电动车辆永磁同步电机转子永磁体涡流损耗及温度场研究

发布时间：2018-05-08 23:17

本文选题：电动车辆 + 永磁同步电机　；参考：《北京理工大学》2014年博士论文

【摘要】：近年来随着电动车辆的迅速发展电驱动系统也进入了快速发展时期，永磁同步电机作为电驱动系统的核心部件更是得到了广泛的关注和研究。但是随着高功率密度和高扭矩密度电机的深入研究，发现永磁同步电机的设计参数和控制方式会引起电机内部磁场波形的畸变，进而在转子永磁体产生大量的涡流损耗，导致转子永磁体温度严重升高甚至出现转子永磁体退磁或转子烧毁的现象。永磁同步电机定转子设计参数如转子永磁体形状、定子槽口宽度和分数槽绕组，都会引起电机内部磁场波形的畸变，使气隙磁场含有大量的时间谐波和空间谐波。这些谐波与转子永磁体磁场以不同转速旋转，进而在转子永磁内感应出涡流、产生大量涡流损耗；当电机采用脉宽调制（PulseWidth Modulation：PWM）控制方式时，尤其当定子绕组电流较大并且含有大量时间谐波时，电机主磁场波形会发生较大畸变并含有大量的谐波，这些谐波与转子永磁体以不同转速旋转，在转子永磁体内感应出大量涡流并产生涡流损耗。上述电机定转子设计方式和大电流PWM控制方式都是高功率密度永磁同步电机设计和控制的常用方法，因此研究转子永磁体涡流损耗在上述设计条件和运行条件下的产生机理和影响因素具有十分重要的意义。本文针对转子永磁体涡流损耗，分别采用具有快速计算速度的解析计算方法和具有较高计算精度的电磁场有限元方法进行分析；并对高功率密度永磁同步电机温度场进行分析，分别采用具有快速计算速度的集中参数热网络法和具有较高精度的温度场有限元方法进行分析。最后分别以大功率电驱动系统所使用内转子大功率永磁同步电机和轮毂电机驱动系统中所使用外转子轮毂永磁同步电机作为研究对象，开展转子永磁体涡流损耗研究和温度场研究，并通过台架实验验证理论分析结果。首先，分析永磁同步电机转子永磁体内涡流损耗产生机理和解析表达方式，提出一种基于穿透深度的涡流损耗分析方法。分别分析转子永磁体对自身产生的涡流损耗，绕组时间谐波在永磁体内产生的涡流损耗，绕组空间谐波在永磁体内产生的涡流损耗，和定子开口槽在转子永磁体内产生的涡流损耗。其次，基于电磁场数值计算方法建立永磁同步电机转子永磁体涡流损耗模型，通过电磁场有限元方法分析电机永磁体、分数槽绕组结构、定子绕组时间谐波和定子槽口宽度对于转子永磁体涡流损耗的影响。分析电机气隙磁场的波形和永磁体内部磁场波形，并得到转子永磁体内部的涡流电流密度分布和涡流损耗密度分布情况。建立各类参数与转子永磁体涡流损耗的关系。再次，分别通过集中参数热网络法和温度场有限元方法研究内转子大功率永磁同步电机和外转子轮毂永磁同步电机的整体温度场和转子永磁体的温度场。在集中参数热网络法研究过程中详细分析电机内对流传热、传导传热以及接触传热，建立整个电机在不同冷却条件下的热网络模型，得到电机各组成部分的温度分布并着重分析转子永磁体的温度场分布。温度场有限元方法研究中，建立电机温度场模型，分析永磁同步电机的温度场分布和热流密度分布，得到不同的运行模式和冷却条件下电机内部的温度场分布，并重点分析转子永磁体温度分布情况和气隙温度分布情况。论文还研究转子永磁体涡流损耗的测量方法，提出一种基于电机反电势下降法测量转子永磁体涡流损耗的方法。利用转子永磁体随温度升高而出现可逆退磁的现象，通过测量反电势电压的下降值得到转子永磁体内涡流损耗值；并通过实验对转子永磁体损耗的三维解析分析方法结果和有限元方法结果进行验证，实验结果与理论分析显示出良好的一致性；通过实验测定电机的温升情况，，对电机温度场热网络法分析结果和温度场有限元方法分析结果进行验证，理论分析结果和实验结果具有良好的一致性。
[Abstract]:In recent years, with the rapid development of electric vehicles, the electric drive system has also entered a rapid development period. As the core component of the electric drive system, permanent magnet synchronous motor has received extensive attention and research. However, with the deep research of high power density and high torque density motor, the design parameters and control of permanent magnet synchronous motor are found. The mode can cause the distortion of the magnetic field wave in the motor, and then produce a lot of eddy current loss in the rotor permanent magnet, which causes the temperature of the rotor permanent magnet to be seriously elevated and even the rotor permanent magnet degaussing or the rotor is destroyed. It can cause the distortion of the internal magnetic field of the motor, which makes the air gap magnetic field contain a lot of time harmonics and space harmonics. These harmonics rotate at different rotational speeds with the magnetic field of the rotor permanent magnet, and then induce eddy current in the rotor permanent magnet, and produce a lot of eddy current loss; when the motor uses pulse width modulation (PulseWidth Modulation:PWM) control mode In particular, when the stator winding current is large and contains a lot of time harmonics, the main magnetic field waveform of the motor will be distorted and contains a lot of harmonics. These harmonics rotate at different rotational speeds with the rotor permanent magnets, induce a large number of eddy current in the rotor permanent magnet and produce the eddy current loss. The PWM control mode is a common method for the design and control of high power density permanent magnet synchronous motor. Therefore, it is of great significance to study the eddy current loss of the rotor permanent magnet in the design conditions and operating conditions.
In this paper, the eddy current loss of rotor permanent magnet is analyzed by the analytical calculation method with fast calculation speed and the finite element method with high calculation precision, and the temperature field of high power density permanent magnet synchronous motor is analyzed. The high precision finite element method of temperature field is analyzed. Finally, the rotor permanent magnet synchronous motor (PMSM) used in the large power permanent magnet synchronous motor and hub motor drive system is used as the research object, and the study of the rotor permanent magnet eddy current loss and the study of the temperature field are carried out. The results of the theoretical analysis are verified by the frame experiment.
Firstly, the mechanism and analytical expression of eddy current loss in permanent magnet synchronous motor rotor permanent magnet are analyzed. A method of eddy current loss analysis based on penetration depth is proposed. The eddy current loss of the rotor permanent magnet to itself, the eddy loss produced by the winding time harmonics in the permanent magnet, and the space harmonics of the winding in the permanent magnet are analyzed. The eddy current loss and the eddy current loss generated by the stator opening slot in the rotor permanent magnet.
Secondly, the eddy current loss model of permanent magnet synchronous motor rotor is established based on the electromagnetic field numerical calculation method. Through the finite element method of electromagnetic field, the influence of the structure of the permanent magnet, the fractional slot winding structure, the stator winding time harmonics and the stator slot width on the eddy current loss of the rotor permanent magnet is analyzed. The distribution of eddy current density and the distribution of eddy current loss in the permanent magnet of the rotor are obtained. The relationship between various parameters and the eddy current loss of the rotor permanent magnet is established.
Thirdly, the temperature field and temperature field of the permanent magnet synchronous motor and the rotor permanent magnet synchronous motor are studied by the concentrated parameter thermal network and the temperature field finite element method. The convection heat transfer, conduction, heat transfer and contact in the motor are analyzed in detail during the study of the centralized parameter thermal network method. The thermal network model of the whole motor under different cooling conditions is established, the temperature distribution of the components of the motor is obtained and the temperature distribution of the permanent magnet is analyzed. In the study of the finite element method of the temperature field, the temperature field model of the motor is established, and the distribution of temperature field and the heat flux distribution of the permanent magnet synchronous motor is analyzed, and the difference of the temperature field is analyzed. The operating mode and the temperature field distribution inside the motor under cooling condition are analyzed, and the temperature distribution and the temperature distribution of the air gap of the rotor permanent magnet are analyzed.
The method of measuring the eddy current loss of the rotor permanent magnet is also studied. A method of measuring the eddy current loss of the rotor permanent magnet based on the back EMF reduction method is proposed. The reversible demagnetization of the rotor permanent magnets with the increase of the temperature is used. The eddy current loss in the rotor permanent magnet is obtained by measuring the drop value of the back EMF voltage; The results of the three dimensional analytical method and the finite element method of the rotor permanent magnet loss are verified by experiments. The experimental results are in good agreement with the theoretical analysis. The results of the thermal network analysis and the finite element analysis of the temperature field are verified by the test of the temperature rise of the motor. The analysis results are in good agreement with the experimental results.

【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM341

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