文献翻译
题
目 学生姓名 专业班级 学
号 院 （系）指导教师 完成时间
逆变器
电子信息工程
电气与信息工程学院
2009年06 月 05日
Inverter 1 Introduction An 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 (
1 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 supplies An 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 heating Inverters 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 transmiion With HVDC power transmiion, 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 drives A 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 drives Adjustable 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 case A transformer allows AC power to be converted to any desired voltage, but at the same
2 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 diipated 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 designs 3.2 Output waveforms The 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
3 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 inverters Three-phase inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmiion.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 cancelled
4 History 4.1 Early inverters From 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 4.2 Controlled rectifier inverters Since 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 proce.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 poible 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 transmiion 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 aists 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.
5 4.3 Rectifier and inverter pulse numbers Rectifier circuits are often claified 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 aociated 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 claified 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“（
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。
7 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。
8 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。对于最基本的控制方案，对三个开关运作协调，以便在每一个开关输出波形的基本操作60度点。这将创建一个线到线输出波形有六个步骤。六步之间有一个波形的方波的正面和负面的部分零电压一步，这样的谐波，是三个被淘汰上述倍数。当载波脉冲调宽技术技术应用到六步波形时，在整体上基本形状，或着波形的包络将被保留，以使三次谐波及其倍数被取消
4 历史
4.1 早期的变频器
从十九世纪晚期到二十世纪中叶直流到交流电源的转换使用旋转逆变器或者发电机组来完成。在二十世纪早期，真空电子管和充气管开始被作为逆变电路开关使用。应用最广的电子管的类型是闸流管。
9 机动电子逆变器一词解释了学术上逆变器的来源。早期的交流到直流转换器使用的感应或同步交流电动机直接连接到一台发电机（发电机），使发电机的整流子扭转在正确的时间来产生直流电。一个后来的发展是同步转换器，其中电机和发电机绕组组合成一个电枢，一个滑环在电枢一端，整流子在另一端，只有一帧。这样的结果是交流输入，直流输出。随着设置，直流电可以被认为是分开的出现的交流电;具有同步转换器，在一定意义上讲，它可以被认为是“机械纠正交流“。只要有了正确的辅助和控制设备，
设置或旋转转换器可“向后跑“，转换直流到交流。因此，逆变器是一个倒置的转换器。4.2 整流逆变器控制
自从1957年初以来晶体管没有足够的电压和额定电流可用于大多数逆变器应用，晶闸管或可控硅整流器的开始到固态逆变器电路过渡。
晶闸管换相的条件是在可控硅电路设计中考虑的关键因素。可控硅不关闭或整流时自动门控制信号被切断。只有当正向电流降至低于最低维持电流，他们才会关闭，通过外部加工，不同类型的晶闸管最低电流也会不同。对于连接到交流电源的可控硅，每一次整流源电压极性都会自然反转。连接到直流电源的可控硅整流通常需要强迫转换，迫使电流为零时，需要换一种途径。最不复杂的电路采用可控硅整流自然代偿，而不是强制。随着附加的代偿电路，可控硅已经用于上述逆变器种类。
在逆变电源将直流电转换为交流电的应用中，它可以使用交流到直流整流控制电路中的反演模式运行。在反转模式，可控整流逆变电路工作作为换一条线。这种类型的操作，可用于高压直流输电系统和再生制动电机控制系统的操作。
另一种类型的可控硅逆变电路是电流源输入的逆变器。电流源输入逆变器是一个双重的六个步骤电压源逆变器。用电流源逆变器，直流电源配置为电流源，而不是一个电压源。可控硅逆变器中切换一个六步序电流指示作为加强电流波形三相交流负载。电流源输入逆变器换相方法包括负载代偿和并联电容器代偿。随着这两种方法，输入电流调节辅助代偿。负载换向，负载是一个同步电动机在运行领先的功率因数。由于他们已能够为更高的电压和额定电流使用，如晶体管或可通过控制信号变成了绝缘栅双极性晶体管的半导体手段已成为首选的开关逆变器电路中使用的组件。
4.3 整流器和逆变器脉冲数
整流电路通常是每周期的交流输入电压流入的直流侧的直流帧数来分类。单相半波整流是一个脉冲电路和单相全波整流是双脉冲电路。一个三相半波整流是三脉冲电路和
10 三相全波整流是一个六脉冲电路。对于三相整流器，有整流器两个或两个以上，有时串联或并联以获得更高的电压或电流额定值。整流器输入，提供从供应特种变压器移相输出。这具有倍增效应阶段。 6个阶段分别从两个变压器，从十二相从三个变压器等。相关的整流电路为12脉冲整流器，18脉冲整流器等。
当控制整流电路中的反向模式时，他们也按输出脉冲数分类。整流电路具有较高的脉冲数减少在交流输入电流，并减少直流输出电压纹波的谐波含量。在反向模式，电路具有较高的脉冲数有较低的交流输出电压波形的谐波含量。
