Diagnosis of Short‐Circuit Faults in Stator Winding Inside Low‐Voltage Induction Motor Using Impulse Voltage Test

Short‐circuit faults in windings due to the deterioration of insulation is among the most common faults in motor drive systems. An easy and effective fault diagnosis method is urgently required to ensure highly reliable operation. This paper proposes a novel method for the diagnosis of short‐circuit faults in stator winding inside a low‐voltage induction motor without removing the rotor, by performing an impulse voltage test. As the rotor does not need to be removed from the motor in this novel diagnosis method, the method can be put to practical use. In this study, first, several impulse voltage tests are carried out on the stator windings of motors. Second, the values of two features that represent the characteristics corresponding to the condition of the motor are calculated, and it is found that the shape of the feature distribution does not depend on the rotor position but on the condition of the winding. Third, the distance between the feature distribution for the healthy motor and features obtained from a target motor is calculated. On the basis of this distance, the condition of the stator winding inside the induction motor is determined. The effectiveness of the proposed diagnosis method is verified by performing experiments that involve several motors with healthy and faulty windings.     

电机定子结构及其绝缘介电常数的频率特性对定子绕组电容值的影响

确定电机定子线棒的高频参数对于研究局部放电信号在电机绕组中的传播特性及研究PWM逆变器驱动的交流电机的定子绕组电压分布有重要意义。文中对大型汽轮发电机定子线棒的电容做了比较详细的研究，内容包括：对电机定子线棒复合绝缘等值介电常数的频率特性的测试研究、采用数值计算方法计算出用铝箔纸裹住的电机定子线棒的多导体传输线模型的单位长度电容、线棒股线间薄绝缘对电容的影响、对铁心硅钢片叠片间隙对电容的影响等。其数值计算结果与之前测量得到的电容值比较吻合，这也证明了通过测量开路阻抗、短路阻抗来得到电机定子线棒分布参数的试验方法是有效的。     

感应电机定子绕组缺相故障的模型仿真

在三相感应电机运行的各种故障中,绕组缺相故障的发生率较高,其主要包括供电电源一相断路和定子绕组一相断路,而这类故障通常不容易观测和诊断。基于感应电机的数学模型,以MATLAB/SIMULINK为工具对电机定子绕组故障瞬变过程进行了建模仿真。通过分析,验证感应电机定子绕组缺相故障理论分析的正确性,为定子绕组故障的快速、准确定位提供有效的手段,且对电机中出现类似故障现象的分析和定位也有一定的参考价值。     

A new structure of universal motor using soft magnetic composites

The universal or ac commutator motor, widely used in hand tools and domestic appliances generally uses a two-pole stator with a concentrated winding and an armature with interlocked coils elements. The copper volume and the axial length of the end windings of such conventional structures are then usually very important. In this paper, the authors present a new universal motor structure based on an efficient use of the isotropic magnetic properties of the soft magnetic composites and on the concentrated winding technique. The stator core presents a claw-pole structure and the armature has a concentrated winding with several coils wound around the same tooth. With this new ac commutator motor structure, a reduction of the total volume by a ratio equal to 200% is obtained when compared to a classical universal motor structure with nearly identical performance.     

Approaches to suppressing shaft voltage in brushless DC motor driven by PWM inverter

This paper describes the approaches to suppressing the shaft voltage and bearing current by electrostatically shielding the stator end windings of the brushless DC motor driven by PWM inverter. At first, measured shaft voltage and bearing current are compared with those calculated waveforms to verify the common mode equivalent circuit of the brushless DC motor. Next, the relationship between shaft voltage and stator winding to rotor capacitance is calculated using the common mode equivalent circuit. Finally, the electrostatic shielding of the stator end windings is evaluated to reduce the shaft voltage by experiments and calculations. ©2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 73–79, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20701     

一种适用于谐波起动电动机的新型定子绕组

通过对谐波起动电动机广泛采用的定子绕组存在问题的分析,提出了一种结构更加简单、控制更加方便的定子绕组,该定子绕组线圈的匝数、线规都相同,解决了谐波起动电动机定子绕组不等匝引起的设计和制造工艺困难的问题.对该绕组的设计方法进行了分析和介绍,并以8极72槽定子绕组实例加以说明.     

基于高频电压信号注入的永磁同步电机转子初始位置估计

提出了一种表面安装式永磁同步电机转子初始位置估计的方法。其原理是向定子绕组中注入脉动的高频电压信号,由于定子电感随转子位置q 而变化,因此绕组的高频电流响应信号中含有q 角的信息,但是该方法无法判断转子磁极的极性,因此在初步辨识出q 角的基础上再向d轴注入高频电压信号,并利用磁场饱和引起的电感量的变化来估计出转子的磁极极性。该方法不需要知道电机的精确参数,也不需要额外的硬件。介绍了实验系统的构成和参数,给出了实验结果,实验结果表明理论分析正确。     

高效高压中型异步电机绝缘结构设计分析

针对高压电机定子主绝缘减薄后电场的分布问题,本文以YKK400 -6(690 kW)中型高压异步电机为例,建立定子绕组静电场的计算模型.在边界条件不变的基础上,通过对场强最大值及电场集中系数分析计算,对定子绕组主绝缘进行减薄处理,并结合设计要求给出了主绝缘角部合理的圆角半径.在电场计算的基础上对主绝缘减薄前后的线圈进行介质损耗角正切与瞬时工频击穿电压试验.结果表明,新的绝缘结构满足要求.本文可为电机定子主绝缘的减薄及绝缘结构设计提供理论依据.同时也可达到提高电机效率的目的.     

A Unique Solution to Improving Motor Winding Life in Medium-Voltage Motors

It has been recognized for years that electrical motors installed in petrochemical plants require protection from condensation. Papers have compared different methods of preventing condensation from collecting in 600-V motor windings. These papers covered the advantages of directly heating the motor windings by introducing a low-voltage ac or dc source to the windings when the motor is not running. Their conclusion was that low-voltage heating. is the most practical solution to motor moisture problems since the heat is evenly distributed throughout the stator windings and does not cause hot spots in the windings as conventional motor heaters can. Many installations in recent years have proven the reliability of this low-voltage application to windings. A case history is given of retrofitting a newly developed motor windings heater to an existing 5000- hp 2300-V synchronous motor that has had numerous winding failures due to moisture. The installation is at ARCO Chemical Company's Port Arthur, TX, plant.     

基于DSP的感应电机参数辨识

感应电机高性能交流调速方法中,电机参数的准确性严重影响着电机控制系统的控制品质。该文基于感应电机的数字控制平台,利用自身固有资源,向电机注入脉冲电压和阶跃直流电流激励,然后检测定子电流或电压响应,通过曲线拟合的方法得到部分电机参数。在介绍原理的基础上,介绍了硬件电路的设计,最后进行了仿真和实验研究,结果表明该辨识方案具有较高的精度。     

无刷直流电机转子位置的电流注入估算新方法

介绍了凸极无刷直流电动机转子位置检测的电流注入法，该方法是在定子绕组中注入微弱的高频交流信号，通过对端电压的处理，计算出转子的位置。文中利用该方法对正常运转的电动机转子位置进行了仿真,验证了其有效性。     

基于脉冲注入法的无刷直流电动机转子位置检测研究

提出了一种采用脉冲注入来检测无刷直流电机在静止状态时转子位置的方法。基于此方法依次向定子绕组注入一系列的脉冲,通过脉冲电流的变化对转子位置进行估算。实验结果表明：该方法不但具有较高的位置检测准确性,同时对电机的参数依赖性小,可以省去电机内部的检测元件,又可以应用到其它电机。     

Self-regulated self-excited brushless three-phase synchronous generator

For lightweight and compact implementation of a generation set, many attempts have been made by some researchers to develop a brushless self-excited synchronous generator without an ac exciter. A previous paper proposed a novel self-excitation scheme by which the second-space harmonic component of armature mmf is used for exciting the rotor field system. In this excitation scheme the effect of the series excitation characteristic, as well as a self-excited and brushless implementation without an ac exciter is automatically obtained. However, in the case of system configuration of the generator already reported, voltage regulation in the inductive load condition was very large. To remove this problem, this paper presents a new system configuration of the generator with a self-regulating feature that can compensate voltage regulation automatically. The new generator consists of a stator installing two three-phase windings, externally connected to a load and a capacitor bank, respectively, and a rotor with field and harmonic windings. In this paper the system configuration and theoretical concepts of the presented generator are described and detailed experimental investigations with a laboratory machine are also shown.     

Inverter-fed drives: which motor stators are at risk?

This article describes measurements of the surge voltage characteristics from a number of motors driven by inverter-fed drives (IFDs). The measurements were done with both laboratory and purpose-built instrumentation. Further, we discuss why certain surges deteriorate the insulation, and we give guidelines for determining which motors may be at risk of failure from IFD voltage surges. The effect of these surges on stator windings is also included, as well as means to determine if a motor installed in a severe surge environment will fail     

Calculating Overvoltages in Windings of Synchronous Motors with Thyristor Frequency Converters

Analysis of overvoltages on the windings of synchronous motors caused by recharging of the insulation capacitances of motor stator windings connected with switching of valve currents has been carried out. The effect of a connecting cable line on the overvoltages of the motor is demonstrated. Formulas for determining the EMF phases of the network and the motor are presented. Expressions for determining bias EMF and zero-sequence EMF are examined. Oscillograms of variations in the current of the motor phases, the output voltage of the rectifier, and the insulation voltage of the motor are presented. Based on an analysis of the calculated quantities, conclusions are drawn and recommendations given for switching on the windings of a smoothing throttle.     

大型汽轮发电机定子线棒高频分布参数的测量

为研究局部放电信号等高频信号在电机定子绕组中的传播特性，需要确定电机定子线棒的高频分布参数。该文提出了基于多导体传输线(MTL)理论的大型电机定子线棒高频分布参数的测量方法。给出了三种不同条件下的大型汽轮发电机定子线棒分布参数的测量结果，分别是：用铝薄纸裹住单根定子线棒的情况；把单根定子线棒放在电机槽里的情况：双根定子线棒放在电机槽里的情况。测试结果较好地解释了陡前沿脉冲信号在电机定子绕组槽部线棒中是以两种速度沿线棒传播的现象。     

大功率变－交变频同步电动机的谐波问题分析

本文研究了由变频器非线性引起的交－交变频器供电的大功率同步电动机系统的谐波问题。重点对稳态运行条件下由定子谐波电压产生的磁势引起的阻尼绕组谐波电流、谐波损耗及脉动转矩进行了计算分析．并以一台５０００ｋＷ交－交变频大功率同步电动机为例做了实例计算．     

ANALYSIS OF A SERIES-DELTA CONNECTED TANDEM INDUCTION MOTOR

Abstract

A tandem induction motor comprised of two independently housed stator windings, one housing stationary and the other able to be physically rotated, and a squirrel-cage rotor common to both stators is described. When the motor is fed from a single source, altering the position of the moveable stator changes shaft speed in a similar manner to operating a normal induction motor at variable terminal voltage

This paper presents an equivalent circuit model of the tandem induction motor for series-delta connected stator windings. Using the equivalent circuit stator current, power factor, and torque are calculated and then compared to laboratory test results obtained from a 3 kW tandem motor test rig     

Analysis of no-load characteristics of a bearingless inductionmotor

This paper presents the design and analysis of a bearingless squirrel cage induction motor. There are two sets of stator windings. The main winding is a four-pole arrangement, while the control winding is a two-pole type. The latter is utilized to produce radial forces on the rotor shaft. The two-pole winding currents are regulated by radial position sensors and control strategies in order to maintain the rotor shaft position near the air gap center. The voltage and current relationships of the two-pole windings were derived from the machine inductance model and equivalent circuits. The influences of the secondary rotor circuits were also taken into account. The theoretical values of current, voltage, and radial force were compared with experimental results. It was found that the two-pole windings need only about 2 percent of the voltampere (VA) requirements of the main motor windings