楊超君 袁愛仁 陳子清 吳盈志 張小鋒 柳康



Abstract:For adjustable-speed magnetic couplers, mechanical properties and adjustable-speed characteristics are both important characteristics. In order to realize the speed regulating function better, these two characteristics above should be studied deeply. An axial-flux solid asynchronous magnetic coupler was proposed, and the calculation model of the transmitted torque was established. From this, the adjustable-speed relationship expressions were derived under the constant torque load and variable load torque conditions, respectively. Moreover, the relationships between the torque and the speed regulation were solved by discretization. In addition, the above two working characteristics of the coupler were simulated by finite element method, respectively. Particularly, the curves of mechanical property and adjustable-speed characteristic were also obtained, and the optimal air gap control ranges under the two different conditions of the constant torque load and variable torque load were determined. Furthermore, the adjustable-speed relationships when the constant torque load or variable torque load were verified experimentally, and the experimental results are in good agreement with the results of theoretical calculation and simulation analysis.
Keywords:axial-flux solid asynchronous magnetic coupler; mechanical property; adjustable-speed characteristic; torque; adjustable-speed relationship
0 引 言
盤式實心異步磁力耦合器是一種新型永磁感應傳動裝置[1],不僅可以實現無接觸傳動,而且對中要求低,特別是因具有過載保護、隔振、輕載啟動和調速節能等優點而在機械工業、石油化工、煤礦開采等各行各業受到廣泛地應用[2]。
由于上述諸多優點,調速型磁力耦合器的研究受到了國內外專家的重視。Mohammadi[3]運用等效磁路法推導了軸向充磁永磁渦流耦合器的磁密公式及轉矩公式,并通過三維有限元模擬驗證了理論計算的正確性;Baiba Ose-Zala[4]分析了圓筒式磁力耦合器的極弧系數、永磁體厚度及長度等基本參數對轉矩的影響,計算了該耦合器的機械轉矩,并進行了實驗驗證;L. Belguerras等[5]提出了采用高溫超導材料的軸向充磁磁力耦合器,利用三維有限元法模擬了耦合器的氣隙磁場及轉矩,并進行了實驗驗證;韓國光云大學王雙[6]運用有限元法分析了混合磁力耦合器的三維磁場,獲得了三維磁場的徑向與軸向分布,并對影響轉矩大小的結構尺寸進行優化,提高了傳動性能。
在國內,江蘇大學楊超君[7-9]針對盤式鼠籠異步磁力耦合器借鑒層理論模型建立了轉矩計算公式,通過數值模擬及實驗測試獲得不同工況下的三維瞬態氣隙磁場分布和轉矩曲線,特別是實驗測得了轉差率及效率與轉矩的關系曲線,由此得出該耦合器合理的工作區間。文獻[10]運用計入了感應電流影響的新穎等效磁路法進行了盤式異步磁力耦合器轉矩特性的研究,并通過有限元分析及實驗進行了驗證。文獻[11]中,根據電機額定點、臨界點和起動點等參數推導了鼠籠異步電動機的機械特性方程,并獲得其機械特性曲線。文獻[12]提出了調速關系的概念,針對筒式磁力耦合器建立了恒轉矩負載及變轉矩負載兩種不同負載下的調速關系式,使得該耦合器的調速節能研究更為直觀有效。文獻[13-14]則提出針對盤式實心異步磁力耦合器的轉矩及調速關系式的研究,為本文的進一步研究奠定基礎。
綜上所述,國外主要側重于磁力耦合器磁密、電磁轉矩公式的推導,以及對影響磁密、電磁轉矩大小的因素進行分析,國內主要側重于轉矩與效率的計算,對磁力耦合器機械特性與調速特性的研究剛剛起步,雖然已經研究了筒式實心異步磁力耦合器的調速特性,但對于盤式實心異步磁力耦合器的機械特性及調速性能的研究還不夠深入。
本文以盤式實心異步磁力耦合器為研究對象,建立傳動轉矩及調速關系的計算模型,并進行離散化求解,獲得其調速關系;通過模擬研究磁力耦合器的機械特性與調速特性,獲得恒轉矩及變轉矩兩種不同負載轉矩下的轉速、轉矩等工作參數的變化規律,探求其合理的調速范圍,為該種調速型磁力耦合器的設計提供方法。
1 轉矩公式及調速關系模型
1.1 結構模型及調速原理
圖1為盤式實心異步磁力耦合器調速模型,其中,電機與輸入轉子相連接,負載與輸出轉子連接,若輸入轉子為永磁盤,輸出轉子為導體盤,根據電磁感應原理,電機帶動輸入轉子轉動導致輸入、輸出轉子之間產生轉速差,使得導體盤切割磁力線而產生感應電流,感應電流產生感應磁場從而帶動負載旋轉。此外,若輸出轉子在作轉動的同時并進行軸向移動導致氣隙厚度的變化,從而實現轉速調節。反之,輸入轉子也可為導體盤,輸出轉子為永磁盤。
4 結 論
1)建立了盤式實心異步磁力耦合器的傳動轉矩及調速關系計算模型,推導出了恒轉矩負載與變轉矩負載下的調速關系式,實現了調速關系式的離散化計算。
2)通過軟件模擬分析了磁力耦合器兩種工作特性,獲得了耦合器的機械特性曲線和調速特性曲線,可知,在轉差率為26%時耦合器達到最大輸出轉矩;針對不同的恒轉矩負載與變轉矩負載可以確定耦合器的調速范圍,并得出調速時最佳的氣隙厚度變化區間;根據調速特性曲線可以判斷耦合器的帶負載能力并提高耦合器的啟動性能。
3)通過實驗驗證了調速關系的理論計算值與模擬分析值在一定范圍內的正確性,確立了耦合器氣隙厚度與轉差率、氣隙厚度與輸出轉速之間的關系,為磁力耦合器實際調速應用提供了實驗參考。
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(編輯:劉琳琳)