本文選題：立式泵　切入點：混合磁軸承　出處：《蘭州理工大學》2013年博士論文

【摘要】：目前,在國內大中型泵站的機組中,導軸承可靠性不高、使用壽命短、維修工作量大是一個普遍性的問題。目前使用廣泛的水潤滑橡膠軸承以及賽龍軸承在比較復雜的環(huán)境中工作時,容易出現軸承損壞或者是主軸損壞等問題,因此尋求一種穩(wěn)定性高、使用壽命長的高性能導軸承,以保證立式斜流泵可靠運行是很有現實意義的。研究表明,磁軸承應用于立式斜流泵具備無接觸、剛度和阻尼可調等傳統(tǒng)軸承無法比擬的優(yōu)勢。 課題在調研了國內、外立式斜流泵導軸承及磁懸浮軸承的現狀和發(fā)展的基礎上,以混合磁軸承應用于HBM-800T立式斜流泵進而改善該型立式斜流泵的運行穩(wěn)定性為研究目標。考慮課題涉及機械學、力學、電磁學、控制理論、電子技術等多學科綜合的特性,在不失系統(tǒng)一般性的前提下,突出研究重點,分別研究磁軸承新結構、葉片振動與轉子及磁軸承耦合動力學、魯棒控制等系統(tǒng)核心組成部分。 主要工作及成果如下： 1.提出一種應用于立式斜流泵的新型混合徑向磁軸承,這種混合磁軸承是永磁磁軸承和電磁磁軸承的組合。其中永磁磁軸承采用的是斥力型Halbach陣列永磁環(huán)堆疊結構,主動磁軸承采用8磁極結構,其中4對磁極徑向分布,每對磁極軸向布置,永磁磁路與電磁磁路相互獨立。小擾動偏移可以由被動磁軸承消除；擾動較大時,轉子的位移由永磁磁軸承和電磁磁軸承共同控制,從而在一定程度上降低主動磁軸承的功耗。研究結果表明,新型混合磁軸承應用于立式斜流泵具備節(jié)能及可控的優(yōu)點。 2.立式斜流泵轉子較長,運轉過程中,容易產生振動,尤其當泵高速運轉時,容易發(fā)生葉片與殼體碰摩,非線性振動等有害因素,因此研究轉子動力學理論,有利于解決泵的非線性動力學問題。課題建立一個葉片-轉子-磁軸承系統(tǒng)的非線性動力學模型來分析葉片、轉子和磁軸承之間的相互作用。利用Lagrange方程獲得系統(tǒng)的耦合動力學微分方程。采用集中質量法、正交變換及周期變換將具有時變系數的耦合方程轉化為常系數微分方程。數值計算結果表明這種系統(tǒng)具有豐富的非線性動力學現象,進入混沌的道路是通過陣發(fā)方式實現的。隨后混沌運動演化為周期1運動,退出混沌運動狀態(tài)；通過在較寬的轉速范圍數值計算表明,系統(tǒng)響應是倍周期運動,說明系統(tǒng)響應在轉速大范圍內是穩(wěn)定的。雖然出現局部混沌運動,但轉子無量綱位移振幅不大,遠小于永磁軸承工作氣隙,沒有發(fā)生碰摩現象。 3.磁懸浮軸承除了無接觸外,還有一個很顯著的特點就是磁軸承的剛度可通過設計合適的控制系統(tǒng)按控制規(guī)律調整。所以研究混合磁軸承系統(tǒng)的組成及相關結構參數與控制系統(tǒng)的承載能力及剛度特性很有必要。課題采用電流分散控制策略,考慮功率放大器、控制電路和位移傳感器增益特性,以及位移傳感器位置耦合問題,并對系統(tǒng)狀態(tài)矩陣及輸入矩陣進行強制解耦,進而實現新型混合磁軸承的轉子系統(tǒng)進行建模。通過以上步驟已經得到單個自由度上的磁軸承-轉子系統(tǒng)傳遞函數,為系統(tǒng)控制器的設計奠定基礎。 4.提出一種應用于立式斜流泵磁軸承轉子控制系統(tǒng)的L2魯棒控制器。由于目前磁懸浮軸承系統(tǒng)的動態(tài)特性還不能完全被人們掌握,很難得到磁懸浮軸承系統(tǒng)精確的數學模型,即存在模型“不確定性”。這些“不確定性”的主要來源是磁軸承電磁鐵與轉子之間以及與所處的環(huán)境體現出來的多場耦合問題。針對立式斜流泵混合磁軸承工作特點,首先將磁懸浮軸承電流控制器的設計問題轉化為標準的L2問題進行設計。其次,基于無源化理論及遞推解法求出系統(tǒng)的存儲函數,并證明滿足耗散不等式及閉環(huán)系統(tǒng)在原點全局漸近穩(wěn)定。最后,用Matlab對L2控制的立式斜流泵磁懸浮軸承系統(tǒng)進行仿真,并與PID控制器的控制效果進行比較研究。結果表明,L2魯棒控制策略相對PID控制策略更能有效抑制未知外擾動的影響。 5.最后,通過立式斜流泵磁懸浮軸承系統(tǒng)的簡化模型實驗研究,結果表明,磁懸浮軸承系統(tǒng)中轉子能實現穩(wěn)定懸浮,響應快,相移小以及具備干擾抑制性能。
[Abstract]:At present, in the domestic large and medium-sized pumping unit, guide bearing reliability, short service life, maintenance workload is a common problem. The use of water lubricated rubber bearings widely and Thordon bearings in complex environment, prone to damage or spindle bearing damage and other problems, so seeking a high stability, long service life and high performance bearing, in order to ensure the reliable operation of vertical mixed flow pump is of great significance. The research results show that applying the AMBs to no contact with the vertical mixed flow pump, the stiffness and damping adjustable bearing and other traditional incomparable advantages.
Study on the research of the domestic and foreign vertical diagonal flow pump guide bearing and magnetic bearing of the present situation and development on the basis of the hybrid magnetic went for running stability of HBM-800T vertical mixed flow pump and improve the vertical oblique flow pump as the research object. Topics related to mechanics, mechanics, electromagnetics, control theory, electronic properties technology of multiple disciplines, without losing generality under the premise of system, highlighting the focus of study, respectively, a new structure of magnetic bearing and rotor blade vibration coupling and magnetic bearing dynamics, robust control system is the core part.
The main work and results are as follows:
1. new hybrid radial magnetic bearing for vertical oblique flow pump, the hybrid magnetic bearing is a combination of permanent magnet bearings and electromagnetic magnetic bearings. The permanent magnet bearings using the repulsion type Halbach array permanent magnet ring stack structure using 8 pole structure of active magnetic bearings, including 4 pairs of pole radial distribution and each pair of magnetic poles arranged axially, permanent magnetic circuit and electromagnetic circuit are independent of each other. The small disturbance offset can be eliminated by passive magnetic bearings; disturbance is larger, the rotor displacement controlled by permanent magnet bearings and electromagnetic magnetic bearings, active magnetic bearings to reduce the power consumption in a certain extent. The results show that the new hybrid magnet bearing used in the vertical diagonal flow pump has the advantages of energy saving and controllable.
2. vertical diagonal flow pump rotor is longer, the process of operation, easy to produce vibration, especially when the pump is running at high speed, prone to leaf and shell rubbing, nonlinear vibration and other harmful factors, so the research on rotor dynamics theory, to solve the problems of nonlinear dynamics analysis of vane pump. The nonlinear dynamic model of subject establishment of a blade the rotor magnetic bearing system, the interaction between the rotor and the magnetic bearing. The coupling dynamics system of differential equations by Lagrange equation. Using the lumped mass method, orthogonal transform and periodic transform coefficients with coupled equations sometimes into differential equations with constant coefficients. The numerical results show that there exists the complicated nonlinear dynamics in the system, the road to chaos is realized by intermittent way. Then chaotic evolution period 1 motion, chaotic motion through the exit; In the wide speed range of numerical calculation shows that the system response is double period motion, the system response speed in large range is stable. Although the local chaotic motion, but the dimensionless rotor displacement amplitude is far less than the permanent magnet bearing working gap, no rubbing phenomenon.
3. in addition to magnetic bearings without contact, there is a very significant feature is the magnetic bearing stiffness can be controlled by appropriate system design according to control law adjustment. So carrying capacity study on composition and structure parameters and control system of hybrid magnetic bearing system and stiffness characteristics is necessary. The current decentralized task considering the control strategy, power amplifier, control circuit and sensor gain characteristics, and the displacement sensor position coupling problem and forced decoupling of system state matrix and input matrix, and then realize the new hybrid magnetic bearing rotor system is modeled. Through the above steps have been a single degree of freedom magnetic bearing - rotor system transfer function. To lay the foundation for design of system controller.
4. this paper proposes a vertical diagonal flow pump control system of magnetic bearing rotor L2 robust controller. Due to the dynamic characteristics of magnetic bearing system is currently still not fully been grasp, it is difficult to get the accurate mathematical model of the magnetic bearing system, namely the existence of model uncertainty. The main sources of the uncertainty is between the electromagnet and the rotor magnetic bearing and the environment to reflect the multi field coupling problem. The vertical diagonal flow pump hybrid magnetic bearing characteristics, firstly the design problem of magnetic bearing current controller is transformed to the standard L2. Secondly, and recursive solution for storage function of the system is based on the passivity theory, and prove the dissipative inequality and the closed-loop system globally asymptotically stable at the origin. Finally, simulation of vertical oblique flow pump magnetic bearing system controlled by L2 Matlab It is compared with the control effect of PID controller. The results show that L2 robust control strategy is more effective than PID control strategy in suppressing the influence of unknown external disturbances.
5., finally, through the simplified model experiment of the magnetic suspension bearing system of vertical diagonal flow pump, the experimental results show that the rotor in the maglev bearing system can achieve stable suspension, quick response, small phase shift and interference suppression performance.

【學位授予單位】：蘭州理工大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TH133.3

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