以改变原边电流波形包络,进而将数字信号调制到系统中,这样原边在发射电能的同时接收来自副边的状态信息,最后通过设计信号解调机构,复原信号。首先介绍了ICPT系统电能与信号同步传输原理,在此基础上,提出电能与信号反向同步传输ICPT系统;然后,通过对该系统进行建模分析得到负载变化情况下不同的信号调制策略,并对系统变负载情况下系统特性进行了分析和研究;最后,针对理论分析进行了仿真与实验验证,实验实现了ICPT系统在电能正向传输情况下的信号的反向低误码率传输。该研究结果可以为ICPT系统电能与信号反向同步传输系统的设计与研究提供参考。

三线圈ICPT系统中继线圈的位置优化

三线圈感应耦合电能传输(ICPT)系统在给定工作频率下,中继线圈与原级线圈、负载线圈间的互感及负载大小是影响系统电能传输效率的主要因素。针对线圈间互感与线圈位置的相互约束关系,提出一种在任意给定原级线圈和负载线圈条件下的中继线圈位置优化模型。该模型以电能传输效率为优化目标,综合考虑三个线圈相互间的互感和负载等参数,通过计算机辅助设计,解决了寻找中继线圈最优位置的问题,理论和实验结果具有较好的一致性,且展示出中继线圈的最优位置与负载大小密切相关。

基于钳位电路的LCC-S补偿型感应电能传输系统抗偏移方法

在感应电能传输(IPT)系统中,线圈错位难以避免,造成的耦合变化会导致系统的传输功率不稳定。为了保证IPT系统的供电灵活性,系统需具有容忍线圈宽范围偏移的能力。为此,该文借鉴模态切换的思想,提出一种基于钳位电路的LCC-S补偿型IPT系统,用于增强系统抗偏移性。与传统多模态切换的IPT系统相比,该系统中的钳位电路可根据耦合变化自适应地导通或关断,以调节工作模态,从而实现近乎恒定的功率输出,该方法无需耦合识别、输出检测及反馈通信等辅助手段。该文对系统不同工作模态的功率传输特性进行了推导和分析,并结合系统设计相关约束条件,提供一套参数化设计方法。最后设计并搭建一套500 W的实验装置,验证了理论分析的正确性与可行性。实验结果表明,该方法在耦合度为0.205~0.42的情况下,输出功率稳定在470~505 W之间,效率为83.29%~90.21%。

双LCL拓扑ICPT系统恒频恒流稳压特性研究

针对负载动态变化及切换易造成感应耦合电能传输(ICPT)系统频率失谐和负载输出电压变化的问题,基于双LCL拓扑电路,提出一种实现原边线圈中电流幅值恒定、负载端稳压输出并保证工作频率稳定性的设计方法。首先分析拾取侧LCL拓扑电路的恒压特性,结合ICPT系统拾取端反射阻抗呈阻容性且容性部分与负载变化无关这一特点,提出两种原边补偿电路设计思路,同时在此基础上分析了原边LCL拓扑实现原边线圈恒流工作的特性条件。然后给出了双LCL拓扑ICPT系统同时实现原边线圈电流恒定、负载端电压稳定、工作频率稳定的总体条件,并分析了主要参数对系统性能的影响。最后,通过仿真和实验结果证明了理论分析方法的正确性。

ICPT系统原边恒压控制及参数遗传优化

针对感应电能传输系统原边串联–副边并联的拓扑结构,发现利用传统原边电流恒定的控制方式在负载变化时不易实现输出稳压,因此提出一种简单的基于原边电压恒定来实现输出稳压的方法,研究了其适用的约束条件。针对ICPT系统多参数多约束的特点,引入遗传算法对系统的参数进行优化设计,利用动态函数改进适应度函数定标及变异算子提高算法性能。仿真和实验结果表明:输出电压在大范围负载切换中具有良好的稳定性,原边电流能够根据负载需求自适应变化;系统实现了低成本、低开关损耗设计,且参数均达到设计要求。证明了原边恒压控制及参数遗传优化的有效性。

基于2FSK的ICPT系统高速信号传输方法

针对感应耦合电能传输(ICPT)系统信号传输存在信号幅值衰减和较强电磁干扰的问题,基于2FSK调制解调方式,提出了一种新型的高速信号传输方法.该方法在不增加系统主电路能量耦合线圈以及不影响主电路正常工作的前提下,实现了高速信号传输.分析了不同结构下主电路信道的阻抗和频域响应特性,确定了调制解调方法及其实现方案,并搭建了系统实验平台,在2.5和1.7 MHz的载波频率下,有效实现了100 kHz脉冲信号的传输.仿真与实验结果验证了所提出的高速信号传输方法的可行性.

动态负载ICPT系统稳频稳压特性研究

为保证感应耦合电能传输(inductively coupled power transfer,ICPT)系统在动态负载工作模式下频率和输出电压的稳定性,提出一种通过对ICPT系统谐振耦合拓扑机构优化选型,并对系统参数进行优化设计,从而实现系统稳频稳压(stable frequency stable voltage,SFSV)输出的新方法。通过对系统谐振网络等效电路进行分析,给出动态负载工作模式下ICPT系统谐振耦合机构优化选型依据,并给出系统谐振耦合环节参数优化设计步骤和方法。最后,通过实验验证理论分析的正确性。

同步整流技术在ICPT系统中的应用

将同步整流(SR)技术引入到ICPT系统中,以解决ICPT系统二次AC-DC电路采用二极管整流(DR)时,系统整体效率较低等问题。本文针对SP型ICPT系统,分析了二次AC-DC电路基于同步整流技术的工作原理。结合系统的谐振特性,提出了在无需其他辅助电路的条件下,AC-DC同步整流电路ZVS软开关控制方法。结合频闪映射方法及周期不动点理论,给出了ZVS软开关工作周期的计算方法。实验验证了本文ICPT系统同步整流技术的可行性。通过同步整流与二极管整流方式的实验对比,结果表明,采用同步整流方式可有效提高系统效率,减小散热器体积及重量,提高系统的功率密度。

高能效导轨式ICPT系统分布式磁路机构研究

针对传统导轨式感应耦合电能传输(ICPT)系统主要通过提高输入电压,增大磁芯容量来提高系统的传输功率和效率存在的弊端,提出了一种新型导轨式ICPT系统分布式磁路机构:通过采用原边磁能发射机构分布式并联、副边磁能拾取机构分布式串联模式,实现了系统能效特性的总体提升。建立新型拓扑结构等效电路模型,给出了系统能效特性计算方法,并分析了最大功率传输条件。理论分析结果表明,在新型磁路结构下,系统最大功率传输能力为传统磁路机构的3倍,总体效率也得到了很大提升。最后,通过实验验证了新型磁路结构的有效性以及理论分析方法的正确性。

ICPT系统谐振频率跟踪方法研究

针对传统的感应耦合电能传输(ICPT)系统的谐振频率跟踪问题,分析了基于初次级串联补偿的ICPT系统拓扑模型。基于对电路的建模和分析,给出了系统的电压增益函数。通过分析系统工作频率与输出功率的关系,提出了基于扰动观察法的谐振频率跟踪方法,使得变换器始终工作在谐振频率处,保证系统具有最大功率输出。该方法通过软件来实现频率的跟踪,降低系统硬件成本。实验结果证明了该方法对于元件参数、负载阻抗和系统耦合距离的改变,都能进行自适应谐振控制。

ICPT系统电能信号共享通道实时同步传输方法研究

针对利用感应耦合电能传输(inductively coupled power transfer,ICPT)系统电能传输通道实现数字信号实时、双向传输问题,提出一种基于载波方式实现信号传输的新方法。电能传输耦合机构作为电能与信号传输的共享通道,可以传输电能与信号这两种不同频率的波。信号加载和检波电路直接并联在电能传输耦合机构上,并在电能传输谐振电容与耦合机构间串联阻波电路,数字信号经调制后加载到传输通道,然后直接经过电能传输耦合机构传输,避免通过电能传输谐振电容而被削弱。通过分析电能传输及信号传输通道的衰减增益,以及电能传输对信号传输的干扰,确定所提方法的可行性,最后搭建实验平台验证所提方法的正确性。

采用CCL/LCC复合谐振网络的电流型ICPT系统

为实现感应耦合电能传输(ICPT)系统在负载及气隙变化时的输出电压和工作频率恒定,提出了一种采用CCL/LCC复合谐振网络的电流型ICPT系统。首先,在基波条件下,依据变压器漏感模型建立系统等效电路,得到了输出电压增益与输入阻抗的表达式;然后,通过系统参数优化设计,推导出了动态负载下系统恒压供电和谐振工作频率稳定的条件。另外,当气隙变化时,利用动态调谐技术重新补偿耦合电感,可使得输出电压和工作频率在气隙变化前后保持不变。系统特性分析表明,所提出的CCL/LCC复合谐振网络电流型ICPT系统,在负载和气隙变化时可以保证输出电压和工作频率稳定。最后,实验验证了理论分析的正确性和有效性。