逆变器外文文献及翻译.doc

Four short words sum up what has lifted most successful individuals above the crowd: a little bit more.-author-date逆变器外文文献及翻译逆变器外文文献及翻译Inverter1 IntroductionAn inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.There are two main types of inverter. The output of a modified sine wave inverter is similar to a square wave output except that the output goes to zero volts for a time before switching positive or negative. It is simple and low cost and is compatible with most electronic devices, except for sensitive or specialized equipment, for example certain laser printers. A pure sine wave inverter produces a nearly perfect sine wave output (<3% total harmonic distortion) that is essentially the same as utility-supplied grid power. Thus it is compatible with all AC electronic devices. This is the type used in grid-tie inverters. Its design is more complex, and costs 5 or 10 times more per unit power The electrical inverter is a high-power electronic oscillator. It is so named because early mechanical AC to DC converters were made to work in reverse, and thus were "inverted", to convert DC to AC.The inverter performs the opposite function of a rectifier.2 Applications2.1 DC power source utilizationAn inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltageGrid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout.Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid. They are grid tie designs by default. 2.2 Uninterruptible power suppliesAn uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. When main power is restored, a rectifier supplies DC power to recharge the batteries.2.3 Induction heatingInverters convert low frequency main AC power to a higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power. 2.4 HVDC power transmissionWith HVDC power transmission, AC power is rectified and high voltage DC power is transmitted to another location. At the receiving location, an inverter in a static inverter plant converts the power back to AC.2.5 Variable-frequency drivesA variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters.2.6 Electric vehicle drivesAdjustable speed motor control inverters are currently used to power the traction motors in some electric and diesel-electric rail vehicles as well as some battery electric vehicles and hybrid electric highway vehicles such as the Toyota Prius and Fisker Karma. Various improvements in inverter technology are being developed specifically for electric vehicle applications.2 In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries. 2.7 The general caseA transformer allows AC power to be converted to any desired voltage, but at the same frequency. Inverters, plus rectifiers for DC, can be designed to convert from any voltage, AC or DC, to any other voltage, also AC or DC, at any desired frequency. The output power can never exceed the input power, but efficiencies can be high, with a small proportion of the power dissipated as waste heat. 3 Circuit description 3.1 Basic designs In one simple inverter circuit, DC power is connected to a transformer through the centre tap of the primary winding. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit. The electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch so that the switch continually switches rapidly back and forth. This type of electromechanical inverter switch, called a vibrator or buzzer, was once used in vacuum tube automobile radios. A similar mechanism has been used in door bells, buzzers and tattoo guns.As they became available with adequate power ratings, transistors and various other types of semiconductor switches have been incorporated into inverter circuit designs3.2 Output waveformsThe switch in the simple inverter described above, when not coupled to an output transformer, produces a square voltage waveform due to its simple off and on nature as opposed to the sinusoidal waveform that is the usual waveform of an AC power supply. Using Fourier analysis, periodic waveforms are represented as the sum of an infinite series of sine waves. The sine wave that has the same frequency as the original waveform is called the fundamental component. The other sine waves, called harmonics, that are included in the series have frequencies that are integral multiples of the fundamental frequency.The quality of output waveform that is needed from an inverter depends on the characteristics of the connected load. Some loads need a nearly perfect sine wave voltage supply in order to work properly. Other loads may work quite well with a square wave voltage. 3.3 Three phase invertersThree-phase inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmission. A basic three-phase inverter consists of three single-phase inverter switches each connected to one of the three load terminals. For the most basic control scheme, the operation of the three switches is coordinated so that one switch operates at each 60 degree point of the fundamental output waveform. This creates a line-to-line output waveform that has six steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of three are eliminated as described above. When carrier-based PWM techniques are applied to six-step waveforms, the basic overall shape, or envelope, of the waveform is retained so that the 3rd harmonic and its multiples are cancelled4 History4.1 Early invertersFrom the late nineteenth century through the middle of the twentieth century, DC-to-AC power conversion was accomplished using rotary converters or motor-generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits. The most widely used type of tube was the thyratron.The origins of electromechanical inverters explain the source of the term inverter. Early AC-to-DC converters used an induction or synchronous AC motor direct-connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame. The result with either is AC-in, DC-out. With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectified AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC. Hence an inverter is an inverted converter. 4.2 Controlled rectifier invertersSince early transistors were not available with sufficient voltage and current ratings for most inverter applications, it was the 1957 introduction of the thyristor or silicon-controlled rectifier (SCR) that initiated the transition to solid state inverter circuits.The commutation requirements of SCRs are a key consideration in SCR circuit designs. SCRs do not turn off or commutate automatically when the gate control signal is shut off. They only turn off when the forward current is reduced to below the minimum holding current, which varies with each kind of SCR, through some external process. For SCRs connected to an AC power source, commutation occurs naturally every time the polarity of the source voltage reverses. SCRs connected to a DC power source usually require a means of forced commutation that forces the current to zero when commutation is required. The least complicated SCR circuits employ natural commutation rather than forced commutation. With the addition of forced commutation circuits, SCRs have been used in the types of inverter circuits described above.In applications where inverters transfer power from a DC power source to an AC power source, it is possible to use AC-to-DC controlled rectifier circuits operating in the inversion mode. In the inversion mode, a controlled rectifier circuit operates as a line commutated inverter. This type of operation can be used in HVDC power transmission systems and in regenerative braking operation of motor control systems.Another type of SCR inverter circuit is the current source input (CSI) inverter. A CSI inverter is the dual of a six-step voltage source inverter. With a current source inverter, the DC power supply is configured as a current source rather than a voltage source. The inverter SCRs are switched in a six-step sequence to direct the current to a three-phase AC load as a stepped current waveform. CSI inverter commutation methods include load commutation and parallel capacitor commutation. With both methods, the input current regulation assists the commutation. With load commutation, the load is a synchronous motor operated at a leading power factor. As they have become available in higher voltage and current ratings, semiconductors such as transistors or IGBTs that can be turned off by means of control signals have become the preferred switching components for use in inverter circuits. 4.3 Rectifier and inverter pulse numbersRectifier circuits are often classified by the number of current pulses that flow to the DC side of the rectifier per cycle of AC input voltage. A single-phase half-wave rectifier is a one-pulse circuit and a single-phase full-wave rectifier is a two-pulse circuit. A three-phase half-wave rectifier is a three-pulse circuit and a three-phase full-wave rectifier is a six-pulse circuit。With three-phase rectifiers, two or more rectifiers are sometimes connected in series or parallel to obtain higher voltage or current ratings. The rectifier inputs are supplied from special transformers that provide phase shifted outputs. This has the effect of phase multiplication. Six phases are obtained from two transformers, twelve phases from three transformers and so on. The associated rectifier circuits are 12-pulse rectifiers, 18-pulse rectifiers and so on. When controlled rectifier circuits are operated in the inversion mode, they would be classified by pulse number also. Rectifier circuits that have a higher pulse number have reduced harmonic content in the AC input current and reduced ripple in the DC output voltage. In the inversion mode, circuits that have a higher pulse number have lower harmonic content in the AC output voltage waveform.逆变器1 简介逆变器是一种能将直流电转化为可变的交流电的电子装置，使用适当的变压器、开关以及控制电路可以将转化的交流电调整到任何需要的电压以及频率值。固定的逆变器没有移动部件，其应用范围极其广泛，从小型计算机开关电源，到大型电力公司高压直流电源应用，运输散货。逆变器通常用于提供从诸如太阳能电池板或电池直流电源转换的交流电源.逆变器有两种主要类型。对修改后正弦波逆变器输出是一个类似方波输出，输出去除了一时间为零伏特，然后才转到正或负。它的电路简单而且成本一般较低，并与大多数电子设备兼容，除了敏感或专用设备，例如某些激光打印机。纯正弦波逆变器产生一个近乎完美的正弦波输出“（<3的总谐波失真），它本质上与公用事业电网提供的相同。因此它与所有的交流电子设备兼容。这是网逆变器配合使用的类型。它的设计更为复杂，成本5人以上每单位功率。1电逆变器是一种高功率电子振荡器的10倍。它是如此命名是因为早期机械AC到DC转换器的工作作了相反，因此是“倒“，转换成直流到交流。变频器的整流执行相反的功能2 应用2.1 直流电源利用率逆变器将直流电，如电池，太阳能电池板，燃料电池等转换为交流电直流电。转换的交流电可以是任意需要大小的交流电，特别是它可以操作交流设备用于电源操作，或者滤波产生任何需要的直流电压。配电网络逆变器可以将能量反馈到分配网络，因为他们产生的交流电和分配网络提供的交流电的波形和频率可以是一样的。而且他们也可以自动关断输出当遇到停电事故时。微型逆变器将由个人太阳能电池板产生的直流电转化为交流电并入电网。接从个人的太阳能电池板的电流。它们使用默认的输电网设计。2.2 不间断电源不间断电源（UPS）当主电源无法使用时使用电池和逆变器提供交流电源。当主电源恢复时，一个整流器供应直流电源对电池进行充电。2.3 感应加热逆变器将低频交流电源转化为更高的频率以用于感应加热使用。要做到这一点，首先交流电源经过滤波提供直流电源。该逆变器，然后更改为高频率的交流电源直流电源。2.4 高压直流输电随着高压直流输电，交流电源进行整流和高压直流电源被传输到另一个位置。在接收的位置，在一个静止变流器厂将直流电源转换回交流电2.5 变频驱动器一个变频驱动控制器通过控制供应给电机的电源电压和频率来控制交流电机的运行速度。逆变器提供控制信号。在大多数情况下，变频驱动器包括一个整流器，因而提供给逆变器的直流电源可以由交流主电源提供。由于逆变器是关键部件，变频驱动器有时也被称为逆变器驱动器或只是逆变器2.6 电动汽车驱动调速电动机控制逆变器是目前用于电力牵引在一些电动和柴油电动轨道车辆以及一些电池电动汽车上的电机，如丰田Prius和菲斯克噶玛混合动力电动汽车高速公路交通工具。在变频技术的各项改善措施正在制定专门针对电动车辆的应用。与更新制动车辆，还需要从变频器的电机（现在作为发电机）和它储存在电池里的电源。2.7 一般情况下一个变压器允许交流电源被转换为任何所需的电压，但是却在相同的频率。逆变器，直流加整流器，可以设计成任何转换电压，交流或直流，在任何需要的频率，以任何其他电压，也可以是交流或直流。输出功率不能超过输入功率，但效率可以很高，可以允许作为一部分余热消耗掉功率很小的一部分。3 电路描述3.1 基本设计在一个简单的逆变电路中，直流电源通过初级绕组的中心抽头连接到变压器。开关以极高的频率来回切换，使电流回流在变压器的初级绕组里流过一个方向后再向另一个方向流动。初级绕组里电流方向的变化通过变压器在次级绕组里产生交变电流。 在开关设备机电版本包括两个固定触点和弹簧支撑移动接触点。弹簧持有一个可移动的触体来和固定触点接触，电磁铁拉动可移动的触体到对面的固定的触体。在电磁铁的电流中断的交换机中，使交换开关不断来回迅速切换迅速。这种机动逆变器式开关，称为一个振动器或蜂鸣器，曾经在真空电子管汽车收音机中使用。一个类似的电子装置已用于门铃，蜂鸣器和纹身枪。当开关管有有足够的额定功率，晶体管和半导体开关各种其他类型的的电子开关器件可用已纳入逆变器电路设计。3.2 输出波形上述简单的逆变器中的开关，当不耦合到输出变压器时，输出电压波形由于开关管简单的导通或关断产生一个方波电压输出，而不是交流电最常见的正弦波形，它是一个AC电源波形通常由于其简单。利用傅里叶分析，周期性波形表示为一个无穷级数的正弦波的总和。正弦波中和原始波形具有相同的频率的波称为基波。其他频率的正弦波，称为谐波，这是该系列中包括有频率是基波频率的整数倍。输出波形是从一个逆变器所需的质量取决于逆变器所连接的负载特性。一些载入需要一个近乎完美的正弦波电压供应才能正常工作。其他的负载可能使用方波电压也能工作的很好。3.3 三相逆变器三相逆变器是用于变频驱动应用以及诸如高压直流输电高功率传输。一个基本的三相逆变器由三个单相开关每个连接到三个负载接线端子之一的逆变器组成。对于最