開(kāi)關(guān)電源外文翻譯--基于壓降型pwm開(kāi)關(guān)電源的建模、仿真和減少傳導(dǎo)性電磁干擾

1、<p>　　1800單詞，9800英文字符，3720漢字</p><p>　　出處：Farhadi A. Modeling, simulation, and reduction of conducted electromagnetic interference due to a PWM buck type switching power supply[C]// International Confere

2、nce on Harmonics and Quality of Power. IEEE, 2008:1-6.</p><p>　　外 文 翻 譯</p><p>　　原文名稱(chēng)：Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Typ

3、e Switching Power Supply </p><p>　　譯文名稱(chēng)：基于壓降型PWM開(kāi)關(guān)電源的建模、仿真和減少傳導(dǎo)性電磁干擾 </p><p>　　專(zhuān) 業(yè)： 電氣工程及其自動(dòng)化 </p><p>　　姓

4、 名： </p><p>　　班級(jí)學(xué)號(hào)： </p><p>　　指導(dǎo)教師： </p><p>　　Modeling, Simulation, and Reducti

5、on of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply </p><p>　　A. Farhadi </p><p>　　Abstract: Undesired generation of radiated or conducted energy in elect

6、rical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters especially in switching power supplies improves efficiency but leads to EMI. Different kind of co

7、nducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power elect</p>

8、<p>　　Index Terms: Conducted, EMC, EMI, LISN, Switching Supply </p><p>　　I. INTRODUCTION </p><p>　　FAST semiconductors make it possible to have high speed and high frequency switching in

9、power electronics . High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency interference appeared . Compliance with electromagnetic compatibility (EMC) regu

10、lations is necessary for producers to present their products to the markets. It is important to take EMC aspects already in design phase . Modeling and simulation is the most effective tool to</p><p>　　II. S

11、OURCE, PATH AND VICTIM OF EMI </p><p>　　Undesired voltage or current is called interference and their cause is called interference source. In this paper a high-speed switching power supply is the source of i

12、nterference. </p><p>　　Interference propagated by radiation in area around of an interference source or by conduction through common cabling or wiring connections. In this study conducted emission is conside

13、red only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of elements, source lines and cabling provi

14、de paths for conducted noise or interference. Electromagnetic conducted interference has two com</p><p>　　A. Differential mode conducted interference </p><p>　　This mode is related to the noise

15、that is imposed between different lines of a test circuit by a noise source. Related current path is shown in Fig. 1 . The interference source, path impedances, differential mode current and load impedance are also shown

16、 in Fig. 1. </p><p>　　B. Common mode conducted interference </p><p>　　Common mode noise or interference could appear and impose between the lines, cables or connections and common ground. Any le

17、akage current between load and common ground could be modeled by interference voltage source. </p><p>　　Fig. 2 demonstrates the common mode interference source, common mode currents Icm1 and Icm2 and the rel

18、ated current paths. The power electronics converters perform as noise source between lines of the supply network. In this study differential mode of conducted interference is particularly important and discussion will be

19、 continued considering this mode only. </p><p>　　III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS </p><p>　　Application of electrical equipment especially static power electronic converters in dif

20、ferent equipment is increasing more and more. As mentioned before, power electronics converters are considered as an important source of electromagnetic interference and have corrupting effects on the electric networks .

21、 High level of pollution resulting from various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers </p><p>　　For d

22、ifferent groups of consumers different classes of regulations could be complied. Class A for common consumers and class B with more hard limitations for special consumers are separated in Fig. 3 and Fig. 4. Frequency ran

23、ge of limitation is different for IEC and VDE that are 150 kHz up to 30 MHz and 10 kHz up to 30 MHz respectively. Compliance of regulations is evaluated by comparison of measured or calculated conducted interference leve

24、l in the mentioned frequency range with the stated requ</p><p>　　IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENT </p><p>　　A. Line Impedance Stabilization Network (LISN)</p><p&

25、gt;　　1-Providing a low impedance path to transfer power from source to power electronics converter and load. </p><p>　　2-Providing a low impedance path from interference source, here power electronics conver

26、ter, to measurement port. </p><p>　　Variation of LISN impedance versus frequency with the mentioned topology is presented in Fig. 7. LISN has stabilized impedance in the range of conducted EMI measurement .

27、</p><p>　　Variation of level of signal at the output of LISN versus frequency is the spectrum of interference. The electromagnetic compatibility of a system can be evaluated by comparison of its interference

28、 spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 kHz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations

29、. In practical situations, the LISN output is connected to a spectrum analyzer and </p><p>　　V.SIMULATION OF EMI DUE TO A PWM BUCK TYPE SWITCHINGPOWER SUPPLY </p><p>　　For a simple fixed frequen

30、cy PWM controller that is applied to a Buck DC/DC converter, it is possible to assume the error voltage (ve) changes slow with respect to the switching frequency, the pulse width and hence the duty cycle can be approxima

31、ted by (1). Vp is the saw tooth waveform amplitude. </p><p>　　A. PWM waveform spectral analysis </p><p>　　The normalized pulse train m (t) of Fig. 8 represents PWM switch current waveform. The n

32、th pulse of PWM waveform consists of a fixed component D/fs , in which D is the steady state duty cycle, and a variable component dn/f sthat represents the variation of duty cycle due to variation of source, reference a

33、nd load. </p><p>　　As the PWM switch current waveform contains information concerning EMI due to power supply, it is required to do the spectrum analysis of this waveform in the frequency range of EMI studie

34、s. It is assumed that error voltage varies around Ve with amplitude of Ve1 as is shown in (2). </p><p>　　fm represents the frequency of error voltage variation due to the variations of source, reference and

35、load. The interception of the error voltage variation curve and the saw tooth waveform with switching frequency, leads to (3) for the computation of duty cycle coefficients. </p><p>　　Maximum variation of pu

36、lse width around its steady state value of D is limited to D1. In each period of Tm=1/fm , there will be r=fs/fm pulses with duty cycles of dn. Equation (4) presents the Fourier series coefficients Cn of the PWM waveform

37、 m (t). Which have the frequency spectrum of Fig.9. </p><p>　　B-Equivalent noise circuit and EMI spectral analysis </p><p>　　To attain the equivalent circuit of Fig.6 the voltage source Vs is re

38、placed by short circuit and converter is replaced by PWM waveform switch current (Iex) as it has shown in Fig. 10. </p><p>　　The transfer function is defined as the ratio of the LISN output voltage to the EM

39、I current source as in (5). </p><p>　　The coefficients di, ni (i = 1, 2, … , 4) correspond to the parameters of the equivalent circuit. Rc and Lc are respectively the effective series resistance (ESR) and in

40、ductance (ESL) of the filter capacitor Cf that model the non-ideality of this element. The LISN and filter parameters are as follows: CN = 100 nF, r = 5 Ω, l = 50 uH, RN =50 Ω, LN=250 uH, Lf = 0, Cf =0, Rc= 0, Lc= 0, fs

41、=25 kHz </p><p>　　The EMI spectrum is derived by multiplication of the transfer function and the source noise spectrum. Simulation results are shown in Fig. 11. </p><p>　　VI. PARAMETERS AFFECTIO

42、N ON EMI </p><p>　　A. Duty Cycle </p><p>　　The pulse width in PWM waveform varies around a steady state D=0.5. The output noise spectrum was simulated with values of D=0.25 and 0.75 that are sho

43、wn in Fig. 12 and Fig. 13. Even harmonics are increased and odd ones are decreased that is desired in point of view of EMC. On the other hand the noise energy is distributed over a wider range of frequency and the level

44、of EMI decreased .</p><p>　　B. Amplitude of duty cycle variation </p><p>　　The maximum pulse width variation is determined by D1. The EMI spectrum was simulated with D1=0.05. Simulations are rep

45、eated with D1=0.01 and 0.25 and the results are shown in Fig.14 and Fig.15.</p><p>　　Increasing of D1 leads to frequency modulation of the EMI signal and reduction in level of conducted EMI. Zooming of Fig.

46、15 around 7th component of switching frequency in Fig. 16 shows the frequency modulation clearly. </p><p>　　C. Error voltage frequency </p><p>　　The main factor in the variation of duty cycle is

47、 the variation of source voltage. The fm=100 Hz ripple in source voltage is the inevitable consequence of the usage of rectifiers. The simulation is repeated in the frequency of fm=5000 Hz. It is shown in Fig. 17 that at

48、 a higher frequency for fm the noise spectrum expands in frequency domain and causes smaller level of conducted EMI. On the other hand it is desired to inject a high frequency signal to the reference voltage intentionall

49、y. </p><p>　　D. Simultaneous effect of parameters </p><p>　　Simulation results of simultaneous application of D=0.75, D1=0.25 and fm=5000 Hz that lead to expansion of EMI spectrum over a wider f

50、requencies and considerable reduction in EMI level is shown in Fig. 18. </p><p>　　VII. CONCLUSION </p><p>　　Appearance of Electromagnetic Interference due to the fast switching semiconductor dev

51、ices performance in power electronics converters is introduced in this paper. Radiated and conducted interference are two types of Electromagnetic Interference where conducted type is studied in this paper. Compatibility

52、 regulations and conducted interference measurement were explained. LISN as an important part of measuring process besides its topology, parameters and impedance were described. EMI spectrum due</p><p>　　VII

53、I. REFRENCES </p><p>　　[1] Mohan, Undeland, and Robbins, “Power Electronics Converters, Applications and Design” 3rd edition, John Wiley & Sons, 2003. </p><p>　　[2] P. Moy, “EMC Related Issu

54、es for Power Electronics”, IEEE, Automotive Power Electronics, 1989, 28-29 Aug. 1989 pp. 46 – 53. </p><p>　　[3] M. J. Nave, “Prediction of Conducted Interference in Switched Mode Power Supplies”, Session 3B,

55、 IEEE International Symp. on EMC, 1986. </p><p>　　[4] Henderson, R. D. and Rose, P. J., “Harmonics and their Effects on Power Quality and Transformers”, IEEE Trans. On Ind. App., 1994, pp. 528-532. </p>

56、;<p>　　[5] I. Kasikci, “A New Method for Power Factor Correction and Harmonic Elimination in Power System”, Proceedings of IEEE Ninth International Conference on Harmonics and Quality of Power, Volume 3, pp. 810 –

57、 815, Oct. 2000. </p><p>　　[6] M. J. Nave, “Line Impedance Stabilization Networks: Theory and Applications”, RFI/EMI Corner, April 1985, pp. 54-56. </p><p>　　[7] T. Williams, “EMC for Product De

58、signers” 3rd edition 2001 Newnes. </p><p>　　[8] B. Keisier, “Principles of Electromagnetic Compatibility”, 3rd edition ARTECH HOUSE 1987. </p><p>　　[9] J. C. Fluke, “Controlling Conducted Emissi

59、on by Design”, Vanhostrand Reinhold 1991. </p><p>　　[10] M. Daniel,”DC/DC Switching Regulator Analysis”, McGrawhill 1988 </p><p>　　[11] M. J. Nave,” The Effect of Duty Cycle on SMPS Common Mode

60、Emission: theory and experiment”, IEEE National Symposium on Electromagnetic Compatibility, Page(s): 211-216, 23-25 May 1989. </p><p>　　基于壓降型PWM開(kāi)關(guān)電源的建模、仿真和減少傳導(dǎo)性電磁干擾</p><p>　　作者：A. Farhadi國(guó)籍：伊朗&

61、lt;/p><p>　　摘要：電子設(shè)備之中雜亂的輻射或者能量叫做電磁干擾(EMI)。尤其是在開(kāi)關(guān)電源中的電力電子轉(zhuǎn)換器經(jīng)常高速切換時(shí)，雖然提高了工作效率，卻導(dǎo)致轉(zhuǎn)換器產(chǎn)生了電磁干擾。在這篇論文之中介紹了各種各樣的傳導(dǎo)干擾，電磁干擾規(guī)章以及傳導(dǎo)性電磁干擾的測(cè)量。如果電子設(shè)備的電磁干擾符合國(guó)家或者國(guó)際規(guī)章稱(chēng)為電磁兼容性（EMC）。電力電子系統(tǒng)生產(chǎn)商一定要重視電子設(shè)備的電磁兼容性。電磁兼容性評(píng)估的第一步就是建模和仿真。在這

62、篇論文中提出了基于壓降型脈寬調(diào)制開(kāi)關(guān)電源的電磁干擾仿真結(jié)果。為了提高電子設(shè)備的電磁兼容性,在論文中介紹了一些技術(shù)，并且通過(guò)仿真提高了電子設(shè)備的工作效率。</p><p>　　關(guān)鍵字：傳導(dǎo)，電磁兼容性，電磁干擾，線路阻抗穩(wěn)定網(wǎng)絡(luò)，開(kāi)關(guān)電源</p><p><b>　　一、前言</b></p><p>　　在電力電子領(lǐng)域中，快速半導(dǎo)體的出現(xiàn)使高速度

63、，高頻率的開(kāi)關(guān)切換成為了可能[1]。高速的開(kāi)關(guān)造成設(shè)備的重量和體積的減少，但與此同時(shí)這也造成了一些不利的影響，比如無(wú)線頻率的干擾[2]。生產(chǎn)商將生產(chǎn)的產(chǎn)品投放到市場(chǎng)，遵守電磁兼容性規(guī)章是必要的。在設(shè)計(jì)階段考慮電磁兼容性問(wèn)題是非常重要的[3]。在開(kāi)發(fā)產(chǎn)品前，建模和仿真是分析電磁兼容性最有效的工具。許多以前的研究都有涉及到電力電子元件的低頻分析[4~5]。不同類(lèi)型的電力電子轉(zhuǎn)換器都能夠被用來(lái)當(dāng)做電磁的干擾源。電磁干擾源可以通過(guò)輻射和傳導(dǎo)兩種

64、方式來(lái)傳播。線路阻抗穩(wěn)定網(wǎng)絡(luò)被用來(lái)測(cè)量和計(jì)算電磁干擾影響的程度[6]。線路阻抗穩(wěn)定網(wǎng)絡(luò)輸出的干擾頻譜被引為電磁兼容性的評(píng)估標(biāo)準(zhǔn)[7,~8]。國(guó)家或國(guó)際規(guī)章是電子設(shè)備電磁兼容性評(píng)估的一個(gè)參考的方面[7~8]。</p><p>　　二、來(lái)源、途徑和電磁干擾的受害者</p><p>　　雜亂的電壓或者電流被稱(chēng)為干擾，而它們的來(lái)源被稱(chēng)為干擾源。本論文中的干擾源就是一個(gè)高速的開(kāi)關(guān)電源。干擾通過(guò)輻射的

65、方式在干擾源周?chē)鷤鞑セ蛲ㄟ^(guò)和常見(jiàn)的電纜或電線連接進(jìn)行傳導(dǎo)。在這項(xiàng)研究中只考慮傳導(dǎo)發(fā)射設(shè)備，如電腦，接收器，放大器，工業(yè)控制器等。這些被干擾源輻射的設(shè)備被稱(chēng)為受害者。常見(jiàn)的元素，源頭接線，布線為噪聲以及干擾的傳導(dǎo)提供了途徑。電磁傳導(dǎo)干擾有差模和共模兩種干擾方法[9]。</p><p><b>　　A.差模傳導(dǎo)干擾</b></p><p>　　這種模式就是將一個(gè)噪聲源的噪

66、聲施加到一個(gè)測(cè)試電路的不同線路。它的電路如下圖1所示[9]。在圖1中也顯示了干擾源，路徑阻抗，差模電流以及負(fù)載阻抗。</p><p>　　圖1差模傳導(dǎo)干擾路徑</p><p><b>　　B.常見(jiàn)的干擾方式</b></p><p>　　共模噪聲或干擾可能出現(xiàn)在電線或者電纜的連接點(diǎn)。負(fù)載和接地點(diǎn)的任意泄露都可以被認(rèn)為是電壓干擾源。圖2演示了共模干

67、擾源在共模電流為Icm1和Icm2時(shí)相關(guān)的電流路徑[9]。電力電子轉(zhuǎn)換器可以被用來(lái)作為供應(yīng)網(wǎng)絡(luò)線路之間的噪音源。在這項(xiàng)研究中不同的傳導(dǎo)干擾模式是非常重要的，所以討論只會(huì)在這種模式下被繼續(xù)考慮。</p><p><b>　　三、電磁兼容性規(guī)章</b></p><p>　　電子設(shè)備的應(yīng)用，特別是那些擁有靜態(tài)電力電子轉(zhuǎn)換器的電子設(shè)備越來(lái)越多。就像前面講的一樣，電力電子轉(zhuǎn)換器

68、被視為一個(gè)重要的電磁干擾源，并能使電網(wǎng)產(chǎn)生腐壞。各種各樣的干擾造成的高污染降低了電網(wǎng)電能的質(zhì)量。另一方面，一些住宅，廣告，特別是醫(yī)療器件對(duì)電力系統(tǒng)的電壓及頻率變化的干擾非常敏感。最好的解決干擾和提高電能質(zhì)量的方法就是遵守國(guó)家或國(guó)際電磁兼容性規(guī)定。國(guó)際無(wú)線電干擾特別委員會(huì)，國(guó)際電工委員會(huì)標(biāo)準(zhǔn)，美國(guó)聯(lián)邦通訊委員會(huì)和德國(guó)電氣工程師協(xié)會(huì)認(rèn)證是歐洲，美國(guó)，德國(guó)最有名的決策并且出版最重要電磁兼容性法規(guī)的組織。IEC和VDE在傳導(dǎo)發(fā)射上的需要和限制如

69、圖 3 和圖 4所示[7,9]。</p><p>　　圖2共模傳導(dǎo)干擾路徑</p><p>　　圖3 IEC管理排放標(biāo)準(zhǔn)</p><p>　　不同的消費(fèi)者群體可以遵守不同類(lèi)別的規(guī)定。A類(lèi)為普通的消費(fèi)者，B類(lèi)為具有更苛刻限制的消費(fèi)者，在圖 3 和圖 4這兩者被分開(kāi)。IEC和VDE頻率范圍不同，前者范圍為150 千赫茲 到 30 兆赫茲，后者的范圍為10 千赫茲 到 3

70、0 兆赫茲，在上述法規(guī)規(guī)定要求的頻率范圍內(nèi)，法規(guī)的遵守情況被用來(lái)測(cè)量或者計(jì)算傳導(dǎo)干擾的水平。在歐美社會(huì)電磁兼容性法規(guī)的遵行是強(qiáng)制的，產(chǎn)品必須要有認(rèn)證的標(biāo)簽以表示達(dá)到法規(guī)的要求[8]。</p><p>　　圖4 VDE管理排放標(biāo)準(zhǔn)</p><p>　　四、電磁傳導(dǎo)干擾測(cè)試</p><p>　　A. 線路阻抗穩(wěn)定網(wǎng)絡(luò)（LISN）</p><p>

71、　　線路阻抗穩(wěn)定網(wǎng)絡(luò)是提供一個(gè)標(biāo)準(zhǔn)的工業(yè)元素被放置在供應(yīng)和電力電子轉(zhuǎn)換器之間， 包括加載一個(gè)接口以便可以對(duì)傳導(dǎo)干擾進(jìn)行測(cè)量[7]，所述的情況如圖5 所示[6]。線路阻抗穩(wěn)定網(wǎng)絡(luò)應(yīng)具有以下幾個(gè)特點(diǎn)，以滿足測(cè)量條件[7]。</p><p>　　提供一個(gè)低阻抗路徑轉(zhuǎn)移源動(dòng)力到電力電子轉(zhuǎn)換器以及負(fù)載。</p><p>　　干擾源提供一個(gè)低阻抗路徑，電力電子轉(zhuǎn)換器用來(lái)測(cè)量路徑端口。</p>

72、;<p>　　圖5 LISN網(wǎng)絡(luò)布局測(cè)量傳導(dǎo)干擾</p><p>　　B. 線路阻抗穩(wěn)定網(wǎng)絡(luò)拓?fù)?lt;/p><p>　　線路阻抗穩(wěn)定網(wǎng)絡(luò)比較常見(jiàn)的拓?fù)浣Y(jié)構(gòu)如圖6所示[7]。</p><p>　　圖6 LISN網(wǎng)絡(luò)常見(jiàn)的拓?fù)浣Y(jié)構(gòu)</p><p>　　圖7中給出了線路阻抗穩(wěn)定網(wǎng)絡(luò)的阻抗與頻率的變化以及前面提到的拓?fù)浣Y(jié)構(gòu)。線性阻抗穩(wěn)定網(wǎng)

73、絡(luò)在電磁干擾測(cè)量范圍之內(nèi)擁有穩(wěn)定的阻抗[7]。</p><p>　　線路阻抗穩(wěn)定網(wǎng)絡(luò)輸出的信號(hào)電平與頻率的變化就是干擾頻譜。一個(gè)系統(tǒng)的電磁兼容性可以通過(guò)比較它的干擾頻譜和標(biāo)準(zhǔn)的限制來(lái)進(jìn)行評(píng)估。線路阻抗穩(wěn)定網(wǎng)絡(luò)輸出的信號(hào)電平范圍在10千赫茲 到30 千赫茲 或者150 千赫茲 到30兆赫茲之間，這就是標(biāo)準(zhǔn)的電磁兼容性，并且它處在標(biāo)準(zhǔn)的限定范圍里。在實(shí)際的情況下，線路阻抗穩(wěn)定網(wǎng)絡(luò)是連接到頻譜分析儀上進(jìn)行干擾測(cè)量的。但

74、是為了建模和仿真的目的，線路阻抗穩(wěn)定網(wǎng)絡(luò)的輸出頻譜是通過(guò)相應(yīng)的軟件來(lái)進(jìn)行計(jì)算的。</p><p>　　五、基于壓降型脈寬調(diào)制開(kāi)關(guān)電源的電磁干擾模擬</p><p>　　對(duì)于一個(gè)簡(jiǎn)單頻率固定的脈寬調(diào)制控制器，適用于降壓型直流/直流轉(zhuǎn)換器，它引起的誤差電壓（ve）的變化相對(duì)于開(kāi)關(guān)頻率變化可能會(huì)比較慢，脈沖寬度和占空比可以會(huì)比較的近似。Vp為鋸齒波形的振幅。</p><p&g

75、t;<b>　　( 1 )</b></p><p>　　圖7 LISN網(wǎng)絡(luò)阻抗與頻率</p><p>　　A. 脈寬調(diào)制波形的頻譜分析</p><p>　　標(biāo)準(zhǔn)脈沖序列m（t）在圖8中 代表的是脈寬調(diào)制開(kāi)關(guān)電流的波形。第n個(gè)脈寬調(diào)制脈沖波形組成一個(gè)固定的部分D/fs，其中D表示為穩(wěn)定狀態(tài)的占空比，一個(gè)可變部分d n/ f s 表示由于來(lái)源，參考

76、和負(fù)載的變化而形成的占空比變化。</p><p>　　圖8壓降型直流/直流轉(zhuǎn)換器中的脈寬調(diào)制開(kāi)關(guān)直流波形</p><p>　　在電力供應(yīng)時(shí)，脈寬調(diào)制開(kāi)關(guān)電源波形中會(huì)包含有關(guān)電磁干擾的信息，它需要做的就是在電磁干擾研究頻率范圍內(nèi)分析波形的頻譜。推測(cè)出來(lái)的電壓誤差Ve和振幅Ve1的變化關(guān)系顯示在方程（2）中。</p><p><b>　　( 2 )</b

77、></p><p>　　調(diào)頻代表的是由于源，參數(shù)和負(fù)載的變化產(chǎn)生的誤差電壓頻率變化。截取的誤差電壓變化曲線和開(kāi)關(guān)頻率的鋸齒波，使方程（3）成為了對(duì)占空比的運(yùn)算。</p><p><b>　　( 3 )</b></p><p>　　圖9 脈寬調(diào)制頻譜（f s =25kHz, f m=100Hz, D=0.5, D1=0.05）</p&

78、gt;<p>　　它的穩(wěn)定值D在最大脈沖寬度變化范圍內(nèi)被限定在D1。每一個(gè)周期Tm=1/fm，這里是r=fs/fm脈沖和dn的占空比。方程（4）列出了脈寬調(diào)制波形m(t)的傅里葉級(jí)數(shù)系數(shù)Cn。Cn具有如圖9中顯示的頻譜。</p><p><b>　　( 4 )</b></p><p>　　B.等效噪音電路和電磁干擾頻譜分析</p><

79、p>　　為了達(dá)到圖6中的等效電路，電壓源Vs被短路了并且轉(zhuǎn)換器被開(kāi)關(guān)電源的脈寬調(diào)制波形所取代，這結(jié)果被顯示在圖10中。</p><p>　　傳遞函數(shù)被確定為用LISN網(wǎng)絡(luò)的輸出電壓比上電磁干擾的源電流，這些被顯示在方程（5）中。</p><p><b>　　( 5 )</b></p><p>　　這些系數(shù)di, ni (i = 1, 2,

80、 … , 4)對(duì)應(yīng)等效電路的參數(shù)。Rc和Lc分別表示等效電路中的等效串聯(lián)電阻（ESR）和等效串聯(lián)電感（ESL）。在這個(gè)模型中的元素即濾波電容CF是不理想的。線路阻抗穩(wěn)定網(wǎng)絡(luò)和過(guò)濾器的參數(shù)如下：CN = 100 nF, r = 5 Ω, l = 50 uH, RN =50 Ω, LN=250 uH, Lf = 0, Cf =0, Rc= 0, Lc= 0, fs =25 kHz </p><p>　　圖10電磁干擾

81、的等效電路</p><p>　　通過(guò)傳遞函數(shù)以及源噪聲頻譜的乘法推導(dǎo)出的電磁頻譜。其模擬結(jié)果顯示在圖11中。</p><p>　　圖11 電磁干擾頻譜</p><p>　　六、電磁干擾參數(shù)的影響</p><p><b>　　A．占空比</b></p><p>　　圖12 D等于0.25時(shí)的電磁干

82、擾頻譜</p><p>　　脈沖寬度在脈寬調(diào)制波形穩(wěn)定值D=0.5周?chē)兓?。輸出噪聲頻譜對(duì)數(shù)值D等于0.25時(shí)和D等于0.75時(shí)進(jìn)行了模擬，顯示在圖12和圖13中。在電磁兼容性中需要波形在偶次諧波時(shí)遞增，在奇次諧波時(shí)遞減，另一方面，噪聲能量分布在更廣泛的頻率范圍之內(nèi)并且電磁干擾的水平下降[11]。</p><p>　　圖13 D等于0.75時(shí)的電磁干擾頻譜</p><

83、p>　　圖14 D等于0.01時(shí)的電磁干擾頻譜</p><p>　　B．振幅占空比的變化</p><p>　　最大脈沖寬度的變化是由D1所決定的。對(duì)D1=0.05進(jìn)行了電磁干擾頻譜模擬。在D1=0.01 和D1=0.25重復(fù)模擬，結(jié)果顯示在圖14和圖15中。</p><p>　　圖15 D等于0.25時(shí)的電磁干擾頻譜</p><p>

84、　　D1的增加影響了電磁干擾信號(hào)頻率的調(diào)制，并且導(dǎo)致傳導(dǎo)電磁干擾程度的降低。放大圖15中關(guān)于第七分量附近的開(kāi)關(guān)頻率，并且在圖16中清晰地顯示調(diào)制頻率。</p><p><b>　　C、誤差電壓頻率</b></p><p>　　圖16 放大電磁干擾頻譜第七部分周?chē)拈_(kāi)關(guān)頻率</p><p>　　引起占空比變化的主要因素是電源電壓的變化。在FM等于

85、100赫茲時(shí)，整流器的使用會(huì)引起電源電壓的波動(dòng)。仿真實(shí)驗(yàn)是對(duì)頻率fm等于5000Hz時(shí)進(jìn)行重復(fù)的仿真。在圖17中顯示了給調(diào)頻波一個(gè)較高頻率讓其在噪音頻譜頻域之中擴(kuò)展。另一方面，在參考電壓中故意加入一個(gè)高頻信號(hào)的方法是理想的。</p><p>　　圖17 fm等于5000Hz時(shí)的電磁干擾頻譜</p><p>　　圖18 D等于0.75,D1等于0.25,fm等于5000Hz時(shí)的電磁干擾頻譜&

86、lt;/p><p><b>　　D．參數(shù)的聯(lián)合作用</b></p><p>　　同時(shí)應(yīng)用D=0.75,D1=0.25和fm=5000赫茲進(jìn)行模擬的結(jié)果使電磁干擾頻譜擴(kuò)展到了一個(gè)更寬的頻率，有關(guān)電磁干擾的程度下降，這些都被顯示在圖18之中。</p><p><b>　　七、結(jié)論</b></p><p>　

87、　本論文提到了由于快速地開(kāi)關(guān)半導(dǎo)體器件會(huì)在電力電子轉(zhuǎn)換器中出現(xiàn)電磁干擾，電磁干擾有輻射干擾和傳導(dǎo)干擾兩種，本論文研究了兩者之中的傳導(dǎo)干擾。論文中對(duì)相容性的法規(guī)和傳導(dǎo)干擾的測(cè)量進(jìn)行了解釋。本文對(duì)線路阻抗穩(wěn)定網(wǎng)絡(luò)進(jìn)行了描述，它是除了拓?fù)浣Y(jié)構(gòu)，參數(shù)和工藝之外測(cè)量過(guò)程中的一個(gè)重要組成部分。本文對(duì)壓降型脈寬調(diào)制 直流/直流 轉(zhuǎn)換器的電磁干擾進(jìn)行了考慮和模擬。對(duì)于現(xiàn)在的機(jī)構(gòu)，減少電磁干擾的水平是非常必要的。這表明壓降型脈寬調(diào)制開(kāi)關(guān)電源的電磁干擾程度

88、可以減弱，通過(guò)控制占空比，占空比變化以及參考電壓頻率的參數(shù)。</p><p><b>　　八、參考文獻(xiàn)</b></p><p>　　[1] Mohan, Undeland, and Robbins, “Power Electronics Converters, Applications and Design” 3rd edition, John Wiley &

89、 Sons, 2003. </p><p>　　[2] P. Moy, “EMC Related Issues for Power Electronics”, IEEE, Automotive Power Electronics, 1989, 28-29 Aug. 1989 pp. 46 – 53. </p><p>　　[3] M. J. Nave, “Prediction of Con

90、ducted Interference in Switched Mode Power Supplies”, Session 3B, IEEE International Symp. on EMC, 1986. </p><p>　　[4] Henderson, R. D. and Rose, P. J., “Harmonics and their Effects on Power Quality and Tran

91、sformers”, IEEE Trans. On Ind. App., 1994, pp. 528-532. </p><p>　　[5] I. Kasikci, “A New Method for Power Factor Correction and Harmonic Elimination in Power System”, Proceedings of IEEE Ninth International

92、Conference on Harmonics and Quality of Power, Volume 3, pp. 810 – 815, Oct. 2000. </p><p>　　[6] M. J. Nave, “Line Impedance Stabilization Networks: Theory and Applications”, RFI/EMI Corner, April 1985, pp. 5

93、4-56. </p><p>　　[7] T. Williams, “EMC for Product Designers” 3rd edition 2001 Newnes. </p><p>　　[8] B. Keisier, “Principles of Electromagnetic Compatibility”, 3rd edition ARTECH HOUSE 1987. <

94、/p><p>　　[9] J. C. Fluke, “Controlling Conducted Emission by Design”, Vanhostrand Reinhold 1991. </p><p>　　[10] M. Daniel,”DC/DC Switching Regulator Analysis”, McGrawhill 1988 </p><p>