兆瓦级超高速永磁电机转子动力学几个关键问题的研究

发布时间：2018-08-30 14:37

【摘要】：兆瓦级超高速永磁电机直驱系统在压缩机、航空动力等领域的应用越来越多,而其转速高带来的机械与电气问题也十分突出。一般超高速永磁电机常采用少极表贴式外加非导磁护套的转子磁极结构,护套增加了电机气隙,致使磁钢用量和表面损耗较大。叠片内置式磁极结构的气隙间隙小,但是漏磁大,且存在磁极冲片表面强度不足等问题。本文重点对兆瓦级超高速永磁电机转子磁极结构进行优化来解决以上问题,同时对超高速带来的临界转速和动不平衡等转子动力学关键问题进行了研究。兆瓦级超高速永磁电机转子圆周速度大,机械强度差。为了寻求一种兼顾机械与电气性能的转子磁极结构,分别对表贴式外加非导磁护套结构,普通的内置式结构以及一种新型叠片内置磁钢间隔高强度非导磁加强筋嵌入的磁极结构进行了机械与电气性能的计算与有限元仿真。对比三种结构转子的性能,确定最优转子磁极结构。依据转子尺寸参数,通过校核键的强度,设计了结构合理的转子轴。采用能量法对转子轴的刚度分段计算,得到总变形量,并采用有限元法进行了验证,判断刚性是否满足要求;为了预知轴的共振,采用当量直径法对轴的一阶临界转速进行计算,并用有限元的模态分析确定了各阶临界转速;考虑轴承刚度后再次进行模态分析,研究轴承刚度对转子轴临界转速的影响规律。针对超高速电机转子轴动平衡难以把握的问题,对其进行不平衡谐响应分析。在计算了转子轴的最大不平衡质量,许用偏心距及许用不平衡量的前提下,基于转子轴动不平衡的假设,给定不平衡质量及偏心距,同时考虑了轴承刚度的影响,进行谐响应分析,研究轴承刚度对转子轴不平衡谐响应的影响规律。
[Abstract]:The application of megawatt superhigh speed permanent magnet motor direct-drive system in compressor, aeronautical power and other fields is more and more, and the mechanical and electrical problems caused by its high rotational speed are also very prominent. The rotor pole structure with less pole surface mount and non-magnetic conduction sheath is often used in the ultra-high speed permanent magnet motor. The sheath increases the air gap of the motor, resulting in the large amount of magnetic steel and surface loss. The air-gap is small, but the magnetic flux leakage is large, and the surface strength of the plate is insufficient. In this paper, the rotor pole structure of megawatt superhigh speed permanent magnet motor is optimized to solve the above problems, and the key problems of rotor dynamics such as critical speed and dynamic unbalance caused by super high speed are studied. Megawatt super high speed permanent magnet motor rotor circumference speed is large, mechanical strength is poor. In order to find a kind of rotor magnetic pole structure with both mechanical and electrical properties, the non-magnetic conducting sheathed structure is attached to the surface separately. The mechanical and electrical properties of the magnetic pole structure embedded in the common built-in structure and a new type of laminated inner magnetic steel spacer with high strength non-magnetic conductance reinforcement are calculated and simulated by finite element method. The optimal rotor pole structure is determined by comparing the performance of the rotor with three kinds of structures. The rotor shaft with reasonable structure is designed by checking the strength of the key according to the rotor dimension parameters. The stiffness of rotor shaft is calculated by energy method, and the total deformation is obtained, and the finite element method is used to verify whether the rigidity meets the requirements. The equivalent diameter method is used to calculate the first order critical speed of the shaft and the modal analysis of the finite element method is used to determine the critical speed of each order. After considering the bearing stiffness the influence of bearing stiffness on the critical speed of the rotor shaft is studied. In order to solve the problem that dynamic balance of rotor shaft of super high speed motor is difficult to grasp, the unbalanced harmonic response analysis is carried out. On the premise of calculating the maximum unbalance mass, allowable eccentricity and allowable unbalance of rotor shaft, based on the assumption of rotor shaft dynamic unbalance, the influence of bearing stiffness is considered on the basis of the assumption that the unbalanced mass and eccentricity are given. The influence of bearing stiffness on the unbalanced harmonic response of rotor shaft is studied by harmonic response analysis.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM351

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