PWM信号发生器设计外文整理.doc

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1、外 文 翻 译毕业设计题目: PWM信号发生器设计 原文1: Control of Unit Power Factor PWM Rectifier 译文1: 单位功率因数PWM整流器的控制 原文1: Pulse-width modulation 译文1: 脉冲宽度调制 Control of Unit Power Factor PWM Rectifier Z. Peroutka, T. GlasbergerUniversity of West Bohemia / Department of Electromechanics and Power Electronics, Plze_, Czech

2、Republice-mail:peroutkaieee.org, tglasberkev.zcu.czABSTRACT To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase con-trolled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is int

3、ro-duced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the defi-ciency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reacti

4、ve current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation. Keywords: Control; PWM Rectifier; Unit Power Factor; d, q Coordinates1 Introduction power factor PWM rectifier has the advantage

5、s of high power factor, low harmonic content of grid side current, energy bidirectional transmission etc, is widely used in AC drive, reactive power Unity compensation, active power filter, unified power flow control, as well as unin-terruptible power supply, etc. This paper introduces the topology

6、of three-phase PWM rectifier, and describes the control method of the rectifier in three-phase static coordinate system. On the basis of the analysis of the advantages and disadvantages of this control method, the control method in two-phase synchronous rotating coor-dinate system is put forward. Th

7、en the mathematical model of three-phase PWM rectifier in d, q coordinates is established and the single control of active current and relative current is realized. 2 The Control Method of Three-phase Voltage Source PWM Rectifier in Three-phase Static Coordinate System Figure 1 shows the topology of

8、 three-phase voltage source PWM rectifier, eaebec is three-phase voltage source, C is the dc side filtering capacity and RL is the load. In order to realize the control of input current and output voltage, the traditional method is controlling the three-phase input current directly. The control of t

9、he in- put current is also the control of the flow of energy, thus the control of the output voltage can be realized. The control method of PWM rectifier in the three-phase stationary coordinate system is shown in Figure 2. In this control method, the outer loop controls the DC voltage. The differen

10、ce value of the command signal and actual signal of DC side voltage is imported to PI regu-lator. The output value of PI regulator is DC current sig-nal Im, Im is proportional to the amplitude of AC input current. So the command signal of three-phase AC cur-rent Ia*, Ib*, Ic* can be obtained by sepa

11、rately multiplying Im by sinusoidal signal whose phase is the same as three-phase voltage. The difference value of command current and actual current is imported to PI regulator, and the sinusoidal modulation wave can be deserved. By comparing the sinusoidal modulation wave with carrier wave, the PW

12、M wave which can control the switch can be deserved. This control method is simple, but the command cur- rent in control system is a varying sine time-varying sig- nal which has a certain frequency, amplitude and phase angle. The effect of steady-state performance is not de- sirable, and the indepen

13、dent control of the active current and the reactive current cant be achieved. Figure 1. The topology of three-phase voltage source PWM rectifier. Figure 2. The control method of PWM rectifier in three- phase stationary coordinate system.3 The Control Method of Three-phase Voltage Source PWM Rectifie

14、r in Two-phase Synchronous Rotating Coordinate System In order to realize the non-static error control of three- phase current and independent control of active current and reactive current, the control method of unit power factor PWM Rectifier in two-phase synchronous rotating coordinate system wil

15、l be introduced. Figure 3. The control method of PWM rectifier in dq rotat-ing coordinate system Figure 3 shows the control method of unity power factor PWM rectifier in dq rotating coordinate system. Through coordinate transformation, three-phase station-ary coordinate system (a, b, c), can be conv

16、erted to syn-chronous rotating (d, q) coordinate system that synchro-nous rotate with the grid fundamental wave. The transformation matrix is: The inverse transformation matrix is: The most prominent advantage of this transformation is the fundamental sinusoidal quantitative in (a, b, c) co-ordinate

17、 system can be converted into a DC variable in (d, q) Coordinate system. In this transformation, the d-axis in two-phase synchronous rotating coordinate system rep-resents the active component, and the q-axis represents the reactive component. If we take the position of input voltage vector as the p

18、ositive direction of d-axis, and the three-phase input voltage can be written as: Through coordinate transformation the power supply voltage in dq coordinate system can be written as: According to the instantaneous power theory, the in-stantaneous active power p and reactive power q of the system is

19、: Because eq = 0 , the equation (5) can be simplified as If we dont consider the fluctuations in grid voltage, ed is a fixed value. So the instantaneous active power p and instantaneous reactive power q of PWM rectifier is proportional to id and iq. So that by controlling id and iq, the active and r

20、eactive power of PWM rectifier can be controlled. In three-phase PWM rectifier, the input instantaneous value of active power in the DC side is p = udcidc, if the loss of PWM rectifier is not considered, from equation pui (6), we can know that udcidc= p = 3edid/2. When the grid voltage is a fixed va

21、lue and the loss of rectifier is ignored, the DC side voltage udc is proportional to id, so that DC side voltage of PWM rectifier can be controlled by the control of id.The control method shown in Figure 3 also consists of voltage outer loop and current inner loop. Introducing DC feedback and the no

22、n-static error control of DC voltage can be realized. Due to the DC voltage can be controlled by the control of id, the output value of volt-age outer loop of PI regulator is the reference value of current inner loop, so that the active power of PWM rectifier can be adjusted. The reference value of

23、reactive current is based on the reference value of reactive power, so when iq* =0, PWM rectifier operates on unit power factor state.In this control method, the PI regulator can realize non- static error control. Compared with the control method in three-phase static coordinate system, the steady s

24、tate performance is better. At the same time, the independent control of active current and reactive current can be real- ized. 4 Conclusions This paper respectively introduced the control strategy of unit power factor PWM rectifier in three-phase static coordinate system and two-phase rotating coor

25、dinate system, and the two control method are compared. The-oretical analysis and simulation results show that the control in synchronous rotating coordinate system has better steady state performance. 作者：Z. Peroutka, T. Glasberger国籍：杰克出处：波西米亚大学电力电子部门 单位功率因数PWM整流器的控制摘要为了解决传统的二极管整流器和相位con-受控整流器引起的电网谐

26、波污染问题所设计的单位功率因数PWM整流器。本文对整流电路的拓扑结构作了介绍，对诱导和在三相静止坐标系的双闭环控制策略进行了分析。对于亏缺的控制策略，在两相同步旋转坐标系下的控制策略作了建议。实现有功电流和无功电流的独立控制。PWM整流器仿真模型的建立和本文所提出的控制方法的有效性通过仿真验证。关键词：控制; PWM整流器;单位功率因数，D，Q坐标1、 介绍单位功率因数PWM整流器具有高功率因数，电网侧电流，电能双向传输，低谐波含量等优点，被广泛应用于交流传动，无功补偿，有源电力滤波器，统一潮流控制，还有不间断电源等1。本文介绍了三相PWM整流器的拓扑结构，并介绍了整流器在三相静止坐标系的控制

27、方法。在此控制方法的优缺点进行分析的基础上，提出了在两相同步旋转坐标系中的控制方法。从而使三相PWM整流器的数学模型在D，Q坐标的建立和有功电流和相电流的单一控制得以实现。2、三相电压型PWM整流器的三相静态的控制方法坐标系图1显示了三相电压型PWM整流器的拓扑结构中，C为直流侧滤波电容，eaebec是三相电压源RL是负载。为了实现输入电流和输出电压的控制，传统的方法是直接控制三相输入电流。通过对电流的控制也是能量的流动的控制，从而可实现对输出电压的控制。PWM整流器的三相静止坐标系中的控制方法示于图2。 在此控制方法中，外环控制直流电压。指令信号和直流侧电压的实际信号的差值被导入到PI调节器

28、。 PI调节器的输出值是直流电流信号Im，Im和 AC输入电流的幅值成正比。这样的三相交流电流的指令信号Ia，Ib，Ic可以分别通过其相位是相同的三相电压相乘的Im的正弦信号来获得。指令电流与实际电流的差值输入到PI调节器，正弦调制波可以得到。通过比较正弦调制波与载波的PWM波，可以控制开关。这种控制方法简单，但命令电流的控制系统是一个变化的正弦时变信号具有一定的频率，振幅和相位角。稳态性能的效果也是不可取的，并不能达到的独立控制有功电流和无功电流3。Figure 1. The topology of three-phase voltage source PWM rectifier. Figu

29、re 2. The control method of PWM rectifier in three- phase stationary coordinate system.3、三相电压型PWM整流器在两相同步旋转坐标系的控制方法为了实现有功电流和无功电流的控制，单位功率因数PWM整流器在两相同步旋转坐标系下的三相电流进行独立控制的非静态误差控制将被设计。Figure 3. The control method of PWM rectifier in dq rotat-ing coordinate system 图3示出了单位功率因数PWM整流器中的dq旋转坐标系的控制方法。通过坐标变换，三相

30、站进制坐标系统（a，b，c），可转化为同步旋转（D，Q）坐标系同步理性与电网基波旋转2。变换矩阵为：逆变换矩阵为：这种转变的最突出的优点是基本正弦量的（a，b，c）坐标系可以转换成直流变量中（D，Q）坐标系。在此变换中，d轴在两相同步旋转坐标系代表不满的活性成分，q轴表示无功分量。如果我们取为d轴的正方向，并且在三相输入电压的输入电压矢量的位置可以表示为：通过坐标变换中的dq电源电压的坐标系可以表示为：根据瞬时功率理论，瞬时有功功率P和系统的无功功率q为：因为eq=0=，公式（5）可以简化为：如果我们不考虑在电网电压波动的影响， ed是一个固定的值。因此，瞬时有功功率p和PWM整流器的瞬时无功

31、功率q正比于id和iq 。这样，通过控制id和iq ，PWM整流器的有功和无功功率就可以被控制4。 在三相PWM整流器中，直流侧有功功率的输入瞬时值是p=udcidc ，如果PWM整流器的损失不考虑，从方程（6）我们就可以知道，udcidc。当电网电压为一个固定值，和整流器的损耗被忽略，直流侧电压的udc正比于id，使PWM整流器的直流侧电压可以通过控制id来被控制。 在图3中所出现的控制方法还包括电压外环和电流内环。引入直流反馈和直流电压的非静态误差控制可以实现的。由于该直流电压可以用id的控制来控制， PI调节器的电压外环的输出值是电流内环的基准值，使PWM整流器的有功功率可调节。无功电流

32、的参考值是基于无功功率的参考价值，所以当iq=0,PWM整流器工作在单位功率因数状态。 在此控制方法中， PI调节器可以实现非静态误差控制。在三相静止坐标系统的控制方法相比，稳态性能更好。在同一时间，能够实现有功电流和无功电流的独立控制5。4、结论本文分别介绍了单位功率因数PWM整流器控制中的三相静止坐标系和两相旋转坐标系，并且对两个控制方法进行了比较。理论分析和仿真结果表明，在同步旋转坐标系下的控制具有更好的稳态性能。Pulse-width modulationPulse-width modulation (PWM), as it applies to motor control, is a

33、 way of delivering energy through a succession of pulses rather than a continuously varying (analog) signal. By increasing or decreasing pulse width, the controller regulates energy flow to the motor shaft. The motors own inductance acts like a filter, storing energy during the “on” cycle while rele

34、asing it at a rate corresponding to the input or reference signal. In other words, energy flows into the load not so much the switching frequency, but at the reference frequency.PWM is somewhat like pushing a playground-style merry-go-round. The energy of each push is stored in the inertia of the he

35、avy platform, which accelerates gradually with harder, more frequent, or longer-lasting pushes. The riders receive the kinetic energy in a very different manner than how its applied.questions&answersQ: Whats the main advantage?A: Efficiency. PWM amplifiers run cooler than standard linear power amps,

36、 requiring substantially less heat sink mass. At about 90% efficiency, PWM makes electromagnetic motion feasible at power levels where hydraulics used to be the only option.Q: Whats the downside?A: Nature doesnt like abrupt changes; high-current switching generates electromagnetic noise as well as v

37、oltage spikes. This calls for special measures like filtering, shielding, and the use of spike-hardened components.Q: Whats the effect on bandwidth?A: As a rule of thumb, the usable bandwidth of the command signal is about one decade (10X) below the switching frequency.Linear amplifiers vary the res

38、istance of a pass element to regulate power. Efficiency is fine at the extremes losses are minimal when R = 0 or but suffers elsewhere, bottoming out at midrange (R = RL) where the amount of energy wasted as heat in the amplifier equals that delivered to the load.The output of a PWM amplifier is eit

39、her zero or tied to the supply voltage, holding losses to a minimum. As the duty cycle changes to deliver more or less power, efficiency remains essentially constant.作者：Yeager Brent国籍：英国出处：PTdesign，.2000.脉冲宽度调制脉冲宽度调制（PWM），适用于电机控制，是一种通过一系列脉冲，而不是连续变化的（模拟）信号传递能量的模拟控制方式。通过增加或减小脉冲宽度，控制器会调节能量流到电机轴。电机自身的电感

40、作用就像一个过滤器，在开环状态下，电机存储能量，同时对应于输入或参考信号的速率释放能量。换句话说，能量按照参考频率而不是开关频率流向负载。 脉冲宽度调制就像推一个操场式的旋转木马。每个推的能量被存储在重平台的惯性中，然后逐渐促进更加有力的，更加频繁的，更加持久的推动。骑旋转木马的人就通过这样一个非常与众不同的方式获得了动能。问题与解答问：脉冲宽度调制有什么主要优点？答：效率。脉冲宽度调制功率放大器运行时比标准的线性放大器放出的热量更少，对散热器的要求降低。即使只有90%的效率，脉冲宽度调制也能使得电磁运动可行，并且达到一般只有液压系统才能达到的能力水平。问：脉冲宽度调制有什么缺点？答：性质上不喜欢突然的变化，大电流开关产生的电磁噪声以及尖峰电压。这就要求采取特殊的措施，如滤波，屏蔽，以及使用穗硬化元件。问：脉冲宽度调制对带宽的影响是什么？答：作为一个经验法则，该命令信号的可用带宽是一个大约是低于开关频率十倍。线性放大器用不同的旁路元件来调节功率电阻。效率优良的极端当R= 0或，损失是最小的但受到其他地方的影响，触底反弹在中端（R = RL），此时放大器的热量损失等于传递到负载上的能量。一个脉冲宽度调制放大器的输出是零或者连接电源电压，持有损失降到最低。随着占空比的变化提供更多或更少的功率，效率基本保持不变。