摘要

本研究主要設計一氣隙保持機制(Gap-retained Mechanism, GRM)與一控制策略並對其進行閉迴路控制以保持對一個偏心飛輪維持定間隙。也就是說GRM為一個二自由度的姿態追蹤機制，好像是一個具有智慧型的追隨器，不管偏心飛輪如何偏擺，其主動式氣隙保持機制仍能即時隨之偏擺，即不會遠離也不會相撞。偏心飛輪透過撓性聯軸器與馬達/發電機單元(Motor/Generator Unit, MGU)連接，其偏擺軌跡即為GRM之追蹤目標。GRM主要由智慧型圓盤(Intelligent Disc)、混合型磁致動器(Hybrid Magnetic Actuator, HMA)及偏心飛輪所構成。智慧型圓盤經由HMA所產生的感應磁吸力驅動，進而追蹤飛輪之運動軌跡。
首先，本論文利用能量法、有限元素分析及電磁學理論推導GRM之系統動態，並對其進行電腦模擬分析。就控制觀點而言，GRM為一開迴路不穩定系統且其數學模型為高度非線性，故本研究以回授線性化(Feedback Linearization)的方法設計一具有強健性之順滑控制器(Sliding Mode Controller)對GRM進行閉迴路控制，使其能夠穩定而又不失精確地追蹤偏心飛輪之偏擺軌跡。
本研究所設計之GRM事實上為“飛輪電池”之一部份。也就是當MGU運作於怠速模式時，其飛輪主軸與MGU脫離，以避免飛輪動能被直流馬達線圈中之反電動勢快速抵銷。但另一方面，卻必須與MGU維持同步傳動，所以藉助於非接觸式離合器(Non-contact Clutch)，此離合器必須與飛輪的中心軸對正(也就是所謂“動態對心”)，這就是GRM的主要角色。GRM也輔助了MGU的能量回充功能，亦即只要搭配電力電子裝置，可將飛輪之轉動動能轉換成電能再生利用，以達到飛輪電池預期之效能。
最後，本研究成功地製作了一個GRM雛形，搭配訊號處理模組(DS-1104 by dSPACE)及軟體(MATLAB/Simulink)進行實驗驗證。另外，以市售變頻器作為能量回充所需之主要電力電子裝置(以維持負滑差)。由實驗結果得知，本論文所設計之GRM具有卓越的暫態響應及追蹤性能，其X軸與Y軸上(即兩個徑向)之穩態追蹤誤差約在5%左右。此外，GRM亦可以輔助MGU達成能量回充之功能，可以滿足飛輪電池快充快放的特性。

Abstract

This thesis principally proposes and validates a Gap-retained Mechanism (GRM) and a control strategy. In order to retain constant gap with respect to the eccentric flywheel, a closed-loop control is employed and implemented. GRM can be regarded as a two-degree-freedom posture tracking mechanism similar to an intelligent follower, i.e., the active GRM is able to real-time track the eccentric flywheel which is wobbling dynamics. The eccentric flywheel is driven by a Motor/Generator Unit (MGU) through a flexible coupling so that the flywheel can tilt and wobble with respect to the axial direction. GRM mainly consists of a flywheel, four sets of hybrid magnetic actuators and an intelligent disc. The intelligent disc is controlled by the magnetic forces induced by HMAs to track the posture of the eccentric flywheel which is both spinning and wobbling.
At first, finite element analysis, energy method and fundamental electromagnetic theory are applied to derive the dynamics of GRM. From the viewpoint of control, GRM is an unstable open-loop system and its mathematical model is highly nonlinear. Hence, a robust Sliding Mode Controller (SMC) is synthesized, on the base of the feedback linearization. SMC enables GRM to accurately track the eccentric flywheel to some extent. In fact, the proposed GRM is a part of an entire flywheel cell. That is, once the MGU operates at idle mode, the shaft of flywheel will be separated apart from MGU in order to avoid the energy loss of the flywheel by the back EMF induced by the magnetic field of MGU. On the other hand, the shaft of flywheel and MGU still need to maintain synchronous power transmission even at idle mode so that a non-contact clutch is equipped. Generally speaking, the role of GRM in a flywheel cell is to ensure the centerline of the flywheel properly aligned with the non-contact clutch. In addition, GRM is also as an auxiliary module to efficiently promote the energy-recycled process by MGU such that the rotational energy of flywheel can be efficiently converted into electrical energy with the aid of power electronic circuits.
Finally, a prototype of GRM is successfully built up in this research. By employing the signal processing interface (Model DS-104 by dSPACE) and the commercial software (MATLAB/Simulink), the feasibility of GRM is verified by intensive experiments and computer simulations. Additionally, a commercial variable frequency drive is included to play the role of power electronic circuits so that a negative slip can be retained, no matter how fast or slow the flywheel is rotating. From the experimental results, GRM exhibits superior transient responses and excellent tracking performance. The steady-state tracking errors are about 5% with respect to the amplitudes of the reference trajectories in two radial directions (i.e., X-axis and Y-axis). At last, by experiments GRM is verified to be able to assist MGU to complete the energy-recycled process and the characteristic of fast charging and discharging by the flywheel cell is evident and outstanding.

參考文獻

[1] S. -Y. Yoo, W. -R. Lee, Y. -C. Bae, M. -Noh, “Design of Magnetically Levitated Rotors in a Large Flywheel Energy Storage System from a Stability Standpoint,” Journal of Mechanical Science and Technology, Vol. 24, No. 1, p 231-235, Feb. 2010.
[2] B. J. Park, Y. H. Han, S. Y. Jung, C. H. Kim, S. C. Han, J. P. Lee, B. C. Park, T. H. Sung, “Static Properties of High Temperature Superconductor Bearings for a 10kWh Class Superconductor Flywheel Energy Storage System” Physica C: Superconductivity and its Applications, Vol. 470, No. 20, p 1772-1776, Nov. 2010.
[3] N. Koshizuka, “R&D of Superconducting Bearing Technologies for Flywheel Energy Storage Systems,” Physica C: Superconductivity and its Applications, Vol. 445-448, No. 1-2, p 1103-1108, Oct. 2006.
[4] J. R. Fang, L. Z. Lin, L. G. Yan, L. Y. Xiao, “A New Flywheel Energy Storage System Using Hybrid Superconducting Magnetic Bearings,” IEEE Transactions on Applied Superconductivity, Vol. 11, No. 1 Ⅱ, p 1657-1660, March 2011.
[5] J. -P. Lee, B. -J. Park, Y. -H. Han, S. -Y. Jung, T. -H. Sung, “Energy Loss by Drag Force of Superconductor Flywheel Energy Storage System With Permanent Magnet Rotor,” IEEE Transactions on Magnetics Vol. 44, No. 11 Part 2, p 4397-4400, Nov. 2008.
[6] I. Masaie, K. Demachi, T. Ichihara, M. Uesaka, “Numerical Evaluation of Rotational Speed Degradation in the Superconducting Magnetic Bearing for Various Superconducting Bulk Shapes,” IEEE Transactions on Applied Superconductivity, Vol. 15, No. 2 Part Ⅱ, p 2257-2260, June 2005.
[7] H. Seino, H. Hasegawa, M. Ikeda, “Numerical Analysis and Evaluation of Electromagnetic Forces in Superconducting Magnetic Bearings and a Non-contact Permanent Magnetic Clutch,” Quarterly Report of RTRI (Railway Technical Research Institute), Japan, Vol. 51, No. 3, p 156-161, Aug. 2010.
[8] Y. Li, J. -W. Xing, S. -F. Han, Y. -P. Lu, “Principle and Simulation Analysis of a Novel Structure Non-contact Electromagnetic Clutch,” The 12th International Conference on Electrical Machines and Systems, ICEMS 2009.
[9] J. Cibulka, “Kinetic Energy Recovery System by Means of Flywheel Energy Storage,” Advanced Engineering 3(2009)1, ISSN 1846-5900.
[10] D. Cross, J. Hilton, “High Speed Flywheel Based Hybrid Systems for Low Carbon Vehicles,” IET Conference Publications, n 546 CP, Hybrid and Eco Friendly Vehicles Conference, HEVC 2008.
[11] Suvire, Gastón O. Mercado, Pedro E, “Improvement of Power Quality in Wind Energy Applications Using a DSTATCOM Coupled with a Flywheel Energy Storage System,” Brazilian Power Electronics Conference, COBEP2009, p 58-64, 2009.
[12] H. -L. Liu, J. -H. Jiang, “Flywheel Energy Storage---An Upswing Technology for Energy Sustainability,” Energy and Buildings, Vol. 39, No. 5, p 599-604, May 2007.
[13] V. Renuganth, T. A. Mohamad, “Flywheel Energy Storage for Spacecraft,” Aircraft Engineering and Aerospace Technology, Vol. 76, No. 4, p 384-390, 2004.
[14] B. H. Kenny, P. E. Kascak, R. Jansen, T. Dever, W. Santiago, “Control of a High-Speed Flywheel System for Energy Storage in Space Applications,” IEEE Transactions on Industry Applications, Vol. 41, No. 4, p 1029-1038, Aug. 2005.
[15] Q. T. Fan, J. Q. Zhu, B. A. Zhang, W. X. Shen, “Factors Affecting the Surface Shape and Removal Rate of Workpiece in CMP,” The International Society for Optical Engineering, Vol. 6149, 2006.
[16] G. E. Menk, S. Dhandapani, C. C. Garretson, S. S. Chang, J. G. Fung, S. Tsai, “Method for Improved CMP Pad Conditioning Performance,”ASMC Proceedings, p 149-153, 2010.
[17] J. -G. Kim, K. -S. Park, N. -C. Park, H. Yang, Y. -P. Park, “Improved Air Gap Control Using Optimized Antishock Control Algorithm for SIL-based Near-field Storage System,” International Symposium on Optomechatronic Technologies, p 98-103, 2009.
[18] J. -G. Kim, W. -H. Shin, J. Jeong, K. -S. Park, N. -C. Park, H. Yang, Y. -P. Park, “Improved Air Gap Controller for Solid Immersion Lens-Based Near-field Recording Servo System,” Japanese Journal of Applied Physics, Vol. 48, No. 3, Part 2, March 2009.
[19] 黃忠立，“轉子－軸承系統在多臨界轉速限制下之輕量化設計”，國立成功大學航太工程學系碩士論文，民國76年。
[20] H. D. Nelson, “A Finite Rotating Shaft Element Using Timoshenko Beam Theory,” Journal of Mechanical Design, ASME, Vol. 102, p 793-803, 1980.
[21] N. -C. Tsai, C. -W. Chiang, H. -Y. Li, “Innovative Active Magnetic Bearing Design to Reduce Cost and Energy Consumption,” Electromagnetics, Vol. 29, No. 5, p406-420, July 2009.
[22] A. -C. Lee, F. -Z. Hsiao, D. KO, “Analysis and Testing of Magnetic Bearing with Permanent Magnets for Bias,” JSME International Journal, Series C, Vol. 37, No. 4, 1994.
[23] S. -L. Chen, C. -T. Hsu, “Optimal Design of A Three-Pole Active Magnetic Bearing,” IEEE Transactions on Magnetics, Vol. 38, No. 5, p 3458-3466, 2002.
[24] 楊憲東，“非線性控制” ，Sept. 2010.
[25] C. -F. Lin, “Advanced Control Systems Design,” 1993.
[26] 王勇勝，“感應機再生煞車控制器研製”，國立彰化大學電機工程 學系，民國96年。
[27] 南榮電機， http://www.balancingmachine.com/.