【作者】 王念先；

【导师】 胡业发；

【作者基本信息】 武汉理工大学 ， 机械电子工程， 2013， 博士

【摘要】 磁悬浮支承技术是利用可控电磁力将物体悬浮起来,使物体与基础之间没有机械接触,从而实现无机械摩擦、无磨损、无需润滑、功耗低和速度高等优点,同时其支承特性(刚度和阻尼等)可通过控制参数实现在线调整,从而增强系统的稳定性,因此,磁悬浮支承技术被誉为支承技术的一场革命。混合磁悬浮轴承是将电磁轴承与永磁轴承组合起来形成的一种磁悬浮轴承系统,它兼顾了电磁轴承和永磁轴承的优点,目前己被广泛研究。但在风力发电机和人工心脏泵等应用场合中,混合磁悬浮轴承的工作气隙大,常规磁悬浮轴承设计理论中磁场均匀、无漏磁等基本假设不成立,需要建立新的设计理论与方法。本文针对一种典型的混合磁悬浮轴承,利用常规的磁路法对不同气隙长度的混合磁悬浮轴承进行了结构设计,建立了其承载力解析模型,并采用有限元分析软件对其承载特性进行了分析；对比了不同气隙长度下的两种混合磁悬浮轴承的解析法结果和有限元结果,结果表明在混合磁悬浮轴承中,当气隙长度较大时采用常规磁路法无论是在设计还是在分析时都存在较大的误差。本文对大气隙混合磁悬浮轴承中磁路法模型计算误差的特性及变化规律进行了研究,并研究了导致磁路法计算误差的主要影响因数和各因数的影响规律。针对忽略漏磁导致的磁路法计算误差这一主要影响因数,采用漏磁系数对漏磁进行了描述,并建立了基于漏磁系数的混合磁悬浮轴承磁路模型；研究了混合磁悬浮轴承的气隙漏磁随结构参数的变化规律,提出了混合磁悬浮轴承漏磁系数的描述方法,并对漏磁系数描述方法的适用范围进行了研究；基于该漏磁系数的描述方法对大气隙和常规气隙混合磁悬浮轴承进行了界定。利用场路结合的方法建立了一种基于漏磁导的气隙磁场漏磁模型,并建立了基于漏磁导修正的混合磁悬浮轴承磁路法承载力模型；对模型的适用范围进行了研究,结果表明该模型能满足大多数工程实际中混合磁悬浮轴承承载力分析的需求；设计了一种单自由度混合磁悬浮实验装置,对该模型进行了验证。最后,对常规磁路法不能进行大气隙混合磁悬浮轴承结构设计的主要原因进行了分析,并基于漏磁系数修正模型和漏磁导修正模型提出了大气隙混合磁悬浮轴承结构设计方法,利用改进后的磁路法对大气隙混合磁悬浮轴承进行了结构设计。更多还原

【Abstract】 Magnetic bearing technology uses controllable electromagnetic force to levitate the object, realizing no mechanical contact between the object and the basis. Thereby it has many advantages, such as no mechanical friction, no wear, no lubrication, low power consumption and high speed. Meanwhile its supporting characteristics (stiffness and damping) can be adjusted online by changing control parameters, which can enhance the system stability. Therefore, magnetic bearing technology is known as a revolution of supporting technology. Hybrid magnetic bearing is a kind of magnetic bearing system which formed by combining electromagnetic bearings and permanent magnetic bearings. It takes into account the advantages of both electromagnetic bearings and permanent magnetic bearing. So it has been widely studied at present. However, in the applications such as wind turbines and artificial heart pump, the working air-gap of hybrid magnetic bearing is large, which causes basic assumption in the conventional magnetic bearing design theory such as uniform magnetic field, no magnetic flux leakage are no longer correct. Therefore, a new design theory and method need to be developed.In this paper, a typical kind of hybrid magnetic bearing has been discussed, and the structures of hybrid magnetic bearings with different air-gap have been designed by using conventional equivalent magnetic circuit method. The bearing capacity models of those hybrid magnetic bearings have been built, and the bearing forces have been analyzed by ANSYS. By comparing the calculation results of traditional equivalent magnetic circuit method and ANSYS, it shows that the conventional equivalent magnetic circuit method cannot meet the requirement of structural design and bearing capacity analysis of large air-gap hybrid magnetic bearings.The characteristics and variation rules of equivalent magnetic circuit method model calculation error in large air-gap hybrid magnetic bearings are studied. What’s more, impact factors which caused equivalent magnetic circuit method calculation error and impact rules of each factor on the error are studied.For the main factor, magnetic flux leakage that causes errors of conventional magnetic circuit method, leakage coefficients are introduced to describe magnetic flux leakage. Furthermore, the magnetic circuit model of large air-gap hybrid magnetic bearings based on leakage coefficients is estabilished. The changing laws between air-gap magnetic flux leakage and structural parameters are studied. The description method of leakage coefficients is presented and application range of this description method is studied. Based on the description method, large air-gap hybrid magnetic bearings are demarcated from conventional air-gap ones.An air-gap magnetic flux leakage model based on leakage permeance has been built by using a combination method of magnetic field and an equivalent magnetic circuit bearing capacity model of hybrid magnetic bearings based on magnetic flux leakage has been built. On this basis, the application range of this model is studied and the results show that this model can satisfy the majority of practical engineering hybrid magnetic bearing capacity analysis needs. Then, a single degree of freedom hybrid magnetic experimental device is designed and manufactured. And the model is validated by utilizing that device.Finally, the main reason that conventional equivalent magnetic circuit method can not be used for structure design of large air-gap hybrid magnetic bearings is analyzed. Furthermore, the structure design method of large air-gap hybrid magnetic bearings based on leakage coefficient correction model and leakage permeance correction model is proposed. And the structural of large air-gap hybrid magnetic bearings is designed by using improved magnetic circuit method.更多还原