结构与材料对高速永磁发电机电磁场及温度场的影响
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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。
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.
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。
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.
引文
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[27]邹继斌,江善林等.考虑邻近效应的高速永磁无刷电机交流损耗[J].电机与控制学报,2010,14(5):48-55.
[28]周凤争.高速永磁无刷直流电机转子涡流损耗的研究.浙江大学[D].博士学位论文,2008.
[29]沈建新,费伟中,陈利根.气隙磁场波形及磁瓦充磁方式对无刷直流电动机性能的影响[J].微特电机,2006.
[30]李冰,邓智泉,严仰光.高速异步电机设计的关键技术[J].微特电机,2002,(6):7-10.
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[32] Co Huynh, Liping Zheng, Dipjyoti Acharya.Losses in high speed permanent magnet machines used in microturbine applications[J].Journal of Engineering for Gas Turbines and Power, 2009,131.
[33]罗成,王祥珩,宁圃奇.十二相高速异步发电机转子损耗[J].清华大学学报,2006,46(1):9-12.
[34]阎学文,刘承榆,王晓远.电机闭口槽漏抗的数值计算[J].电工技术学报,1987:27-31.
[35]王凤翔.高速电机的设计特点及相关技术研究[J].沈阳工业大学学报,2006,28(3):259-264.
[36]朱德明;严仰光.表贴式永磁电机的两种充磁方式[J].南京航空航天大学学报,2006,38(3):304-308.
[37]李伟力,李守法,谢颖,丁树业.感应电动机定转子全域温度场数值计算及相关因素敏感性分析[J].中国电机工程学报,2007,27 (24):85-91.
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[2]徐建中.分布式供电和冷热电联产的前景[J].节能与环保2002,12(3):12-14.
[3]郑健超.电力前沿技术的现状和前景[J].中国电力, 1999,32(10):9-14.
[4]梁才浩,段献忠.分布式发电及其对电力系统的影响[J].电力系统自动化,2001:53-56.
[5]孙奉仲,杨祥良,高明等.热电联产技术与管理[M].中国电力出版社,2008.
[6]王民生,张侠.高速无刷直流电动机及其应用[J].微电机,2006,39(4).
[7]王凤祥.高速电机的设计特点及相关技术研究[J].沈阳工业大学学报,2006,28(3):258-263.
[8]高云峰.高速电动机综述[J].控制微电机,1979:14-18.
[9] Zwyssig C., Kolar J.M, Thaler W, et al.Design of a 100W, 500000 rpm permanent magnet generator for mesoscale gas turbines[C]. Hong Kong: Conference Record of the IEEE Industry Applications Society Fortieth Annual Meeting, 2005.
[10] G. Lagerstrom, A. Malmquist.Advanced hybrid propulsion system for Volvo ECT[J].Volvo Technology Report, 1995.
[11] G. Munteanu, A. Binder.No-load tests of a 40 kW high-speed bearingless permanent magnet synchronous motor[C].SPEEDAM 2010.
[12] O. Aglén.Back-to-back tests of a high-speed generator[C].Electric Machines and Drives Conference, 2003.
[13] L. Zheng, T.X. Wu, D. Acharya etal.Super-high speed cryogenic PMSM design[C].Digests of the Intermag Conference, Nagoya, Japan, 2005:981.
[14] M. Hippner, R.G. Harley . Looking for an optimal rotor for high speed permanent magnet synchronous machine[C].Proceedings of IEEE IAS Annual Meeting, Houston, TX, 4-9 Oct. 1992:265-270.
[15] Aglen, O. . Thermal analysis of a high-speed generator[C] . Industry Applications Conference, 12-16 Oct. 2003,1:547-554.
[16] H.W. Chol, S.M. Jang, S.K. Choi.A design approach to reduce rotor losses in high-sppeed permanent magnet machine for turbo-compressor[C].IEEE Trans. On Magnetics, 2006,42(10):3521-3523.
[17] H. Polinder and M.J. Hoeijmakers.Eddy-current losses in the segmented surface-mounted magnets of a PM machine[C].1999IEE Proc.-Elecrr. Power Appl., 46(3).
[18] N. Bianchi, S. Bolognani, F. Luise.Analysis and design of a PM brushless motor for high-speed operations[J].Energy Conversion, 2004,4:2041-2043.
[19] H. Polinder, M.J. Hoeijmakers.Effect of a shielding cylinder on the rotor losses in a rectifier-loaded PM machine[C].Industry Applications 2000,1:163-170.
[20] Shah, M.R., El-Refaie, A.M..Eddy current loss minimization in conducting sleeves of high speed machine rotors by optimal axial segmentation and copper cladding[C].Industry Applications Conference, 2007:544-551.
[21] Nagorny A.S., Dravid N.V., Jansen R.H., Kenny B.H..Design aspects of a high speed permanent magnet synchronous motor generator for flywheel applications[J].Electric Machines and Drives, 2005,635- 641.
[22]唐任远,郭忠保等.研制和设计高速高效太阳能发电机的一些问题[J].太阳能学报,1981,2(2):131-137.
[23]陈庆文,毛志超.高速永磁同步电机的研制[J].中小型电机,1992,19(4):8-12.
[24]唐任远,郭忠保,李革.稀土永磁高速同步发电机的研制和设计[J].中小型电机技术情报,1980,6(3):10-16.
[25]王凤翔.高速永磁电机的设计特点[C].中国科协2003年学术年会,2003:282.
[26]黄允凯,余莉,胡虔生.高速永磁电动机设计的关键问题[J].微电机,2006,39(8):6-9.
[27]邹继斌,江善林等.考虑邻近效应的高速永磁无刷电机交流损耗[J].电机与控制学报,2010,14(5):48-55.
[28]周凤争.高速永磁无刷直流电机转子涡流损耗的研究.浙江大学[D].博士学位论文,2008.
[29]沈建新,费伟中,陈利根.气隙磁场波形及磁瓦充磁方式对无刷直流电动机性能的影响[J].微特电机,2006.
[30]李冰,邓智泉,严仰光.高速异步电机设计的关键技术[J].微特电机,2002,(6):7-10.
[31]汤蕴璆.电机内的电磁场[M].北京科学出版社,1998.
[32] Co Huynh, Liping Zheng, Dipjyoti Acharya.Losses in high speed permanent magnet machines used in microturbine applications[J].Journal of Engineering for Gas Turbines and Power, 2009,131.
[33]罗成,王祥珩,宁圃奇.十二相高速异步发电机转子损耗[J].清华大学学报,2006,46(1):9-12.
[34]阎学文,刘承榆,王晓远.电机闭口槽漏抗的数值计算[J].电工技术学报,1987:27-31.
[35]王凤翔.高速电机的设计特点及相关技术研究[J].沈阳工业大学学报,2006,28(3):259-264.
[36]朱德明;严仰光.表贴式永磁电机的两种充磁方式[J].南京航空航天大学学报,2006,38(3):304-308.
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