【作者】 王晶；

【导师】 李伟力；

【作者基本信息】 哈尔滨理工大学 ， 电机与电器， 2011， 硕士

【摘要】 高速永磁电机作为微型燃气轮机组常用发电设备,具有结构简单、功率密度大、节省材料、传动系统效率高等特点,成为电工领域研究的热点之一。高速永磁电机工作时,定子铁心磁场的交变频率可达上千赫兹,会引起高损耗和温升进而引发一系列危害,所以如何从结构和应用新材料方面改进高速永磁电机以降低电机温升具有重要意义。针对这些问题,本文主要研究了以下内容:首先,建立了高速永磁发电机二维瞬态电磁场数学模型,利用时步有限元法对电机瞬态电磁场进行计算,对比研究了定子采用闭口槽和半闭口槽时电机的电磁性能;对绕组采用环形绕法和常规绕法时发电机输出特性分别进行了计算分析,进而得出了定子绕组型式对电机输出性能的影响规律;计算当转子磁极采用平行充磁时多块分布式和2块集中式电机磁场分布,并从气隙磁密及其谐波含量变化、电压、电流方面分析两者差异。其次,从护套结构和材料方面入手,通过对比分析电机电磁性能和温度分布变化情况,探讨了几种转子护套复合结构的实用性。计算了护套分别采用铜屏蔽套与合金护套复合、铜套与碳纤维绑带复合时转子涡流变化情况,得到了铜屏蔽套厚度对转子涡流损耗的影响规律;并把碳纤维复合材料护套、陶瓷隔热涂层应用到电机转子上,研究碳纤维复合材料导电性与护套涡流损耗关系,分析了护套不同材料和结构在解决电机温升过高问题中起到的作用。最后,分析高速永磁发电机电磁场及输出电压、电流随转速变化关系,分析在无油冷措施下电机三维稳态温度场随转速的变化情况;同时,开展了相关的温升试验研究工作,并通过试验验证有关计算结果的可靠性;设计一种转子侧冷却措施——轴孔强迫通风冷却,研究了轴孔冷却时风速与冷却效果的关系,并对轴孔通风与陶瓷隔热涂层并用时的冷却作用展开讨论。本文得出结论可以为高速永磁同步电机的改进设计及结构优化提供参考。更多还原

【Abstract】 High-speed permanent magnet (PM) machine, because of its simple structure, large power density, material saving, high efficiency driving system, is usually used as micro-gas turbine power generation equipment, becomes one of the hot in electrotechnical field. When the high-speed PM machine rotating, the frequency of magnetic field in stator will be too high that cause high losses and temperature rise. So how to optimize high-speed PM machines by exploring new materials and structure to reduce temperature is very important. To solve these problems, the following contents are studied in this thesis:First of all, a 2-D mathematical model of transient electromagnetic field is established, transient electromagnetic field is calculated by using time stepping finite element method. The difference between electromagnetic properties of stators with semi-closed slots and closed slots is studied. Distinction of the electrical output characteristics between round windings and conventional winding is discussed, and the relationship between windings and output performance is analyzed. When parallel magnetization is introduced in rotor, air-gap flux density and the harmonic content are compared when PM is distributed and centralized, voltage and current waveforms are simulated as well.Secondly, the usefulness of several composite shield structures is discussed from the view of finding new structure and material by comparing the electrical performance and temperature distribution. Distributions of rotor eddy current loss are calculated when shield is composed by copper screen and alloy jacket or copper screen and carbon fiber bandage, and the way how the thickness of copper screen affect the rotor eddy current are studied. Carbon fiber composite materials, ceramic coating are introduced in shields, the relationship between conductivity of carbon fiber composite materials and rotor eddy loss is studied. The effect of different shield structure this thesis involved in solving temperature rising problem is discussed.Finally, the relationship of electromagnetic field, output voltage and current according to speed are obtained. Steady-state temperature field of high speed PM generator without cooling method is calculated, and 3-D steady state temperature distributions of generators under different speeds are calculated. At the same time, related test works are carried out, and the reliability of the calculation results is verified. A new cooling measure that pushes cooling air through shaft is proposed, and the relationship between wind speed and the cooling effect is analyzed, effect of cooling ability when shaft air and ceramic thermal barrier coating are both used is also studied.The conclusions received in this thesis could provide reference when high-speed permanent magnet synchronous machine is designed and optimized.更多还原