外文翻譯---低電壓反激式dc-dc轉換器的在電源中的應用

1、<p>　　Low Voltage Flyback DC-DC Converter For</p><p>　　Power Supply Applications</p><p>　　Hangzhou Liu1, John Elmes2, Kejiu Zhang1, Thomas X. Wu1, Issa Batarseh1</p><p>　　Depar

2、tment of Electrical Engineering and Computer Science,</p><p>　　University of Central Florida, Orlando, FL 32816, USA</p><p>　　Advanced Power Electronics Corporation, Orlando, FL 32826, USA</p

3、><p>　　Abstract — In this paper, we design a low voltage DC-DC converter with a flyback transformer. The converter will be used as a biased power supply to drive IGBTs. The flyback transformer using planar EI-c

4、ore is designed and simulated using ANSYS PExprt software. Besides, anLT3574 IC chip from Linear Technology has been chosen for converter control. Finally, the converter modeling and simulation are presented and PCB layo

5、ut is designed.</p><p>　　Keywords：Flyback, anLT3574IC, PCB </p><p>　　INTRODUCTION</p><p>　　The goal of this project is to develop and build a prototype of a high-efficiency, high-t

6、emperature isolated DC-DC converter to be used as a biased power supply for driving a complementary IGBT pair. It is important that the converter can deliver the required power at an ambient temperature of up to 100℃; th

7、erefore it has to be efficient so that its components do not exceed their maximum temperature ratings. The final converter will be completely sealed and potted in a metal case. The input volt</p><p>　　KEY DE

8、SIGN OUTLINE </p><p>　　For this flyback topology, the output voltage can be determined by both the transformer turns ratio and the flyback loop resistor pairs. Therefore, at the initial design stage, we can

9、choose a convenient turn’s ratio for the transformer, and modify it later on if necessary to make sure the output performance is desirable and the transformer will not saturate [1].</p><p>　　The relationship

10、 between transformers turns ratio and duty cycle can be found as</p><p>　　Where n is the transformer turns ratio, D is the duty cycle, VO` is the sum of the output voltage plus the rectifier drop voltage, VI

11、N is the input voltage of the transformer.</p><p>　　The value of feedback resistor can be calculated as</p><p>　　Where RREF is the reference resistor, whose value is typically 6.04k?; α is a con

12、stant of 0.986;VBG is the internal band gap reference voltage, 1.23V; and VTC is normally 0.55V [1].</p><p>　　With a specific IC chosen, the converter circuit can be designed based on a demo circuit and some

13、 parameters may need to be modified if necessary to optimize the performance. Furthermore, in LT Spice, a large number of simulations need to be done with different conditions such as load resistor values and input volta

14、ge levels. It is important to make sure that the output voltage can be regulated well with all these different conditions.</p><p>　　The most critical part of the design is the flyback transformer. With high

15、switching frequency, the AC resistance can only be estimated based on some traditional methods such as Dowell’s curve rule [2].In order to get more accurate values of AC resistance values; we propose to use finite elemen

16、t electromagnetic software ANSYS PExprt to do the design [3]. At the initial design stage, key parameters such as the worst-case input voltage, frequency, material, inductance values will be decided. After</p><

17、;p>　　CONVERTER SIMULATION RESULTS</p><p>　　We choose LT3574 chip in this design. From the simulation results in Figure 1 and Table 1, it clearly shows that the output voltages which are﹢16V and -6V respec

18、tively can be regulated pretty well with the input voltage range from 9V to 36V. The voltage tolerance ranges are from ﹢15V to ﹢19V and -12V to - 5V, respectively. In addition, the current is also under control, which is

19、 around 100mA in this design</p><p>　　Figure 1 . Output voltage and current simulation results</p><p>　　Table 1 . LT Spice simulation resuits</p><p>　　TRANSFORMER SIMULATION RESULTS

20、</p><p>　　With the initial design parameters of the transformer, we use ANSYS PExprt to simulate and further optimize the transformer [4].Figure 2 shows the primary winding voltage. In order to make the tran

21、sformer work correctly in all cases, it is important to make sure that it can work at the worst case, which is the minimum input voltage in the range. Figure 3 shows the current through the primary winding.</p>&l

22、t;p>　　Figure 2 . Voltage of the primary winding</p><p>　　Figure 3 . Current of the primary winding</p><p>　　Since it is a low power converter in this design, it is critical to minimize the po

23、wer losses. We choose to use the planar type transformer structure. After doing the winding interleaving, the power loss can be reduced by approximately 25% and the temperature rise can be reduced by approximately 15% [5

24、].The structure can be found in Figure 4. The primary winding is marked in yellow, which has 6 turns in series. The first secondary winding is marked in red, which has 3 turns in parallel. The seco</p><p>　　

25、Figure 4 . Winding geometry by interleaving method</p><p>　　Based on the computer simulation, the 6-layer planar transformer winding structure can be drawn in Figures 5 -10. The primary side winding has 6 tu

26、rns in series. In Figures 6 and 9, it clearly shows that the turns in different layers are connecting through via hole. In one of the secondary winding which is the +16V one, it has 3 turns in parallel as shown in Figure

27、s 5, 8 and 10. The one turn secondary winding (6V) is shown in Figure 7.</p><p>　　Figure 5 . Top layer winding structure (secondary 1)</p><p>　　Figure 6 . Inner Layer 1 winding structure (primar

28、y)</p><p>　　Figure 7 . Inner Layer 2 winding structure (secondary 2)</p><p>　　Figure 8 . Inner Layer 3 winding structure (secondary 1)</p><p>　　Figure 9 . Inner Layer 4 winding stru

29、cture (primary)</p><p>　　Figure 10 . Bottom layer winding structure (secondary 1)</p><p>　　The core loss of the transformer is approximately 47mW, comparing to the winding loss of 154mW, it i s

30、about 30%, as shown in Figure 11 [7].</p><p>　　Figure 11. Power loss of transformer</p><p>　　The E-I core transformer PCB in this design will be integrated into the converter’s PCB, rather than

31、a separate board being added to the whole circuit [8], which will reduce the cost of the PCB fabrication since multi-layer PCB layout is expensive.</p><p>　　CONVERTER CIRCUIT PCB LAYOUT</p><p>　

32、　In this project, we make the transformer part layout as one component; it will be integrated into the whole circuit PCB layout. It has 6 layers totally. The isolation requirement is 1500V, so the layout takes a little m

33、ore space than the one without any isolation rules. In Figure 12, we make the primary side components all in the right hand side of the board, the secondary sides all in the left hand side of the board, and the transform

34、er in between them.The wire traces have been marked with dif</p><p>　　Figure 12. PCB layout of the flyback converter</p><p>　　CONCLUSION</p><p>　　In this paper, a flyback DC - DC c

35、onverter for low voltage power supply application has been designed. The modeling and simulation results are presented. Based on the design specifications, a suitable IC from Linear Technology is chosen. A large amount o

36、f circuit simulations with different conditions such as load resistor values and input voltage levels are presented to get the desirable output voltage and current performance. The transformer has been designed including

37、 electrical, mechanical an</p><p><b>　　REFERENCE</b></p><p>　　[1] Linear Technology Application Notes , Datasheet of Isolated Flyback Converter Without an Opto-Coupler, http://cds.

38、linear.com/docs /Datasheet/3574f.pdf.</p><p>　　[2] P.L.Dowell, “Effect of eddy currents in transformer windings” Proceedings of the IEE, NO.8 PP.1387-1394, Aug 1966. </p><p>　　[3] S.Xiao, “Pla

39、nar Magnetics Design for Low- Voltage DC-DC Converters” MS, 2004.</p><p>　　[4] ANSYS Application Notes, PEmag Getting Started: A Transformer Design Example, http://www.cadfamily.com/download/ EDA/Maxwell9/pl

40、anarGS0601.pdf.</p><p>　　[5] K. Zhang; T. X.Wu; H.Hu; Z. Qian; F.Chen.; K.Rustom; N.Kutkut; J.Shen; I.Batarseh; "Analysis and design of distributed transformers for solar power conversion" 2011 IEE

41、E Applied Power Electronics Conference and Exposition (APEC), v l., no., pp.1692-1697, 6-11 March 2011. </p><p>　　[6] Zhang.; T.X.Wu.; N.Kutkut; J.Shen; D.Woodburn; L.Chow; W.Wu; H.Mustain; I. Batarseh; ,&qu

42、ot;Modeling and design optimization of planar power transformer for aerospace applic ation," Proceedings of the IEEE 2009 National, Aerospace & Electronics Conference (NAECON) , vol., no., pp.116-120, 21-23 July

43、 2009. </p><p>　　[7] Ferroxcube Application Notes, Design of Planar Power Transformer, </p><p>　　低電壓反激式DC-DC轉換器的在電源中的應用</p><p>　　Hangzhou Liu1, John Elmes2, Kejiu Zhang1, Thomas X.

44、 Wu1, Issa Batarseh1</p><p>　　Department of Electrical Engineering and Computer Science, </p><p>　　University of Central Florida, Orlando, FL 32816, USA</p><p>　　Advanced Power Elec

45、tronics Corporation, Orlando, FL 32826, USA</p><p>　　摘要：在本文中，我們設計了一個低電壓反激式DC-DC轉換器。該轉換器將被用來作為一個偏置電源來驅動器的IGBT。該反激式變壓器采用平面EI磁芯設計并且使用ANSYS PExprt軟件仿真。此外，該變換器控制芯片選用凌力爾特公司的anLT3574IC芯片。最后，介紹該轉換器的建模與仿真和PCB布局設計。<

46、;/p><p>　　關鍵詞：反激式,，anLT3574IC，PCB</p><p><b>　　1．引 言</b></p><p>　　該項目的目標是開發(fā)和建立一個高效率的原型，高溫隔離式DC-DC轉換器，作為偏置電源用來驅動一對互補的IGBT。更重要的是，該轉換器可提供所需的功率，在環(huán)境溫度高達 100℃，因此它必須是高效的，以便它的組件不超過

47、其最大額定溫度。最終轉換器將用金屬外殼完全密封。該轉換器的輸入電壓范圍為9V至36V。輸出端有兩個接地端子，一個是+16 V，而另一個是﹣6V。為了獲得所需的性能，采用了凌力爾特anLT3574 IC芯片。這種設計的關鍵是在反激式變壓器。變壓器采用平面EI磁芯設計且使用ANSYS PExprt軟件仿真。最后，介紹了該轉換器的印刷電路板的布局。</p><p><b>　　2．關鍵的設計大綱</b&

48、gt;</p><p>　　對于這種反激式拓撲結構，輸出電壓可以通過變壓器匝數比和反激回路電阻確定。因此，在最初的設計階段，我們可以選擇一個簡便的變壓器匝數比，以后如有必要通過修改變壓器匝數比，確保變壓器的輸出性能是可靠的，不會飽和[1]。</p><p>　　變壓器匝數比和占空比之間的關系可以得到</p><p>　　其中，n是變壓器的匝數比，D為占空比，VO是輸

49、出電壓加上整流電壓降的總和，Vin是變壓器的輸入電壓。</p><p>　　反饋電阻的值可以計算為</p><p>　　其中，RREF是參考電阻，其值通常是6.04kΩ。α是一個常數0.986 VBG是內部帶隙參考電壓，1.23V和V TC 通常是0.55V [1]。</p><p>　　與一個特定的集成電路的選擇相比，轉換器電路設計的基于一個參數可修改的演示電路，

50、如有必要，修改某些可能需要修改的參數來優(yōu)化電路性能。此外，在LT Spice，需要大量的做不同的條件下的仿真，如負載的電阻值和輸入電壓值。更重要的是要確保，在所有這些不同的條件下，輸出電壓是可調節(jié)的。</p><p>　　最關鍵的部分的設計是反激式變壓器。在高開關頻率下，交流電阻參數只能基于在一些傳統(tǒng)的方法上，如Dowell的曲線規(guī)則[2]，進行估計。為了得到更準確的值的交流電阻值，我們建議使用電磁學有限元發(fā)分析

51、軟件ANSYS PExprt做設計[3]。在最初的設計階段，關鍵的參數，例如在最壞情況下的輸入電壓，頻率，素材，電感值將被決定。之后，這些數據將被導入到軟件中，從中將產生一個優(yōu)化的解決方案。</p><p>　　3. 轉換器的仿真結果</p><p>　　在這個設計中我們選擇的LT3574芯片。從圖1和表1的仿真結果，它清楚地表明，輸出電壓分別是+16 V，-6V在從9V至36V的輸入電壓

52、范圍可調節(jié)效果相當不錯。輸出電壓所能承受的電壓范圍分別是從+15 V至+19 V和-12V - 5V。另外，電流也在控制范圍中，其中在本設計中是大約100毫安。</p><p>　　圖1. 輸出電壓和電流的模擬結果</p><p>　　表1 . LT Spice仿真結果</p><p>　　4. 變壓器仿真結果</p><p>　　與最初的

53、設計參數的變壓器中，我們使用ANSYS PExprt仿真來進一步優(yōu)化變壓器設計[4]。圖2 示出的初級繞組電壓。為了使變壓器在所有的情況下的正常工作，更重要的是要確保，它可以在最壞的情況下工作，且在輸入電壓最低限度范圍內。圖3顯示了通過初級繞組的電流 。</p><p>　　圖2在初級繞組的電壓 圖 3.初級繞組的電流</p><p>　　在本設計中因

54、為它是一個低功耗的轉換器，關鍵是盡量減少功率損耗。我們選擇使用平面型變壓器的構造。交錯繞組后，功率損耗可以降低約25％，并且可減少約15％的溫升。這種交錯繞組的結構，可以參見在圖4。初級繞組被標記為黃色，有6匝串聯(lián)。第一次級繞組被標記為</p><p>　　圖 4.繞組幾何交織方法</p><p>　　紅色，其中有3圈并聯(lián)。第二次級繞組被標記為藍色，其中有1圈。這將是總共6層的多層變壓器結

55、構[6]。</p><p>　　根據在計算機上仿真，6層的平面變壓器繞組結構可以如圖5 -10中那樣繪制。初級側繞組串聯(lián)有6匝。在圖6和9中，它清楚地表明，在不同的層中的匝數，通過導通孔連接。+16 V一個繞組與一個次級繞組連接，它具有圖5，圖8和圖10中3匝并聯(lián)連接3匝。圖7中所示為次級繞組的一匝（6V）。</p><p>　　圖5. 頂層繞組結構（中一）

56、圖6. 內1層繞組結構（主）</p><p>　　圖7.內部第2層繞組結構（中2） 圖8.內部第3層繞組結構（中一）</p><p>　　圖 9. 內4層繞組結構（主） 圖10.底層繞組結構（中1）</p><p>　　該變壓器的磁心損耗是約47MW，同154mW的繞組損耗相比，它的損耗約30％，如在圖11中所示的[7]。</p>&l

57、t;p>　?。ㄗ髨D） 圖11.變壓器的功率損耗</p><p>　　該EI芯變壓器印刷電路板的計將被集成到轉換器的印刷電路板上，而不是一個單獨的電路板被添加的整個電路中[8]，這將降低由多層PCB布局而產生昂貴的PCB制造工藝的成本。</p><p>　　5. 轉換電路 PCB布局</p><p>　　在這個項目中，我們使變壓器部分布局的一個組成部分，它將被

58、集成到整個電路的PCB布局。它 總共 有 6層。隔離的要求是1500V，所以布局需要更多一點的空間比一個沒有任何隔離規(guī)則。如圖12中，我們將初級側元件放置在印刷電路板的右邊，二級側元件放置在印刷電路板的左邊，轉換器放置在他們中間。電線的痕跡已用不同顏色標記，以顯示指定層的痕跡是在電路板面積大約是1.4×0.7英寸。它總是可以減少電路板的大小，通過添加更多的層。然而，成本將更加昂貴。重要的是要平衡這些因素。在PCB板的尺寸符合該

59、項目的規(guī)格。</p><p>　　圖12. 反激式轉換器的PCB布局</p><p><b>　　6.結論</b></p><p>　　在本文中，反激式直流- 直流轉換器的低電壓電源應用已經設計完畢。它的建模與仿真結果都已介紹。根據設計規(guī)格，從凌力爾特公司產品中選擇一個合適的IC。在不同的條件，做了大量的仿真，如負載的電阻值和輸入電壓電平的電路

60、仿真，有助于以獲得所需要的輸出電壓和電流的性能。包括電氣，機械和熱性能的變換器就已經設計完成了。隨著所有特定元器件的確定，該轉換器的印刷電路板布局已經被設計完成了。</p><p><b>　　參考文獻</b></p><p>　　[1] Linear Technology Application Notes , Datasheet of Isolated Flyb

61、ack Converter Without an Opto-Coupler, http://cds.linear.com/docs /Datasheet/3574f.pdf.</p><p>　　[2] P.L.Dowell, “Effect of eddy currents in transformer windings” Procedings of the IEE, vol.113, No.8, pp.1

62、387-1394, Aug 1966.</p><p>　　[3] S.Xiao, “Planar Magnetics Design for Low- Voltage DC-DC Converters” MS thesis, University of Central Florida, 2004.</p><p>　　[4] ANSYS Application Notes, PExpr

63、t Getting Started: A Transformer Design Example,http://www.cadfamily.com/download/EDA/ANSOFTpex//pextran.pdf.</p><p>　　[5] K. Zhang; T. X.Wu; H.Hu; Z. Qian; F.Chen.; K.Rustom; N.Kutkut; J.Shen; I.Batarseh;

64、, "Analysis and design of distributed transformers for solar power conversion" 2011 IEEE Applied Power Electronics Conference and Exposition (APEC), v l., no., pp.1692-1697, 6-11 March 2011.</p><p>

65、;　　[6] K. Zhang.; T.X.Wu.; N.Kutkut; J.Shen; D.Woodburn; L.Chow; W.Wu; H.Mustain; I. Batarseh; , "Modeling and design optimization of planar power transformer for aerospace applic ation," Proceedings of the IEE