被動式微小型磁懸浮馬達之動態特性研究

Abstract

本論文主要的目的是研究所提出的一種全被動式微型磁浮軸承馬達的動態特性與其相關效應，該軸承的實現概念是利用高磁能積(N45材質)的燒結鈮鐵硼磁石產生充分的排斥力，以使得轉子在徑向無接觸地懸浮。本研究非但開發出一種磁浮軸承數學模型，可以成功地分析所發展的微型馬達之動態特性外，而且一種原型製造的設計流程也被成功地提出。結合磁浮軸承數學模型與原型，從理論與實驗指出此微型磁浮馬達的可行性。除基礎的陀螺儀效應與轉子不平衡量效應被觀察之外，微型磁浮軸承相關效應研究尚包含：阻尼效應、軸向偏移的磁力與尺寸小型化也逐一地被加以探討。 在阻尼效應方面，新穎的阻尼裝置由一個高導磁率的磁性環與環狀的橡膠片組成。透過實驗與理論的計算，展示此一創新的阻尼結構可以顯著地提升磁浮馬達的抗衝擊效能。針對軸向偏移磁力的研究方面，一個簡潔的方法運用一種磁石偏移方式，以感應出一個軸向偏移的磁力，可進一步地降低所研究的微型磁浮馬達的徑向振動。關於尺寸效應的研究方面，一款由上述所開發的磁浮軸承小型化之後的原型 (外部磁環的內直徑是5mm，外直徑是8mm，厚度是3.6mm)被加以研究，內部與外部由堆疊式架構的高磁能積之環狀永久磁環所組成，這些磁環被配置在轉軸上，且位於轉子的永久磁石與馬達定部之上。經由實驗觀察，心軸在徑向無任何接觸摩擦的狀況之下旋轉。與傳統微型滾珠馬達相互比較之下，微型磁浮馬達可展示出較低的摩擦扭矩損耗。再者，所研究的微型磁浮馬達之徑向振動量，比傳統的微型滾珠馬達者降低了21%。 前述的論文研究方向以徑向氣隙型馬達為主，本論文最後針對扁平式馬達(軸向氣隙型)，預先進行軸向振動特性研究，研究結果指出：軸向預壓力對此型式馬達的軸向振動表現影響明顯，對未來微型磁浮軸承置入此一系統的研究，具有相當的參考價值。

The goal of this dissertation was to investigate the dynamic behaviours and the related effects of a proposed passive magnetic bearing (MB) motor. The concept of the bearing used the repulsive magnetic force to levitate the rotor in the radial direction by utilizing the sintered magnet (N45) with high energy product. Not only a mathematical model for the MB was proposed, which can predict the dynamic characteristics of the developed motor, but also a design procedure for fabricating the prototype was introduced. The mathematical model and the prototype points out that the micro magnetic bearing motor can be carried out on the basis of the developed theory and experiments. Beside the basic gyroscopic effect and rotor unbalance effect were observed, the interesting effects including damping effect, bias-magnetic force effect, and scaled-down effect were discussed one by one. Regarding the damping effect, an innovative damping device consisting of a magnetic ring of high permeability and an annular rubber pad can apparently increase the anti-shock ability of the MB motor. Moreover, an approach of the vibration reduction utilizing an induced magnetic force was developed. In addition, a prototype of scaled-down MB motor (the outer magnet with an inner diameter of 5 mm, an outer diameter of 8 mm, and a height of 3.6 mm) was studied. Both the inner and outer part was comprised of a stack structure of high energy product magnet. These rings were arranged on the shaft above the PM of the rotor and the stator. From the experimental observation, the shaft can be rotated without any frictional contacts in radial direction. It shows that the micro magnetic bearing (MMB) demonstrates the lower friction torque loss in comparison with the conventional micro ball bearing (MBB). Moreover, the radial vibration of our device is 21 % lower than the conventional MBB type. The research mentioned above was focused on the motor type with radial air gap. Finally, the dissertation gave the pre-study report regarding a study of axial vibration for a flat-type motor (axial air gap). The results indicate that axial pre-load apparently affects the axial vibration of the motor, and this will be a valuable reference for the research which will be aimed to study the system with the MMB.