无线电能传输系统控制方法综述

输出控制方法在无线电能传输系统的实际应用中具有非常重要的意义。以磁感应耦合式无线电能传输(ICPT)和磁谐振耦合式无线电能传输(MRC)为代表的无线电能传输系统(WPT),其输出功率易受自身参数和环境变化的影响。以ICPT系统和MRC系统为主要研究对象,分析了其统一的等效电路模型条件,在此基础上详细分析了无线电能传输系统现有各种输出控制方法,并总结了其优缺点。     

中距离传输共振磁耦合无线取能装置设计与实验

基于磁耦合机构的等效电路模型,开展无线传能耦合特性分析,提出一种新型空间螺旋线圈结构,应用ANSYS有限元分析软件开展发射线圈和接收线圈的电磁场仿真建模,对线圈结构进行电磁优化设计,并对比有无中继线圈的磁耦合机构,发现添加中继线圈可以在有效增加传输距离的同时将系统的传输效率提高1.475倍。最后,构造了一台共振磁耦合无线取能模型样机,实验结果表明,该样机能够实现传输距离为3 m、功率为40 W的LED灯负载供电,由此验证了无线取能线圈设计的有效性。     

基于磁耦合谐振式无线供电系统的分析研究

无线供电技术能够让用电设备摆脱线路的限制,实现电器和电源的完全分离;文中首先介绍了磁耦合谐振式无线电能传输的基本理论,并进行了带负载无线电能传输实验,研究了谐振频率、距离、障碍物对传输性能的影响;最后对磁耦合谐振式无线电能传输装置各个环节进行设计,构建了一套无线电能传输系统;该无线供电系统可以为很多小型化、低功耗的电子设备进行无线供电,且功率和距离能达到设计需求,因此具有一定的应用价值和研究价值。     

磁耦合谐振无线输电系统不同拓扑结构的分析

无线输电系统中,工作频率和距离是主要的输入变量,而较高的输出功率和传输效率是目标。对于磁耦合谐振无线输电系统,输入变量与目标的关系取决于磁耦合谐振无线输电系统的拓扑结构,磁耦合谐振无线输电系统的拓扑结构可分为串串结构、串并结构、并串结构和并并结构,本文应用等效电路方法对这四种拓扑结构进行了详细的分析,得到了输出功率和传输效率的表达式,研究了功率和效率关于频率、距离的关系,并进行了比较。通过研究和仿真分析发现,在谐振频率点附近四种拓扑结构的系统均达到最优匹配,并且得到了最佳传输距离。还证明了系统最大传输效率只与接收端电路结构有关,与发射端电路结构没有必然联系。本文还制作了串并结构的实验模型,验证了理论分析和仿真结论的正确性。     

一种基于磁耦合共振式的无线取能电流互感器电源设计

针对现有电子式电流互感器高压侧取能电源设计中存在的电源复杂、寿命短等问题,提出了一种基于磁耦合共振式的无线取能电源设计方法。建立了能量传输模型,推导出了输出功率表达式,通过分析电压、频率、互感对功率的影响,为硬件电路的参数设计提供了理论参考。通过对供电装置和绝缘子采用一体化设计并采用环氧树脂填充完成了系统的样机制作。结果表明,该取能电源在保证有效绝缘距离的前提下,可实现长时间的稳定供能,验证了本设计的有效性。研究成果可为磁耦合共振式的无线取能电流互感器的电源设计提供参考。     

风力机叶片双锤作动疲劳加载系统及试验研究

设计一套双作动器共振型风力机叶片疲劳加载系统,对系统能量耗散计算及动力参数匹配,基于多级网络模式制定共振疲劳加载控制策略。对同步控制策略与算法进行研究,确立虚拟主令点动控制方式,采用配重块优化叶片展向弯矩分布误差,以振幅偏差及加载频率为输入输出建立控制系统,控制器基于控制同步方式驱动伺服电机,搜索跟踪共振频率,对振动参数数据采集、存储与分析,实现叶片等幅稳定振动。现场试验结果表明,系统控制同步有效,共振频率搜索与跟踪效果较好,共振时叶片振幅误差保持在5%之内,刚度无明显变化,试验精度与效率得到提高,可为风力机叶片疲劳加载的工程应用提供理论与试验参考。     

单端补偿的新型无线电能传输系统研究

传统的无线电能传输系统需要同时在发射端和接受端串联或并联电容来补偿线圈间的漏感,从而提高系统的传输效率。一旦电容器发生故障或者随温度变化发生改变,系统就会失谐,导致传输效率降低。文章针对这一弊端提出单端补偿的新型无线电能传输系统,其接受端采用PWM可控整流,与传统的二极管不控整流相比,可以通过移相控制来调节输出功率。通过在不同移相角的仿真结果和5 kW的实验平台,验证了理论分析的正确性和控制策略的有效性。     

共振式消声器声学性能分析

在保持连接管结构形状及尺寸不变、共振腔容积不变的条件下，分析了单节共振式消声器腔体结构对其声学特性的影响。结果表明；共振式消声器腔体深宽比对其共振频率有较大的影响，截面宽高比有一定的影响，但相对较小。当腔体形状接近于立方体时，消声器共振频率最大，此时用集中参数模型估算消声器共振频率与实际值偏差最小，腔体深宽比减小或增大，共振频率均向低频方向移动，当腔体深度大于波长的10％～16％时，用一维轴向模型估算消声器共振频率与实际值吻合较好；随着截面宽高比的增加，消声器共振频率向低频方向移动，截面形状愈扁，共振频率变化幅度愈大。     

多层屏蔽电缆耦合影响的数值预测

针对工程中的电缆耦合问题,采用多导体传输线方法.构建了多层屏蔽电缆电磁耦合的等效电路模型,分析了相关的感性耦合和容性耦合影响效果,并对某屏蔽电缆受邻近电缆耦合引起的串扰电压的幅频响应进行了仿真.结果表明,采取双层屏蔽较单层屏蔽能较大程度地减小耦合干扰.     

筏式波浪能转换和摩擦纳米发电机能量输出耦合系统的模拟研究

发展海洋能源转化技术是优化能源结构、拓展“蓝色经济”空间的战略要求。为此,设计了一种基于筏式波浪能转换和点头鸭型摩擦纳米发电机能量输出的耦合系统,并对影响系统中筏体装置部分捕能特性的压载吃水、筏体尺寸参数以及影响系统输出电势分布的尼龙球径、滚动距离参数进行了仿真分析。结果表明：增大筏体装置的吃水（增加压载）和优化筏体装置的尺寸都可以降低装置的固有频率,使其与波浪频率达到共振,从而可以提高装置捕获波浪能的能力;摩擦纳米发电机两电极之间的电势差随着尼龙球球径的增大呈现出先增大后减小的趋势,在球径为30 mm时电势差达到最大值,该电势差还随着尼龙球滚动距离的增大而增大,并在外部负载电阻为770 MΩ时实现了瞬时最大功率密度3.7 W/m³。由此可见,当在筏式波浪能转换装置中布置多个摩擦纳米发电机阵列时,完全可以将海洋中原本无法利用的大量低频波浪能转化为电能,从而满足深海传感器网络供电需求,这大大扩展了波浪能的发电潜力,使得蓝色能源在未来有望得到更有效地开发。     

Stimulation of piezoelectric devices through bidirectional wireless energy transfer

A bidirectional energy transfer method is proposed and investigated for wireless excitation of piezoelectric devices. In the proposed bidirectional system, two receiving coils are deployed on both sides of a transmitting coil so as to capture the generated magnetic fields based on magnetic resonance coupling. The piezoelectric devices connected across each receiving coils get energized wirelessly because of the mechanism of electromagnetic resonance as well as piezoelectric resonance. It is found that the power across driven piezoelectric devices arrive at maximum for operating resonant frequency. The optimum power received by piezoelectric devices wirelessly through the bidirectional energy transfer system is significantly higher than that of the single‐sided receiver system. By implementing the proposed bidirectional energy transfer method, two piezoelectric devices can be energized simultaneously instead of a single piezoelectric device through the usual single‐side receiver system without affecting the maximum power transfer efficiency. Copyright © 2015 John Wiley & Sons, Ltd.     

Electrowetting-on-Dielectric by Wireless Powering

Electrowetting-on-dielectric (EWOD), in which microdroplets are manipulated using electrical inputs, has drawn a great deal of attraction with applications of digital lab-on-a-chip and hot-spot cooling. In most EWOD actuations, the commonly used powering method is wired transmission, which may not be suitable for isolating and employing EWOD devices in hard-to-reach areas. In this study, we investigate wireless power transmission for EWOD utilizing inductive coupling. Since EWOD is typically operated by a high-input voltage although the current is minimal, wireless EWOD also requires a similarly high voltage at the receiver, unlike conventional inductive coupling. To meet this condition, the resonant inductive coupling method at a high resonant frequency is introduced and investigated. To optimize the transmission efficiency, we study the effects of many parameters, such as the frequency, inductance, and capacitance at the transmitter and receiver, the gap between the transmitter coil and receiver coil, and the droplet size, by measuring the voltage at the receiver and the contact angle of the droplet placed on a wirelessly operated EWOD chip. In addition, by applying amplitude modulation to the resonant inductive coupling, wireless AC-EWOD, which generates droplet oscillations and is a common mode for EWOD droplet handling, is also achieved. Finally, it is successfully demonstrated that a droplet is transported laterally by using an array of electrodes, which is also powered by an amplitude-modulated wireless signal.     

Design and analysis of a wireless power transfer system with alignment errors for electrical vehicle applications

In this study, a 15 kW wireless power transfer system with high frequency and large air gap for electrical vehicle battery charge systems is designed and co-simulations with ANSYS-Maxwell and Simplorer software are performed. The air gap between the primary and the secondary windings are determined as 20 cm for the 15 kW wireless power transfer system. Operation of the designed system for different operation conditions such as completely aligned windings (ideal condition) and windings with alignment errors, which can occur because of user error or another reason, are analyzed and obtained results are reported. The resonant frequency of the designed system which has a 60 × 60 cm secondary winding and a 60 × 100 cm primary winding is 17.702 kHz, and the maximum efficiency of the system is obtained as 75.38% for completely aligned windings. The distribution and density of the electromagnetic flux, and variation of efficiency versus load level of the system and responses of the system in case of different alignment errors are also investigated and reported for both ideal operation conditions and in case of alignment errors.     

Analysis of resonant coupling coil configurations of EV wireless charging system: a simulation study

Nowadays, internal combustion engine vehicles are considered as one of the major contributors to air pollution. To make transportation more environmentally friendly, plug-in electric vehicles (PEVs) have been proposed. However, with an increase in the number of PEVs, the drawbacks associated with the cost and size, as well as charging cables of batteries have arisen. To address these challenges, a novel technology named wireless charging system has been recently recommended. This technology rapidly evolves and becomes very attractive for charging operations of electric vehicles. Currently, wireless charging systems offer highly efficient power transfer over the distances ranging from several millimeters to several hundred millimeters. This paper is focused on analyzing electromagnetically coupled resonant wireless technique used for the charging of EVs. The resonant wireless charging system for EVs is modeled, simulated, and then examined by changing different key parameters to evaluate how transfer distance, load, and coil’s geometry, precisely number of coin’s turns, coin’s shape, and inter-turn distance, influence the efficiency of the charging process. The simulation results are analyzed and critical dimensions are discussed. It is revealed that a proper choice of the dimensions, inter-turn distance, and transfer distance between the coils can result in a significant improvement in charging efficiency. Furthermore, the influence of the transfer distance, frequency, load, as well as the number of the turns of the coil on the performance of wireless charging system is the main focus of this paper.     

基于锁相环1 MHz感应加热电源频率跟踪的研究

针对高频感应加热电源负载参数变化引起固有谐振频率变化,导致逆变器效率降低现象提出并实现了一种以集成高速锁相环74HC4046为核心的应用于采用功率MOSFET为主开关器件的1MHz串联谐振感应加热电源的无相差频率跟踪控制系统,对电源的输出频率进行实时控制,实现逆变器工作频率对负载谐振频率的同步跟踪,并就控制系统的相位补偿和启动等问题进行了分析讨论;其次推出了适用于高频逆变电源的锁相环数学模型并用Pspice进行了仿真分析;最后进行了实验验证。     

Eco-green portable wireless power charger design with low-voltage,high-current fuel cell power source features

Since portable wireless power charger devices have grown rapidly in the market, this device has potential to become standard power charger for portable electronic devices. It offers enhanced consumer convenience and experience. This article presents an innovative portable wireless power charger that is more environmental-friendly because it uses a hydrogen gas fuel cell as the power source. Compared with fossil energy, the fuel cell is clean and renewable, which does not contribute a negative impact on the environment. A wireless power transmission (WPT) system was developed based on the electromagnetic induction technique in order to propagate electromagnetic energy from the transmitter to the receiver with operating frequency at 110 kHz. A four-cell proton exchange membrane fuel cell (PEMFC) planar module with open type at cathode side was applied to provide 4.11 W with its low-voltage and high-current features. A single-cell PEMFC produces output voltage ranging from 0.6 to 0.7 V and configures in serial to form a four-cell PEMFC planar module. Two DC-DC boost converter module in a parallel configuration was used to convert to a suitable voltage and current to the WPT module. The experimental validation shows that the developed system provides power around 1.6 W to the device battery under recharging with power efficiency delivery up to 70%. The charging experiment reveals the device battery capacity under recharging (cell phone) increases 1% in 3.3 minutes and it consumes the hydrogen at around 1.2 L.     

The history of wireless power transmission

The history of wireless power transmission at microwave frequencies is reviewed with emphasis upon the time period starting with the post World War II efforts to use the new microwave technology developed during the war. A nationally televised demonstration of a microwave powered helicopter at the Spencer Laboratory of the Raytheon Co., in 1964 was the result of these early efforts and broadly introduced the concept of wireless power transmission to scientific and engineering communities and to the public. Subsequent development efforts centered on improving the efficiency of the interconversion of d.c. and microwave power at the ends of the system to reach a demonstrated overall d.c. to d.c. system efficiency of 54% in 1974. The response to the requirements of applications such as the Solar Power Satellite and high altitude microwave powered aircraft have changed the direction of technology development and greatly expanded the technology base. Recent and current efforts are centered on examining the use of higher frequencies than the baseline 2.45 GHz, and in reducing the system costs at 2.45 GHz.     

基于布谷鸟算法的电子变压器输出端谐振参数优化

常用来降低电子变压器主开关损耗的方法。目前是基于LLC谐振网络的软开关技术。其中谐振参数的选取是否合适直接影响到电子变压器输出性能的好坏。为此,该文引入布谷鸟搜索算法对谐振参数进行智能优化设计。该搜索算法能够对存在不可导点的目标函数进行优化,并且其特有的巢寄生行为和莱维飞行特性能够使得谐振参数避免陷入局部最优。其优化过程首先利用基波分析法对变换器的参数进行建模,然后分析和研究谐振电感、励磁电感与谐振网络直流增益、输入阻抗角以及原、副边电流、励磁电流的直接关系,从而得到参数优化的约束条件。在此基础上,利用布谷鸟搜索算法优化得到使电路损耗最小的谐振网络参数。最后,以半桥LLC谐振变换电路为例,通过实验验证了在宽输入电压下,全负载范围内,该优化设计方法比"FHA+仿真"法的效率提高了1%~2%,样机最高效率达97%,证明了论文所提优化方法的有效性。