【作者】 邢军强；

【导师】 王凤翔；

【作者基本信息】 沈阳工业大学 ， 电机与电器， 2011， 博士

【摘要】 高速永磁电机具有体积小、功率密度大和效率高等优点,目前已成为国际电工领域的研究热点之一。高速永磁电机的旋转速度每分钟高达数万转甚至数十万转,转子的空气摩擦损耗及高频涡流损耗要比普通电机大得多。同时由于高速永磁电机体积小散热困难,受电枢反应去磁和转子过热影响,容易产生不可逆失磁。因此,高速永磁电机转子抗去磁研究、转子损耗的准确计算和通风散热设计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,重点针对高速永磁电机的防失磁技术、高速转子的空气摩擦损耗、涡流损耗计算以及电机的冷却方法进行了深入的理论分析与实验研究。主要包括以下内容：(1)基于磁场、应力场和温度场分析,研究了可能导致永磁体失磁的电枢反应去磁和高温失磁的可能性,提出了从永磁体及其护套的材料和结构选用、气隙与定子铁心结构以及通风散热方式等方面,如何减小永磁转子损耗和提高散热能力的防止永磁转子失磁的设计方法。(2)建立不同定子结构的高速永磁电机有限元模型,分析定子槽数对电机性能及转子涡流损耗的影响。基于流体场和实验相结合方法,对6槽无内风道和24槽有内风道两台高速永磁电机的温升进行了对比分析与实验,研究轴向通风结构与参数对高速电机温升的影响。(3)研究电机转速、气隙长度、定转子表面粗糙度和轴向风速等对于转子表面空气摩擦损耗的影响,基于流体场分析建立转子空气摩擦损耗的计算模型；通过对高速电机磁场分析建立了转子涡流损耗与转速的关系式,利用实验损耗分离方法验证了转子表面空气摩擦损耗和转子涡流损耗的计算模型。(4)基于流固耦合分析,建立高速永磁电机通风散热的空冷和油冷温升计算模型,计算永磁电机温升。通过对24槽空冷和12槽油冷高速永磁电机的温升测量与计算结果的对比,验证温升计算方法的有效性。(5)利用高速电机转子的高速旋转特性,研究一种在高速电机转子上直接设置轴流风扇的新结构,通过内风道设计,建立一种高速永磁电机的自扇冷通风系统,简化高速电机的通风散热结构。更多还原

【Abstract】 The high speed permanent magnet (PM) machine has been widely investigated in the field of electrical engineering since it has small volume, high power density and high efficiency. Compared with the convertional low-speed machine, the rotor speed can reach up to or even above 100000r/min, so that the air friction loss and high frequency eddy current loss of its rotor are much greater than that of the convertional one. Due to the small size and difficulty of heat dissipation, the PM rotor is easier to be overheated and irreversible demagnetized. Therefore, Anti-demagnetization of PM rotor, accurate calculation of rotor loss and effective design of ventilation cooling system are key techniques for the design of the high-speed PM machine.The research work of this thesis is a part of the project-"The distributed high speed generator system driven 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 the anti-demagnetization technology of PM rotor, calculation of air friction loss and high frequency eddy current loss on the rotor surface, and ventilation cooling of high speed PM machine. The main contents are as follows:(1) Based on the analysis of magnetic field, stress field and temperature field,-the demagnetization possibility of PM rotor caused by armature reaction and overheating is investigated. The design methods to reduce rotor losses, enhance heat dissipation and prevent the PM rotor from demagnetization are proposed through the choice of the material and structure of the PM and its enclosure, air gap and stator core structure, ventilation and heat dissipation structure, etc.(2) The influence of the number of stator slots on machine performance and eddy current loss of the rotor is analyzed using FEM. Based on the fluid field analysis combined with experiment, the temperature rises of the 6-slot high speed machine without inner vents and 24-slot machine with inner vents are comparatively studied, and the influences of axial ventilation structure and parameter on the temperature rise are investigated. (3) The influences of rotor speed, length of air gap, surface roughness of rotor and stator and axial wind speed on the air friction loss of the rotor are studied. Based on fluid field analysis, the calculation model of the air friction loss of rotor is proposed. Through finite element analysis, the relationship between eddy-current loss and rotor speed is established. The validity of the proposed calculation methods of air friction and eddy-current losses of the rotor is verified by the experiment of losses segregation.(4) On the basis of fluid-solid coupled analysis, the calculation model of temperature rise of high speed PM machine with air cooling and oil cooling systems is established. Through the comparison of the calculated temperature rises with tested results of the 24-slot machine with air cooling and 12-slot machine with oil cooling, the effctivity of the temperature calculation method is validated.(5) Based on the high-speed characteristics of the high-speed machine, a new structure of axial fan which is directly mounted on the rotor of high-speed machine is investigated. Through the design of internal ventilation, a self-cooling system is established to simplify the ventilation and cooling structure of high-speed PM machines.更多还原