臺灣博碩士論文加值系統

為提高電子產品之散熱效能，故散熱風扇多朝高轉速設計。但在轉速上升的同時，噪音也相對地提高。而散熱風扇品質良窳，常以散熱效能及噪音來做為依據。因此，在提高轉速增加散熱效能的前提下，對於噪音的要求亦為風扇在設計時必需考量之重要議題。有鑑於此，本文將針對電腦散熱風扇之噪音問題，就扇葉結構與直流無刷驅動馬達之電磁噪音進行分析研究，並提出可行之改善方案。

風扇流場與噪音有最直接之影響，而軸流式風扇之葉型設計對於風扇流場影響甚鉅。為改善風扇流場達到降低噪音的目的，本研究首先以變更風扇動葉上圓弧角幾何尺寸，並於無響室中進行噪音值量測，了解圓弧角參數對風扇噪音之影響，並找出最佳之圓弧角尺寸。此外，亦在前後軸承處置入不同數目之墊片，以提高轉子及定子間之軸向力，降低風扇軸向振動，改善風扇因振動所產生之噪音。電磁噪音改善部分，由文獻得知頓轉扭矩為影響風扇噪音因素之一，較小之頓轉扭矩值具較小之噪音。因此，以MagneForce電磁分析軟體對風扇內轉子與定子間氣隙與定子開口槽寬度的參數，進行數值分析，了解在不同參數尺寸與頓轉扭矩值間之關聯性。

研究結果顯示，在最佳圓弧角幾何尺寸之設計變更方案，約可降低1.5 dB之風扇噪音，且風扇性能測試遠比初始風扇佳。此外，在軸承處置入墊片確具降低噪音效果。而電磁分析中，歸納出頓轉扭矩值隨氣隙尺寸增大而降低，當氣隙大小在0.5 mm時之頓轉扭矩與原始模型比較降低約23 %。定子開口槽寬度部份，縮減寬度至1.0 mm降低頓轉扭矩約49 %，而在實際風扇設計上，較低之頓轉扭矩值相對具較小之噪音值。綜合以上，將模型中氣隙變更為0.5 mm與開口槽寬度縮減至1.0 mm，其頓轉扭矩與原始模型比較之下降低約57 %。

In order to increase the heat dissipation capability of the electronic system, the cooling fan is often designed with high rotational speed recently. The accompanying noise becomes louder then ever before relatively. However, both the heat dissipation efficiency and the noise it generates are key indices of the cooling fan quality. Therefore, reducing the noise is an important factor that must be taken into consideration for the fan design of high rotational speed and better heat dissipation efficiency. The study then aimed at reducing the fan noise through a series of fan blade structure redesign and the analysis of the electromagnetic noise of its brushless DC motor. Some of the feasible improvement schemes are also presented after the study.

The air flow field relates to the fan noise directly. And the design of the blade geometry for the axial flow fan affects the air flow field remarkably. In order to improve the flow fields so as to reduce the noise, the study starts from modifying the dimensions of fan blade’s arc angle on the rotor blade. Then, by measuring the noise in a semi-anechoic chamber thereafter, the effects of the arc angle parameter on the fan noise are then understood and the best arc angle dimension is thus determined. In addition, different number of pieces of the shim at the rear and the front bearings are inserted for increasing the axial forces and then improving the vibration which brings out the noise between the rotor and stator. Regarding the electromagnetic noise, it is based on the literatures that the dominate factor influencing the electromagnetic fan noise is the cogging torque. It is emphasized that the less cogging torque, the less noise. Therefore, the parameters of the slot opening size on the stator and the air gap between the rotor and the stator are analyzed with the MagneForce electromagnetic analysis software. The corresponding relations between different parameters on the cogging torque are fully investigated.

The results show that one of the modification design for the best arc angle geometry can reduce the fan noise around 1.5dB, and the performance is even much better than the original fan. Moreover, shims insertion at the bearing locations did reduce the noise. In the electromagnetic analysis, it is found that the cogging torque decreases with the increase of the air gap. When the air gap size is 0.5 mm, the reduction of the cogging torque is about 23% when comparing with the original model. In the stator slot open sizes study, it is observed that when the slot opening size is decreased to 1.0 mm, the cogging torque is reduced about 49 %. In reality, less cogging torque causes less noise. It is then concluded for all the cases studied that while the air gap is set as 0.5 mm, and the slot opening is decreased to 1.0 mm, it can be reduced 57% of the cogging torque by comparing to the original model.

中文摘要..…………………………………………………………………..I
英文摘要………………………………………………………..….………II
誌謝……...……………………………………………………..….………IV
目錄…………………………………………………………......………….V
表目錄 ……………………………………………………...……...…….VIII
圖目錄.....…………………………………………………..……...……...IX
符號說明……...………………………………………………...…….….XV
第一章 緒論…..….………………………………………………….…….1
1.1前言……………………………………………………………...……1
1.2文獻回顧…………………………………………………………...…2
1.3研究目的…………………………………………...…………………5
1.4本文大綱………………………………………………………..…….6
第二章 風扇結構設計理論與有限元素分析…………………………….8
2.1設計轉動葉片之幾何參數……………………...…………………....8
2.2風扇結構有限元素分析…………………….…………………….…11
2.3風扇馬達定子結構有限元素分析………………………………….15
第三章 結構振動與噪音實驗……………………………………….......22
3.1機械噪音……………………………………………...……………..22
3.2氣流噪音…………………………………………………………….23
3.3電磁噪音………………………………………………….................24
3.4風扇噪音測試實驗……………………………………...…………..25
3.5風扇結構實驗與結果…………………………………...…………..30
3.6變更不同靜葉數目對噪音振動之影響…………………………….33
3.7動葉幾何圓角設計對噪音振動之影響……………...………….….35
3.7.1動葉幾何圓角設計之定義…….…………………..…………..….35
3.7.2不同圓弧角設計下之噪音量測結果…………………..………....43
3.8於軸承處設置墊片對噪音與振動之影響…………………………..48
第四章 變更動葉圓角設計對P-Q曲線之影響………………………....53
4.1風扇性能測試之實驗架設………….................................................53
4.2動葉圓角設計對P-Q曲線之影響……………................................55
第五章 直流無刷馬達電磁特性分析…...……………………………....62
5.1頓轉扭矩之影響…………….………………………………………62
5.1.1直流無刷馬達頓轉扭矩理論.………………….…………………64
5.1.2馬達頓轉轉矩之計算………………………………......................66
5.2直流無刷馬達風扇轉速量測……………………………………….67
5.2.1實驗架設流程…….…………………………...……..……………67
5.3 MagneForce有限元素分析………….……………………..……….70
5.3.1 MagneForce有限元素模型建構與材料參數設定……..………...71
5.4直流無刷馬達轉數實驗量測與分析結果……………………….…74
5.5不同氣隙與定子槽開口寬度之影響……………………………….76
第六章 結論………………………………………………...…………....81
6.1研究結果與討論…………………….…...……………………….....81
6.2未來建議研究方向…………………....………………………….…91
參考文獻…………………………………………………………...…......93

1.Bruno Eck, “FANS, ”Pergamon Press, New York, 1973.

2.Cyril M. Harris, “Handbook of Acoustical Measurement and Noise Control, ”McGraw-Hill, New York, 1991.

3.Leo Leroy Beranek and I. L. Vèr, “Noise and Vibration Control Engineering, ”Wiley. Interscience, New York, 1992.

4.T. Fukano and C.-M. Jang, “Tip Clearance Noise of Axial Flow Fans Operating at Design and off-Design, ”Journal of Sound and Vibration, No.275, pp.1027-1050, 2004.

5.Wan-Ho Jeon, “A Numerical Study on the Effects of Design Parameters on the Performance and Noise of a Centrifugal Fan, ”Journal of Sound and Vibration, No.265, pp.221-230, 2003.

6.Kota Shimada, Kazuhide Kimura and Hiroshi Watanabe, “A Study of Radiator Cooling Fan with Labyrinth Seal, ”Society of Automotive Engineer of Japan, No.24, pp.431-439, 2003.

7.M. Tournour, et al. “Investigation of Tonal Noise Radiated by Subsonic Fans Using the Aero-Acoustic Analogy, ”Proceedings of the FAN NOISE 2003 International Symposium Senlis, 23-25 Sep, 2003.

8.S. L. Nau and H. G. G. Mello, “Acoustic Noise in Induction Motor：Cause and Solutions, ”Material IEEE, pp.253-263, 2000.

9.C. T. Lin, T. S. Chiang, and A. Horng, “Three-Dimensional Flux Analysis and Guidance Path Design of an Axial-Flow Radial Flux Permanent Magnet Motor, ”Industry Applications Conference, Vol.3, pp.1691-1695, 3-7 Oct. 2004.

10.Z. X. Yao and D. D. Liu, “Vortex Dynamics of Blade-Blade Interaction, ” AIAA Journal, Vol.36, NO.4, pp.379-399, 1998.

11.S. F. Wu and S. G. Su, “Modeling of The Noise Spectra of Axial Flow Fans in A Free Field, ”Journal of Sound and Vibration, Vol.200, NO.4, pp.379-399, 1997.

12.C-M. Jang, et al. “Effect of Tip Clearance on Vertical Flow and it’s Relation to Noise in an Axial Flow Fan, ”JSME International Journal, Vol.46, NO.3, 2003.

13.C. C. Hwang, S. B. John and S. S. Wu, “Reduction of Cogging Torque
in Spindle Motor for CD-ROM Drive, ”IEEE Trans on Magnetics,
Vol.34, NO.2, Mar. 1998.

14.T. Li and G. Slemon, “Reduction of Cogging Torque in Permanent Motors, ”IEEE Trans on Magnetics , Vol.24, NO.6, NOV. 1988.

15.B. Ackermann, et al. “New Technique for Reducing Cogging Torque in a Class of Brushless DC Motors, ”IEEE Proceeding-B, Vol.139, NO.4, Jul. 1992.

16.K. J. Han, et al. “Optimal core shape design for cogging torque reduction of brushless DC motor using genetic algorithm, ” IEEE Transactions on Magnetics, Vol.36, No.41, pp.1927-1931, 2000.

17.Y. D. Yao, et al. “Simulation Study of the Reduction of Cogging Torque in Permanent Magnet Motors, ” IEEE Transactions on Magnetics, Vol.33, No.5, Sep. 1997.

18.D. R. Huang, et al. “Cogging Torque Reduction of Single-Phase Brushless DC Motor, ” IEEE Transactions on Magnetics, Vol.34, No.4, Jul. 1998.

19.S. M. Hwang, et al. “Cogging Torque and Acoustic Noise Reduction in Permanent Magnet Motor by Teeth Pairing , ” IEEE Transactions on Magnetics, Vol.36, No.5, Sep. 2000.

20.D. Parente, M. Villani, “Noise Reduction in Permanent Magnet DC Motor for Rear Wiper , ”Electric Machines and Drives Conference, 2001, Page(s):582 – 584.

21.F. C. Yulong, P. P. Zheng and S. Cheng, “ Analysis and restrain strategy of cogging torque in double-stator permanent magnet brushless motor, ”Electric Machines and Drives Conference, 2003. IEMDC''03. IEEE International, Vol. 2, 1-4 June 2003, Page(s):1073 – 1077.

22.陳文亮、周永泰、羅玉山、林顯群和周建安， “電腦散熱扇葉片外型對性能及噪音影響”， 中華民國振動與噪音工程學術研討會， 第十二屆，民國九十三年六月。

23.任文堂、趙劍和李孝寬， “工業噪聲和振動控制技術，” 冶金工業出版社，河北，民國八十二年二月。

24.鐘玉堆， “電工學”， 高立出版社，民國八十年七月十五日，第四版。

25.株式會社日立製作綜合馬達教育所，“小型馬達技術”， 全華科技圖書股份有限公司，民國八十年五月，第一版。

26.孫清華，民國八十年七月十五日， “最新無刷直流馬達”， 全華科技圖書股份有限公司，民國 九十年十二月，第一版。

27.李漢超， “變更靜葉設計對電子系統冷卻風扇噪音之影響研究”， 私立元智大學機械工程研究所碩士論文，民國九十四年六月。

28.蔡嘉豪，“風扇性能曲線預測方法之研究”， 國立清華大學工程與系統科學研究所碩士論文，民國九十三年七月。

29.胡世賢，“軸向繞線徑向氣隙光碟機主軸馬達性能之研究”， 私立輔仁大學物理系研究所碩士論文，民國八十七年六月。

30.林源峰，“DVD主軸馬達3D不平衡磁路模擬分析之研究”， 私立元智大學電機工程研究所碩士論文，民國九十二年。

31.顧哲安，“筆記型電腦之風扇設計與振動分析”， 國立成功大學機械工程學系研究所碩士論文，民國九十年六月。

32.賴益志，“無刷直流馬達之磁路特性分析”， 國立成功大學機械工程學系研究所碩士論文，民國八十九年六月。

33.林翰宏、蔡建峰，“頓轉扭矩”， 馬達小百科Motor Express，第63期。


34.黃國華、陳鴻誠，“永磁電機頓轉轉矩之分析”， Electric Motor Technology Research Center，第72期，民國九十三年四月。

35.簡明扶，“直流馬達噪音”， Electric Motor Technology Research Center，第74期，民國九十三年四月。

36.葉進純，“IPM 無刷直流馬達噪音與振動源模式分析”， Electric Motor Technology Research Center，第128期，民國九十四年五月。

37.「B40x40x28mm」，零組件類產品，電子工業股份有限公司，2006年6月6日，http://www.delta.com.tw/ch/product/cp/dcfans/dcfans_main

38.「平衡等級標準設定」，IRD BALANCING 軟式、硬式平衡機設備，全全科技公司，2006年5月25日，http://www.albest.com.tw/pd.htm#1