現今能源意識的高漲，故散熱工程師需著重於電子產品耗電量的管控，而散熱風扇為目前常見應用於許多電子產品的解熱元件，主要是馬達經由電能轉換為機械能的方式來帶動扇葉產生解熱所需的氣流，因此馬達效率的優劣則關係風扇於氣動力與耗電量的表現；其中單相直流無刷馬達有著效率高、噪音低與易控制等的優勢，更是廣泛應用於小型散熱風扇，因此本文以改善此類型的馬達設計作為主要研究目標。 首先，以電磁分析軟體(Ansoft Maxwell)建立馬達設計參數，利用有限元素法模擬定子矽鋼片以預知齒型變化對於馬達頓轉轉矩、磁力線與磁通密度之影響，經由系統化的比較分析以求得較佳之矽鋼片齒型。接著以CNC的方式製作定子原型，再與其他構件組裝成馬達原型以驗證馬達效率，並於依據AMCA 210-99與CNS-8753標準建立之風洞與半無響室，檢測120x120x25 mm3軸流扇於4,000rpm的性能與噪音。實驗結果顯示，馬達的頓轉轉矩確實因定子矽鋼片的齒型改善由0.0145N-m明顯降至0.009N-m，且最大效率由58%提升至65%；並且維持了風扇原有的空氣動力表現與噪音品質，透過數值模擬與原型驗證結果，確實達到馬達效率的提升與風扇節能之最終目標。

Because of the growing demand on energy saving nowadays, thermal engineers are motivated to reduce the power consumption of electrical product. Among the active components inside the PC related system, cooling fan is commonly adopted in the thermal management for providing the cool air. It can generate a sufficient airflow with the proper pressure gain via the rotating impeller, which is powered by a motor to transfer the electric energy to mechanical energy. Thus, the motor efficiency plays an essential part on the fan aerodynamic performance and its energy consumption. Besides, because of the high efficiency, low noise, and easy-to-control features, the single-phase DC brushless motor has been widely utilized in the small cooling fan. Hence, the design improvement of this kind of motor becomes the topic of this research.
At first, the finite-element simulation code (Ansoft Maxwell) is used to solve the electromagnetic field for predicting the electromagnetic flux line, the flux density, and the cogging torque for different contours of stator. Accordingly, the comparison of these numerical outcomes yields an appropriate stator contour. Next, the stator prototype is fabricated via the CNC technique and incorporated with other parts to form a new motor mockup for validating the corresponding motor efficiency and fan performance. Furthermore, fan performance and acoustic experiment are conducted in an AMCA 210-99 test chamber and a semi-anechoic chamber following CNS-8753 code for ensuring a reliable test platform. Consequently, for a 120x120x25 mm3 axial-flow fan operating at 4,000 rpm, a significant reduction (0.0145 N-m to 0.009 N-m) on the cogging torque is achieved by introducing a smoother contour and a smaller gap clearance. Also, the maximum motor efficiency is enhanced from 58% to 65% while the aerodynamic and acoustic characteristics of this axial-flow fan are maintained in the same level. In conclusion, this integrated numerical and experimental effort has successfully improved the motor efficiency and reduced the energy consumption for fan operation.

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