逆变电源毕业设计文献翻译
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目 学生姓名 专业班级 学
号 院 （系）指导教师 完成时间
逆变器
电气工程及其自动化
电气信息工程系 王刚 2012年02 月 21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引言
逆变器是一种电动装置，转换成直流电（DC），交流电流转换的AC（交流）可以在任何所需的电压和频率使用适当的变压器，开关，控制circuits.Solid状态逆变器有没有移动部件，用于广泛的应用范围从小型计算机开关电源，高压大型电力公司电力，运输散装直接电流应用。逆变器通常用于提供交流电源，直流电源，如太阳能电池板或电池。
逆变器的主要有两种类型。修改后的正弦波逆变器的输出是类似方波输出，输出变为零伏前一段时间切换积极或消极的除外。它是简单，成本低，是大多数电子设备兼容，除敏感或专用设备，例如某些激光打印机。一个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
逆变器从交流电力来源，如电池，太阳能电池板，燃料电池的直流电转换成。电力，可以在任何所需的电压，特别是它可以操作交流电源操作而设计的设备，或纠正，以产生任何所需的voltage Grid领带逆变器的直流送入分销网络的能量，因为它们产生电流交替使用相同的波形和频率分配制度提供。他们还可以关掉一个blackout.Micro逆变器的情况下自动转换成交流电电网的电流直接从当前个别太阳能电池板。默认情况下，他们是格领带设计。
2.2不间断电源
不间断电源（UPS），电池和逆变器，交流电源，主电源不可用时使用。当主电源恢复正常时，整流提供直流电源给电池充电。
7 2.3感应加热
逆变器的低频交流主电源转换到更高频率的感应加热使用。要做到这一点，首先纠正交流电源提供直流电源。逆变器，然后改变高频率的交流电源，直流电源。
2.4高压直流输电
随着高压直流输电，交流电源经过整流和高压直流电源传输到另一个位置。在接收的位置，在静态逆变器厂逆变器转换回交流电源。
2.5变频驱动器
一个变频驱动控制向电动机提供电源的频率和电压控制交流电机的运行速度。逆变器提供控制电源。在大多数情况下，变频驱动，包括整流器，使逆变器的直流电源，可从交流主电源提供。由于逆变器是关键部件，变频驱动，有时被称为逆变器驱动器，或只是逆变器。
2.6电动汽车驱动器
目前使用的权力，在一些电动和柴油交流功率转换完成使用旋转器或马达发电机组（爵套）。在二十世纪初，真空管和充满气体管开始被用于逆变器电路中的开关。最广泛使用的管型晶闸管。
9 机电逆变器的起源解释源长期变频器。早期的AC至DC转换器采用感应或同步交流电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刻其连接生产直流。后来的发展是同步的转换器，电机和发电机绕组结合成一个电枢，一端与滑环和整流子在其他只有一个领域的框架。结果要么是交流，直流。与MG组，直流，可考虑将分别从AC生成，同步器，它在一定意义上可以认为是“机械纠正交流”。由于正确的辅助设备和控制设备，MG集或旋转转换，可以“倒着跑”，将直流转换为交流电。因此，逆变器是一个倒置的转换。
4.2可控整流逆变器
自从1957年初年初以来，晶体管不能提供足够的电压和额定电流最逆变器应用，它是1957年的晶闸管或可控硅（SCR）的介绍，开始过渡到固态逆变电路。
可控硅的换相的条件是在可控硅电路设计的关键考虑因素。不要关闭可控硅整流自动门控制信号被切断时。他们只关闭当正向电流降至低于最低维持电流，每一种可控硅变化，通过一些外部进程。对于连接到交流电源的可控硅，整流发生自然每次源??电压极性反转。可控硅直流电源连接到通常需要强迫换，强制要求减刑时电流为零的一种手段。最复杂的可控硅电路采用自然，而不是被迫换减刑。此外被迫换电路，可控硅已被用于在以上所述的逆变器电路的类型。
在逆变器传输到AC电源由直流电源供电的应用程序，它可以使用交流 - 直流可控整流电路的反演模式经营。在反演模式，可控整流电路整流逆变器行。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（CSI）逆变器。一个CSI逆变器是一个六步的电压源逆变器的双。用一个电流源逆变器，直流电源作为电流源而非电压源配置。变频器可控硅开关在六步序列直接阶梯电流波形作为一个三相交流负载的电流。沪深逆变器换方法包括整流负载和并联电容器减刑。这两种方法，输入电流调节协助减刑。带整流负载，负载是在领先的功率因数运行的同步电机。因为他们已经成为在更高的额定电压和电流，如可以通过控制信号的晶体管或IGBT的半导体已成为首选开关元件逆变电路使用。
4.3整流器和逆变器的脉冲数
整流电路往往流的每个周期的AC输入电压整流的直流侧电流脉冲的数量分类。单
10 相半波整流是一个脉冲电路和单相全波整流是两个脉冲的电路。一个三相半波整流是一个三脉冲电路和三相全波整流是一个六脉冲电路。两个或两个以上的整流器三相整流器，有时串联或并联连接以获得更高的电压或额定电流。提供特种变压器提供相移输出整流器的输入。这有相乘法效应。六个阶段是从两个变压器，12个阶段从三变等。 12脉冲整流器，18脉冲整流器等相关的整流电路。当可控整流电路的反演模式在运作，他们将分为脉冲数也。整流电路具有较高的脉冲数减少交流输入电流和减少直流输出电压纹波的谐波含量。在反演模式，有较高的脉冲个数的电路，在AC输出电压波形的谐波含量较低。
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