電氣專業(yè)畢業(yè)論文外文翻譯--控制電路設(shè)計

1、<p><b>　　本科畢業(yè)設(shè)計</b></p><p><b>　　外文文獻及譯文</b></p><p>　　文獻、資料題目：Designing Stable Control Loops</p><p>　　文獻、資料來源：期刊</p><p>　　文獻、資料發(fā)表（出版）日期：2010

2、.3.25</p><p>　　院 （部）： 信息與電氣工程學(xué)院</p><p>　　專 業(yè)： 電氣工程與自動化</p><p><b>　　班 級： </b></p><p><b>　　姓 名： </b></p><p><b>　　學(xué)

3、號： </b></p><p><b>　　指導(dǎo)教師： </b></p><p>　　翻譯日期： 2011.3.10</p><p><b>　　外文文獻：</b></p><p>　　Designing Stable Control Loops</p><p>

4、　　The objective of this topic is to provide the designer with a practical review of loop compensation techniques applied to switching power supply feedback control. A top-down system approach is taken starting with basic

5、 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 designs are demonstrated with Ma

6、th cad simulations to illustrate gain and phase margins and th</p><p>　　I. INTRODUCTION</p><p>　　Insuring stability of a proposed power supply solution is often one of the more challenging aspec

7、ts of the design process. Nothing is more disconcerting than to have your lovingly crafted breadboard break into wild oscillations just as its being demonstrated to the boss or customer, but insuring against this unfortu

8、nate event takes some analysis which many designers view as formidable. Paths taken by design engineers often emphasize either cut-and-try empirical testing in the laboratory or compu</p><p>　　II. STABILITY

9、DEFINED</p><p>　　Fig. 1. Definition of stability</p><p>　　Fig. 1 gives a quick illustration of at least one definition of stability. In its simplest terms, a system is stable if, when subjected

10、to a perturbation from some source, its response to that perturbation eventually dies out. Note that in any practical system, instability cannot result in a completely unbounded response as the system will either reach a

11、 saturation level – or fail. Oscillation in a switching regulator can, at most, vary the duty cycle between zero and 100% and while that may not</p><p>　　Another way of visualizing stability is shown in Fig.

12、 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-signal stability is an impor

13、tant 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 mi

14、ght per</p><p>　　Fig. 2. Large-signal vs. small-signal stability</p><p>　　III. FEEDBACK CONTROL PRINCIPLES</p><p>　　Where an uncontrolled source of voltage (or current, or power) is

15、 applied to the input of our system with the expectation that the voltage (or current, or power) at the output will be very well controlled. The basis of our control is some form of reference, and any deviation between t

16、he output and the reference 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 spend the effort to achieve. Typic</

17、p><p>　　The 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

18、input voltage variations, to be reduced to tolerable levels at the output Without feedback, the reference-to-output transfer function y/u is equal to G, and we can express the output asy ??Gu</p><p>　　With t

19、he addition of feedback (actually the subtraction of the feedback signal)</p><p>　　y ??Gu ??yHG</p><p>　　and the reference-to-output transfer function becomes</p><p>　　y/u=G/1+GH<

20、;/p><p>　　If we assume that GH __ 1, then the overall transfer function simplifies to</p><p><b>　　y/u=1/H</b></p><p>　　Fig. 3. Flow graph of feedback control</p><

21、;p>　　Not 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 sol

22、ely 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 contribute to an output er

23、ror. In practice, the feedback control system, as modeled in Fig. 4,</p><p>　　Fig. 4. The general power regulator</p><p>　　IV. THE BUCK CONVERTER</p><p>　　The simplest form of the a

24、bove general power regulator is the buck – or step down – topology whose power stage is shown in Fig. 6. In this configuration, a DC input voltage is switched at some repetitive rate as it is applied to an output filter.

25、 The filter averages the duty cycle modulation of the input voltage to establish an output DC voltage lower than the input value. The transfer function for this stage is defined by</p><p>　　tON=switch on -ti

26、me</p><p>　　T = repetitive period (1/fs)</p><p>　　d = duty cycle</p><p>　　Fig. 5. The buck converter.</p><p>　　Since we assume that the switch and the filter components

27、 are lossless, the ideal efficiency of</p><p>　　This conversion process is 100%, and regulation of the output voltage level is achieved by</p><p>　　controlling the duty cycle. The waveforms of F

28、ig.6 assume a continuous conduction mode (CCM)</p><p>　　Meaning that current is always flowing through the inductor – from the switch when it is closed,</p><p>　　And from the diode when the swit

29、ch is open. The analysis presented in this topic will emphasize</p><p>　　CCM operation because it is in this mode that small-signal stability is generally more difficult</p><p>　　to achieve. In

30、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 zero inductor current)

31、, thus effectively reducing the system order by one and making small-signal stable performance much easier to achieve. Although beyond the scope of this topic, there may be specialized instances where the large-signal st

32、ability of a DCM system is of greater concern</p><p>　　There are several forms of PWM control for the buck regulator including,</p><p>　　? Fixed frequency (fS) with variable tON and variable tOF

33、F</p><p>　　? Fixed tON with variable tOFF and variable fS</p><p>　　? Fixed tOFF with variable tON and variable fS</p><p>　　? Hysteretic (or “bang-bang”) with tON, tOFF, and fS all v

34、ariable</p><p>　　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 switching frequency component and it

35、s associated harmonics as well as the intended DC output, electromagnetic interference and noise considerations have made fixed frequency operation by far the most popular.</p><p>　　With the exception of hys

36、teretic, all other forms of PWM control have essentially the same</p><p>　　small-signal behavior. Thus, without much loss in generality, fixed fS will be the basis for our discussion of classical, small-sign

37、al stability.</p><p>　　Hysteretic 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 t

38、urn-on occurs at a lower threshold. By definition, this is</p><p>　　a large-signal controller to which small-signal stability considerations do not apply. In a small signal sense, it is already unstable and,

39、 in a mathematical sense, its fast response is due more to feed forward than feedback.</p><p>　　REFERENCES</p><p>　　[1] D. M. Mitchell, “DC-DC Switching Regulator Analysis”, McGraw-Hill, 1988,&l

40、t;/p><p>　　DMMitchell Consultants, Cedar Rapids, IA, 1992(reprint version).</p><p>　　[2] D. M. Mitchell, “Small-Signal Mathcad Design Aids”, (Windows 95 / 98 version), e/j</p><p>　　BLO

41、OM Associates, Inc., 1999.</p><p>　　[3] George Chryssis, “High-Frequency Switching Power Supplies”, McGraw-Hill Book</p><p>　　Company, 1984.</p><p>　　[4] Ray Ridley, “A More Accurat

42、e Current- Mode Control Model”, Unitrode Seminar</p><p>　　Handbook, SEM-1300, Appendix A2.</p><p>　　[5] Lloyd Dixon, “Control Loop Design”, Unitrode Seminar Handbook, SEM-800.</p><p&g

43、t;　　[6] Lloyd Dixon, “Control Loop Design – SEPIC Preregulator Design”, Unitrode Seminar</p><p>　　Handbook, SEM-900, Topic 7.</p><p>　　[7] Lloyd Dixon, “Closing the Feedback Loop”, Unitrode Sem

44、inar Handbook, SEM-300.</p><p><b>　　中文翻譯：</b></p><p><b>　　控制電路設(shè)計</b></p><p><b>　　摘要：</b></p><p>　　本篇論文的寫作目的，是為給設(shè)計師們提供一個實際性的說明，那就是線性補

45、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。一個組織管理嚴密的系統(tǒng)電路需要一開始就有一個基礎(chǔ)的電流反饋操作理論的支持，并且通過一步步的設(shè)計步驟，從初步階段應(yīng)用到一個簡單升壓調(diào)節(jié)器，然后再擴展到其他的拓撲學(xué)與算數(shù)控制學(xué)中去。matchad模擬器也驗證了設(shè)計樣本中幅相裕度整定在分布設(shè)計中是存在的，并且還影響著實驗的分析報告。</p><p><b>　　一、簡介：</b></p>

46、<p>　　驗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)計過程中一個極具挑戰(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驗的重要階段中，被突然闖入的無序振蕩所打亂，而是你實驗恰恰驗證了許多電路設(shè)計者感到最為頭疼的數(shù)據(jù)分析。電路設(shè)計師常常強調(diào)，在實驗室里要注重切換實驗的實用價值，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)計的前提為基礎(chǔ)。于是，對反饋原理最基本的理

47、解將幫助我們?nèi)ザx接受性補償網(wǎng)系統(tǒng)的最小值計算范圍。</p><p><b>　　二、穩(wěn)定性的界定：</b></p><p><b>　　圖1 穩(wěn)定的定義</b></p><p>　　圖1直接展示了至少一個關(guān)于穩(wěn)定性的界定。用最簡潔的術(shù)語來說，如果一個電路系統(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，返回的微擾的也將

48、會一并抵消。需要注意的是，在任何實用電路中，不穩(wěn)定性不會導(dǎo)致一個完全無束縛的反應(yīng)，這就如同電路既會達到飽和狀態(tài)——也會處于缺損狀態(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荷周期中波動，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。</p><p>　　圖2 展示的是另外一個設(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，但與此同時，也指出了我們必須將大信號的穩(wěn)定性與小信號的

49、穩(wěn)定性嚴格區(qū)分開來。然而小信號的穩(wěn)定性是一個非常重要和非常需要的判斷標準，一個電路也可以滿足這個要求，并且會與一個大信號的微擾一起變得不穩(wěn)定。重要的是，電路設(shè)計師們需要記得，所有我們可能執(zhí)行的幅相裕度整定計算僅僅只是確保了小信號的穩(wěn)定性。這些計算結(jié)果主要依靠——并且只適用于——線性電路，和一個轉(zhuǎn)換調(diào)節(jié)器——被定義為——非線性的電路。我們通過用圍繞小信號直流工作點周圍小信號的微擾，來演算我們的分析結(jié)果，去解決這個迷團。這之中的具體差別將會

50、在接下來的設(shè)計過程的有關(guān)探討來說明。</p><p>　　圖2 強信號和弱信號</p><p>　　三、反饋電流控制原理：</p><p>　　展示的是一個最基本的調(diào)節(jié)器，在這里，不受控制的電壓來源（或者電流，或者功率）將會被應(yīng)用到電路的輸入，且在輸出過程中被這個不受控制的電壓（電流或者功率）的預(yù)期值完全的掌控。電流控制的基礎(chǔ)是一些基準電壓的結(jié)構(gòu)，任何在輸出電流和基

51、準電壓之間的偏差都是會導(dǎo)致電路的錯誤。在一個反饋操作電路中，負反饋回流電是用來減少在可接受的標準內(nèi)這種錯誤——就如我們希望能從一開始付出努力，一直堅持到最后能成功一樣。然而，按照典型的案例來說，我們也希望讓錯誤不會那么快的發(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)定的危險性就越大。</p><p>　　在這一點上我們應(yīng)該注意，另外一個控制方法——前反饋。通過前反饋

52、的控制，一個控制信號將被直接地發(fā)展到去回應(yīng)一個輸出波動或者微擾中。前反饋沒有回流電那么精準，因為檢測輸出電流不是那么復(fù)雜難懂，然而，無法否認的是，等待一個輸出電流的錯誤信號會被發(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)器對動態(tài)輸入變動的響應(yīng)頻率。</p><p>　　圖3中的電流圖闡述了反饋控制

53、的基礎(chǔ)，目標就是為了輸出功率能跟著可以預(yù)測的基準電壓，為了將外部微擾的影響，如同輸出功率的變動一樣，能會被減少到輸出功率所能接受的等級上。</p><p><b>　　圖3 反饋控制流圖</b></p><p>　　如果沒有反饋電，基準電壓到輸出功率的轉(zhuǎn)換函數(shù)y/u就跟G是一樣的，我們可以這樣表達輸出功率：</p><p><b>　

54、　y=Gu</b></p><p>　　另外反饋電流（實際上是反饋信號的減法）：</p><p>　　y ? Gu ? yHG</p><p>　　之后r基準電壓與輸出功率的轉(zhuǎn)換函數(shù)：</p><p><b>　　Y=G</b></p><p><b>　　u=1 ? GH&

55、lt;/b></p><p>　　如果我們假設(shè)GH=1，那么整體的轉(zhuǎn)換函數(shù)就是：</p><p><b>　　y/u=1/h</b></p><p>　　這個函數(shù)不僅使得G現(xiàn)在成為獨立，它還使所有的電路參數(shù)都變得獨立，這這可能會影響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，被基準電壓作用）所代替來決定它。

56、值得一提的是，H的準確性（通常稱為電阻的公差）和電路的總和（錯誤放大補償功率）將繼續(xù)造成輸出電流的錯誤。在實際中，反饋控制電路，如圖4的模型所示，如此設(shè)計是為了使G ：H和GH=1的振動頻率能越大范圍越好并且不會產(chǎn)生任何不穩(wěn)定性。</p><p>　　我們可以進一步的改良概括功率調(diào)節(jié)器就像圖4所見到的一樣。在這里我們有單獨分開的功率系統(tǒng)進去到兩個板塊——功率段和控制電路。功率段處理電流的負荷，并且功率段通常是大、

57、重、經(jīng)歷廣闊的溫度范圍波動。它的轉(zhuǎn)換功能被定義為，大信號現(xiàn)象，通常在最穩(wěn)定的分析結(jié)果中進行模擬，就像在負荷周期中的兩極轉(zhuǎn)換一樣。輸出電流過濾器被當(dāng)做為線性板塊。控制電路通常有一個增長板塊——錯誤發(fā)大器——和寬脈沖波調(diào)幅器所組成，用來定義電壓轉(zhuǎn)換。</p><p><b>　　圖4 一般電源穩(wěn)壓</b></p><p>　　四、降壓轉(zhuǎn)換器： 上述一般動力的最簡單

58、形式降壓穩(wěn)壓器- 或降壓- 拓撲它的功率級，如圖6所示在這配置，直流輸入電壓起動，有些重復(fù)率，因為它是適用于輸出過濾器。該過濾器的占空比平均輸入電壓的調(diào)制建立輸出直流電壓比輸入值低。變量的傳遞函數(shù)定義如下其中</p><p><b>　　tON為開關(guān)時間</b></p><p>　　T 為重復(fù)周期（頻率的倒數(shù)）</p><p><b>

59、;　　D為占空比</b></p><p><b>　　圖5.降壓轉(zhuǎn)換器</b></p><p>　　由于我們假設(shè)開關(guān)和過濾器組件是無損的，理想的效率這個轉(zhuǎn)換過程是100％，與規(guī)制輸出電壓的水平是通過控制占空比。在波形圖。6假設(shè)連續(xù)傳導(dǎo)模式（CCM）這意味著電流始終流經(jīng)當(dāng)它從封閉開關(guān) - 電感從二極管當(dāng)開關(guān)處于打開狀態(tài)。該在這個主題提出的分析會強調(diào)CCM工作

60、，因為正是在這一模式小信號穩(wěn)定，一般比較困難來實現(xiàn)。在非連續(xù)導(dǎo)通模式（DCM）的，有三分之一的開關(guān)狀態(tài)，其中電感器，開關(guān)和二極管電流都為零。每個開關(guān)周期開始從同一狀態(tài)（零電感電流），從而有效地該系統(tǒng)減少了一個順序，使小信號性能穩(wěn)定，更容易實現(xiàn)。雖然超出了本專題的范圍，可能有專門的情況是，大信號的DCM系統(tǒng)的穩(wěn)定性是更令人關(guān)注的比小信號穩(wěn)定。 也有幾種形式的PWM控制降壓穩(wěn)壓??器，包括?固定頻率和開關(guān)變量?修正開的變量和變量

61、頻率關(guān)變量?可變開和變量頻率固定關(guān)變量?遲滯與開、關(guān)頻率變量， 所有的變量和fS這些形式各有各的一套優(yōu)勢和局限性，并已全部成功使用，但因為所有的開關(guān)模式監(jiān)管機構(gòu)產(chǎn)生的開關(guān)頻率組件及其相關(guān)諧波以及如預(yù)期的直流輸出，電磁干擾和噪聲問題作出迄今為止最固定頻率操作受歡迎。 隨著滯后，所有其</p><p><b>　　參考文獻</b></p><p>　　

62、[1]米切爾四米，“DC - DC開關(guān)調(diào)節(jié)分析”，麥格勞希爾，1988年，DMMitchell顧問，錫達拉皮茲，保險業(yè)監(jiān)督，1992年（重印版）。</p><p>　　[2]四米米切爾，“小信號的Mathcad設(shè)計輔助“，（視窗95 / 98版），電子/日本布盧姆Associates公司，1999。</p><p>　　[3]喬治Chryssis，“高頻交換式電源供應(yīng)“，麥格勞希爾預(yù)訂公司

63、，1984。</p><p>　　[4]雷里德利“一個更精確的電流模式控制模式“，Unitrode研討會手冊，掃描電鏡- 1300，附錄A2。</p><p>　　[5]勞埃德迪克遜，“控制回路設(shè)計“，Unitrode研討會手冊，掃描電鏡- 800。</p><p>　　[6]勞埃德迪克遜，“控制回路設(shè)計 -SEPIC型前置穩(wěn)壓器設(shè)計“，Unitrode研討會手冊，