本文選題：磁軸承 + 電磁場分析��； 參考：《湘潭大學》2017年碩士論文

【摘要】：磁懸浮軸承是依靠電磁力懸浮支撐的軸承,較之于一般軸承,具有零摩擦、無需潤滑、轉(zhuǎn)子位移精度高、可支撐轉(zhuǎn)速高、壽命長、轉(zhuǎn)動性能可主動控制等優(yōu)勢,因此,磁懸浮軸承的應用已經(jīng)涉及工業(yè)、航天、醫(yī)療、計算機等多個國家支柱產(chǎn)業(yè)。但由于復雜且昂貴的控制系統(tǒng),磁懸浮軸承的應用難以得到工業(yè)化普及。為了提高綜合控制性能,需要從磁場分布的理論角度進行建模分析。通過電磁場仿真發(fā)現(xiàn)磁極間存在磁路耦合,耦合程度與幾何結(jié)構(gòu)和勵磁方式有關,磁路耦合會導致磁力誤差從而影響控制性能,因此從磁軸承的幾何結(jié)構(gòu)設計入手,分析了不同定子幾何參數(shù)下的磁場分布,研究了磁場分布對磁力的影響,建立考慮磁路耦合的磁力數(shù)學模型,由此提出一種解耦自適應控制策略以實現(xiàn)對磁力的精確控制。文章主要從幾何結(jié)構(gòu)、電磁場分布和磁路解耦控制三個方面對主動磁懸浮軸承展開研究。通過對不同的目標優(yōu)化模型有限元電磁場仿真結(jié)果對比分析,發(fā)現(xiàn)磁場的分布不僅與勵磁方式有關,幾何結(jié)構(gòu)對磁場分布的影響也不容小覷,不同幾何參數(shù)下的磁場分布可能出現(xiàn)不同程度的磁路耦合和漏磁,其中絕大部分的非理想磁場以磁路在磁極間的耦合形式呈現(xiàn),從而引起了實際電磁力的誤差。因此需要進一步研究幾何結(jié)構(gòu)參數(shù)對磁路耦合影響,以及磁路耦合將如何影響磁力誤差。建立了磁路耦合等效模型,并分析了磁路的耦合模式,提出耦合系數(shù)?作為磁路耦合程度的評價參數(shù)。在磁路耦合等效模型的基礎上根據(jù)畢奧-薩伐爾定理建立了考慮磁路耦合的磁場分布模型,繪制出了定子磁場分布展開圖。得到磁路耦合受幾何參數(shù)影響的變化趨勢。綜合考慮電磁軸承的機械耦合和磁路耦合,建立了磁力誤差動態(tài)數(shù)學參考模型,分別分析了耦合系數(shù)、轉(zhuǎn)子偏移量和控制電流對磁力誤差的影響,由分析結(jié)果得出,可以改變控制電流來補償由于磁路耦合引起的磁力誤差,并建立了以消除磁力誤差為目的解耦控制策略。為實現(xiàn)自適應控制,設計了參數(shù)辨識模塊和參數(shù)修正控制模塊,根據(jù)時變的磁場分布和轉(zhuǎn)子位移狀態(tài)來調(diào)整參考模型中的動態(tài)參數(shù),從而得到正確、實時的修正控制電流。通過對磁路耦合的理論分析,得到修正控制電流與磁力誤差的先驗模糊關系,建立模糊控制模型,進一步提高了控制的快速性、容錯性和魯棒性。分別對普通PID控制,解耦自適應控制以及模糊解耦自適應控制進行建模分析,結(jié)果證明了磁路解耦的重要性,也說明了自適應解耦容易獲得更好的綜合控制性能。通過物理實驗,驗證了理論模型的正確性,通過二自由度的靜態(tài)懸浮實驗和沖擊實驗證明了解耦自適應控制的優(yōu)越性。
[Abstract]:Magnetic bearing is a bearing which relies on electromagnetic force suspension support. Compared with ordinary bearing, it has the advantages of zero friction, no lubrication, high displacement accuracy, high supporting speed, long life, active control of rotational performance, etc. Magnetic bearing applications have been involved in industrial, aerospace, medical, computer and other national pillar industries. However, because of the complicated and expensive control system, the application of maglev bearing is difficult to be popularized in industry. In order to improve the comprehensive control performance, it is necessary to model and analyze the magnetic field distribution theory. Through the electromagnetic field simulation, it is found that there is magnetic circuit coupling between magnetic poles, the coupling degree is related to geometry structure and excitation mode. Magnetic circuit coupling will lead to magnetic force error and affect the control performance. Therefore, starting with the geometric structure design of magnetic bearing, The magnetic field distribution under different stator geometry parameters is analyzed, and the influence of magnetic field distribution on magnetic force is studied. A mathematical model of magnetic force considering magnetic circuit coupling is established, and a decoupling adaptive control strategy is proposed to realize the precise control of magnetic force. In this paper, the active magnetic bearing (AMB) is studied from three aspects: geometric structure, electromagnetic field distribution and magnetic circuit decoupling control. By comparing and analyzing the finite element electromagnetic simulation results of different objective optimization models, it is found that the distribution of magnetic field is not only related to the excitation mode, but also the influence of geometric structure on the distribution of magnetic field is not to be underestimated. The magnetic field distribution under different geometric parameters may have different degrees of magnetic circuit coupling and magnetic leakage. Most of the non-ideal magnetic fields are presented in the form of magnetic circuit coupling between the magnetic poles, thus causing the error of the actual electromagnetic force. Therefore, it is necessary to further study the effect of geometric structure parameters on magnetic coupling and how magnetic coupling will affect magnetic force error. The equivalent model of magnetic circuit coupling is established, the coupling mode of magnetic circuit is analyzed, and the coupling coefficient is proposed. As an evaluation parameter of coupling degree of magnetic circuit. Based on the equivalent model of magnetic circuit coupling, the magnetic field distribution model considering magnetic circuit coupling is established according to the Beo-Savart theorem, and the stator magnetic field distribution expansion diagram is drawn. The change trend of magnetic circuit coupling affected by geometric parameters is obtained. Considering the mechanical coupling and magnetic circuit coupling of electromagnetic bearing, the dynamic mathematical reference model of magnetic force error is established. The effects of coupling coefficient, rotor offset and control current on magnetic force error are analyzed respectively. The control current can be changed to compensate the magnetic force error caused by magnetic circuit coupling, and the decoupling control strategy is established to eliminate the magnetic force error. In order to realize the adaptive control, the parameter identification module and the parameter correction control module are designed. According to the time-varying magnetic field distribution and the rotor displacement state, the dynamic parameters in the reference model are adjusted, and the correct and real-time modified control current is obtained. Through the theoretical analysis of magnetic circuit coupling, the priori fuzzy relation between the modified control current and the magnetic force error is obtained, and the fuzzy control model is established, which further improves the speed, fault tolerance and robustness of the control. The modeling and analysis of general PID control decoupling adaptive control and fuzzy decoupling adaptive control are carried out respectively. The results prove the importance of magnetic decoupling and show that adaptive decoupling is easy to obtain better comprehensive control performance. The correctness of the theoretical model is verified by physical experiments. The advantages of decoupling adaptive control are proved by static suspension experiments and shock experiments with two degrees of freedom.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TH133.3;TP273

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