【精品】无线电力传输外文文献翻译
电力系统毕业论文中英文外文文献翻译精选全文完整版
可编辑修改精选全文完整版电力系统电力系统介绍随着电力工业的增加,与用于生成和处置现今大规模电能消费的电力生产、传输、分派系统相关的经济、工程问题也随之增多。
这些系统组成了一个完整的电力系统。
应该着重提到的是生成电能的工业,它不同凡响的地方在于其产品应按顾客要求即需即用。
生成电的能源以煤、石油,或水库和湖泊中水的形式贮存起来,以备以后所有需。
但这并非会降低用户对发电机容量的需求。
显然,对电力系统而言服务的持续性相当重要。
没有哪一种服务能完全幸免可能显现的失误,而系统的本钱明显依托于其稳固性。
因此,必需在稳固性与本钱之间找到平稳点,而最终的选择应是负载大小、特点、可能显现中断的缘故、用户要求等的综合表现。
但是,网络靠得住性的增加是通过应用必然数量的生成单元和在发电站港湾各分区间和在国内、国际电网传输线路中利用自动断路器得以实现的。
事实上大型系统包括众多的发电站和由高容量传输线路连接的负载。
如此,在不中断整体服务的前提下能够停止单个发电单元或一套输电线路的运作。
现此生成和传输电力最普遍的系统是三相系统。
相关于其他交流系统而言,它具有简便、节能的优势。
尤其是在特定导体间电压、传输功率、传输距离和线耗的情形下,三相系统所需铜或铝仅为单相系统的75%。
三相系统另一个重要优势是三相电机比单相电机效率更高。
大规模电力生产的能源有:1.从常规燃料(煤、石油或天然气)、城市废料燃烧或核燃料应用中取得的蒸汽;2.水;3.石油中的柴油动力。
其他可能的能源有太阳能、风能、潮汐能等,但没有一种超越了试点发电站时期。
在大型蒸汽发电站中,蒸汽中的热能通过涡轮轮转换为功。
涡轮必需包括安装在轴承上并封锁于汽缸中的轴或转子。
转子由汽缸周围喷嘴喷射出的蒸汽流带动而平稳地转动。
蒸汽流撞击轴上的叶片。
中央电站采纳冷凝涡轮,即蒸汽在离开涡轮后会通过一冷凝器。
冷凝器通过其导管中大量冷水的循环来达到冷凝的成效,从而提高蒸汽的膨胀率、后继效率及涡轮的输出功率。
无线电力传输系统
实现方法
3.辐射式:利用微波辐射传输能量
1979年,美国航空航天局NASA和美国能源部联合提出太阳 能计划,建立“SPS太阳能卫星基准系统”。 SPS(Solar Power satellite)是太阳能发电卫星,处在地球约36000km 的静止轨道上,那里太阳的能量约为地球上的1.4倍。据测算, 一个SPS所装载的太阳电池的直流输出功率为10GW,其输 出的电力通过振荡器变换成微波电力,从送电的天线向地球 表面以微波(2.45GHz)形式无线送电。地球上的接收天线 由半波长的偶极天线、整流二极管、低通滤波器及旁路电容 组成,可接收到5GW的电力。
无线电力传输系统
—WIRELESS POWER TRANSMISSION
综述
Wireless power or wireless energy transmission is the transmission of electrical energy from a power source to an electrical load without man-made conductors. —
实现方法
优点:传输距离非常远,可定向传输能量,也可全方 向传输。
缺点:传输效率低,安全性有待验证。
前景展望
谢谢!
沃登克里弗塔
综述
20世纪60年代初期雷声公司(Raytheon)的布朗(W. C. Brown)做了大量的无线电能 传输研究工作,从而奠定了无线电能传输的实验基础,使这一概念变成了现实。 2007年,美国麻省理工学院的Marin Soljacic等人在无线电能传输方面取得了新 进 展,他们用两米外的一个电源,“隔空”点亮了一盏60瓦的灯泡。 2008年12月17日成立无线充电联盟(Wireless Power Consortium),2010年8月 31日,无线充电联盟在北京正式将无线充电技术引入中国。
读英语文章 远程电力传输
February 25,2021(CNN)A solar panel in space is collecting energy that could one day be beamed to anywhere on Earth太空中的一块太阳能电池板正在收集能量,这些能量有一天可能会被发射到地球上的任何地方Scientists working in the US have successfully tested a solar panel the size of a pizza box in space, designed as a prototype for a future system to send electricity from space back to any point on Earth.美国的科学家们成功地在太空中测试了一块披萨盒大小的太阳能电池板,该电池板被设计为未来系统的原型,可以将太空中的电力发送回地球上的任何地方。
The panel -- known as a Photovoltaic Radiofrequency Antenna Module (PRAM) -- was first launched in May 2020, attached to the Pentagon's X-37B unmanned drone, to harness light from the sun to convert to electricity. The drone is looping Earth every 90 minutes.该电池板被称为光伏射频天线模块(PRAM),于2020年5月首次发射,连接在五角大楼的X-37B无人机上,利用来自太阳的光转化为电能。
无人机每90分钟在地球上空盘旋一次。
The panel is designed to make best use of the light in space, which doesn't pass through the atmosphere, and so retains the energy of blue waves, making it more powerful than the sunlight that reaches Earth. Blue light diffuses on entry into the atmosphere, which is why the sky appears blue.这种电池板的设计是为了充分利用太空中的光线,因为太空光线不会穿过大气层,所以它保留了蓝波的能量,使其比到达地球的阳光更有能量。
无线电力传输外文文献翻译
无线电力传输外文文献翻译(含:英文原文及中文译文)文献出处:Weaver, Bill. " Can't Touch This: Wireless power transmission." 26.3(2009).英文原文Can't touch this - wireless power transmissionWilliam L. WeaverA few years ago, a colleague and I participated in a field trip project organized by the college student group to study the West Orange at the Edison National Historic Site in New Jersey. We visited with the public and participated in a laboratory set up inside a building to understand the development of incandescent light bulbs and film technology. However, what impressed me most was the two complex additional functions.First, it is a research library equipped with all publications of the then US Patent Office. Representatives of scientists and engineers are concerned that marketable products may be useful in creating new technologies. The university is a great place to discover science and technology with it, but Edison's laboratory exists as a company. In the late 19th century, there was no internet connection, so the library took up the laboratory's information repository. Just like today, when the researchers needed information about chemical reactions, a mathematical formula or their most advanced engineering solution and consulted the currentliterature, it was only through paper at the time.By simplifying the adoption of standards, this process is further simplified by the rapid adoption of standards. Since most of the tools and equipment can be developed locally, they can deploy their own standards and create the facility on a multi-acre campus.One of these criteria is the method of distribution of power. The final known power supply for grid development is the famous Edison bulb. The tools used in the early Edison lab were a long axis of rotation like a rear-wheel drive automobile driveshaft made up of a universal cable shaft or a marine vessel. The propeller shaft disperses the potential energy of the entire plant in the form of mechanical energy generated by the boiler.A belt and a simple clutch system are connected to the line shaft and the strength of the lever is enhanced by using a surrounding shaft belt. Over time, the belt was worn out due to excessive friction. However, this technology provides a less complex power distribution method than earlier high-pressure steam and hydraulic systems.Over time, as well as the development of electrical and electronic equipment, high-voltage power supplies and more distribution standards must be used in our production plants, offices and homes in the near future. In the United States, the electricity generated is 60 Hz and is eventually produced at a nominal voltage between 120, 240 and 480 volts.A typical power outlet is specified to accommodate 15 amps of currentand is equipped with three familiar prongs, a vertical and U-shaped ground pin consisting of two paddles. Forward-looking retailers make pins of different shapes and orientations to prevent other incompatible devices from connecting. Unless there are not enough power outlets, plugs or extension cords, the standard three-hole power cord is a ubiquitous device to "plug in" the power distribution system.With the continuous development of technology, mobile and handheld devices we currently have are booming, so battery companies will follow. Physically connecting these small devices to the grid will seriously affect their functionality. It is for this reason that they should exhaust their own power supplies or produce rechargeable batteries. Battery manufacturers quickly develop their own industry standards, including "AA" and "C" units, to reduce the confusion that consumers may have when replacing batteries.Although transistor radios and toy sensors were popular at the beginning of the year, single-use chemical batteries could not provide enough current for devices such as laptops, smart phones and personal entertainment games that have complicated computational requirements. Their rechargeable batteries are incorporated into the equipment and rarely need to be replaced by the user. These device manufacturers can choose how the battery is manufactured, such as size, battery life, and internal configuration capabilities of the device components. This featureof the battery has given manufacturers' industrial designers more rights to differentiate their products in style, look and feel.However, the disadvantage of rechargeable batteries is that they eventually still need to be charged. We can easily connect to the power supply via an AC/DC power adapter. However, it is more difficult to connect the battery to the adapter or "charger" because each battery manufacturer is free to design the battery's shape and interface. what? In the lovely 100-year-old innovation after this, it did not change with the mode it should have.A conspiracy theory may indicate that portable device manufacturers admit that battery chargers are a lucrative source of income. Similar bubble jet printer manufacturers rely on the consumption of ink in the device as a sales channel to make up for the difference between the selling price and the cost. Users pay $25 to $100 to replace the damaged or missing power adapter, which cancels out a service. The "real cost of freedom" in a planned or low-cost laptop phone. An innocent non-conspiratorial theory may be related to the 2000 (Y2K) problem. Programmers wou ldn’t expect much trouble for this device made in a two-digit year to create for the future, and few portable device designers may expect to consume laptops, mobile phones, MP3 players, and digital cameras today. The number of people. These functions may eventually be provided by an independent "super smartphone", but at present,individual charger users are still inconvenient. Chargers also have similar, incompatible problems between devices, and users may cause exchanges to rise or lose devices. If you are using your fifth mobile phone, it is very likely that there will be four outdated chargers on your garage's work bench.In February this year, the European Union Telecommunications Authority (CEPT) and the subsequent European Union (EU) jointly authorized the establishment of the Publicis Group Special Mobile Association (GSMA), which was developed in 2012 as a standard for use by mobile phones. Micro USB interface charger specification. In addition to making the user more convenient, this specification has also been applied to the recycling of discarded adapters. Although it is not aimed at the standardization of adapters between different mobile devices, it seems to be a good start.However, imagine that if the AC/DC adapter is completely eliminated. This is the future of wireless energy transfer. Nikola Tesla first published his utility in 1893. Inductively coupled transformers use wireless technology to replace an ordinary power adapter, correcting the drawbacks of the DC voltage required to charge the two inductive coils of an inductively coupled transformer supplied by an AC outlet. Unfortunately, as the distance between the transmitter and receiver increases, the inductance effect quickly diminishes and is often affectedby interference. In other recent developments, Professor Malinsoor and his colleagues at the Massachusetts Institute of Technology recently developed inductive coupling coils that can be tuned to specific resonant frequencies to overcome these limitations. This improves the understanding of the coupling efficiency of the power supply and reduces the interference around other devices or between coils in other indifferent locations. It is called eCoupled technology.While taking advantage of the high efficiency of the Witricity Resonance Sensing, the eCoupled system, including the sender and receiver, does not include the switching of a metal device or device of the RFID chip into sleep mode. The additional data services are robust and canonical communications, and will automatically power off when the battery is full. If widely adopted, wireless power transmission will be listed as a public service facility. Imagine eCoupled transmitters are simple when it comes to using new standards that are used to spur their own, usually using two main methods. To the new standard, there are usually two main methods used to promote its development. The first is a strong regulatory code. Second, inventing a technology that allows manufacturers to imitate and make it widely popular is powerful, but I prefer the latter's non-intervention method.中文译文不能触碰这个—无线电力传输William L. Weaver几年前, 一个同事和我参加在校大学生团体的组织的一个实地考察项目, 考察地位于新泽西州的爱迪生国家历史遗址的西橙。
无线电力传输论文
无线电力传输【摘要】无线电力传输(wpt)是一种利用无线电配合无线能量转换装置进行电力传输的新型方式。
介绍了无线电力传输的原理和三种不同的传输形式,以及在三种不同的形式下相应的应用前景。
【关键词】无线电力输电;wpt;共振;电磁感应“无线电力”这个全新的概念,在最新出版的《科学》杂志中被提了出来。
在文中有提到,如果条件成熟,可以在未来有限的时间内研制出一种新型充电系统,对多种设备如移动电话,ipad进行无线充电。
这样的概念的类似于太阳能电池,可以现充电现使用,但是无线电力传输比太阳能更有优势,一是不用考虑阴雨天气的不良影响,二是能去除电池,不仅为设备微型化创造条件,而且从根本上缓解因电池的过度使用与报废而带来的环境问题。
无线电力传输就是利用无线电的方法,将发电厂产生的电力转换成为无线电波发送出去,再由无线能量转换装置将无线电波收集转化为电能,供给用户。
其实,无线电力传输与无线通讯有着异曲同工之妙,无线能量转换装置也是根据频率有选择接受电磁波,但不同于无线通讯的是,它通过接受电磁波产生振动直接获得电流,相比之下对传输效率有着较高的要求。
无线电力传输利用了共振原理。
早前参与无线电力传输实验的科学家主导的线圈的实验(左右两边相隔两米的线圈点亮了一个功率60瓦的电灯泡)很好了解释了共振这个概念:具有相同振幅的物体间的能量传递效率不受周围事物影响。
20世纪在英国曼彻期特发生的因军队过桥步伐整齐造成桥倒塌的事故就是共振的证明。
无线电力传输利用的是低频电磁波共振。
在实验中,两个感应接受装置都以50hz的频率震动,形成共振,才得以进行装置间能量的传送。
从形成共振到完成能量的传输不是瞬时的,需要一定的时间用于积累。
每一次发生共振,感应接受器中便会积累更多的电压,多次共振就会聚集足够的能量使灯泡发亮。
其实早在19世纪就有科学家提出了无线能量转换这个概念。
因为从17世纪开始人类发明了发电机并利用有线的方式传输电能,并随着电能的普及至今日,供电网、高压线已遍布世界。
(完整版)电力系统外文英语文献资料
Electric Power SystemElectrical power system refers to remove power and electric parts of the part,It includes substation, power station and distribution. The role of the power grid is connected power plants and users and with the minimum transmission and distribution network disturbance through transport power, with the highest efficiency and possibility will voltage and frequency of the power transmission to the user fixed .Grid can be divided into several levels based on the operating voltage transmission system, substructure, transmission system and distribution system, the highest level of voltage transmission system is ZhuWangJia or considered the high power grids. From the two aspects of function and operation, power can be roughly divided into two parts, the transmission system and substation. The farthest from the maximum output power and the power of the highest voltage grade usually through line to load. Secondary transmission usually refers to the transmission and distribution system is that part of the middle. If a plant is located in or near the load, it might have no power. It will be direct access to secondary transmission and distribution system. Secondary transmission system voltage grade transmission and distribution system between voltage level. Some systems only single second transmission voltage, but usually more than one. Distribution system is part of the power system and its retail service to users, commercial users and residents of some small industrial users. It is to maintain and in the correct voltage power to users responsible. In most of the system, Distribution system accounts for 35% of the total investment system President to 45%, and total loss of system of the half .More than 220kv voltage are usually referred to as Ultra high pressure, over 800kv called high pressure, ultra high voltage and high pressure have important advantages, For example, each route high capacity, reduce the power needed for the number of transmission. In as high voltage to transmission in order to save a conductor material seem desirable, however, must be aware that high voltage transmission can lead to transformer, switch equipment and other instruments of spending increases, so, for the voltage transmission to have certain restriction, allows it to specific circumstances in economic use. Although at present, power transmission most is through the exchange of HVDC transmission, and the growing interest in, mercury arc rectifier and brake flow pipe into the ac power generation and distribution that change for the high voltage dc transmission possible.Compared with the high-voltage dc high-voltage ac transmission has the following some advantages: (1) the communication with high energy; (2) substation of simple maintenance and communication cost is low; (3) ac voltage can easily and effectively raise or lower, it makes the power transmission and high pressure With safety voltage distributionHVDC transmission and high-voltage ac transmission has the following advantages: (1) it only need two phase conductors and ac transmission to three-phase conductors; (2) in the dc transmission impedance, no RongKang, phase shift and impact overvoltage; (3) due to the same load impedance, no dc voltage, and transfer of the transmission line voltage drop less communication lines, and for this reason dc transmission line voltage regulator has better properties; (4) in dc system without skin effect. Therefore, the entire section of route conductors are using; (5) for the same work, dc voltage potential stress than insulation. Therefore dc Wire need less insulation; (6) dc transmission line loss, corona to little interference lines of communication; (7) HVDC transmission without loss of dielectric, especially in cable transmission; (8) in dc system without stability and synchronization of trouble.A transmission and the second transmission lines terminated in substation or distribution substations, the substation and distribution substations, the equipment including power and instrument transformer and lightning arrester, with circuit breaker, isolating switch, capacitor set, bus and a substation control equipment, with relays for the control room of the equipment. Some of the equipment may include more transformer substations and some less, depending on their role in the operation. Some of the substation is manual and other is automatic. Power distribution system through the distribution substations. Some of them by many large capacity transformer feeders, large area to other minor power transformer capacity, only a near load control, sometimes only a doubly-fed wire feeders (single single variable substation)Now for economic concerns, three-phase three-wire type communication network is widely used, however, the power distribution, four lines using three-phase ac networks.Coal-fired power means of main power generating drive generators, if coal energy is used to produce is pushing the impeller, then generate steam force is called the fire. Use coal produces steam to promote the rotating impeller machine plant called coal-fired power plants. In the combustion process, the energy stored in the coal to heat released,then the energy can be transformed into the form within vapor. Steam into the impeller machine work transformed into electrical energy.Coal-fired power plants could fuel coal, oil and natural gas is. In coal-fired power plant, coal and coal into small pieces first through the break fast, and then put out. The coal conveyer from coal unloader point to crush, then break from coal, coal room to pile and thence to power. In most installations, according to the needs of coal is, Smash the coal storage place, no coal is through the adjustable coal to supply coal, the broken pieces of coal is according to the load changes to control needs. Through the broken into the chamber, the coal dust was in the second wind need enough air to ensure coal burning.In function, impeller machine is used to high temperature and high pressure steam energy into kinetic energy through the rotation, spin and convert electricity generator. Steam through and through a series of impeller machine parts, each of which consists of a set of stable blade, called the pipe mouth parts, even in the rotor blades of mobile Li called. In the mouth parts (channel by tube nozzle, the steam is accelerating formation) to high speed, and the fight in Li kinetic energy is transformed into the shaft. In fact, most of the steam generator is used for air is, there is spread into depression, steam turbine of low-pressure steam from the coagulation turbine, steam into the condenses into water, and finally the condensate water is to implement and circulation.In order to continuous cycle, these must be uninterrupted supply: (1) fuel; (2) the air (oxygen) to the fuel gas burning in the configuration is a must; (3) and condenser, condensed from the condensed water supply, sea and river to lake. Common cooling tower; (4) since water vapour in some places in circulation, will damage process of plenty Clean the supply.The steam power plant auxiliary system is running. For a thermal power plant, the main auxiliary system including water system, burning gas and exhaust systems, condensation system and fuel system. The main auxiliary system running in the water pump, condensation and booster pump, coal-fired power plants in the mill equipment. Other power plant auxiliary equipment including air compressors, water and cooling water system, lighting and heating systems, coal processing system. Auxiliary equipment operation is driven by motor, use some big output by mechanical drive pump and some of the impeller blades, machine drive out from the main use of water vaporimpeller machine. In coal-fired power plant auxiliary equipment, water supply pump and induced draft fan is the biggest need horsepower.Most of the auxiliary power generating unit volume increased significantly in recent years, the reason is required to reduce environment pollution equipment. Air quality control equipment, such as electrostatic precipitator, dust collection of flue gas desulfurization, often used in dust in the new coal-fired power plants, and in many already built in power plant, the natural drive or mechanical drive, fountain, cooling tower in a lake or cooling canal has been applied in coal-fired power plants and plants, where the heat release need to assist cooling system.In coal-fired power stations, some device is used to increase the thermal energy, they are (1) economizer and air preheater, they can reduce the heat loss; (2) water heater, he can increase the temperature of water into boiling water heaters; (3) they can increase and filter the thermal impeller.Coal-fired power plants usually requires a lot of coal and coal reservoirs, however the fuel system in power plant fuel handling equipment is very simple, and almost no fuel oil plants.The gas turbine power plants use gas turbine, where work is burning gas fluid. Although the gas turbine must burn more expensive oil or gas, but their low cost and time is short, and can quickly start, they are very applicable load power plant. The gas turbine burn gas can achieve 538 degrees Celsius in the condensing turbine, however, the temperature is lower, if gas turbine and condenser machine, can produce high thermal efficiency. In gas turbine turbine a combined cycle power plant. The gas through a gas turbine, steam generator heat recovery in there were used to generate vapor heat consumption. Water vapor and then through a heated turbine. Usually a steam turbine, and one to four gas turbine power plant, it must be rated output power.。
无线通信外文文献译文
无线通信电机及电子学工程师联合会2005年国际研讨会上关于微波,天线,传播和无线通信的电磁兼容技术在技术发展上的最新动态竹内清一地区10主任东京电机大学摘要本文介绍无线通信技术的最新发展趋势以及组成无线通信技术的四个部分。
第一个也是最重要的发展是全球互联网流量的增长。
在全球互联网流量增长的重要趋势总结在全球地理区域和他们的互联网渗透方面。
第二个部分是实现无线通信所必备的骨干网络中的硬件配套技术的发展。
第三部分是无线通信的中心问题,特别是本地个人用户,第四和最后一个部分是总结发言。
1简介许多技术的发展显然是需要通过无线通信的实现,以满足环保要求的社会背景需要这的种技术发展。
例如,互联网流量每年约增加一倍,而这种快速增长的互联网流量和WWW(全球资讯网)需要为骨干网络配置无线并不一定需要,但对本地无线通信的实现至关重要的巨大带宽。
骨干网主要靠光纤电缆的技术发展以及相关的配套技术配套支持运行的。
这样的等配套技术包括信息处理和WDM(波分复用)和他们使取得的高效无线通信成为了可能。
无线通信,特别是无线互联网特别是无线互联网对于集中,甚至不断移动的短距离范围内的本地个人用户非常重要。
在IEEE 802.11是无线局域网用于与合作媒介访问控制协议的一般原则,也可以扩展到其他类型的无线网络,如无线个人区域网络(WPAN的)。
该服务区的范围变得越来越小,以便让当地个人用户的充分利用无线通讯媒介用于无线互联网流量。
无线通信是无线互联网最便捷的传输介质,这种无线传输介质的有效使用是至关重要的。
可靠的访问几十兆赫可以跨相当大的在其中无线互联网将需要十倍多的细胞的语音系统的地理区域,每个这样的monocles将测量面积小,几十平方米的大约是百分之常规细胞的大小。
它比传统电池可以容纳更多给定的数据速率的有源器件。
为了使这成为可能的,有效的射频频谱空间复用是必要的,从而能够让个人用户访问更贴近低功率的传输点。
对于快速增长的互联网流量的整体通信系统可以由的三个关键的重要领域的技术发展来支持,1)硬件技术需要个人用户的高密度无线传输的实现,2)配套硬件技术的光纤电缆,3)整体通信系统的运作和维护方面的软件技术,我们主要回顾了前两部分的硬件方面2互联网的发展表1显示了最高的互联网普及率最高的24个国家。
一篇电气专业英语文献与翻译
The Load Estimation and Power Tracking Integrated Control Strategy for Dual-Sides Controlled LCC Compensated WirelessCharging SystemABSTRACT In this paper, the wireless power transfer (WPT) system with dynamic loads such as batteries is studied comprehensively. An integrated control technology of load estimation and power tracking of LCC compensated is proposed, which realizes load estimation, mode judgment and charging control at the transmitter, and standard load setting and decoupling control at the receiver. Based on the inflfluence of reflflection impedance on the output current of the inverter, a method of identifying coupling coeffificient and equivalent load is proposed and a mathematical model is established. Receiver controller provides standard reference load for load estimation. Transmitter controller judges battery status according to the estimation of equivalent load and adopts double closed-loop control to regulate power and current. Receiver decouples control when battery charging voltage reaches the threshold, and providing mode conversion sign for transmitter controller to realize constant current (CC) and constant voltage (CV) charging of battery.The Dual-sides integrated control scheme has no data communication between transmitter and receiver, so it can control independently, which reduces the complexity of the system and is suitable for different charging modes. The proposed controller is more effificient as it maintains a track current, and dynamically alters the pick-up characteristics to suit the load demand. Finally, the simulation and experimental results validate the feasibility of proposed control method, which realizes the estimation of the load and CC/CV charging of the battery. The proposed WPT system achieved the effificiency at 91.16% while delivering 2 kW to the load with a vertical air gap of 150 mm.INDEX TERMS Wireless power transfer, integrated control, load estimation, constant current/voltage charging, LCC compensation, phase shift control.Wireless Power Transmission (WPT) or Contactless Power Transmission (CPT) achieves the power transmission without physical connection, which makes up for the shortcomings of traditional power transmission methods . Wireless charging will promote the development of electric vehicles (EVs), because it provides more convenient, reliable and safer charging options than conductive charging . There are many research fields in WPT for EVs, especially the WPT system is sensitive to coupling coefficient, air gap, resonant frequency, and load change, which makes it hard for There are many research fields in WPT for EVs, especially the WPT system issensitive to coupling coefficient, air gap,resonant frequency, and load change, which makes it hard for robust control, and most scholars focus on the steady state of the WPT systems .When the resonant frequency, position, parameters and load of the wireless charging system change, which result in a higher volt-ampere rating and lower power transfer efficiency. Therefore, resonant compensation is an important part at the transmitter and receiver of the system. Different compensation topologies have been proposed and implemented to tune the two coils working at a resonant frequency in a wide range of applications. there are four basic compensation topologies, namely Series-Series (SS), SeriesParallel (SP), Parallel-Series (PS) and Parallel-Parallel (PP),are widely adopted for EV applications.Many other novel compensation topologies are also used to improve the power transfer efficiency and to simplify the control of WPT systems. Literatures show that LCL topology and series LC topology are the commonly used primary compensation networks for WPT. Compared with series LC, LCL performs better in power conversion efficiency over the full range of coupling and loading imposed, and its constant current source characteristic make its closed-loop control implementation easier. More advantageous compensation topologies are put forward in . The double-sided LCC compensation topology is outstanding since not only is its resonant frequency independent of coupling coefficient and load condition, but also its advantages of facilitating zero voltage switch (ZVS) or zero current switch (ZCS) of the inverter, realize CC charging at zero phase angle (ZPA) condition, increasing lateral misalignment tolerance, and improving WPT efficiency have been demonstrated.The other problem with WPT charger systems is implementing a charge process for EV batteries.Since batteries are considered to be varying loads during charging, the charge converter needs to regulate its output precisely to implement the constant current (CC) charge and constant voltage (CV) mode charge. Thus, meticulous control and tuning of the inverter is necessary since the load varies violently as the receive coil moves with the online EV.This adds to the control complexity and may reduce systematic reliability. In order to improve battery life and charging efficiency, it is necessary for a charger to provide accurate charge current and voltage through stable operations. In recent years, various control strategies have been studied to provide the required output currentorvoltagefortime-varyingloadsatdifferentcharging stages.The traditional control method is to use wireless communication to send the load state information to the transmitter controller to adjust the output power of the inverter to achieve CC/CV charging in . In order to simplify the control of an WPT charger system and avoid the above drawbacks of conventional control methods under wide variations of the load in implementing the CC/CV charge, some researchers have started to utilize the load-independent characteristics of the compensation topologies at their resonant frequencies proposes a design method which makes it possible to implement the CC/CV mode charge with minimum frequency variation during the entire charge process by using the load-independent characteristics of an WPT system under the ZPA condition without any additional switches. But, frequency variation may result in a bifurcation phenomenon,where the control ability and stability of the system are lost.In order to realize ZPA condition in the whole charging process, a switchablehybrid topology is proposed in [19], and [20]. CC and CV charging are realized in different compensation topologies. However, the addition of switches complicates the system, and changes in system parameters can also lead to instability.In[21], a new control technique was proposed, which only employs the controller at transmitting and and load identification approach to adjust charging voltage/current for SS and SP compensated WPT systems. The advantages are that dual-side wireless communication for real-time charging current/voltage adjustment is avoided as well as it is suitable for different charging modes. However, switching between two kinds of topologies is still needed. For the CC/CV charging control at constant frequency, some approaches employ a DC/DC converter to control the output current or voltage while the front-end converter operates at the resonant frequency to achieve the ZPA condition in [22] and [23]. However, this increases the component counts, losses and complexity. In [24], DC/DC converters are used for decoupling control rather than CC or CV charging.In [25]and [26], a single primary-side controller based on phase shift H-bridge inverter are proposed to adjust the charging current or charging voltage against various load, may make it hard for the High frequency inverter to achieve ZVS in full load range, especially with light load condition. Then, the primary-side control method that realizes CC/CV charging for battery is analyzed, which is the main contribution of this paper.The objective of this research is to study and develop a new integrated control strategy for load and power tracking that realizes CC/CV charging for LCC compensation through the double-loop controlled phase shift H-bridge inverter and load identification approach. The system adopts dual-side controller to avoid wireless communication, and the mathematical models of load estimation and mode judgment are derived by using the topological compensation characteristics of double-sided LCC. The working state of the battery is fed back to the transmitter controller by reflecting the impedance of the receiver, and the coupling coefficient of coils and load value are estimated.The transmitter judges the charging mode according to the estimated load, adjusts the output power of the inverter, and maintains CC/CV charging by phase-shifting control. In CC mode, the transmitter can transfer more power and prevents overloading. In CV mode, the output power can be adjusted according to the charging curve. The receiver control circuit adopts Buck-Boost structure. Different from the traditional impedance matching or CC/CV charging control mode, the receiver controller sets the standard reference value of load estimation control by impedance matching. Buck-Boost converter operates in switching mode during charging. When the charging voltage reaches the reference value, the switching action changes the reflection impedance and provides the mode conversion mark for the transmitter. Based on the feedback signal and the amount of transferred power, the controlling module continuously adjusts the transmitting coil current during the charging.The rest of the sections are organized as follows:Section II gives the system structure and basic theoretical analysis. Section III proposes the integrated control method of load estimation and power tracking, and then the double closed-loop PIcontroller of transmitter and receiver is designed. Section IV validates the proposed method with simulations and experiments.Finally,last section summarizes the conclusions drawn from the investigation.II. SYSTEM STRUCTURE AND THEORETICAL ANALYSISIn this section, the system structure and methodology for analyzing the WPT system are discussed. Then, basic output characteristics for LCC compensation are analyzed to propose the Integrated control method on the transmitting side and the receiving side.A.WIRELESS POWER TRANSMISSION SYSTEM TRUCTURE In this paper, the most widely used variable impedance load battery is taken as the research object.Charging characteristic curve of the battery is shown in Figure 1. Charging process includes CC/CV charging. In CC stage, the output power of the power supply increases with the increase of the battery terminal voltage, while the equivalent impedance of the battery increases with little change. In the CV stage, the charge current and power decrease,and the equivalent impedance of the battery increases rapidly.B. LOAD ESTIMATE AND MODEL RECOGNITION The transmitter controller measures Iinv to estimate the load and mutual inductance changes, and judges the working state of the receiver. The inverter operates at ZPA resonant frequency and the controller adjusts fro m 180◦ phase shift, which means that the minimum input voltage is applied to the transmitting coil. According to the requirement of the receiver, the power control unit uses phase shift control to adjust the It and VC to keep the CC and CV working modes at the receiver.The transmitter can control the power output according to the working mode of the receiver and the load demand. In order to achieve this function, the designed controller should be able to estimate mutual inductance and equivalent load, and then judge the charging mode of the receiving end. The control block diagram of load estimation and mode judgment strategy is shown in Figure 5. Where, Rx is the standard reference load of the receiver.CONCLUSION An integrated control method of load estimation and power tracking is proposed in this paper to achieve CC/CV charging.of LCC compensation WPT system. Firstly, through theoretical analysis, the LCC compensation topology can realize the charge of CC mode under ZPA condition, and get the relationship between the equivalent load and the current of the inverters. Then, a standard reference load is set at the receiver so that the transmitter can estimate the equivalent load by calculating the refection impedance and detecting the output current of the inverter. Finally, according to the estimated load value and the conversion mark given by the decoupling control of the receiver, the CC/CV charging for LCC compensation are realized by PI controlled phase shift full-bridge inverter. The simulation and experimental results validate the feasibility of the proposed control method for whole load changes. The proposed WPT system can achieve a high effenciency at 91.16% with a 20-cm air gap when delivering 0.2−2kW to the load in different charging stages.双边控制的LCC补偿型无线充电系统的负载估计与功率跟踪集成控制策略摘要本文对电池等动态负载下的无线电能传输(WPT)系统进行了全面的研究。
【经典外文翻译】英文(电气类)-电信现代运营telecommunication modern operation__毕业论文
Telecommunication Modern OperationTelephoneIn an analogue telephone network, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.The fixed-line telephones in most residential homes are analogue — that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m). In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8. This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely. There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.Radio and televisionIn a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal isvaried continuously with respect to the information) or digital (information is encoded as a set of discrete values).The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011 — a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards; the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2. The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the Digital Audio Broadcasting standard (also known as the Eureka 147 standard). The exception being the United States which has chosen to adopt HD Radio. HD Radio, unlike Eureka 147, is based upon a transmission method known as in-band on-channel transmission that allows digital information to "piggyback" on normal AM or FM analogue transmissions.However, despite the pending switch to digital, analogue receivers still remain widespread. Analogue television is still transmitted in practically all countries. The United States had hoped to end analogue broadcasts on December 31, 2006; however, this was recently pushed back to February 17, 2009. For analogue television, there are three standards in use. These are known as PAL, NTSC and SECAM. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers are a fraction of the cost of digital receivers. The choice of modulation for analogue radio is typically between amplitude modulation (AM) or frequency modulation (FM). To achieve stereo playback, an amplitude modulated subcarrier is used for stereo FM.The InternetThe Internet is a worldwide network of computers and computer networks that can communicate with each other using the Internet Protocol. Any computer on the Internet has a unique IP address that can be used by other computers to route information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. In this way, the Internet can be seen as an exchange of messages between computers.An estimated 16.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (69.7%), Oceania/Australia (53.5%) and Europe (38.9%).In terms of broadband access, Iceland (26.7%), South Korea (25.4%) and the Netherlands (25.3%) lead the world.The Internet works in part because of protocols that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an Internet browser to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or Wi-Fi connection. Protocols are often talked about in terms of their place in the OSIreference model, which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fibre. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.At the network layer, things become standardized with the Internet Protocol (IP) being adopted for logical addressing. For the world wide web, these “IP addresses” are derived from the human readable form using the Domain Name System (e.g.72.14.207.99 is derived from ). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). TCP is used when it is essential every message sent is received by the other computer where as UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered or retransmitted if lost. Both TCP and UDP packets carry port numbers with them to specify what application or process the packet should be handled by. Because certain application-level protocols use certain ports, network administrators can restrict Internet access by blocking the traffic destined for a particular port.Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. These protocols ensure that the data transferred between two parties remains completely confidential and one or the other is in use when a padlock appears at the bottom of your web browser. Finally, at the application layer, are many of the protocols Internet users would be familiar with such as HTTP (web browsing), POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent (file sharing) and OSCAR (instant messaging).Local area networksDespite the growth of the Internet, the characteristics of local area networks (computer networks that run at most a few kilometres) remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them.In the mid-1980s, several protocol suites emerged to fill the gap between the data link and applications layer of the OSI reference model. These were Appletalk, IPX and NetBIOS with the dominant protocol suite during the early 1990s being IPX due to its popularity with MS-DOS users. TCP/IP existed at this point but was typically only used by large government and research facilities. As the Internet grew in popularity and a larger percentage of traffic became Internet-related, local area networks gradually moved towards TCP/IP and today networks mostly dedicated to TCP/IP traffic are common. The move to TCP/IP was helped by technologies such as DHCP that allowed TCP/IP clients to discover their own network address —a functionality that came standard with the AppleTalk/IPX/NetBIOS protocol suites.It is at the data link layer though that most modern local area networks diverge from the Internet. Whereas Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) are typical data link protocols for larger networks, Ethernet and Token Ring are typical data link protocols for local area networks. These protocols differ from the former protocols in that they are simpler (e.g. they omit features such as Quality of Service guarantees) and offer collision prevention. Both of these differences allow for more economic set-ups.Despite the modest popularity of Token Ring in the 80's and 90's, virtually all local area networks now use wired or wireless Ethernet. At the physical layer, most wired Ethernet implementations use copper twisted-pair cables (including the common 10BASE-T networks). However, some early implementations used coaxial cables and some recent implementations (especially high-speed ones) use optic fibres. Optic fibres are also likely to feature prominently in the forthcoming 10-gigabit Ethernet implementations. Where optic fibre is used, the distinction must be made between multi-mode fibre and single-mode fibre. Multi-mode fibre can be thought of as thicker optical fibre that is cheaper to manufacture but that suffers from less usable bandwidth and greater attenuation (i.e. poor long-distance performance).。
5G无线通信网络中英文对照外文翻译文献
5G无线通信网络中英文对照外文翻译文献(文档含英文原文和中文翻译)翻译:5G无线通信网络的蜂窝结构和关键技术摘要第四代无线通信系统已经或者即将在许多国家部署。
然而,随着无线移动设备和服务的激增,仍然有一些挑战尤其是4G所不能容纳的,例如像频谱危机和高能量消耗。
无线系统设计师们面临着满足新型无线应用对高数据速率和机动性要求的持续性增长的需求,因此他们已经开始研究被期望于2020年后就能部署的第五代无线系统。
在这篇文章里面,我们提出一个有内门和外门情景之分的潜在的蜂窝结构,并且讨论了多种可行性关于5G无线通信系统的技术,比如大量的MIMO技术,节能通信,认知的广播网络和可见光通信。
面临潜在技术的未知挑战也被讨论了。
介绍信息通信技术(ICT)创新合理的使用对世界经济的提高变得越来越重要。
无线通信网络在全球ICT战略中也许是最挑剔的元素,并且支撑着很多其他的行业,它是世界上成长最快最有活力的行业之一。
欧洲移动天文台(EMO)报道2010年移动通信业总计税收1740亿欧元,从而超过了航空航天业和制药业。
无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力无线移动通信的显著成就表现在技术创新的快速步伐。
从1991年二代移动通信系统(2G)的初次登场到2001年三代系统(3G)的首次起飞,无线移动网络已经实现了从一个纯粹的技术系统到一个能承载大量多媒体内容网络的转变。
4G无线系统被设计出来用来满足IMT-A技术使用IP面向所有服务的需求。
在4G系统中,先进的无线接口被用于正交频分复用技术(OFDM),多输入多输出系统(MIMO)和链路自适应技术。
4G无线网络可支持数据速率可达1Gb/s的低流度,比如流动局域无线访问,还有速率高达100M/s的高流速,例如像移动访问。
LTE系统和它的延伸系统LTE-A,作为实用的4G系统已经在全球于最近期或不久的将来部署。
然而,每年仍然有戏剧性增长数量的用户支持移动宽频带系统。
Wireless Power Transfer via Coupled Magnetic
2020/12/2
《测控技术与仪器英语教程》
7
Language in use
•Vocabulary
–WPT
• Notes • Exercises
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《测控技术与仪器英语教程》
8
ห้องสมุดไป่ตู้
WPT in dictionary
• Wire power transfer (WPT) 无线电能传输
2020/12/2
Lesson16 Wireless Power Transfer via Coupled Magnetic Resonances
2020/12/2
《测控技术与仪器专业英语教程》
1
Backgrounds
• Terminology
– Wireless power transfer (WPT) 无线电能传输 – Laptop 便携式电脑;笔记本电脑 – Validation 生效;批准;验证 – Colpitts oscillator 考毕兹振荡器 – Quality factor 品质因数
am (t) (im m )am (t) ikmnan (t) Fm (t) (16-1) nm
2020/12/2
《测控技术与仪器英语教程》
4
16.2 Theoretical Model for Selfresonant Coils
• Our experimental realization of the scheme consists of two self-resonant coils. One coil (the source coil) is coupled inductively to an oscillating circuit; the other (the device coil) is coupled inductively to a resistive load.
无线电力传输的电车辆应用-英文
Wireless Power Transfer for Electric Vehicle ApplicationsSiqi Li,Member,IEEE,and Chunting Chris Mi,Fellow,IEEEAbstract—Wireless power transfer(WPT)using magnetic resonance is the technology which could set human free from the annoying wires.In fact,the WPT adopts the same basic theory which has already been developed for at least30 years with the term inductive power transfer.WPT tech-nology is developing rapidly in recent years.At kilowatts power level,the transfer distance increases from several mil-limeters to several hundred millimeters with a grid to load efficiency above90%.The advances make the WPT very attractive to the electric vehicle(EV)charging applications in both stationary and dynamic charging scenarios.This paper reviewed the technologies in the WPT area applicable to EV wireless charging.By introducing WPT in EVs,the obstacles of charging time,range,and cost can be easily mitigated.Battery technology is no longer relevant in the mass market penetration of EVs.It is hoped that researchers could be encouraged by the state-of-the-art achievements,and push forward the further development of WPT as well as the expansion of EV.Index Terms—Dynamic charging,electric vehicle(EV), inductive power transfer(IPT),safety guidelines,stationary charging,wireless power transfer(WPT).I.I NTRODUCTIONF OR energy,environment,and many other reasons,theelectrification for transportation has been carrying out for many years.In railway systems,the electric locomotives have already been well developed for many years.A train runs on a fixed track.It is easy to get electric power from a conductor rail using pantograph sliders.However,for electric vehicles(EVs), the highflexibility makes it not easy to get power in a similar way.Instead,a high power and large capacity battery pack is usually equipped as an energy storage unit to make an EV to operate for a satisfactory distance.Until now,the EVs are not so attractive to consumers even with many government incentive ernment subsidy and tax incentives are one key to increase the market share of EV today.The problem for an electric vehicle is nothing else but the electricity storage technology,which requires a battery which is the bottleneck today due to its unsatisfactory energy density,limited life time and high cost. Manuscript received February2,2014;revised April6,2014;accepted April18,2014.Date of publication April23,2014;date of current ver-sion January29,2015.Recommended for publication by Associate Editor ler.S.Li is with the Department of Electrical Engineering,Kunming Uni-versity of Science and Technology,Kunming650500,China(e-mail: lisiqi@).C. C.Mi is with the Department of Electrical and Computer Engineering,University of Michigan,Dearborn,MI48128USA(e-mail: chrismi@).Color versions of one or more of thefigures in this paper are available online at .Digital Object Identifier10.1109/JESTPE.2014.2319453In an EV,the battery is not so easy to design because of the following requirements:high energy density,high power density,affordable cost,long cycle life time,good safety, and reliability,should be met simultaneously.Lithium-ion batteries are recognized as the most competitive solution to be used in electric vehicles[1].However,the energy density of the commercialized lithium-ion battery in EVs is only 90–100Wh/kg for afinished pack[2].1This number is so poor compared with gasoline,which has an energy density about 12000Wh/kg.To challenge the300-mile range of an internal combustion engine power vehicle,a pure EV needs a large amount of batteries which are too heavy and too expensive. The lithium-ion battery cost is about500$/kWh at the present time.Considering the vehicle initial investment,maintenance, and energy cost,the owning of a battery electric vehicle will make the consumer spend an extra1000$/year on average compared with a gasoline-powered vehicle[1].Besides the cost issue,the long charging time of EV batteries also makes the EV not acceptable to many drivers.For a single charge, it takes about one half-hour to several hours depending on the power level of the attached charger,which is many times longer than the gasoline refueling process.The EVs cannot get ready immediately if they have run out of battery energy. To overcome this,what the owners would most likely do is tofind any possible opportunity to plug-in and charge the battery.It really brings some trouble as people may forget to plug-in andfind themselves out of battery energy later on. The charging cables on thefloor may bring tripping hazards. Leakage from cracked old cable,in particular in cold zones, can bring additional hazardous conditions to the owner.Also, people may have to brave the wind,rain,ice,or snow to plug-in with the risk of an electric shock.The wireless power transfer(WPT)technology,which can eliminate all the charging troublesome,is desirable by the EV owners.By wirelessly transferring energy to the EV,the charging becomes the easiest task.For a stationary WPT system,the drivers just need to park their car and leave.For a dynamic WPT system,which means the EV could be powered while driving;the EV is possible to run forever without a stop. Also,the battery capacity of EVs with wireless charging could be reduced to20%or less compared to EVs with conductive charging.Although the market demand is huge,people were just wondering whether the WPT could be realized efficiently at1Although lithium ion battery can achieve up to200Wh/kg for individual cells,the battery pack requires structure design,cooling,and battery manage-ment systems.The over energy density of a battery pack is much lower than the cell density.2168-6777©2014IEEE.Personal use is permitted,but republication/redistribution requires IEEE permission.See /publications_standards/publications/rights/index.html for more information.a reasonable cost.The research team from MIT published a paper in Science[3],in which60W power is transferred at a2-m distance with the so called strongly coupled magnetic resonance theory.The result surprised the academia and the WPT quickly became a hot research area.A lot of interesting works were accomplished with different kinds of innovative circuit,as well as the system analysis and control[4]–[9].The power transfer path can even be guided using the domino-form repeaters[10],[11].In order to transfer power more efficiently and further,the resonant frequency is usually selected at MHz level,and air-core coils are adopted.When the WPT is used in the EV charging,the MHz frequency operation is hard to meet the power and efficiency criteria.It is inefficient to convert a few to a few hundred kilowatts power at MHz frequency level using state-of-the-art power electronics devices.Moreover,air-core coils are too sensitive to the surrounding ferromagnetic objects.When an air-core coil is attached to a car,the magneticflux will go inside the chassis causing high eddy current loss as well as a significant change in the coil parameters.To make it more practical in the EV charging,ferrite as a magneticflux guide and aluminum plate as a shield are usually adopted in the coil design[12].With the lowered frequency to less than100kHz, and the use of ferrite,the WPT system is no different from the inductive power transfer(IPT)technology which has been developed for many years[13]–[39].In fact,since the WPT is based on the nonradiative and near-field electromagnetic,there is no difference with the traditional IPT which is based on magneticfield coupling between the transmitting and receiving coils.The IPT system has already been proposed and applied to various applications,such as underwater vehicles[32]–[34], mining systems[16],cordless robots in automation production lines[36]–[39],as well as the charging of electric vehicles [13],[14],[25]–[27].Recently,as the need of EV charging and also the progress in technology,the power transfer distance increases from several millimeters to a few hundred millimeters at kilowatts power level[12],[14],[40]–[60].As a proof-of-concept of a roadway inductively powered EV,the Partners for Advance Transit and Highways(PATH)program was conducted at the UC Berkeley in the late1970s[14],[54].A60kW, 35-passanger bus was tested along a213m long track with two powered sections.The bipolar primary track was supplied with1200A,400Hz ac current.The distance of the pickup from the primary track was7.6cm.The attained efficiency was around60%due to limited semiconductor technology.During the last15years,researchers at Auckland University have focused on the inductive power supply of movable objects. Their recent achievement in designing pads for the stationary charging of EV is worth noting.A766mm×578mm pad that delivers5kW of power with over90%efficiency for distances about200mm was reported[48],[55].The achieved lateral and longitudinal misalignment tolerance is 250and150mm,respectively.The knowledge gained from the on-line electric vehicle(OLEV)project conducted at the Korea Advanced Institute of Science and Technology(KAIST) also contributes to the WPT design.Three generations of OLEV systems have been built:a light golf cart as thefirst Fig.1.Typical wireless EV charging system.generation,a bus for the second,and an SUV for the third. The accomplishment of the second and the third is noteworthy: 60kW power transfer for the buses and20kW for the SUVs with efficiency of70%and83%,respectively;allowable vertical distance and lateral misalignment up to160mm and up to200mm,respectively[56],[57].In the United States, more and more public attention was drawn to the WPT since the publication of the2007Science paper[3].The WiTricity Corporation with technology from MIT released their WiT-3300development kit,which achieves90%efficiency over a 180mm gap at3.3kW output.Recently,a wireless charging system prototype for EV was developed at Oak Ridge National Laboratory(ORNL)in the United States.The tested efficiency is nearly90%for3kW power delivery[53].The research at the University of Michigan–Dearborn achieved a200mm distance,8kW WPT system with dc to dc efficiency as high as95.7%[61].From the functional aspects,it could be seen that the WPT for EV is ready in both stationary and dynamic applications.However,to make it available for large-scale commercialization,there is still abundant work to be done on the performance optimization,setup of the industrial standards, making it more cost effective,and so on.This paper starts with the basic WPT theory,and then gives a brief overview of the main parts in a WPT system, including the magnetic coupler,compensation network,power electronics converter,study methodology,and its control,and some other issues like the safety considerations.By introduc-ing the latest achievements in the WPT area,we hope the WPT in EV applications could gain a widespread acceptance in both theoretical and practical terms.Also,we hope more researchers could have an interest and make more brilliant contributions in the developing of WPT technology.II.F UNDAMENTAL T HEORYA typical wireless EV charging system is shown in Fig.1. It includes several stages to charge an EV wirelessly.First, the utility ac power is converted to a dc power source by an ac to dc converter with power factor correction.Fig.2.General two-coil WPT system.Then,the dc power is converted to a high-frequency ac todrive the transmitting coil through a compensation network.Considering the insulation failure of the primary side coil,a high-frequency isolated transformer may be inserted betweenthe dc-ac inverter and primary side coil for extra safety andprotection.The high-frequency current in the transmitting coilgenerates an alternating magneticfield,which induces an acvoltage on the receiving coil.By resonating with the secondarycompensation network,the transferred power and efficiencyare significantly improved.At last,the ac power is rectifiedto charge the battery.Fig.1shows that a wireless EV chargerconsists of the following main parts:1)the detached(or separated,loosely coupled)transmittingand receiving ually,the coils are built withferrite and shielding structure,in the later sections,theterm magnetic coupler is used to represent the entirety,including coil,ferrite,and shielding;2)the compensation network;3)the power electronics converters.The main difference between a wireless charger and aconventional conductive or wired charger is that a transformeris replaced by a set of loosely couple coils.To give a quickidea of the WPT principle,the coil and the compensationnetwork are pulled out separately,as shown in Fig.2,whereL1represents the self-inductance of the primary side transmit-ting coil and L2represents the self-inductance of the receivingcoil;˙I1and˙I2are the current in the two coils;˙U12is thevoltage in the secondary coil that is induced by the currentin the primary side coil.˙U21is the voltage in the primarycoil that is induced by the current in secondary side coil dueto coupling,or mutual inductance between the primary andsecondary coils.S1and S2are the apparent power goes intoL1and L2,respectively.S3and S4are the apparent powerprovided by the power converter.S12and S21represent theapparent power exchange between the two coils.The form ofthe compensation network is not specified.The characteristicsof the compensation network will be discussed later.As shown in Fig.2,neglecting the coil resistance andmagnetic losses,we can calculate the simplified form ofexchanged complex power from L1to L2˙S12=−˙U12˙I∗2=−jωM˙I1˙I∗2=ωM I1I2sinϕ12−jωM I1I2cosϕ12(1)˙S21=−˙U21˙I∗1=−jωM˙I2˙I∗1=−ωM I1I2sinϕ12−jωM I1I2cosϕ12(2)where I1and I2are the root mean square value andϕ12isthe phase difference between˙I1and˙I2.The active powertransfer from the primary side to the secondary side can beexpressed asP12=ωM I1I2sinϕ12.(3)The system shown in Fig.2can transfer active power inboth directions.In the analysis below,we assume the poweris transferred from L1to L2.Whenϕ12=π/2,which means˙I1leads˙I2by a quarter cycle,the maximum power can betransferred from L1to L2.The total complex power goes into the two-coil system is˙S=˙S1+˙S2=jωL1˙I1+ωM˙I2˙I∗1+jωL2˙I2+ωM˙I1˙I∗2=jωL1I21+L2I22+2M I1I2cosϕ12.(4)Therefore,the total reactive power goes into the two-coilsystem isQ=ωL1I21+L2I22+2M I1I2cosϕ12.(5)For a traditional transformer,the reactive power representsthe magnetizing power.Higher magnetizing power bringshigher copper and core loss.To increase the transformerefficiency,the ratio between the active power and reactivepower should be maximized.The ratio is defined byf(ϕ12)=|P12||Q|=ωM I1I2sinϕ12ωL1I21+ωL2I22+2ωM I1I2cosϕ12=k1−cos2ϕ12L1L2I1I2+L2L1I2I1+2k cosϕ21=k1−cos2ϕ12x+1x+2k cosϕ12(6)whereπ/2<ϕ12<πx=L1L2I1I2>0k is the coupling coefficient between L1and L2.To achieve the maximum value of f(ϕ12),we solve thefollowing equations:∂∂ϕ12f(ϕ12)=0,∂2∂2ϕ12f(ϕ12)<0(7)and the solutions arecosϕ12=−2kx+1x,sinϕ12=1−4k2x+1x2.(8)When k is close to1,it is a traditional transformer.In this case,if˙I2is an induced current by˙I1,x will be close to1. Thus,cosϕ12≈−1.The phase difference between˙I1and˙I2 is nearly180°.While for WPT,k is close to0.f(ϕ12)is maximized at sinϕ12=1,at which point the transferred power is also maximized.The phase between˙I1and˙I2is around90°instead of180°.Hence we can see the difference between the tightly and the loosely coupled coils.The degree of coupling affects the design of the compensa-tion network.Taking the series–series topology as an example, there are two ways to design the resonant capacitor.One way is design the capacitor to resonate with the leakage inductance [46],[62]which could achieve a higher f(ϕ12).Another way is to resonate with the coil self-inductance[27],[41],[63] which could maximum the transferred power at a certain coil current.When the coupling is tight with a ferrite,like k>0.5, it is important to increase f(ϕ12)to achieve better efficiency. In this case,resonate with the coil self inductance,which makesϕ12=π/2and lowers f(ϕ12),is not recommended. Otherwise the magnetizing loss may significantly increase. When the capacitor resonates with the leakage inductance,it is like the leakage inductance is compensated.This makes the transformer perform as a traditional one and increases f(ϕ12). However,the overall system does not work at a resonant mode.When the coupling is loose,like k<0.5,which is the case for the EV wireless charging,usually the capacitor is tuned with the self inductance to make the system working at a resonate mode to achieve maximum transferred power at a certain coil current.In this case,most of the magnetic field energy is stored in the large air gap between the two coils.The hysteresis loss in the ferrite is not so relative to the magnetizing power.However,the loss in the copper wire is proportional to the square of the conducting current. To efficiently transfer more power at a certain coil current,the induced current˙I2should lag˙I1by90°.Since the induced voltage˙U12on the receiving coil lags˙I1by90°,˙U12and˙I2 should be in phase.The secondary side should have a pure resistive characteristic seen from˙U12at the frequency of˙I1. At the meanwhile,the primary side input apparent power S3 should be minimized.At cosϕ12=0,the complex power˙S1is˙S1=jωL1I21+ωM I1I2.(9) Ideally,the primary side compensation network should cancel the reactive power and make S3=ω0M I1I2,where ω0is the resonant frequency.From the above analysis,we see for a certain transferred power,it is necessary to make the secondary side resonant to reduce the coil volt-ampere(V A) rating,which reduces the loss in the coils;and to make the primary side resonant to reduce the power electronics converter V A rating,which reduces the loss in the power converter. Therefore,we transfer power at the magnetic resonance. With the above analysis,we can calculate the power transfer efficiency between the two coils at the resonant frequency.We haveU12=I2(R2+R Le)=ωM I1=ωkL1L2I1(10) where R2is the secondary winding resistance and R Le is the equivalent load resistance.By defining the quality factor of the two coils, Q1=ωL1/R1,Q2=ωL2/R2,the transferred efficiency can be expressed asη=I22R LeI21R1+I22R2+I22R Le=R Le(R2+R Le)2k2Q1Q2R2+R2+R Le.(11)By defining a=R Le/R2,we obtain the expression of efficiency as a function of aη(a)=1a+1a+2k2Q1Q2+1a+1.(12)The maximum efficiency is obtained by solving the follow-ing equations:∂∂aη(a)=0,∂2∂2aη(a)<0.(13) The maximum efficiencyηmax=k2Q1Q21+1+k2Q1Q22is achieved at aηmax=1+k2Q1Q21/2.In[64],the maximum efficiency is also derived based on several different kinds of compensation network.The results are identical and accord with the above results.The analysis here does not specify a particular compensation form.It can be regarded as a general formula to evaluate the coil performance and estimate the highest possible power transfer efficiency. In EV wireless charging applications,the battery is usu-ally connected to the coil through a diode-bridge rectifier. Most of the time,there is some reactive power required. The reactive power can be provide by either the coil or the compensation network like a unit-power-factor pickup.The battery could be equivalent to a resistance R b=U b/I b,where U b and I b is the battery voltage and current,respectively. If the battery is connected to the rectifier directly in a series-series compensation form,the equivalent ac side resistance could be calculated by R ac=8/π2·R b.Thus,a battery load could be converted to a resistive load.The R ac equation is different for different battery connection style,like with or without dc/dc converter,parallel or series compensation. Most of the time,the equivalent R ac could be derived.Some typical equivalent impendence at the primary side is given in paper[42].By calculating the equivalent ac resistances,the above equations could also be applied to a battery load with rectifier.For stationary EV wireless charging,the coupling between the two coils is usually around0.2.If both the sending and receiving coils have a quality factor of300,the theoretical maximum power transfer efficiency is about96.7%.More efficiency calculations under different coupling and quality factors are shown in Fig.3.Fig.3.Theoretical maximum transfer efficiency between two coils.III.M AGNETIC C OUPLER D ESIGNTo transfer power wirelessly,there are at least two magnetic couplers in a WPT system.One is at the sending side,named primary coupler.The other is at the receiving side,named pickup coupler.Depending on the application scenarios,the magnetic coupler in a WPT for an EV could be either a pad or a track form.For higher efficiency,it is important to have high coupling coefficient k and quality factor Q. Generally,for a given structure,the larger the size to gap ratio of the coupler is,the higher the k is;the thicker the wire and the larger the ferrite section area is,the higher the Q is. By increasing the dimensions and materials,higher efficiency can be achieved.But this is not a good engineering approach. It is preferred to have higher k and Q with the minimum dimensions and cost.Since Q equalsωL/R,high frequency is usually adopted to increase the value of Q.The researchers at Massachusetts Institute of Technology(MIT)used a frequency at around10MHz and the coil Q value reached nearly 1000[3].In high power EV WPT applications,the frequency is also increased to have these benefits.In Bolger’s early design,the frequency is only180Hz[13].A few years later, a400Hz frequency EV WPT system was designed by System Control Technology[14].Neither180Hz nor400Hz is high enough for a loosely coupled system.Huge couplers were employed in the two designs.Modern WPT system uses at least10kHz frequency[15].As the technical progress of power electronics,100kHz could be achieved[65]at high power level.The WiTricity Company with the technology from MIT adopts145kHz in their design.In the recent researches and applications,the frequency adopted in an EV WPT system is between20and150kHz to balance the efficiency and cost.At this frequency,to reduce the ac loss of copper coils, Litz wire is usually adopted.Besides the frequency,the coupling coefficient k is sig-nificantly affected by the design of the magnetic couplers, which is considered one of the most important factors in a WPT system.With similar dimensions and materials,different coupler geometry and configuration will have a significant difference of coupling coefficient.A better coupler design may lead to a50%–100%improvement compared with some nonoptimal designs[48].Fig.4.Mainflux path of double-sided and single-sided coupler.(a)Double-sided type.(b)Single-sided type.A.Coupler in the Stationary ChargingIn a stationary charging,the coupler is usually designed in a pad form.The very early couplers are just like a simple split core transformer[19],[38],[56].Usually this kind of design could only transfer power through a very small gap. To meet the requirements for EV charging,the deformations from spilt core transformers and new magnetic coupler forms are presented for large gap power transfer[12],[31],[37],[42], [47]–[50],[66]–[71].According to the magneticflux dis-tribution area,the coupler could be classified as the double-sided and single-sided types.For the double-sided type,theflux goes to both sides of the coupler[12], [31],[67].Aflattened solenoid inductor form is pro-posed in[12]and[67].Because theflux goes through the ferrite like through a pipe,it is also called aflux-pipe coupler.To prevent the eddy current loss in the EV chassis,an aluminum shielding is usually added which bring a loss of1%–2%[12].When the shielding is added, the quality factor of aflux-pipe coupler reduces from 260to86[48].The high shielding loss makes the double-sided coupler not the optimal choice.For the single-sided coupler, most of theflux exists at only one side of the coupler.As shown in Fig.4,the mainflux pathflows through the ferrite in a single-sided coupler.Unlike the double-sided coupler having half of the mainflux at the back,the single-sided coupler only has a leakageflux in the back.This makes the shielding effort of a single-sided type much less.Two typical single-sidedflux type pads are shown in Fig.5. One is a circular unipolar pad[47].Another one is a rectan-gular bipolar pad proposed by University of Auckland,which is also named DD pad[48].Besides the mechanical support material,a single-sided pad is composed of three layers.The top layer is the coil.Below the coil,a ferrite layer is inserted for the purpose of enhancing and guiding theflux.At the bottom is a shielding layer.To transfer power,the two pads are put closed with coil to coil.With the shielding layer, most of the high-frequency alternating magneticflux can be confined in the space between the two pads.A fundamental flux path concept was proposed in theflux pipe paper[67].Fig. 5.Two typical single-sidedflux type pads.(a)Circular pad.(b)DD pad.Theflux path height of a circular pad is about one-fourth ofthe pad’s diameter.While for a DD pad,the height is abouthalf of the pad’s length.For a similar size,a DD pad has asignificant improvement in the coupling.The charge zone fora DD pad could be about two times larger than a circular padwith similar material cost.The DD pad has a good tolerant inthe y-direction.This makes the DD pad a potential solutionfor the dynamic charging when the driving direction is alongwith the y-axis.However,there is a null point for DD pad inthe x-direction at about34%misalignment[48].To increasethe tolerant in x-direction,an additional quadrature coil namedQ coil is proposed to work together with the DD pad,whichis called DDQ pad[48],[49],[68].With a DDQ receivingpad on a DD sending pad,the charge zone is increased tofivetimes larger than the circular configuration.As the additionalQ coil in the receiver side,the DDQ over DD configurationuses almost two times copper compared with the circularone[48].A variant of a DDQ pad,which is called a newbipolar pad,was also proposed by University of Auckland[49],[50].By increasing the size of each D pad and havingsome overlap between the two D coils,the new bipolar padcould have a similar performance of a DDQ pad with25%less copper.With all the efforts,at200mm gap,the cou-pling between the primary and secondary pads could achieve0.15–0.3with an acceptable size for an EV.Referred to Fig.3,at this coupling level,efficiency above90%could possibly beachieved.B.Coupler in the Dynamic ChargingThe dynamic charging,also called the OLEVs[56]orroadway powered electric vehicles[14],is a way to chargethe EV while driving.It is believed that the dynamic chargingcan solve the EVs’range anxiety,which is the main reasonlimits the market penetration of EVs.In a dynamic chargingsystem,the magnetic components are composed of a primaryside magnetic coupler,which is usually buried under the road,and a secondary side pickup coil,which is mounted under anEV chassis.There are mainly two kinds of primary magneticcoupler in the dynamic charging.Thefirst kind is a long trackcoupler[26],[31],[57],[70],[72]–[76].When an EV withaFig.6.Top view of W-shape and I-shape track configuration.pickup coil is running along with the track,continues powercan be transferred.The track can be as simple as just twowires[37],[77],or an adoption of ferrites with U-type orW-type[26],[56]to increase the coupling and power trans-fer distance.Further,a narrow-width track design with anI-type ferrite was proposed by KAIST[72],[73].The dif-ferences between the W-type and I-type are shown in Fig.6.For W-type configuration,the distribution area of the ferrite Wdetermines the power transfer distance,as well as the lateraldisplacement.The total width of W-type should be about fourtimes the gap between the track and the pickup coil.For I-typeconfiguration,the magnetic pole alternates along with the road.The pole distance W1is optimized to achieve better coupling atthe required distance.The width of pickup coil W2is designedto meet the lateral misalignment requirement.The relationbetween track width and transfer distance is decoupled andthe track can be built at a very narrow form.The width forU-type and W-type is140and80cm,respectively[73].ForI-type,it could be reduced to only10cm with a similar powertransfer distance and misalignment capacity.35kW power wastransferred at a200mm gap and240mm displacement usingthe I-type configuration[73].With the narrowed design,theconstruction cost could be reduced.Also,the track is far awayfrom the road side,the electromagneticfield strength exposedto pedestrians can also be reduced.The problem of the track design is that the pickup coil onlycovers a small portion of the track,which makes the couplingcoefficient very small.The poor coupling brings efficiencyand electromagnetic interference(EMI)issues.To reduce theEMI issue,the track is built by segments[52],[70],[75]with a single power converter and a set of switches to powerthe track.The excitation of each segment can be controlledby the switches’ON-OFF state.The electromagneticfieldabove the inactive segments is reduced significantly.However,there is always a high-frequency currentflowing through thecommon supply cables,which lowers the system efficiency.The published systems efficiency is about70%–80%,whichis much lower than the efficiency achieved in the stationarycharging.When each segment is short enough,the track becomes likea pad in the stationary charging,which is the other kind ofthe primary magnetic coupler.Each pad can be driven by anindependent power converter.Thus,the primary pads can beselectively excited without a high-frequency common current.Also,the energized primary pad is covered by the vehicle.Theelectromagneticfield is shielded to have a minimum impact。
电磁传播中英文
文摘This paper attempts to provide some insight into the nature of radio propagation in that part of the spectrum (upper VHF to microwave) used by experimenters forhigh-speed digital transmission. 本文试图提供一些深入的无线电传播的本质中这一部分的频谱(上部甚高频微波)使用高速数字传输实验人员。
It begins with the basics of free space path loss calculations, and then considers the effects of refraction, diffraction and reflections on the path loss of Line of Sight (LOS) links. 它开始于基本的自由空间路径损耗的计算,然后考虑折射的影响、衍射、反思的路径损耗的视线(LOS)链接。
The nature of non-LOS radio links is then examined, and propagation effects other than path loss which are important in digital transmission are also described.non-LOS无线链路的本质是然后检查,其他的作用和传播路径损耗这很重要,数字传输也进行了描述。
Introduction介绍The nature of packet radio is changing. 小包收音机的性质正在发生变化。
As access to the Internet becomes cheaper and faster, and the applications offered on the "net" more and more enticing, interest in the amateur packet radio network which grew up in the 1980s steadily wanes. 访问互联网变得更快、更便宜,而应用程序提供的“净”更多,更吸引人,兴趣业余无线电网络数据包成长于1980年代逐步减弱。
通过无线电传播英语作文
Growing up in a small town, the world outside my immediate surroundings felt distant and unreachable. But there was one magical device that bridged the gap between my little world and the vast universe of knowledge and culture: the radio. It was through the airwaves that I first encountered the English language, and it was a journey of discovery that continues to shape my life.The first time I heard English spoken fluently was on a latenight radio program. The host was discussing a book, their words flowing like a river, smooth and enchanting. I was captivated. The language was so different from my native tongue, with its unique rhythm and melody. It was like listening to a song, but one with meaning and depth. I knew right then that I wanted to learn this language, to understand the stories and ideas it carried.My journey with English began with the radio. Every day, I would tune in to various programs, trying to grasp the essence of the language. I started with simple phrases and gradually moved on to more complex sentences. The radio was my tutor, my companion, and my inspiration. It was through the radio that I learned about different cultures, histories, and perspectives, all through the medium of English.One of the most significant moments in my learning journey was when I started listening to English news broadcasts. It was a challenge at first, as the speed and accent were quite different from what I was used to. But with persistence and practice, I began to understand the gist of the news. It was exhilarating to be able to follow global events and understand theworld beyond my town.The radio also introduced me to English music. The lyrics were a treasure trove of vocabulary and idiomatic expressions. I would listen to the songs repeatedly, trying to decipher the meaning behind the words. It was a fun and engaging way to learn the language. Moreover, the music helped me appreciate the beauty and expressiveness of English.As I became more comfortable with English, I started participating in radio contests and quizzes. It was a thrilling experience to interact with the hosts and other listeners in English. The feedback and encouragement I received boosted my confidence and motivated me to keep improving.The radio also played a crucial role in preparing me for English exams. I would listen to educational programs that focused on grammar, vocabulary, and pronunciation. The explanations and examples provided by the experts were invaluable in honing my language skills.In addition to learning English, the radio also exposed me to other languages and dialects. It broadened my understanding of linguistic diversity and the importance of communication in connecting people from different backgrounds.Today, as a high school student, I am grateful for the role the radio played in my language learning journey. It opened up a world of opportunities and possibilities. The radio taught me that learning a language is not just about memorizing words and grammar rules its about immersing oneselfin the culture, history, and spirit of the language.The radio also instilled in me the importance of curiosity and perseverance. It showed me that learning is a lifelong journey, and that there is always more to explore and understand. The radio was my first step into the world of English, and it continues to inspire me to keep learning and growing.In conclusion, the radio was a powerful tool in my English learning journey. It was more than just a medium for entertainment it was a gateway to knowledge, understanding, and selfimprovement. As I continue to learn and grow, I will always cherish the memories and lessons from my time with the radio. It was through the airwaves that I discovered the beauty and power of the English language, and it will always hold a special place in my heart.。
文献检索无线电力传输地应用
题目:无线电力传输的应用The use of wireless power transmission一、背景知识:1、现代的有线电路传输虽然取得了巨大的发展与成就,但是其消耗了大量的线材,无论是橡胶、塑料抑或铜、锡等金属,浪费了社会资源、增加环境污染,不利于可持续发展的理念,而且其占用人类生活空间,给城市布局规划等造成巨大的不便。
2、国家坚持走可持续发展的科学发展观,坚持充分的利用现有的人类资源,建设环保型生态环境国家,并且国家设立了国家环保总局,统一管理我国的环保工作,以及一些有关生态、环境保护的法律。
在这种形势下,无线电力传输是很受欢迎的一种输电方式,它的实现将给人们生活带来革命性的变化,因此将迎来巨大的发展机遇。
二、课题分析: 人类追逐自由的本能,在现实面前屡屡受挫。
自从广泛使用电能以来,许多人都为了那些电器拖着的长长电线而绞尽脑汁,但无线供电却一直只能作为一个在前方远远招手的梦想。
现在,我们也许看到了一线曙光。
但要使无线电力传输在我们的日常生活当中得以广泛使用,我们应该解决什么样的问题,其主要的瓶颈在什么地方,如何才能解决无线电力传输的使用问题,这是我们首先要了解的知识。
进而可以从以下两方面考虑:1、当前无线电力传输的利用现状,特别是其在使用当中的具体情况,目前科学技术有限的条件下,无线传输领域在哪些方面有比较成熟的应用。
2、除了实用理论、技术方面,还应关注我国政府对此类无线电力传输技术的管理政策,同时希望了解:该项事业在拥有巨大社会效益的同时,是否能实现较好的经济效益,找到国内外典型的应用实例。
三、希望通过检索解决的问题:1、希望了解无线电力传输的历史发展及应用,相应的应用手段有哪些?目前比较可行的方法是什么?政府是否支持其发展应用?找一些专家分析和说明各方面问题的案例;2、希望了解我国在电力传输安全应用方面的法律规定,经济可行性。
国内外优秀环保组织的宗旨、主要活动介绍,先进经验的学习。
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【关键字】精品无线电力传输外文文献翻译(含:英文原文及中文译文)文献出处:Weaver, Bill. " Can't Touch This: Wireless power transmission."26.3(2009).英文原文Can't touch this - wireless power transmissionWilliam L. WeaverA few years ago, a colleague and I participated in a field trip project organized by the college student group to study the West Orange at the Edison National Historic Site in . We visited with the public and participated in a laboratory set up inside a building to understand the development of incandescent light bulbs and film technology. However, what impressed me most was the two complex additional functions.First, it is a research library equipped with all publications of the then US Patent Office. Representatives of scientists and engineers are concerned that marketable products may be useful in creating new technologies. The university is a great place to discover science and technology with it, but 's laboratory exists as a company. In the late 19th century, there was no internet connection, so the library took up the laboratory's information repository. Just like today, when the researchers needed information about chemical reactions, a mathematical formula or their most advanced engineering solution and consulted the current literature, it was only through paper at the time.By simplifying the adoption of standards, this process is further simplified by the rapid adoption of standards. Since most of the tools and equipment can be developed locally, they can deploy their own standards and create the facility on a multi-acre campus.One of these criteria is the method of distribution of power. The final known power supply for grid development is the famous bulb. The tools used in the early lab were a long axis of rotation like a rear-wheel drive automobile driveshaft made up of a universal cable shaft or a marine vessel. The propeller shaft disperses the potential energy of the entire plant in the form of mechanical energy generated by the boiler. A belt and a simple clutch system are connected to the line shaft and the strength of the lever is enhanced by using a surrounding shaft belt. Over time, the belt was worn out due to excessive friction. However, this technology provides a less complex power distribution method than earlier high-pressure steam and hydraulic systems.Over time, as well as the development of electrical and electronic equipment, high-voltage power supplies and more distribution standards must be used in our production plants, offices and homes in the near future. In the , the electricity generated is 60 Hz and is eventually produced at a nominal voltage between 120, 240and 480 volts. A typical power outlet is specified to accommodate 15 amps of current and is equipped with three familiar prongs, a vertical and U-shaped ground pin consisting of two paddles. Forward-looking retailers make pins of different shapes and orientations to prevent other incompatible devices from connecting. Unless there are not enough power outlets, plugs or extension cords, the standard three-hole power cord is a ubiquitous device to "plug in" the power distribution system.With the continuous development of technology, mobile and handheld devices we currently have are booming, so battery companies will follow. Physically connecting these small devices to the grid will seriously affect their functionality. It is for this reason that they should exhaust their own power supplies or produce rechargeable batteries. manufacturers quickly develop their own industry standards, including "AA" and "C" units, to reduce the confusion that consumers may have when replacing batteries.Although transistor radios and toy sensors were popular at the beginning of the year, single-use chemical batteries could not provide enough current for devices such as laptops, smart phones and personal entertainment games that have complicated computational requirements. Their rechargeable batteries are incorporated into the equipment and rarely need to be replaced by the user. These device manufacturers can choose how the battery is manufactured, such as size, battery life, and internal configuration capabilities of the device components. This feature of the battery has given manufacturers' industrial designers more rights to differentiate their products in style, look and feel.However, the disadvantage of rechargeable batteries is that they eventually still need to be charged. We can easily connect to the power supply via an AC/DC power adapter. However, it is more difficult to connect the battery to the adapter or "charger" because each battery manufacturer is free to design the battery's shape and interface. what? In the lovely 100-year-old innovation after this, it did not change with the mode it should have.A conspiracy theory may indicate that portable device manufacturers admit that battery chargers are a lucrative source of income. Similar bubble jet printer manufacturers rely on the consumption of ink in the device as a sales channel to make up for the difference between the selling price and the cost. Users pay $25 to $100 to replace the damaged or missing power adapter, which cancels out a service. The "real cost of freedom" in a planned or low-cost laptop phone. An innocent non-conspiratorial theory may be related to the 2000 (Y2K) problem. Programmers wouldn’t expect much trouble for this device made in a two-digit year to create for the future, and few portable device designers may expect to consume laptops, mobile phones, MP3 players, and digital cameras today. The number of people. These functions may eventually be provided by an independent "super smartphone", but at present, individual charger users are still inconvenient. Chargers also have similar, incompatible problems between devices, and users may cause exchanges to rise or lose devices. If you are using your fifth mobile phone, it is very likely that there will be four outdated chargers on your garage's work bench.In February this year, the European Union Telecommunications Authority (CEPT)and the subsequent European Union (EU) jointly authorized the establishment of the Publicis Group Special Mobile Association (GSMA), which was developed in 2012 as a standard for use by mobile phones. Micro USB interface charger specification. In addition to making the user more convenient, this specification has also been applied to the recycling of discarded adapters. Although it is not aimed at the standardization of adapters between different mobile devices, it seems to be a good start.However, imagine that if the AC/DC adapter is completely eliminated. This is the future of wireless energy transfer. Nikola Tesla first published his utility in 1893. Inductively coupled transformers use wireless technology to replace an ordinary power adapter, correcting the drawbacks of the DC voltage required to charge the two inductive coils of an inductively coupled transformer supplied by an AC outlet. Unfortunately, as the distance between the transmitter and receiver increases, the inductance effect quickly diminishes and is often affected by interference. In other recent developments, Professor Malinsoor and his colleagues at the Massachusetts Institute of Technology recently developed inductive coupling coils that can be tuned to specific resonant frequencies to overcome these limitations. This improves the understanding of the coupling efficiency of the power supply and reduces the interference around other devices or between coils in other indifferent locations. It is called eCoupled technology.While taking advantage of the high efficiency of the Witricity Resonance Sensing, the eCoupled system, including the sender and receiver, does not include the switching of a metal device or device of the RFID chip into sleep mode. The additional data services are robust and canonical communications, and will automatically power off when the battery is full. If widely adopted, wireless power transmission will be listed as a public service facility. Imagine eCoupled transmitters are simple when it comes to using new standards that are used to spur their own, usually using two main methods. To the new standard, there are usually two main methods used to promote its development. The first is a strong regulatory code. Second, inventing a technology that allows manufacturers to imitate and make it widely popular is powerful, but I prefer the latter's non-intervention method.中文译文不能触碰这个—无线电力传输William L. Weaver几年前, 一个同事和我参加在校大学生团体的组织的一个实地考察项目, 考察地位于新泽西州的爱迪生国家历史遗址的西橙。