電氣專業(yè)畢業(yè)論文外文翻譯

1、本科畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文文獻(xiàn)、資料題目：Designing Stable Control Loops文獻(xiàn)、資料來源：鯉文獻(xiàn)、資料發(fā)表（出版）日期：2010.3.25 院 （部）：信息與電氣工程學(xué)院專業(yè)：電子信息工程班級(jí)：電信B124姓名：尚營(yíng)軍學(xué)號(hào)：_4扌旨導(dǎo)教師： 黃成玉翻譯日期：2016. 5. 10外文文獻(xiàn):Designing Stable Control LoopsThe objective of this topic is to provide the designet with a practical review of loop compensation techniques

2、applied to switching power supply feedback contro 1 A top-down system approach is taken starting with basic feedback control concepts and leading to step-by-step design procedures, initially applied to a simple buck regulator and then expanded to other topologies and control algorithms Sample design

3、s are demonstrated with Math cad simulations to illustrate gain and phase margins and their impact on performanee analysisI. IntroductionInsuring stability of a proposed power supply solution is often one of the more challenging aspects of the design process Nothing is more disconcerting than to hav

4、e your lovingly crafted breadboard break into wild oscillations just as its being dem on strated to the boss or customer, but insuring against this unf ortu nate event takes some analysis which many designers view as formidable Paths taken by design engineers often emphasize either cutand-try empiri

5、cal testing in the laboratory or computer simulations looking for numerical solutions based on complex mathematical models While both of these approach a basic understanding of feedback theory will usually allow the definition of an acceptable compensation network with a minimum of computational eff

6、ort.II. Stability DefinedPerturbationPerturbationFig 1 Definition of stabilityFig. 1 gives a quick illustration of at least one definition of stability In its simplest terms, a system is stable if, when subjected to a perturbation from some source, its response to that perturbation eventually dies o

7、ut Note that in any practical system, instability cannot result in a completely unboundec! response as the system will either reach a saturation level - or fai 1. Oscillation in a switching regulator can, at most, vary the duty cycle between zero and 100% and while that may not prevent failure, it w

8、ills ultimate limit the response of an unstable systemAn other way of visualizing stability is show n in Fig 2. While this graphically illustrates the concept of system stability, it also points out that we must make a further distinction between large-signal and small-signal stability While small-s

9、ignal stability is an important and necessary criterion, a system could satisfy thisrt quirement and yet still become unstable with a large-signal perturbation. It is important that designers remember that all the gain and phase calculations we might perform are only to insure small-signal stability

10、. These calculations are based upon - and only applicable to - linear systems, and a switching regulator is - by definition - a non-linear system We solve this conundrum by performing our analysis using small-signal perturbations around a large-signal operating point, a distinction which will be fur

11、ther clarified in our design procedure discussion。StableFig 2. Large-signal vs. small-signal stabilityIII. Feedback Control PrinciplesWhere an uncontrolled source of voltage (or current, or power) is applied to the input of our system with the expectation that the voltage (or current, or power) at t

12、he output will be very wel 1 controlled. The basis of our control is some form of reference, and any deviation between the output and the referenee becomes an error In a feedback-controlled system, negative feedback is used to reduce this error to an acceptable value - as close to zero as we want to

13、 spend the effort to achieve Typically, however, we also want to reduce the error quickly, but in here nt with feedback control is the tradeoff between system response and system stability The more responsive the feedback network is, the greater becomes the risk of instability At this point we shoul

14、d also mention that there is another method of control - feedforward .With feed forward control, a control signal is developed directly in response to an input variation or perturbation. Feed forward is less accurate than feedback since output sensing is not involved, however, there is no delay wait

15、ing for an output error signal to be developed, andfeedforward control cannot cause instability It should be clear that feed forward control will typically not be adequate as the only control method for a voltage regulator, but it is often used together with feedback to improve a regulator * s respo

16、nse to dynamic input variationsThe basis for feedback control is illustrated with the flow diagram of Fig 3 where the goal is for the output to follow the reference predictably and for the effects of external perturbations, such as input voltage variations, to be reduced to tolerable levels at the o

17、utput Without feedback, the reference-to-output transfet function y/u is equal to G, and we can express the output asy GuWith the addition of feedback (actually the subtraction of the feedback signal) y Gu yHGand the reference-to-output transfer function becomes y/u=G/l+GHIf we assume that GH 1, the

18、n the overall transfer function simplifies to y/u=l/HFig 3 Flow graph of feedback controlNot only is this result now independent of G, it is also independent of all the parameters of the system which might impact G (supply voltage, temperature, component tolerances, etc) and is determined instead so

19、lely by the feedback network H (and, of course, by the reference)Note that the accuracy of H (usually resistor tolerances) and in the summing circuit (error amplifier offset voltage) will still con tribute to an output error In practice, the feedback control system, as modeled in Fig z, is designed

20、so thatG H and GH _ 1 over as wide a frequency range as possible without incurring instability We can make a further refinement to our generalized power regulator with the block diagram shown in Fig 5 Here we have separated the power system into two blocks - the power section and the control circuit

21、ry. The power section handles the load current and is typically large, heavy, and subject to wide temperature fluctuations. Its switching functions are by definition, large-signal phenomenon, normally simulated in most stability analyses as just a two states witch with a duty cycle The output filter

22、 is also considered as a part of the power section but can be considered as a linear blockPower SystemFig 4. The general power regulatorIV. The Buck ConverterThe simplest form of the above general power regulator is the buck - or step down 一 topology whose power stage is shown in Fig 6. In this conf

23、iguration, a DC in put voltage is switched at some repetitive rate as it is applied to an output filter The filter averages the duty cycle modulation of the input voltage to establish an output DC voltage lower than the input value The transfer functionfor this stage is defined bytOM二switch on -time

24、T = repetitive period (1/fs)cl = duty cycle_ S IrYYl十斗廠、+亠 Vi J 丿 PWM K VS2S R Vo- Control 一Fig. 5. The buck converter.Since we assume that the switch and the filter components are lossless, the ideal efficiency ofThis conversion process is 100%, and regulation of the output voltage level is achieve

25、d bycontrol ling the duty cycle The waveforms of Fig .6 assume a continu ous conducti on mode (CCM)Meaning that current is always flowing through the inductor - from the switch when it is closed,And from the diode when the switch is open. The analysis presented in this topic will emphasizeCCM operat

26、ion because it is in this mode that small-signal stability is generally more difficultto achieve In the discontinuous conduction mode (DCM), there is a third switch condition in which the inductor, switch, and diode currents are all 5-4 zero. Each switching period starts from the same state (with ze

27、ro inductor current), thus effectively reducing the system order by one and making small-signal stable per forma nee much easier to achieve Although bey ond the scope of this topic, there may be specialized instances where the large-signal stability of a DCM system is of greater concern than small-s

28、ignal stability.There are several forms of PWM control for the buck regulator including, Fixed frequency (fS) with variable tON and variable tOFF Fixed tON with variable tOFF and variable fS Fixed tOFF with variable tON and variable fS Hysteretic (or ubang-bangM ) with tON, tOFF, and fS all variable

29、Each of these forms have their own set of advantages and limitations and all have been successfully used, but since all switch mode regulators generate a switch ing freque ncy comp orient and its associated harmonics as well as the in tended DC output, electromagnetic interferenee and noise consider

30、ations have made fixed frequency operation by far the most popularWith the exception of hysteretic, all other forms of PWM control have essentially the samesmall-signal behavior Thus, without much loss in generality, fixed fS will be the basis for our discussion of classical, small-signal stabilityH

31、ysteretic control is fundamentally different in that the duty factor is not controlled, per se. Switch turn-off occurs when the output ripple voltage reaches an upper trip point and turn 一 on occurs at a lower threshold By def in iti on, this isa large-signal controller to which small-signal stabili

32、ty considerations do not apply. In a small signal sense, it is already unstable and, in a mathematical sense, its fast response is due more to feed forward than feedbackReferences1 D. M. Mitchell, UDCDC Switching Regulator Analysis , McGraw-Hill, 1988, DMMitchell Consultants, Cedar Rapids, IA, 1992(

33、reprint version).1.2 D. M. Mitchell, Small-Signal Ma thcad Design A ids , (Windows 95 / 98 version), e/jBLOOM Associates, Inc., 1999.3 George Chryssis, High-Frequency Switching Power Supplies , McGraw-Hill Book Company, 1984.4 Ray Ridley, 4 More Accurate Current- Mode Control Model , Unit rode Sem i

34、nar Handbook, SEM-1300, Appendix A2.15 Lloyd Dixon, Control Loop Design、Unitrode Seminar Handbook, SEM-800.16 Lloyd Dixon, “Control Loop Design - SEPIC Preregulator Design , Unitrode SeminarHandbook, SEM-900, Topic 7.1.7 Lloyd Dixon, “Closing the Feedback Loop , Unitrode Seminar Handbook, SEM-300.中文

35、翻譯：控制電路設(shè)計(jì)摘要：本篇論文的寫作目的，是為給設(shè)計(jì)師們提供一個(gè)實(shí)際性的說明，那就是線性補(bǔ)償技術(shù) 在電源轉(zhuǎn)換與電流反饋操作中是如何應(yīng)用的。一個(gè)組織管理嚴(yán)密的系統(tǒng)電路需要一開始就 有一個(gè)基礎(chǔ)的電流反饋操作理論的支持，并且通過一步步的設(shè)計(jì)步驟，從初步階段應(yīng)用到 一個(gè)簡(jiǎn)單升壓調(diào)節(jié)器，然后再擴(kuò)展到其他的拓?fù)鋵W(xué)與算數(shù)控制學(xué)中去。matchad模擬器也驗(yàn)證了設(shè)計(jì)樣本中幅相裕度整定在分布設(shè)計(jì)中是存在的，并且還影響著實(shí)驗(yàn)的分析報(bào)告。一、簡(jiǎn)介：驗(yàn)證所提議的電源供給解決方案的穩(wěn)定性，一直就是電路設(shè)計(jì)過程中一個(gè)極具挑戰(zhàn)性 的方面。最讓你感到窘迫的，并不是你最為得意之作的電路板正在實(shí)驗(yàn)的重要階段中，被 突然闖入的無

36、序振蕩所打亂，而是你實(shí)驗(yàn)恰恰驗(yàn)證了許多電路設(shè)計(jì)者感到最為頭疼的數(shù)據(jù)分析。電路設(shè)計(jì)師常常強(qiáng)調(diào)，在實(shí)驗(yàn)室里要注重切換實(shí)驗(yàn)的實(shí)用價(jià)值，或者是以復(fù)雜的數(shù) 學(xué)模式為電腦集成系統(tǒng)所需要的數(shù)據(jù)處理。然而這兩者的方向都是以電路設(shè)計(jì)的前提為基 礎(chǔ)。于是，對(duì)反饋原理最基本的理解將幫助我們?nèi)ザx接受性補(bǔ)償網(wǎng)系統(tǒng)的最小值計(jì)算圍。二、穩(wěn)定性的界定:n擾動(dòng)擾動(dòng)圖1穩(wěn)定的定義圖1直接展示了至少一個(gè)關(guān)于穩(wěn)定性的界定。用最簡(jiǎn)潔的術(shù)語(yǔ)來說，如果一個(gè)電路系 統(tǒng)是穩(wěn)定的，就算被從某些來源說產(chǎn)生的微擾所壓制時(shí)，返回的微擾的也將會(huì)一并抵消。 需要注意的是，在任何實(shí)用電路中，不穩(wěn)定性不會(huì)導(dǎo)致一個(gè)完全無束縛的反應(yīng)，這就如同 電路既會(huì)達(dá)到飽和

37、狀態(tài)一一也會(huì)處于缺損狀態(tài)一樣。正在調(diào)節(jié)器轉(zhuǎn)化過程中的振蕩極有可 能在零和百分之一百間的負(fù)荷周期中波動(dòng)，并且這種變化不可能阻止失敗，它將最終制約 不穩(wěn)定電路的回流電。圖2展示的是另外一個(gè)設(shè)想的穩(wěn)定性。盡管該圖形象地展示了電路穩(wěn)定性的觀點(diǎn)，但 與此同時(shí)，也指出了我們必須將大信號(hào)的穩(wěn)定性與小信號(hào)的穩(wěn)定性嚴(yán)格區(qū)分開來。然而小 信號(hào)的穩(wěn)定性是一個(gè)非常重要和非常需要的判斷標(biāo)準(zhǔn)，一個(gè)電路也可以滿足這個(gè)要求，并 且會(huì)與一個(gè)大信號(hào)的微擾一起變得不穩(wěn)定。重要的是，電路設(shè)計(jì)師們需要記得，所有我們 可能執(zhí)行的幅相裕度整定計(jì)算僅僅只是確保了小信號(hào)的穩(wěn)定性。這些計(jì)算結(jié)果主要依靠一并且只適用于一一線性電路，和一個(gè)轉(zhuǎn)換調(diào)節(jié)器

38、一一被定義為一一非線性的電路。我們 通過用圍繞小信號(hào)直流工作點(diǎn)周圍小信號(hào)的微擾，來演算我們的分析結(jié)果，去解決這個(gè)迷 團(tuán)。這之中的具體差別將會(huì)在接下來的設(shè)計(jì)過程的有關(guān)探討來說明。圖2強(qiáng)信號(hào)和弱信號(hào)三、反饋電流控制原理：展示的是一個(gè)最基本的調(diào)節(jié)器，在這里，不受控制的電壓來源（或者電流，或者功率） 將會(huì)被應(yīng)用到電路的輸入，且在輸出過程中被這個(gè)不受控制的電壓（電流或者功率）的預(yù) 期值完全的掌控。電流控制的基礎(chǔ)是一些基準(zhǔn)電壓的結(jié)構(gòu)，任何在輸出電流和基準(zhǔn)電壓之 間的偏差都是會(huì)導(dǎo)致電路的錯(cuò)誤。在一個(gè)反饋操作電路中，負(fù)反饋回流電是用來減少在可 接受的標(biāo)準(zhǔn)這種錯(cuò)誤一一就如我們希望能從一開始付出努力，一直堅(jiān)持到最

39、后能成功一樣。 然而，按照典型的案例來說，我們也希望讓錯(cuò)誤不會(huì)那么快的發(fā)生，但是回流電控制電路 本身就存在著頻率響應(yīng)與電路穩(wěn)定性的互換?；亓麟娐返念l率響應(yīng)越多，不穩(wěn)定的危險(xiǎn)性 就越大。在這一點(diǎn)上我們應(yīng)該注意，另外一個(gè)控制方法一一前戾饋。通過前反饋的控制，一個(gè) 控制信號(hào)將被直接地發(fā)展到去回應(yīng)一個(gè)輸出波動(dòng)或者微擾中。前反饋沒有回流電那么精 準(zhǔn)，因?yàn)闄z測(cè)輸出電流不是那么復(fù)雜難懂，然而，無法否認(rèn)的是，等待一個(gè)輸出電流的錯(cuò) 誤信號(hào)會(huì)被發(fā)現(xiàn)，而且前反饋控制無法產(chǎn)生不穩(wěn)定性。需要清楚表明的是，典型的前反饋 控制將不像只有一個(gè)電壓調(diào)節(jié)器的控制線路那么有效，但是前反饋的控制經(jīng)常被用于和反 饋一起去加快調(diào)節(jié)器對(duì)動(dòng)

40、態(tài)輸入變動(dòng)的響應(yīng)頻率。圖3中的電流圖闡述了反饋控制的基礎(chǔ)，目標(biāo)就是為了輸出功率能跟著可以預(yù)測(cè)的基準(zhǔn) 電壓，為了將外部微擾的影響，如同輸出功率的變動(dòng)一樣，能會(huì)被減少到輸出功率所能接圖3反饋控制流圖如果沒有反饋電，基準(zhǔn)電壓到輸出功率的轉(zhuǎn)換函數(shù)y/u就跟G是一樣的，我們可以這樣 表達(dá)輸出功率：y=Gu另外反饋電流（實(shí)際上是反饋信號(hào)的減法）：y Gu yHG之后r基準(zhǔn)電壓與輸出功率的轉(zhuǎn)換函數(shù)：Y=Gu=l GH如果我們假設(shè)GH=1,那么整體的轉(zhuǎn)換函數(shù)就是：y/u=l/h這個(gè)函數(shù)不僅使得G現(xiàn)在成為獨(dú)立，它還使所有的電路參數(shù)都變得獨(dú)立，這這可能會(huì)影 響G （供給功率、溫度、元件公差，等等）并且被只被回流電路H （并且，理所當(dāng)然的，被基 準(zhǔn)電壓作用）所代替來決定它。值得一提的是，H的準(zhǔn)確性（通常稱為電阻的公差）和電路 的總和（錯(cuò)誤放大補(bǔ)償功率）將繼續(xù)造成輸出電流的錯(cuò)誤。在實(shí)際中，反饋控制電路，如圖 4的模型所示，如此設(shè)計(jì)是為了使G : H和GH=1的振動(dòng)頻率能越大圍越好并且不會(huì)產(chǎn)生任何不 穩(wěn)定性。我們可以進(jìn)一步的改良概括功率調(diào)節(jié)器就像圖4所見到的一樣。在這里我們有單獨(dú)分開 的功率系統(tǒng)進(jìn)去到