定子斜槽十二相发电机-整流系统的非线性二维场-路耦合方程

本文提出了采用二维有限元技术近似计算定子斜槽时电机内三维电磁场的新方法,阐述了其计算原理.基于此方法,建立了考虑定子斜槽时十二相(四Y移15°相带)同步发电机整流系统的非线性二维瞬态涡流"场-路"耦合方程,并对电机内的电磁场以及空载电势波形进行了计算,分析了定子斜槽对齿谐波电势的削弱作用,得出了与谐波磁导分析法完全相同的结论,验证了二维有限元技术计算斜槽电机内电磁场的可行性和有效性.     

异步电机高频杂耗的自适应时步法有限元计算

异步电机杂散损耗的准确计算是一个十分困难的问题。本文论述了对非斜槽异步电机高次谐波杂散损耗的计算方法。文中采用的数学模型把电磁场有限元方程与电路方程耦合在一起,当输入电压波形给定后,电机中的之流和磁密波形可通过时步法直接求得。根据计算所得的高次谐波电磁场,就可进一步计算出高次谐波杂散损耗。计算结果通过样机试验得到验证。在计算中采用了自适应时间步长的方法,并首次提出了一种估计局部截断误差简单实用的方法。     

远场涡流似波特性的现象与本质研究

远场涡流效应在数学上遵守扩散方程，但是其电磁特性又呈现某些似波动特性。本文从电磁场基本理论出发，以电磁场有限元分析为工具，首次较完整、系统地研究了远场涡流的似波特性，主要集中在电磁场量的相速特征和瞬时扩散能量流特征这两个方面。研究结果表明，远场涡流的电磁场量在远场区具有稳定的相速度，但其值远小于光速；瞬时扩散能量流的变化可以用能流分界线来表示，滞后于激励电流源的变化，呈现出似波动特性。似波特性的实质是管壁中涡流的影响。     

异步电机时步法有限元软件的研制

介绍了异步电机时步法有限元软件的研制。采用在异步电机数字模型中把电磁场方程、电路方程、转矩方程耦合在一起并用时步法求解的方法,可直接计算出电机的电流和转矩等的波形,计算结果中包含了高次谐波等复杂因素的影响。     

基于分段斜槽技术的电机斜槽特性分析

普通斜槽电机的计算通常采用三维有限元分析方法,计算量庞大,不适合工程应用。本文阐述了基于电机电磁场软件EasiMotor利用分段斜槽技术分析斜槽电机的原理,分析了电机轴向分段方法对计算精度收敛性能的影响,并针对不同斜槽角度,分析了电机分段数对计算精度的影响。文中利用Flux 10.3对仿真结果进行验证,并基于该分段斜槽技术进行了电机的电磁场分析验证,实验结果进一步表明EasiMotor软件有限元分析的可靠性。     

实心转子异步电机机械特性及涡流效应分析

在实心转子异步电机中，存在着复杂的电磁现象，如涡流现象，饱和现象，集肤效应等。本文利用有限元数值计算方法，对其进行了深入研究，并与用磁阻抗法及实验法所得的结果作了比较，结果表明数值计算方法的精确性，证明实心转子异步电机的机械特性与具有高转子电阻的普通异步电机的特性相类似，且具有良好的起动特性。     

求解非线性电磁场有限元方程的快速线性迭代法

本文针对求解非线性电磁场有限元方程的简单迭代法,提出了一种新的算法-快速线性迭代法。该算法取消了收敛因子,提高了收敛速度和收敛稳定性,用模型计算加以验证。並实例计算了非线性正弦交变涡流的电机电磁场方程。与简单迭代法比较,充分显示其优越性。     

一种双转子电磁热机及其磁场和涡流分析

为了提高传统的单转子电磁热机永磁体的利用率,增加热机的致热功率,提出一种双转子电磁热机。介绍了该热机的基本结构及工作原理,建立了该热机的二维简化求解模型,在此基础上给出了二维电磁场方程,并得出该热机的致热功率及涡流解析模型。基于有限元求解方法,分析了该热机的磁场及涡流分布特点。比较了双转子热机与单转子热机在不同转速下的致热功率及传热管道内的磁场分布。有限元分析的结果表明,采用双转子结构设计的热机,致热功率明显提高,同时定子传热管道中可获得高强度且近均匀分布的交变磁场,有利于传热水媒质的磁化效应。     

实心转子异步电机机械特性及涡流效应分析

在实心转子异步电机中,存在着复杂的电磁现象,如涡流现象、饱和现象、集肤效应等。本文利用有限元数值计算方法,对其进行了深入研究,并与用磁阳抗法及实验法所得的结果作了比较。结果表明数值计算方法的精确性,证明实心转子异步电机的机械特性与具有高转子电阻的普通异步电机的特性相类似,且具有良好的起动特性。     

用混合有限元和边界元法求解圆筒型直线异步电机的稳态特性

用混合有限元和直接边界元法计算了圆筒型直线异步电机的稳态运行特性。电机的初级和次级场域用有限元法分析，空气隙场域用边界元法分析，同时考虑了铁心的饱和、涡流效应以及齿槽效应的影响。计算结果与实验结果吻合较好。     

Representation of skew in time-stepped two-dimensionalfinite-element models of electrical machines

The authors outline a technique which enables two-dimensional finite-element analysis to be applied to skewed machines. It involves representing the continuous skewing in a series of discrete steps. Each step may be modeled in two dimensions. The model has been applied to a salient-pole synchronous generator and to a cage induction motor. It is shown that the model is successful in removing phantom slot-ripples from the current and voltage waveforms     

抑制分数槽永磁电机轴电压定子斜槽法

特定极槽配合的分数槽永磁电机在空载情况下会产生固有轴电压,对轴承有着不可忽视的危害,同时对电机运行的稳定性及安全性也会造成极大的影响。斜槽作为电机性能优化的常用方法,对谐波的削弱也有着很好的效果,故可以采用定子斜槽法来削弱永磁电机空载轴电压的主要谐波。首先,基于磁路原理和法拉第电磁感应定律,推导出考虑斜槽时的分数槽永磁电机空载轴电压的解析模型,分析轴电压的主要谐波成分与斜槽数的关系,给出可使轴电压得到削弱的最佳斜槽数,然后利用二维有限元法分析了不同斜槽度下的4台分数槽永磁电机的空载轴电压,结果证明了解析分析的正确性和有效性。     

Impact of iron loss on behavior of vector controlled inductionmachines

Vector control principles are derived under the assumption that iron core loss may be neglected. The paper discusses effects of this simplification on performance of vector controlled induction machines. Indirect stator, air gap and rotor flux oriented control of a current fed machine are dealt with, with the emphasis on indirect rotor flux oriented control. Models of vector controlled induction machines that account for the iron loss are derived, and the mechanism of core loss influence on behavior of the drives is highlighted. It is shown that detuning caused by neglecting the core loss will inevitably take place. The amount of detuning is investigated for steady-state operation, for all three types of vector control. Some insight into detuning during transient operation is provided for the case of indirect rotor flux oriented induction machine. The concluding part of the paper presents a new decoupling circuit for indirect rotor flux oriented control. The circuit accounts for iron loss and thus eliminates detuning which is otherwise present     

Simulating the operation of auxiliary machines of a 2(3)ES5K locomotive

Auxiliary machines of electric trains provide the operation of traction motors and electrical and pneumatic equipment. The main condition of safe operation of the asynchronous electric drive of auxiliary machines is the maintenance of the operation mode of the electric drive in terms of the basic technical data, according to which NVA-55 electric drives are matched by nominal operation (long-term) mode S1. The effect of supply voltage on the operation of locomotive auxiliary machines is considered. Auxiliary machines are used under poor conditions on alternating current electric trains. Disbalance of the motor currents occurs even at nominal voltage of the overhead contact system and operable phase-shifting device. In operation, the voltage on the contact wire line is not constant and the equipment modes can be inconsistent with the nominal one, which leads to a significant number of failures of auxiliary equipment. This makes it necessary for the microprocessor control system to use the controlled auxiliary electric drive. An individual autonomous inverter with fully balanced sinusoidal output voltage allows one to increase the reliability of the induction motor drive, while the proportional control of the blower motor reduces the power consumption.     

Stator current fault diagnosis of induction motor bearings based on the fast Fourier transform

Monitoring of the technical state of induction motor bearings is one of the important indicators of reliable and efficient operation of industrial electrical drives. This article considers the problems of fault diagnosis of induction motor bearings with a squirrel-cage rotor by stator consumption current. Test results on an experimental test bench with an electromagnetic powder brake are presented and analyzed. Experiments were carried out during tests of the induction motor at the rated mode with an operable bearing and alternately with two faulty bearings with defects at the inner and outer parts of cages. The characteristic harmonic components of stator currents appearing during operation of the induction motor with faulty bearings are presented. It is revealed that an anticipatory diagnosis of induction motors by stator current makes it possible to reveal the air-gap eccentricity due to the operation of an electric motor with a damaged bearing. Control of the technical state of bearings is important both during at the stage of manufacturing machines, in particularly for powerful and crucial mechanisms, and during their use. The basic features of monitoring the bearings are revealed, and recommendations for diagnosis by stator currents are presented.     

MRAS-based sensorless control of a vector controlled five-phase induction motor drive

Multi-phase ac motor drives are nowadays considered for various applications, due to numerous advantages that they offer when compared to their three-phase counterparts. In principle, control methods for multi-phase machines are the same as for three-phase machines. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information of the rotor speed is extracted from measured stator currents and voltages at motor terminals. Vector controlled drives require estimating the magnitude and spatial orientation of the fundamental magnetic flux waves in the stator or in the rotor. Open-loop estimators and closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an open-loop and model reference adaptive system (MRAS)-based sensorless control of vector controlled five-phase induction machine with current control in the stationary reference frame. The MRAS-based sensorless operation of a three-phase induction machine is well established and the same principle is extended in this paper for an IRFOC five-phase induction machine. Performance, obtainable with hysteresis current control, is illustrated for a number of operating conditions on the basis of simulation results. Full decoupling of rotor flux control and torque control is realised. Dynamics, achievable with a five-phase vector controlled induction machine, are shown to be essentially identical to those obtainable with a three-phase induction machine. Experimental verification is also provided.     

电压跌落时感应电动机反馈电流计算及转速影响研究

大容量感应电动机会影响工业配网的短路电流水平,准确计算其反馈电流对系统保护配置及全网短路电流计算具有重要作用。电压跌落时电动机转速变化会影响电动机的反馈电流,不考虑转速变化可能会导致反馈电流计算结果不准确,影响保护的正确动作。利用感应电动机静态等值电路和复常系数线性微分方程组解法求解定转子磁链正负序强制分量和自由分量,进而得到电压跌落时计及转速变化的感应电动机反馈电流计算方法,并进一步探讨了转速对磁链和反馈电流各分量的影响。采用PSCAD/EMTDC仿真软件中感应电动机的5阶动态模型仿真验证了该分析的正确性。     

Quad Demodulation: A Time-Domain Diagnostic Method for Induction Machines

Motor Current Signature Analysis is the reference method for the diagnosis of induction machines. However, it features some drawbacks, as it is bound to steady-state conditions, and fault signatures may be created by different overlapping phenomena. This paper presents a full-time domain-based method for the quantitative evaluation of electrical faults in induction machines. It relies on stator current measurements; thus, it is compliant with switching power converter drives, provided that a proper current measurement technique is available. Moreover, it allows an accurate quantification of faults without requiring spectrum analysis; hence, it achieves high resolution even with a low time acquisition period. A fault index is computed as the energy of the signal in a suitable “fault bandwidth,” thus reducing the effects of frequency variations. The aforementioned advantages are perfectly suited to time varying signals and to embedded drive diagnostic systems.      

DEVELOPMENT OF A STATOR-CONTROLLED BRUSHLESS INDUCTION MACHINE WITH LEADING VAR CAPABILITY

ABSTRACT

The use of the DC-component of rotor current to continuously generate large amounts of reactive kVA from the stator of cage-rotor induction machines in which the total line current may be at a leading power factor, has been recently discussed [ 1-3 ] with initial test results from a 35 H.P. unit. The only constructional difference between these space-transient machines and conventional rotary motors is in the stator MMF layout which includes mixing of two wavelengths in operation simultaneously. The rotor current distribution is no longer sinusoidal but contains a series of harmonics similar to those present in a sheet-secondary linear induction motor with a pronounced longitudinal exit-edge effect at high speed. The development of the 35 and 150 H.P. machines which operate at unity power factor on 50?Hz is presented in light of the work performed earlier[4]to neutralize the exit-edge effect in a 17?kW LIM which attained an 80% terminal power factor at 50?Hz by the use of an asynchronous condenser winding of a second pole-pitch smaller than the main stator pole-pitch     

双斜槽转子感应电机的快速场路耦合分析

为克服双斜槽感应电机轴向拓扑仿真时需采用低效率高精度的三维有限元仿真的问题,针对错开双斜槽转子感应电机(DSRIM)提出一种等效电路,然后基于多层有限元模型建立DSRIM的轴向分层等效电路。在等效电路与磁场耦合分析的基础上,运用分布磁路法求出气隙磁场分布与稳态性能指标。与试验结果进行对比,对比结果显示该方法的计算结果具有指导意义。