磁力轴承等效摩擦特性研究

发布时间：2018-04-09 21:46

本文选题：等效摩擦力矩　切入点：磁力轴承　出处：《武汉理工大学》2013年硕士论文

【摘要】：摩擦存在于人们的生产、生活各个方面,在人类的文明建设中它有着十分重要的作用。在机械工程领域内,人类研究摩擦除了利用摩擦外,最重要的还是研究避免摩擦,减少磨损,最大限度地发挥机械效能。磁力轴承具有非接触、无磨损、无须润滑、适合高速运动等特点,具有广泛的应用前景。尽管如此,磁力轴承虽无机械摩擦,但仍存在“电磁摩擦”和“气体摩擦”。这种“摩擦”的特点体现在能量的损耗和对运动的阻力方面,因而可类似于机械的摩擦。本文首先在对磁力轴承工作原理及发展历程做简要介绍后,将从磁悬浮转子转矩平衡的角度分析研究磁悬浮支承条件下的摩擦学问题,同时也会从传统摩擦角度对磁力轴承摩擦特性做相关定义。其次,借助Ansys软件,以径向磁力轴承为对象,对旋转电磁场进行有限元分析,得到转子转速变化对磁场分布以及气隙磁通密度大小的影响规律。然后,按照等效摩擦力以及力矩的定义,建立起转子自由减速时的转矩平衡方程。接着,进行五自由度磁悬浮转子rundown实验,获取了转子自由减速的规律以及转子减速的实测值,求得了不同转速下的等效摩擦力矩变化规律。从结果来看,磁力轴承等效摩擦力矩及等效摩擦力的大小与速度有关,表现为随转速的升高而升高,其升高趋势逐渐减弱。从磁场角度解释为：当转子从静止到开始转动时,其切割磁力线的数量逐渐增加,涡流损耗以及磁滞损耗也逐渐增大,电磁阻力相应增大；由于材料有电阻,当转子转速升到某一数值时,转子表面涡流达到一恒定值,速度再增加时对其影响明显减小,导致其等效摩擦力矩及等效摩擦力有升高并且升高趋势逐渐减弱的现象。
[Abstract]:Friction exists in all aspects of people's production and life and plays an important role in the construction of human civilization.In the field of mechanical engineering, in addition to the use of friction, the most important research is to avoid friction, reduce wear, and maximize mechanical efficiency.Magnetic bearing has the characteristics of non-contact, no wear, no lubrication, suitable for high-speed movement, and has a wide application prospect.However, magnetic bearings do not have mechanical friction, but there are still electromagnetic friction and gas friction.This kind of "friction" is characterized by energy loss and resistance to motion, so it can be similar to mechanical friction.After a brief introduction of the working principle and development history of the magnetic bearing, the tribological problem under the condition of the magnetic suspension bearing will be analyzed and studied from the angle of the torque balance of the magnetic suspension rotor.At the same time, the friction characteristics of magnetic bearings are defined from the traditional friction angle.Secondly, with the help of Ansys software and taking radial magnetic bearing as the object, the finite element analysis of rotating electromagnetic field is carried out, and the influence of rotor speed on the magnetic field distribution and the flux density of air gap is obtained.Then, according to the definition of equivalent friction force and torque, the torque balance equation of rotor free deceleration is established.Then, the rundown experiment of magnetic levitation rotor with five degrees of freedom is carried out, and the law of rotor free deceleration and the measured value of rotor deceleration are obtained, and the law of equivalent friction torque under different rotational speeds is obtained.The results show that the equivalent friction torque and the equivalent friction force of the magnetic bearing are related to the speed, which increases with the increase of the rotational speed and decreases gradually.From the magnetic field point of view, when the rotor moves from rest to rotation, the number of cutting magnetic lines increases gradually, the eddy current loss and hysteresis loss increase gradually, and the electromagnetic resistance increases accordingly.When the rotor speed rises to a certain value, the eddy current on the rotor surface reaches a constant value, and the influence on the rotor surface vortex reaches a constant value when the rotor speed increases, which leads to the increase of the equivalent friction torque and the equivalent friction force and the decrease of the increasing trend.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH133.3

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