一种利于开关磁阻电机降噪的新散热筋结构

振动和噪声问题阻碍了开关磁阻电机的推广应用.由于定子的径向振动是开关磁阻电机噪声的主要根源,因此定子振动系统的模态分析是降噪研究的有效手段.本文在散热筋用料一定的条件下,通过改变散热筋结构形式、高度、根数以及形状,建立了八种计算模型,利用三维有限元模态分析对这些模型进行了仔细的分析和比较,最后得出了最有利于降噪和散热的散热筋结构是高度高、根数多、上窄下宽的梯形截面的周向散热筋的结论.本文的研究对于低噪声开关磁阻电机设计具有很好指导意义.     

开关磁阻电机定子振动的有限元分析

开关磁阻电机(SR电机)定子固有频率的研究对降低电机的噪声和优化控制策略有重要的意义,本文给出了SR电机振动模态分析的数学模型,利用ANSYS有限元软件对不同求解模型进行了详细的计算和分析.结果表明,考虑散热筋、机座和接线盒的三维模型的有限元分析结果与实验测得值有较好的一致性.     

基于物理模型开关磁阻电机定子模态和固有频率的研究

准确计算定子模态和固有频率是降低电机噪声和振动的基础。该文基于开关磁阻电机(SR电机)物理模型，利用3维有限元软件，全面研究了定子模态和固有频率，系统分析了绕组、端盖和安装对定子模态和固有频率的影响。研究表明，对小功率SR电机，2阶模态对噪声和振动的贡献最大。定子绕组对固有频率的影响非常严重，弹性模数远低于实心铜材，绕组不宜采用质量计入磁极或铁心的方式处理。端盖、底脚安装均导致定子固有频率明显升高。最后讨论了2维有限元模型与3维有限元模型计算结果的差异。计算结果与试验结果进行了比较验证。     

开关磁阻电机定子振动的有限元分析

开关磁阻电机(SR电机)定子固有频率的研究对降低电机的噪声和优化控制策略有重要的意义，本文给出了SR电机振动模态分析的数学模型，利用ANSYS有限元软件对不同求解模型进行了详细的计算和分析。结果表明，考虑散热筋、机座和接线盒的三维模型的有限元分析结果与实验测得值有较好的一致性。     

新型可变磁通磁阻电机振动和噪声研究与开关磁阻电机的比较

本文主要介绍一种新型可变磁通磁阻电机振动和噪声,其研究方法主要是通过电磁和机械的有限元方法进行计算的。这种电机使用与开关磁阻电机相比虽然有一定的相同之处,但是由于这种电机在定子侧增加了一套直流励磁绕组,因此,会在很大程度上将电机所产生的振动和噪声削弱。文章在介绍完新型电机之后,通过实证来对新型可变磁通磁阻电机振动和噪声研究与开关磁阻电机进行比较,以此来更深入的对新型可变磁通磁阻电机振动和噪声进行研究。     

开关磁阻电机降噪的新结构探索

噪声是开关磁阻电机的主要缺点,而径向力突变引起的定子振动是噪声的主要来源.本文利用二维有限元方法计算出开关磁阻电机定子所受的径向力,对于在设计阶段探索电机新结构以降低噪声有很好的指导意义.     

绕组连接方式对开关磁阻电机振动影响的研究

开关磁阻电机（SRM）具有结构简单坚固、控制灵活简便等优点,但较大的振动和噪声在一定程度上制约了其在各行业的广泛应用。SR电机的绕组连接方式不仅会对电机的电磁性能带来影响,也会影响电机振动噪声的大小。径向力是引起开关磁阻电机电磁噪声的主要原因。本文针对四相8/6开关磁阻电机,分析NNNNSSSS、NSNSSNSN这两种常用绕组连接方式下磁链和径向力差异;并以径向力为激励建立SR电机振动的有限元模型,研究不同绕组连接方式对振动响应的影响。通过实验进行验证得到结论:当SR电机运行在磁路饱和工作状态下,采用NNNNSSSS定子极性排布的连接方式更有利于减小电机运行时的振动。     

基于磁固耦合法对比经典与新型双励磁开关磁阻电机电磁振动特性分析

通过电磁和机械有限元方法对比研究一种新型多励磁电机的电磁振动特性。这种新型电机在定子侧放置一套直流励磁绕组,基于该模型计算并对比与传统开关磁阻电机(SRM)的电磁特性。利用MATLAB软件对气隙磁密和径向电磁力进行了谐波分析;其次对定子进行模态分析,得出其固有频率和模态振型;最后通过电磁-结构耦合法计算定子的电磁振动响应,对其振动特性进行分析。研究表明这种新型双励磁电机对减小电磁振动有明显作用。     

基于有限元模型的开关磁阻电机振动研究

振动和噪声问题阻碍了开关磁阻电机的推广应用。防止径向力的谐波频率与定子固有频率产生谐振是减小振动和噪声的有效手段,因此确定定子径向力及振动加速度波形并进行频谱分析是减振降噪研究的首要前提。本文通过有限元计算得出不同转子位置、不同电流激励下的定子径向力,基于有限元模型并结合开关磁阻电机振动频域响应函数在Matlab/Simulink仿真环境下建立了开关磁阻电机振动仿真模型,对输出的径向力及振动加速度波形进行频谱分析,从而可找到其主要的谐波分量。本文的研究对于选择合适控制策略来减小开关磁阻电机的振动和噪声有积极意义。     

开关磁阻电机非线性径向力的有限元计算

开关磁阻电机的径向力存在着严重的非线性,它是转子位置角和定子相电流的非线性函数,因此如何分析和计算开关磁阻电机的非线性径向力模型是研究振动与噪声的关键问题。该文基于有限元原理,通过虚位移法对开关磁阻电机的径向力非线性模型进行分析和计算。最后,应用ANSYS软件计算样机径向力的有限元模型,得到了径向力与转子位置角和定子相电流的非线性关系曲线,为开关磁阻电机非线性振动及控制研究奠定了基础。     

Impact of stator windings and end-bells on resonant frequencies and mode shapes of switched reluctance motors

One of the main drawbacks of switched reluctance motors (SRMs) is vibration and acoustic noise, which limits their application. An accurate predication of the modal vibration frequencies of the SRM stator is essential in order to design a low-vibration motor and operate it quietly. Electronic techniques for noise reduction also depend on knowledge of the resonant frequencies, which depend on the mechanical structure surrounding the laminations. This paper examines the effects of the stator windings and end-bells on stator modal vibration frequencies. The error in the calculation of the resonant frequencies can be up to 20% if the influence of end-bells is neglected. The numerical computations of the stator mode shapes and resonant frequencies are validated with experimental results.     

Radial force calculation and acoustic noise prediction in switched reluctance machines

This paper presents an analytical method for calculating the radial force and predicting the acoustic noise in switched reluctance machines (SRMs). The main source of acoustic noise in an SRM is the radial magnetic force inducing resonant vibration with circumferential mode shapes of the stator. An analytical relationship between radial force and radial vibration is determined, which can be used to predict the noise power level at the frequency of operation. The vibration and sound are functions of machine dimensions, material properties, and rotational speed. The knowledge of the circumferential mode shapes of vibration, the natural mode frequencies of the stator, and the frequency spectrum of the radial magnetic force can be effectively utilized to design SRMs with minimal noise through geometrical design variations. The effect of the number of stator and rotor poles on acoustic noise can also be analyzed with the model presented in this paper. Magnetodynamic simulation by finite-element analysis software has also been carried out to verify the calculation of radial force using the proposed analytical model.     

Evaluation of acoustic noise and mode frequencies with design variations of switched reluctance machines

The stator mode frequency, as well as the intensity of acoustic noise generated by magnetic radial force, is related to the geometry, configuration, and material properties of the switched reluctance machine (SRM). Two different four-phase 8/6 SRMs with similar specifications, torque-speed requirements, and envelope dimensions have been designed and built for experiments related to noise intensity and stator mode frequencies. One of these two SRMs, labeled as low-noise SRM is designed following the low-noise design guidelines. The other one, labeled as conventional SRM is designed following the conventional design methodology. The mode frequencies and noise pressure levels for both the SRMs have been calculated using the analytical models. Acoustic-noise data collected from a test bench are analyzed to correlate the experimental and theoretical results.     

开关型磁阻电动机固有频率解析计算

运用机电类比法分析了开关型磁阻电动机(SRM)定子振动特性，针对传统解析计算方法仅将定子凸极和绕组以附加质量归入磁轭、但不计其刚度影响的局限性，提出了基于定子凸极归算算法的SRM固有频率解析计算方法。两台典型结构的SRM样机解析计算和二维有限元分析、模态实验结果表明，采取不计定子绕组影响而等效计及定子凸极对磁轭质量和刚度影响的机械阻抗法是一种对SRM定子振动特性进行解析分析的工程实用方法。     

Prediction of electromagnetic forces and vibrations in SRMs operating at steady-state and transient speeds

Although some research has been conducted on vibrations in switched reluctance motors (SRMs), the response during transients, which may occur during sudden load changes or braking, has not received much investigation. In this paper, a simulation model to predict the transient vibration of SRMs is developed. The vibration prediction model is built based on the detailed normal force versus phase current and rotor position lookup table using finite-element calculations. The model is then verified by a running motor test, which shows acceptable accuracy. The results reveal that there are abundant harmonics of transient force during transients and, thus, resonance may be excited. This model allows the possibility of improved design of SRMs from a vibration and acoustic noise point of view.     

车用永磁同步电机径向电磁振动特性

随着转速升高和负载加重,车用高功率密度永磁同步电机的电磁振动和噪声问题逐渐突出,同时电动汽车对机械振动和噪声强度的限制却更加严格.针对这一问题,建立永磁同步电机沿空问分布的径向力波解析式,从电磁力波角度研究分析永磁同步电机电磁振动成因,并分析其分布规律以及电磁振动相关的影响因素.同时,进行两种实验样机的机械有限元分析,获取模态振型和频率特征的详细分析数据.最后,对实验样机高速下的振动和噪声特性进行实验测量和数值分析,验证了径向电磁力波解析式以及模态分析结论与实验测试数据频谱特征的一致性.     

Analysis and reduction of vibration and acoustic noise in theswitched reluctance drive

This paper describes the results of an extensive study into the production and reduction of acoustic noise and vibration in the switched reluctance motor drive. Time domain analysis has been used to draw conclusions about the effects of changing the operating parameters of the power electronic controller on the vibration and acoustic noise. Experimental results have been taken from a four-phase switched reluctance motor drive with one-, two-, or four-phase excitation. The results of this time domain study reveal important information about the stator vibration which would not be apparent from frequency spectra. The results have been used to derive operational concepts for the power electronic controller to reduce the acoustic noise and vibration produced by the drive. A new control technique has been developed to cancel the stator vibration. Using this novel control method, experimental results show that the vibration and acoustic noise produced by a switched reluctance drive can be reduced dramatically without affecting the performance of the drive     

Young's modulus for laminated machine structures with particular reference to switched reluctance motor vibrations

The switched reluctance motor (SRM) has a disadvantage of higher acoustic noise, caused by stator vibrations. Techniques for noise reduction require knowledge of the modal frequencies, which depend on mechanical shapes and dimensions as well as material properties, for example, Young's modulus, Poisson's ratio, mass density, etc. It is found that the generally accepted value of Young's modulus is not valid for a machine with laminations and no frame. This paper introduces a simple and nondestructive method for the measurement of Young's modulus; it is then used in a finite-element (FE) program to determine the resonant frequencies of SRM stator vibration. The effects of mass density and Poisson's ratios are also discussed. The FE results are validated by vibration tests, which show good accuracy.     

Characterization of vibration and acoustic noise in a gradient-coil insert

High-speed switching of current in gradient coils within high magnetic field strength magnetic resonance imaging (MRI) scanners results in high acoustic sound pressure levels (SPL) in and around these machines. To characterize the vibration properties as well as the acoustic noise properties of the gradient coil, a finite-element (FE) model was developed using the dimensional design specifications of an available gradient-coil insert and the concentration of the copper windings in the coil. This FE model was then validated using experimentally collected vibration data. A computational acoustic noise model was then developed based on the validated FE model. The validation of the finite-element analysis results was done using experimental modal testing of the same gradient coil in a free-free state (no boundary constraints). Based on the validated FE model, boundary conditions (supports) were added to the model to simulate the operating condition when the gradient-coil insert is in place in an MRI machine. Vibration analysis results from the FE model were again validated through experimental vibration testing with the gradient-coil insert installed in the MRI scanner and excited using swept sinusoidal time waveforms. The simulation results from the computational acoustic noise model were also validated through experimental noise measurement from the gradient-coil insert in the MRI scanner using swept sinusoidal time waveform inputs. Comparisons show that the FE model predicts the vibration properties and the computational acoustic noise model predicts the noise characteristic properties extremely accurately.