【作者】 王天煜；

【导师】 王凤翔；

【作者基本信息】 沈阳工业大学 ， 电机与电器， 2010， 博士

【摘要】 高速电机由于体积小、功率密度大和效率高,成为电机领域的研究热点之一。永磁电机以其结构简单,力能密度高和无励磁损耗效率高等优点,最适合于高速电机。高速高频电机与普通电机相比设计难度较大,为了减少离心力及产生需要的输出功率,转子一般为细长型,同时转子还应具有足够的刚度,特别是对于采用磁悬浮轴承的高速电机转子,为了减小跨越弯曲模态临界转速时磁悬浮控制的难度,对于转子刚度的要求更高。对于永磁电机来说,转子强度问题更为突出,因为永磁体不能承受高速旋转产生的拉应力而必须对其采取保护措施。因此转子强度的准确计算和动力学分析是高速永磁电机设计的关键技术。本文研究内容是国家自然科学基金重点资助项目“微型燃气轮机—高速发电机分布式发电与能量转换系统研究”(编号50437010)的部分研究内容,重点针对转子强度、动力学分析及转子结构综合设计进行了深入研究,并对高速电机及其机组进行实验研究。主要包括以下内容:(1)对高速永磁转子进行基于电磁、强度及动力学特性分析的综合设计。首先根据高速旋转下转子表面线速度初选转子外径,进行强度计算,根据转子材料的强度要求确定转子外径允许变化范围;其次根据电机的输出功率要求,选取永磁体结构和转子的轴向尺寸,进行电磁特性分析;然后进行转子的动力学分析,根据刚度及动力学要求确定转子长度;最后,在综合满足强度、刚度和电磁性能基础上,对转子结构进行多场综合设计。(2)利用有限元非线性接触方法建立护套和永磁体轴对称模型,计算永磁体和护套在各种工况下应力及其接触压力,确定合适的过盈量。分析几种典型高速永磁电机转子结构在不同工况下的应力分布情况,选择满足强度要求适合于高速电机的转子结构。(3)为了准确计算转子临界转速,建立同时考虑剪切变形和转动惯量影响的磁力轴承转子有限元模型。确定各向异性有限元模型中的材料属性,利用磁悬浮转子系统自身悬浮特性进行激振实验,确定有限元模型中磁力轴承支承刚度。分析磁力轴承刚度、转子结构参数对转子临界转速及振动模态的影响,研究通过改变磁力轴承刚度及结构参数避免共振使转子具有良好动态特性的设计方法。(4)建立柔性联轴器耦合的多跨转子系统有限元模型。用弹簧单元模拟弹性联轴器的轴向、径向及扭转刚度,计算轴系振动模态及固有频率,分析联轴器结构及刚度对轴系临界转速的影响及避免共振的方法。(5)振动是高速电机稳定运行的瓶颈,通过振动分析研究减小和抑制振动的方法。通过有限元及Newmark积分法计算转子在不平衡力作用下的非线性不平衡响应,分析高速电机运行中振动产生的频率成分,并对仿真结果进行实验验证。(6)对高速电机进行实验研究。在空载及负载条件下,测试电动机及发动机电磁特性及单转子、机组轴系的振动位移、振动频谱、轴心轨迹、机座振动加速度等。更多还原

【Abstract】 The high speed machine, due to its small volume, high efficiency and great power density, is one of the great concerns in electrical engineering. The PM machine is appropriate for high speed operation due to its simple structure and high power density. It is quite difficult to design such a high speed and high frequency machine than designing a common machine. From the point of view to reduce the centrifugal force and produce the required output power, the rotor should be slender. The rotor should have enough rigidity to avoid spaning the critical speed of bending mode for magnetic-bearing rotor. The rotor strength is more prominent for high-speed PM machine, beacause the PM is not able to withstand large centrifugal forces and must be encapsulated in some high-strength material. Therefore, strength and dynamic character analysis of rotor are key techniques for high-speed PM machine.The research work of this thesis is a part of the project“The distributed high speed generator drove by micro-turbines and its energy conversion system”, which is supported by the National Natural Science Foundation of China (No. 50437010). The study of the thesis is concentrated to strength, dynamic characteristic analysis and combined design for high-speed rotor system. The main contents are listed as follows:(1) Rotor design of high-speed PM machine is investigated based on combined mechanical with electromagnetic and dynamic properties analysis. First, rotor external diameter can be considered according to the surface velocity. The variation range of rotor diameter is determined according to mechanical constraints based on stress analysis. Then, in accordance with output power, rotor structure and axial length are selected by electro-magnetic analysis. The rotor length is determined together with rigidity and dynamics requests. The end, the optimized design of the rotor structure is carried on based on strength, rigidity and the electromagnetism requests.(2) The nonlinear contact FEA model of rotor is established to calculate the stress for different operation conditions and determinate suitable interference fit between PM and enclosure. The satisfied strength structure of rotor is choosed by stress analysis.(3) In order to calculate the rotor critical speeds accurately, the FEA model of magnetic-bearing rotor is established, which influences of detrusion and rotational inertia are considered simultaneously. The anisotropic material properties in FEA model are definited. According to the suspension character of magnetic-bearing system, the magnetic-bearings stiffness in FEA model is obtained by exciting experiment. Influences of stiffness and structural parameters to critical speeds and vibration modes of rotor are analysed. The design method of rotor changing magnetic-bearing stiffness and design parameter to avoid resonance is investigated.(4) The FEA model of multi-span rotor system coupled by flexible couplings is established. The spring element simulates the axial, radial and torsional stiffness of elastic coupling. The influences of stiffness and structure parameters of the coupling on the critical speeds of rotor system are analyzed. The method to avoid resonance of rotor system through changing the structure parameter and supporting stiffness of parts is investigated.(5) Vibration is the bottleneck of stable operation for high-speed machine. The methods of reducing and suppression vibration are researched by vibration analysis. The combined FEA and Newmark method is used to calculate the non-linear unbalance response due to the unbalanced force. The simulation results of different vibration frequencies are verified by tests.(6) In the no-load and load conditions, the electrical and magnetic properties of motor and generator, vibration displacement, vibration spectrum, orbit of rotor and shafting, vibration acceleration of frame and so on are measured.更多还原