“电机学”中特种电机内容的教学

“电机学”是电气类专业一门重要课程。由于课时不断压缩，特种电机这部分内容往往会被舍弃或由学生自学，因此学习效果很难保证。本文讨论了笔者采用多种有效教学方法和手段，用尽可能少的课时帮助学生掌握几类重要或日常用的特种电机，对电机学的主干知识进行有益补充。     

问题求解法在直流电机结构教学中的应用

"电机学"课程中电机结构教学是关键的环节之一,旋转电机内部定转子磁场极对数相同且保持相对静止,产生定转子磁场的场源和结构不同形成不同的电机类型。大中型直流电机不仅需要励磁绕组、电枢绕组和换向器,而且需要补偿绕组和换向极绕组。本文通过校企合作将问题求解法用于直流电机结构教学实践,让学生在课堂中了解大中型直流电机结构复杂性的原因,建立创造性工程思维的理念。     

电机学多媒体课件的体系结构和知识表示方法

电机学多媒体辅助教学课件覆盖了一般《电机学》、《电机与拖动》等教材中的典型重点难点问题。这些问题多涉及到空间结构、电磁量的时空分布以及饱和、谐波等。本文以交流电机的脉振磁场和旋转磁场为例．介绍如何实现对知识结构的描述．如何利用三维动画模拟及人机交互等技术并适当结合有限元等数值仿真技术．将内涵的知识结构和界面的美感紧密结合。课件具有激发兴趣、易于理解、易于记忆和便于应用这种综合的效果。     

电机学多媒体CAI教学课件的研制

介绍了笔者开发的一个电机学多媒体CAI教学课件的内容结构，并结合开发经验，阐述了开发过程中的几个关键环节。该课件包含电机结构模块、绕组模块、铁磁材料及磁路模块、电机磁场模块和同步机块等五个功能模块，集成了电机学中难于用传统教学模式讲授的部分内容。     

电机理论教学的探索与实践

分析了“电机学”课程的课堂教学现状,针对教学过程中存在的若干问题——电机理论内在联系不够紧密、结构淡化导致学生对理论理解下降、电机内部磁场描述过于抽象以及与后续相关专业课程缺乏联系等,阐述了抓住电机基本理论的内在联系、强化电机结构的理解、突出工程的分析方法、深刻理解磁动势的平衡以及注重与后续课程的联系等一系列想法和做法。通过近三年的教学实践,取得了良好的教学效粜。     

参数化分析法在电机类课程教学中的应用

电机结构参数对电机性能的影响是电机学及电机设计等课程学习的重点和难点,求电机性能指标随电机结构参数变化而变化的关系曲线的过程称为参数化分析。探讨了参数化分析法作为辅助教学手段应用于电机学及电机设计等课程教学的内容与方法,这对于深入理解电机学及电机设计基本理论和基本方法,准确把握电机结构参数变化对电机性能的影响,以及设计和研究新型电机非常有利。     

交流电机旋转磁场的教学研究

“电机学”课程中的旋转磁场是交流电机理论的一个重要的知识点。但是由于磁场本身比较抽象,它成为教学中的一个难点。为此,笔者在本知识点的教学中设计了研究性训练环节,让学生应用电磁场有限元数值计算软件进行交流电机电磁场的数值计算,分析旋转磁场,脉振磁场和多极磁场的特点,归纳总结出旋转磁场的规律。这种研究性训练促进了学生对交流...     

基于Matlab的气隙磁场教学实践

气隙磁场是电机机电能量转化的媒介,也是电机学理论教学中的重要内容。通常,这部分知识点通过全电流定律来介绍,侧重于定性的分析,没有定量的计算和波形的影响因素分析。本文基于Matlab的许-克映射（Schwarz-Christoffel）工具箱,编制仿真程序,能够快速计算任意定转子结构下电机的气隙磁密波形,从而能够分析励磁电流、电枢电流、齿槽效应、磁路饱和、气隙长度等对气隙磁密的影响,为电机学类课程的教学提供重要的支持。     

“电机学”课程实践环节教学改革的探索

“电机学”是电气工程类专业的一门主要技术基础课,具有理论性强,与工程实际联系紧密的特点.以往,学生由于缺乏对电机结构的感生认识,工程意识差,在理论学习中颇感困难.为使电机学课程教学做到理论联系实际,除在课堂教学中运用电化教学手段和电机模型加强直观教学外,还应加强电机生产实习和电机教学实验等实践性环节教学,这对学生动手能力的培养,加深对电机理论的理解,增强工程意识均有着十分重要的作用.近几年来,我们在电机学课程实践环节教学中,对电机生产实习和电机学教学实验课进行了改革,培养了学生的工程能力,收到良好效果.现介绍如下.     

电机统一电磁耦合模型研究

等效电路是"电机学"课程教材中各类电机的重要内容,但教材着力于不同电机结构,因此存在各种不同的等效电路。本文利用磁场和材料特性不变原则,通过坐标变换和绕组折算,将不同频率的电压方程转换成相同频率和统一磁链形式,再引入磁势与统一匝数乘积的新物理量AT2,将磁势与磁通描述的磁路模型转换成AT2与磁链模型,从而获得统一电磁耦合模型。理论研究揭示了不同种类电机之间存在的共同电磁耦合本质,将有助于深入理解《电机学》教材的内容。     

两相异步电机绕组结构对气隙磁场的影响

研究了两相异步电机不同的绕组结构对气隙磁场谐波的影响。应用Ansoft软件中的MAXWELL模块建立了两相异步电机的有限元模型,并进行了气隙磁场的有限元计算,利用MATLAB程序对有限元计算的数据进行分析,对分析结果进行对比,获得减少谐波的结构。     

Three-phase modular permanent magnet brushless Machine for torque boosting on a downsized ICE vehicle

The paper describes a relatively new topology of 3-phase permanent magnet (PM) brushless machine, which offers a number of significant advantages over conventional PM brushless machines for automotive applications, such as electrical torque boosting at low engine speeds for vehicles equipped with downsized internal combustion engine (ICEs). The relative merits of feasible slot/pole number combinations for the proposed 3-phase modular PM brushless ac machine are discussed, and an analytical method for establishing the open-circuit and armature reaction magnetic field distributions when such a machine is equipped with a surface-mounted magnet rotor is presented. The results allow the prediction of the torque, the phase emf, and the self- and mutual winding inductances in closed forms, and provide a basis for comparative studies, design optimization and machine dynamic modeling. However, a more robust machine, in terms of improved containment of the magnets, results when the magnets are buried inside the rotor, which, since it introduces a reluctance torque, also serves to reduce the back-emf, the iron loss and the inverter voltage rating. The performance of a modular PM brushless machine equipped with an interior magnet rotor is demonstrated by measurements on a 22-pole/24-slot prototype torque boosting machine.     

“航空电机及电气传动”课程机辅教学实践

本文以"航空电机及电气传动"课程中开关磁阻电机及其系统为例,利用电磁场有限元分析及电力电子仿真软件,以电机的基本结构、工作原理、工作特性和应用场合为主线,进一步直观呈现其磁场分布及电气传动系统运行曲线,使得理论教学内容紧密结合工程实际。本文所述的软件对于其他电机及其电气传动系统的教学具有一定的参考价值,亦可用于学生本科毕业设计环节。     

Design and analysis of a novel wound rotor for a bearingless induction motor

The traditional squirrel-type bearingless induction motor (BIM) suspension winding generates induced current in its squirrel-cage rotor and affects the phase and amplitude of the suspension force. Based on the analysis of the spatial distribution of torque winding magnetic field and suspension winding magnetic field, a new type of wound rotor BIM is designed. Different from the squirrel-cage rotor, the wound rotor uses a special method of embedding a set of coils at any symmetrical four rotor slot positions, so as to only induce the torque winding magnetic field. The induced current, air-gap magnetic density, magnetic field line distribution, suspension force as well as electromagnetic torque of the traditional squirrel-cage motor and the new wound motor are analysed by Maxwell finite element calculation. The results show that the designed new wound BIM can not only effectively suppress the induced current of suspension winding, eliminating its influence on the suspension force, but also has a better starting performance.     

Two-DOF magnetic orientation sensor using distributed multipole models for spherical wheel motor

This paper presents a new method for measuring a two degree-of-freedom (DOF) orientation of a permanent magnet (PM) based system using magnetic field measurements. The method exploits distributed multipole (DMP) modeling method to accurately predict a magnetic field, and provides a rational basis to inversely solve for the orientation of the PM from measured data. The PM-based magnetic sensor along with the ability to characterize the magnetic field in real-time offers advantages in sensing and control such as contact-free measurements eliminating frictional wears commonly encountered in existing designs with a combination of single-axis encoders, and high-speed sampling rate thus offering a higher bandwidth than methods based on imaging sensors. This paper demonstrates the efficient method capable of measuring the orientation of the PM by implementing it on a spherical wheel motor (SWM), where the two-DOF orientation is measured. Sensor performance has been studied both analytically and experimentally to validate the DMP-based sensor model. The results can offer valuable insights for optimizing contact-free sensor designs.     

基于ANSYS的潜油电机电磁场计算

异步电机的电磁场计算是属于比较复杂的研究对象之一,而潜油电机因其特殊的结构和用途又是异步电机中的比较特殊的情况。针对某典型潜油电机的电磁场,应用ANSYS有限元软件建立有限元模型,通过数值计算得到了該潜油电机的电磁场的磁场分布、磁力线分布、磁密分布,同时计算出了定子轭部磁密和齿部磁密。经数据分析表明,该潜油电机定子采用闭口18槽,转子采用16槽的配合是比较合理的。     

基于有限元方法模拟电机旋转磁场

本文采用有限元方法对三相交流电机内部磁场的实际运动情况进行了模拟仿真,仿真结果很好地展示了电机磁场正反转的实现方法、不同极对致电机的磁场分布以及磁场旋转速度与极对数之间的关系.分析结果在教学中的应用可对学生掌握和熟悉电工学课程中三相交流电机内部磁场分布、正反转实现以及磁场旋转速度有一定的帮助.     

Analytical and experimental investigation on the magnetic field and torque of a permanent magnet spherical actuator

This paper presents the torque model of a ball-joint-like three-degree-of-freedom (3-DOF) permanent magnet (PM) spherical actuator. This actuator features a ball-shaped rotor with multiple PM poles and a spherical stator with circumferential air-core coils. An analytical expression of the magnetic field of the rotor is obtained based on Laplace's equation. Based on this expression and properties of air-core stator coils, Lorentz force law is employed for the study of the relationship between the rotor torque and coil input currents. By using linear superposition, the expression of the actuator torque in terms of current input to the stator coils can be obtained in a matrix form. The linear expression of the actuator torque will facilitate real-time motion control of the actuator as a servo system. Experimental works are carried out to measure the actual magnetic field distribution of the PM rotor in three-dimensional (3-D) space as well as to measure the actual 3-D motor torque generated by the actuator coils. The measurement results were coincident with analytical study on the rotor magnetic field distribution and actuator torque expressions. The linearity and superposition of the actuator torque were also verified through the experiments.