Magnetic suspension force in an induction bearingless motor with a squirrel cage rotor

Theoretical equations of magnetic force in an induction bearingless motor have been reported. In the bearing‐less motor, both 4‐pole and 2‐pole windings are stored in stator slots for torque and suspension force generation. In the analysis, squirrel cage rotor currents are considered. These currents are induced by both torque and suspension winding currents. Inductance matrix is represented by four sets of three‐phase windings, thus a 12×12 matrix is constructed. A simplification and reasonable assumptions are introduced to obtain understandable expressions for suspension force and torque representation. The rotor flux linkages in an induction bearingless motor are derived, and a simulation model of suspension force is then constructed. It is shown that the response and the phase of suspension force are delayed in the case of cage rotors. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 77–87, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20340     

Magnetic field analysis of a squirrel cage induction motor considering rotor skew and higher harmonics in the secondary current

This paper describes a method to analyze harmonic magnetic fields of squirrel cage induction motors considering rotor skew and higher harmonics in the secondary current. The proposed method is based on a two‐dimensional finite element method. The rotor skew structure is expressed by multiple 2D finite element mesh models, produced in suitable axial positions, and the magnetic field in each mesh model is calculated by the revised secondary current taking into account the skew effect. The secondary currents, magnetic flux densities, and electromotive forces are calculated by the proposed method. Then the differences between a skewed rotor and a nonskewed rotor are discussed. From the comparison between the calculated and the experimental results, the proposed method is shown to be appropriate and useful for quantitative estimation of harmonic components of induction motors. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 98–109, 1999     

变频电源笼型异步电机断条故障诊断仿真

为了探讨笼型异步电动机转子导条断裂故障诊断的有效方法,根据多回路电机模型参数及正弦脉宽调制(SPWM)原理,建立了变频电源供电笼型异步电机在正常情况和转子断条故障情况下的运行状态仿真模型,并在MATLAB仿真环境比较电机定子单相电流频谱及三相平均瞬时功率频谱。通过分析检验了仿真系统模型的可行性和实用性,证实了平均瞬时功率频谱比电机定子电流频谱具有更佳的断条故障特征分辨力和故障判断准确性,尤其是在变频供电情况下优势极为突出,从而确立了合适的断条故障判据。     

双定子笼型感应电动机的数学模型及性能计算

对双定子笼型感应电动机建立了数学模型,进行了性能分析与计算,利用Ｃ＋＋语言编制了计算机辅助设计程序,并设计与试制了两台２２ｋＷ、６极的模型机,通过实验证明了理论分析与计算的正确性。     

A study of the electromagnetic vibration of a capacitor induction motor caused by time-harmonic voltages

In recent years, power source voltage waveform distortion has become noticeable, as electrical appliances with rectifier circuits have become widely used. Connecting capacitor inductor motor (CRM) to such distorted supply, or controlling CRM by simple controller with a switching device (such as triacs), harmonic voltage is supplied to CRM. In that case, CRM produces electromagnetic vibrations caused by not only the fundamental voltage but also time-harmonic voltages in the distorted voltage. In addition, CRM produces electromagnetic vibration due to backward magnetic fields. Thus, it is difficult to clarify a relationship between electromagnetic vibration of CRM and harmonic voltages. In this paper, the causes of the electromagnetic vibration of CRM operating under distorted wave supply voltage are discussed. First, a general equation of dominant electromagnetic force waves is shown considering not only forward magnetic fields but also backward magnetic fields. Using a general equation, causes of dominant electromagnetic vibration can be clarified. Next, by discussing in detail some examples of the dominant vibration, the relationship between the vibration and harmonic voltages becomes evident. Furthermore, the relationship between the vibration and backward magnetic field is clarified.     

鼠笼异步电机起动性能的时步有限元计算

时步有限元方法是计算鼠笼异步电机暂态起动特性的一种有效方法,本文针对当前该方法在工程应用中存在的问题展开了研究。在转子转动的处理方面,通过对现有方法进行改进,得到了一种新的处理有限元运动问题的方法——边界耦合法,解决了现有方法存在的效率低、通用性不强和时闻步长不确定等问题。本文还讨论了转子电路方程的建立和电磁转矩计算等方面的问题。     

笼型转子断条感应电动机的易解数学模型

针对断条破坏了电机原有对称关系而使建模仿真变得困难,采用综合矢量法,建立了转子断条感应电动机易于求解的数学模型.对电机暂态及稳态仿真揭示了定子电流幅值与转矩随时间脉动的故障特征,得出了转子导条电流分布规律,表明与断条相邻及相距一对极距的导条电流最大.引人关注的是在转子端环间出现端电压,其值反映了转子电路不对称程度;揭示了故障特征随电机负载变化规律.定子电流实测与仿真结果相吻合证实了结论正确,有助于感应电机在线故障诊断.     

基于笼型电动机转子断条故障的诊断分析

为了解决目前已有的故障诊断方法只能诊断出电机是否发生转子断条故障而不能诊断出转子断条数目的问题,对电机转子断条故障进行了仿真和断条数目诊断方法的研究。首先对Y2-132M-4型的鼠笼式三相异步电机进行了建模,利用建立的模型对发生不同断条数的电机故障进行了仿真研究。然后,提出了基于机器学习的对转子断条故障的断条数目进行诊断的算法。实验结果表明,所提出的故障诊断分类方法实现了电机不同数目的转子断条故障的智能诊断分类,且诊断分类准确率达100%。     

Magnetostriction and motor vibration

A quiet induction motor is strongly demanded today. Electromagnetic factors are a main cause of vibration and acoustic noise in a small induction motor. Electromagnetic forces and magnetostrictive forces are considered as the origin of electromagnetic vibration and noise. In this paper, magnetostrictive vibration of a ring of electrical steel sheets was simulated by the mechanical finite element method. Magnetostriction was assumed as external forces and they were added at each node of the meshed ring. Resonant frequency and the mode of the ring were calculated. In the steel sheet ring excited by a PWM voltage source inverter, the frequency spectrum of vibration of ring was measured and compared with the calculated results. It was confirmed that these procedures simulated magnetostriction behavior of electrical steel sheets. Furthermore, the electromagnetic forces of a small induction motor were calculated and compared with the magnetostriction data. It became clear that electromagnetic vibration was affected by the magnetostriction of steel. These results will be useful in the reduction of acoustic noise and the development of quiet motors. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 8–13, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10338     

Characteristic analysis of an induction motor with an unequal slot pitch cage rotor

Recent developments in induction motors have been moving forward reducing the size and weight of motors. At the same time, there are demands for much quieter operating conditions. Various design methods have been applied to reduce the vibration and acoustic noise of induction motors. One method is to make the slot pitches of the cage rotor unequal, to avoid the resonance with the natural frequencies of the stator frame. In this paper, our purpose is to create guidelines for reducing noise. As the first step for this purpose, we developed a method to analyze the voltage and torque equations of an induction motor with an unequal slot pitch cage rotor and discussed the characteristics from the analyzed currents. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 44–52, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10032     

电力综合负荷感应电动机模型参数的研究

描述电力综合负荷感应电动机模型的数学表达，模型参数和辨识原理。讨论获取综合负荷故障特性的实验方法和步骤，利用实验室实测数据用总体测辨法辨识出感应电动机模型参数，并与调查所得的感应电动机的空载和短路实验数据所计算出的参数进行对比分析，得出一些有益的结论，为研究湖南电网综合负荷特性提供了可靠的理论和工程依据。     

双鼠笼异步电机笼条断裂分析与预防措施

分析了鸭溪电厂300MW汽轮发电机组几年来高压异步电动机转子鼠笼断裂的原因,介绍了现场处理方法并提出了防断裂措施。     

Effect of the stator slot opening on the electromagnetic vibration in a squirrel-cage induction motor

Field harmonics produce a radial electromagnetic force in a squirrel-cage induction motor with a particular number of rotor slots corresponding to the number of poles. The radial force causes vibration and acoustic noise. In this paper, a simplified equation for the radial force at no-load is introduced, and the relation between the width of the stator slot opening and the radial force is discussed quantitatively. The field harmonic component produced by the interaction between the fundamental magnetomotive force due to the stator current and the pulsation of air-gap permeance dominates for the radial force. Furthermore, the vibration of the stator core due to the radial force is calculated under a simple assumption. The calculated results are verified by experiments.     

Electromagnetic noise of induction motors driven by PWM inverters

When a squirrel cage induction motor is driven by a PWM inverter, electromagnetic noise different from that during commercial power source drive is experienced. This is because of sideband wave voltage induced in PWM inverter output voltage. This paper first describes the mechanism of electromagnetic noise generation in commercial power source drive, and then electromagnetic force considering the sideband frequency and voltage content and the mechanism of electromagnetic noise generation in PWM inverter drive. It also refers to the sideband frequency and voltage content because of operating time control. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 55–62, 2000     

Development of voltage sag compensator and UPS using a flywheel induction motor and an engine generator

Flywheel energy storage systems are attracting attention as uninterruptible power supplies (UPS) from the viewpoint of environmental friendliness and high durability performance. Using a low‐speed, heavy flywheel and a low‐cost squirrel‐cage induction motor/generator, two applications are proposed: (1) an 11‐kW voltage sag compensator using a capacitor self‐excited induction generator without semiconductor converters and (2) a UPS composed of the flywheel system and an engine generator. Based on experimental results, an ideal voltage sag compensator and UPS are realized by the low‐technology flywheel system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 74– 81, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20784     

Flywheel size design considerations and experimental verification using a 50‐kW system for voltage sag compensator with flywheel induction motor

Flywheel energy storage systems can be used as an uninterrupted power supply system because they are environmentally friendly and have high durability. The use of a simple voltage sag compensator with a low‐speed heavy flywheel and a low‐cost squirrel‐cage induction motor/generator is proposed. First, the ability of the proposed system to maintain the load voltage at 100% when the grid is experiencing voltage sag is validated experimentally. Next, design guidelines for the flywheel stored energy are discussed. Experimental verification of a 50‐kW‐class system is carried out, and the results show good agreement with the developed design guidelines. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 36–44, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21252     

高压异步电动机故障原因分析及对策

分析了贵溪发电厂高压异步电动机频发性且对后果较严重的故障情况,从电机定子、转子两个方面分别进行分析。同时针对电机的操作、工艺、结构、材料等方面提出相应的解决方案。     

Basic principle and maximum torque characteristics of a six-phase pole change induction motor for electric vehicles

In addition to basic characteristics such as small size, lightweight and easy maintenance, the electric vehicle (EV) motor is required to possess characteristics that allow for the production of high torque in low-speed region and to realize a wide-speed range of constant power in high-speed region. In an attempt to improve further the constant power operation of the induction motor (IM), this paper proposes a six-phase pole change IM (six-phase PCIM). The six-phase PCIM further expands the constant power operation range without increasing either volume or current of IM. To clarify the basic principle and torque characteristics of the six-phase PCIM, its winding method and distribution of magnetomotive force (mmf) will first be examined. Then, by establishing a performance calculation method based on a quasisinusoidal wave method, the feasibility of a highly precise performance calculation sufficient for actual use will be demonstrated. Furthermore, by clarifying through experiment the maximum torque characteristics, the feasibility of expansion of the constant power operation range will be confirmed and its effectiveness in the EV will be discussed. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (3): 78–91, 1997     

鼠笼式异步电动机的键合图建模与仿真

在Ghosh和Bhadra所建立的电机键合图模型基础上,根据鼠笼式异步电动机原理和结构,应用功率键合图理论,建立了鼠笼式异步电动机的统一扩展键合图模型,使之物理意义更明确.特别是转子导条的键合图模型的建立更具有实际意义.并利用现有键合图仿真软件对Ghosh和Bhadra电机模型与鼠笼式异步电动机模型进行了仿真对比,同时...     

双鼠笼感应电动机的结构及转子槽形设计

介绍双鼠笼感应电动机的结构特点、转子上下导条在电机起动与运行中的作用、转子导条的不同形状、导条材质的选择和转子槽形的类型,并展示了两种转子槽形的比较结果及它们在电机设计中的适用性。