開關(guān)電源外文翻譯

1、電氣信息工程學院 外 文 翻 譯原文名稱：Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply 譯文名稱：基于壓降型PWM開關(guān)電源的建模、仿真和減少傳導性電磁干擾 專 業(yè)： 電氣工程及其自動化 姓 名： 班級學號： 指導教師： 譯文出處：0:8000/rewriter/EI 二一七 年 四 月 三 日 Modeling, Simulation, and Reductio

2、n of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply A. Farhadi Abstract: Undesired generation of radiated or conducted energy in electrical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters espec

3、ially in switching power supplies improves efficiency but leads to EMI. Different kind of conducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power elec

4、tronic systems producers must regard EMC. Modeling and simulation is the first step of EMC evaluation. EMI simulation results due to a PWM Buck type switching power supply are presented in this paper. To improve EMC, some techniques are introduced and their effectiveness proved by simulation. Index

5、Terms: Conducted, EMC, EMI, LISN, Switching Supply I. INTRODUCTION FAST semiconductors make it possible to have high speed and high frequency switching in power electronics . High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency inter

6、ference appeared . Compliance with electromagnetic compatibility (EMC) regulations 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 analyze EMC consideration before

7、 developing the products. A lot of the previous studies concerned the low frequency analysis of power electronics components . Different types of power electronics converters are capable to be considered as source of EMI. They could propagate the EMI in both radiated and conducted forms. Line Impeda

8、nce Stabilization Network (LISN) is required for measurement and calculation of conducted interference level . Interference spectrum at the output of LISN is introduced as the EMC evaluation criterion . National or international regulations are the references for the evaluation of equipment in point

9、 of view of EMC . II. SOURCE, PATH AND VICTIM OF EMI 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 interference. Interference propagated by radiation in area around of an interfere

10、nce source or by conduction through common cabling or wiring connections. In this study conducted emission is considered only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of ele

11、ments, source lines and cabling provide paths for conducted noise or interference. Electromagnetic conducted interference has two components as differential mode and common mode . A. Differential mode conducted interference This mode is related to the noise that is imposed between different lines of

12、 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 in Fig. 1. B. Common mode conducted interference Common mode noise or interference could appear and impose between the li

13、nes, cables or connections and common ground. Any leakage current between load and common ground could be modeled by interference voltage source. Fig. 2 demonstrates the common mode interference source, common mode currents Icm1 and Icm2 and the related current paths. The power electronics converter

14、s 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 continued considering this mode only. III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS Application of electrical equipment especiall

15、y static power electronic converters in different 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 . High level of pollution resulting fr

16、om various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers are so sensitive to power system disturbances including voltage and frequency variations. The best solution to reduce corruption and improve powe

17、r quality is complying national or international EMC regulations. CISPR, IEC, FCC and VDE are among the most famous organizations from Europe, USA and Germany who are responsible for determining and publishing the most important EMC regulations. IEC and VDE requirement and limitations on conducted e

18、mission are shown in Fig. 3 and Fig. 4 . For different 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 range of limitation is different for

19、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 level in the mentioned frequency range with the stated requirements in regulations. In united European community compl

20、iance of regulation is mandatory and products must have certified label to show covering of requirements . IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENT A. Line Impedance Stabilization Network (LISN)1-Providing a low impedance path to transfer power from source to power electronics converte

21、r and load. 2-Providing a low impedance path from interference source, here power electronics converter, to measurement port. 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 . Var

22、iation 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 spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 k

23、Hz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations. In practical situations, the LISN output is connected to a spectrum analyzer and interference measurement is carried out. But for modeling and simulation purposes, the LISN output spec

24、trum is calculated using appropriate software. V.SIMULATION OF EMI DUE TO A PWM BUCK TYPE SWITCHINGPOWER SUPPLY For a simple fixed frequency 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,

25、 the pulse width and hence the duty cycle can be approximated by (1). Vp is the saw tooth waveform amplitude. A. PWM waveform spectral analysis The normalized pulse train m (t) of Fig. 8 represents PWM switch current waveform. The nth pulse of PWM waveform consists of a fixed component D/fs , in whi

26、ch 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 and load. As the PWM switch current waveform contains information concerning EMI due to power supply, it is required to do the spectrum analysis of th

27、is waveform in the frequency range of EMI studies. It is assumed that error voltage varies around Ve with amplitude of Ve1 as is shown in (2). fm represents the frequency of error voltage variation due to the variations of source, reference and load. The interception of the error voltage variation c

28、urve and the saw tooth waveform with switching frequency, leads to (3) for the computation of duty cycle coefficients. Maximum variation of pulse 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) p

29、resents the Fourier series coefficients Cn of the PWM waveform m (t). Which have the frequency spectrum of Fig.9. B-Equivalent noise circuit and EMI spectral analysis To attain the equivalent circuit of Fig.6 the voltage source Vs is replaced by short circuit and converter is replaced by PWM wavefor

30、m switch current (Iex) as it has shown in Fig. 10. The transfer function is defined as the ratio of the LISN output voltage to the EMI current source as in (5). The coefficients di, ni (i = 1, 2, , 4) correspond to the parameters of the equivalent circuit. Rc and Lc are respectively the effective se

31、ries resistance (ESR) and inductance (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 , l = 50 uH, RN =50 , LN=250 uH, Lf = 0, Cf =0, Rc= 0, Lc= 0, fs =25 kHz The EMI spectrum is derived by multiplication

32、of the transfer function and the source noise spectrum. Simulation results are shown in Fig. 11. VI. PARAMETERS AFFECTION ON EMI A. Duty Cycle 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 shown in

33、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 of EMI decreased . B. Amplitude of duty cycle variation The maximum pulse width variat

34、ion is determined by D1. The EMI spectrum was simulated with D1=0.05. Simulations are repeated with D1=0.01 and 0.25 and the results are shown in Fig.14 and Fig.15.Increasing of D1 leads to frequency modulation of the EMI signal and reduction in level of conducted EMI. Zooming of Fig. 15 around 7th

35、component of switching frequency in Fig. 16 shows the frequency modulation clearly. C. Error voltage frequency The main factor in the variation of duty cycle is the variation of source voltage. The fm=100 Hz ripple in source voltage is the inevitable consequence of the usage of rectifiers. The simul

36、ation is repeated in the frequency of fm=5000 Hz. It is shown in Fig. 17 that at 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

37、y. D. Simultaneous effect of parameters 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 frequencies and considerable reduction in EMI level is shown in Fig. 18. VII. CONCLUSION Appearance of Electromagnetic Interfer

38、ence due to the fast switching semiconductor devices 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 regulations and conducted inter

39、ference measurement were explained. LISN as an important part of measuring process besides its topology, parameters and impedance were described. EMI spectrum due to a PWM Buck type DC/DC converter was considered and simulated. It is necessary to present mechanisms to reduce the level of Electromagn

40、etic interference. It shown that EMI due to a PWM Buck type switching power supply could be reduced by controlling parameters such as duty cycle, duty cycle variation and reference voltage frequency. VIII. REFRENCES 1 Mohan, Undeland, and Robbins, “Power Electronics Converters, Applications and Desi

41、gn” 3rd edition, John Wiley & Sons, 2003. 2 P. Moy, “EMC Related Issues for Power Electronics”, IEEE, Automotive Power Electronics, 1989, 28-29 Aug. 1989 pp. 46 53. 3 M. J. Nave, “Prediction of Conducted Interference in Switched Mode Power Supplies”, Session 3B, IEEE International Symp. on EMC, 1986

42、. 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. 5 I. Kasikci, “A New Method for Power Factor Correction and Harmonic Elimination in Power System”, Proceedings of IEEE Ninth International Conference on

43、 Harmonics and Quality of Power, Volume 3, pp. 810 815, Oct. 2000. 6 M. J. Nave, “Line Impedance Stabilization Networks: Theory and Applications”, RFI/EMI Corner, April 1985, pp. 54-56. 7 T. Williams, “EMC for Product Designers” 3rd edition 2001 Newnes. 8 B. Keisier, “Principles of Electromagnetic C

44、ompatibility”, 3rd edition ARTECH HOUSE 1987. 9 J. C. Fluke, “Controlling Conducted Emission by Design”, Vanhostrand Reinhold 1991. 10 M. Daniel,”DC/DC Switching Regulator Analysis”, McGrawhill 1988 11 M. J. Nave,” The Effect of Duty Cycle on SMPS Common Mode Emission: theory and experiment”, IEEE N

45、ational Symposium on Electromagnetic Compatibility, Page(s): 211-216, 23-25 May 1989. 基于壓降型PWM開關(guān)電源的建模、仿真和減少傳導性電磁干擾作者：A. Farhadi國籍：伊朗摘要：電子設備之中雜亂的輻射或者能量叫做電磁干擾(EMI)。尤其是在開關(guān)電源中的電力電子轉(zhuǎn)換器經(jīng)常高速切換時，雖然提高了工作效率，卻導致轉(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干擾，電磁干擾規(guī)章以及傳導性電磁干擾的測量。如果電子設備的電磁干擾符合國家或者國際規(guī)章稱為電磁兼容性（EMC）。電力電子系統(tǒng)生產(chǎn)商一定要重視電子

46、設備的電磁兼容性。電磁兼容性評估的第一步就是建模和仿真。在這篇論文中提出了基于壓降型脈寬調(diào)制開關(guān)電源的電磁干擾仿真結(jié)果。為了提高電子設備的電磁兼容性,在論文中介紹了一些技術(shù)，并且通過仿真提高了電子設備的工作效率。關(guān)鍵字：傳導，電磁兼容性，電磁干擾，線路阻抗穩(wěn)定網(wǎng)絡，開關(guān)電源一、前言在電力電子領(lǐng)域中，快速半導體的出現(xiàn)使高速度，高頻率的開關(guān)切換成為了可能1。高速的開關(guān)造成設備的重量和體積的減少，但與此同時這也造成了一些不利的影響，比如無線頻率的干擾2。生產(chǎn)商將生產(chǎn)的產(chǎn)品投放到市場，遵守電磁兼容性規(guī)章是必要的。在設計階段考慮電磁兼容性問題是非常重要的3。在開發(fā)產(chǎn)品前，建模和仿真是分析電磁兼容性最有效

47、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45。不同類型的電力電子轉(zhuǎn)換器都能夠被用來當做電磁的干擾源。電磁干擾源可以通過輻射和傳導兩種方式來傳播。線路阻抗穩(wěn)定網(wǎng)絡被用來測量和計算電磁干擾影響的程度6。線路阻抗穩(wěn)定網(wǎng)絡輸出的干擾頻譜被引為電磁兼容性的評估標準7,8。國家或國際規(guī)章是電子設備電磁兼容性評估的一個參考的方面78。二、來源、途徑和電磁干擾的受害者雜亂的電壓或者電流被稱為干擾，而它們的來源被稱為干擾源。本論文中的干擾源就是一個高速的開關(guān)電源。干擾通過輻射的方式在干擾源周圍傳播或通過和常見的電纜或電線連接進行傳導。在這項研究中只考慮傳導發(fā)射設備，如電腦，接收器，放大器，工業(yè)控制

48、器等。這些被干擾源輻射的設備被稱為受害者。常見的元素，源頭接線，布線為噪聲以及干擾的傳導提供了途徑。電磁傳導干擾有差模和共模兩種干擾方法9。A.差模傳導干擾這種模式就是將一個噪聲源的噪聲施加到一個測試電路的不同線路。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，差模電流以及負載阻抗。圖1差模傳導干擾路徑B.常見的干擾方式共模噪聲或干擾可能出現(xiàn)在電線或者電纜的連接點。負載和接地點的任意泄露都可以被認為是電壓干擾源。圖2演示了共模干擾源在共模電流為Icm1和Icm2時相關(guān)的電流路徑9。電力電子轉(zhuǎn)換器可以被用來作為供應網(wǎng)絡線路之間的噪音源。在這項研究中不同的傳導干擾模式是非常重要的，所以

49、討論只會在這種模式下被繼續(xù)考慮。三、電磁兼容性規(guī)章電子設備的應用，特別是那些擁有靜態(tài)電力電子轉(zhuǎn)換器的電子設備越來越多。就像前面講的一樣，電力電子轉(zhuǎn)換器被視為一個重要的電磁干擾源，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家或國際電磁兼容性規(guī)定。國際無線電干擾特別委員會，國際電工委員會標準，美國聯(lián)邦通訊委員會和德國電氣工程師協(xié)會認證是歐洲，美國，德國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在傳導發(fā)射上的需要和限制如圖 3 和

50、圖 4所示7,9。 圖2共模傳導干擾路徑圖3 IEC管理排放標準不同的消費者群體可以遵守不同類別的規(guī)定。A類為普通的消費者，B類為具有更苛刻限制的消費者，在圖 3 和圖 4這兩者被分開。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 30 兆赫茲，在上述法規(guī)規(guī)定要求的頻率范圍內(nèi)，法規(guī)的遵守情況被用來測量或者計算傳導干擾的水平。在歐美社會電磁兼容性法規(guī)的遵行是強制的，產(chǎn)品必須要有認證的標簽以表示達到法規(guī)的要求8。 圖4 VDE管理排放標準四、電磁傳導干擾測試A. 線路阻抗穩(wěn)定網(wǎng)絡（LISN）線路阻抗穩(wěn)定網(wǎng)絡是提供一個標準的工業(yè)元素被放置在供應

51、和電力電子轉(zhuǎn)換器之間， 包括加載一個接口以便可以對傳導干擾進行測量7，所述的情況如圖5 所示6。線路阻抗穩(wěn)定網(wǎng)絡應具有以下幾個特點，以滿足測量條件7。1- 提供一個低阻抗路徑轉(zhuǎn)移源動力到電力電子轉(zhuǎn)換器以及負載。2- 干擾源提供一個低阻抗路徑，電力電子轉(zhuǎn)換器用來測量路徑端口。 圖5 LISN網(wǎng)絡布局測量傳導干擾B. 線路阻抗穩(wěn)定網(wǎng)絡拓撲線路阻抗穩(wěn)定網(wǎng)絡比較常見的拓撲結(jié)構(gòu)如圖6所示7。圖6 LISN網(wǎng)絡常見的拓撲結(jié)構(gòu)圖7中給出了線路阻抗穩(wěn)定網(wǎng)絡的阻抗與頻率的變化以及前面提到的拓撲結(jié)構(gòu)。線性阻抗穩(wěn)定網(wǎng)絡在電磁干擾測量范圍之內(nèi)擁有穩(wěn)定的阻抗7。線路阻抗穩(wěn)定網(wǎng)絡輸出的信號電平與頻率的變化就是干擾頻譜。一

52、個系統(tǒng)的電磁兼容性可以通過比較它的干擾頻譜和標準的限制來進行評估。線路阻抗穩(wěn)定網(wǎng)絡輸出的信號電平范圍在10千赫茲 到30 千赫茲 或者150 千赫茲 到30兆赫茲之間，這就是標準的電磁兼容性，并且它處在標準的限定范圍里。在實際的情況下，線路阻抗穩(wěn)定網(wǎng)絡是連接到頻譜分析儀上進行干擾測量的。但是為了建模和仿真的目的，線路阻抗穩(wěn)定網(wǎng)絡的輸出頻譜是通過相應的軟件來進行計算的。五、基于壓降型脈寬調(diào)制開關(guān)電源的電磁干擾模擬對于一個簡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）的變化相對于開關(guān)頻率變化可能會比較慢，脈沖寬度和占空比可以會比較的近似。Vp為鋸齒波形的振幅。

53、 ( 1 )圖7 LISN網(wǎng)絡阻抗與頻率A. 脈寬調(diào)制波形的頻譜分析標準脈沖序列m（t）在圖8中 代表的是脈寬調(diào)制開關(guān)電流的波形。第n個脈寬調(diào)制脈沖波形組成一個固定的部分D/fs，其中D表示為穩(wěn)定狀態(tài)的占空比，一個可變部分d n/ f s 表示由于來源，參考和負載的變化而形成的占空比變化。圖8壓降型直流/直流轉(zhuǎn)換器中的脈寬調(diào)制開關(guān)直流波形在電力供應時，脈寬調(diào)制開關(guān)電源波形中會包含有關(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。推測出來的電壓誤差Ve和振幅Ve1的變化關(guān)系顯示在方程（2）中。 ( 2 )調(diào)頻代表的是由于源，參數(shù)和負載的變化產(chǎn)生的誤差電壓頻率變化。截取的誤

54、差電壓變化曲線和開關(guān)頻率的鋸齒波，使方程（3）成為了對占空比的運算。 ( 3 ) 圖9 脈寬調(diào)制頻譜（f s =25kHz, f m=100Hz, D=0.5, D1=0.05）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)的傅里葉級數(shù)系數(shù)Cn。Cn具有如圖9中顯示的頻譜。 ( 4 )B.等效噪音電路和電磁干擾頻譜分析為了達到圖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。傳遞函數(shù)被確定為用LISN網(wǎng)絡的輸出電壓比上電磁干擾的源電流，這

55、些被顯示在方程（5）中。 ( 5 )這些系數(shù)di, ni (i = 1, 2, , 4)對應等效電路的參數(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)絡和過濾器的參數(shù)如下：CN = 100 nF, r = 5 , l = 50 uH, RN =50 , LN=250 uH, Lf = 0, Cf =0, Rc= 0, Lc= 0, fs =25 kHz 圖10電磁干擾的等效電路通過傳遞函數(shù)以及源噪聲頻譜的乘法推導出的電磁頻譜。其模擬結(jié)果顯示在圖11中。圖11 電磁干擾頻譜六、電磁干擾參數(shù)的影響A占空比

56、圖12 D等于0.25時的電磁干擾頻譜脈沖寬度在脈寬調(diào)制波形穩(wěn)定值D=0.5周圍變化。輸出噪聲頻譜對數(shù)值D等于0.25時和D等于0.75時進行了模擬，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遞增，在奇次諧波時遞減，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。 圖13 D等于0.75時的電磁干擾頻譜 圖14 D等于0.01時的電磁干擾頻譜B振幅占空比的變化最大脈沖寬度的變化是由D1所決定的。對D1=0.05進行了電磁干擾頻譜模擬。在D1=0.01 和D1=0.25重復模擬，結(jié)果顯示在圖14和圖15中。 圖15 D等于0.25時的電磁干擾頻譜D1的增加影響了電磁干擾信號頻率的調(diào)制，并且導致傳導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關(guān)頻率，并且在圖16中清晰地顯示調(diào)制頻率。C、誤差電壓頻率 圖16 放大電磁干擾頻譜第七部分周圍的開關(guān)頻率引起占空比變化的主要因素是電源電壓的變化。在FM等于100赫茲時，