电加热紫外光固化浸漆工艺在新能源汽车电机制造中的应用

随着电机制造技术的进步,电机绝缘技术也在快速发展。根据在电动汽车/混合动力汽车（EV/HEV）驱动电机制造领域的工程实践,从绝缘浸渍漆、工艺、设备3方面出发,介绍了一种适用于散嵌绕组电机的新型绝缘处理技术：电加热紫外光固化工艺（E-UV）。通过实际应用,证实了该技术具有能耗低、生产周期短、绝缘浸渍漆利用率高等特点,适用于EV/HEV驱动电机的批量生产。     

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.     

New specs for ASD motors

The two main issues in pulse-width modulated ASD motors namely: stress concentration at slot exits and at junctions between stress grading and corona protection materials, and winding insulation aging due to partial discharge and/or dielectric heating, often intensified between turns as well as across the main-wall of the stator coils. This paper explores the IEC-60034-18-41 and IEC-60034-18-42 technical specifications for inverter duty motor insulation. These specifications describe the qualification and acceptance tests for both low and medium voltage motor windings in order to ensure reliability     

高压电机定子采用散绕组的绝缘结构分析

高压电机的定子通常采用成型绕组,同时需配套开口槽,导致电机成本增加、气隙磁场谐波含量增大、齿槽转矩增大等一系列问题。为了解决上述问题,可以采用散嵌圆铜线绕组。对于高压电机采用散绕组,绝缘问题是关注和研究的重点。以1台高压散绕组电机为例,利用有限元法分析了高压电机采用散绕组的绝缘结构可靠性,分别分析了匝间绝缘、主绝缘、层间绝缘和端部绝缘的绝缘情况以及主绝缘被冲片毛刺划伤情况下的电场强度分布,并根据分析结果针对电机槽内绝缘做出了优化,制造了1台样机并对样机进行了耐电压试验。验证了高压电机定子采用散绕组在一定程度上是可行的,为高压电机定子绝缘结构设计提供了参考。     

变频牵引电机定子绕组绝缘老化特性研究

对比测量了不同运行年限的变频牵引电机的定子绕组绝缘诊断参数,包括绝缘电阻、介质损耗因数、局部放电起始电压(PDIV)、剩余击穿电压等特征参数,以及沿绕组不同部位的绝缘材料取样进行了热失重分析(TGA)来研究绝缘老化特征。介电性能测量结果表明,与新电机相比,运行后定子绕组的绝缘介电性能有不同程度的下降,出槽口附近绝缘的老化程度高于槽内。TGA分析结果表明,使用了长达10年的牵引电机定子绕组绝缘性能略有下降,且线圈下层边的绝缘老化比上层边明显。     

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.     

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.     

基于三相半桥功率变换器的无轴承开关磁阻电机绕组结构分析

无轴承开关磁阻电机兼有开关磁阻电机和磁轴承的优点。功率变换器是无轴承开关磁阻电机的重要组成部分,其控制绕组电流,对电机旋转和悬浮性能有重要影响。悬浮绕组功率变换器采用三相半桥结构时,由于负载的不对称,存在中点电压漂移问题。该文简要介绍了电机悬浮原理和数学模型,将功率变换器和电机作为一个整体,分析了中点电压漂移的原因及绕组配置对中点电压的影响。给出了5种绕组结构形式下,各相悬浮力之和及其对中点电压的影响。通过合理配置绕组结构,使电机在恒定径向负载的情况下,中点电压波动大为减小。给出了4种优化的无轴承开关磁阻电机绕组结构。实验结果证明了理论分析的正确性。     

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 Failure Mode for PWM Inverter-Fed AC Motors Due to the Antiresonance Phenomenon

A failure mode for pulsewidth-modulation inverter-fed ac motors due to the antiresonance phenomenon is introduced and investigated in this paper. At high frequencies, an ac motor behaves as a series RLC circuit with a resonance point, so-called antiresonance, typically above 1.0 MHz. If the voltage oscillation frequency caused by the reflected-wave phenomenon matches the motor antiresonance frequency, an amplified voltage will appear internally between the turns of the stator windings. This externally unobservable state can cause winding insulation failure in the ac motor. This phenomenon is experimentally verified using a rewound permanent-magnet motor with accessible taps along the stator windings, and the results are presented in this paper.     

Development of a new off-line test procedure for low voltage rotating machines fed by adjustable speed drives (ASD)

Using adjustable speed drives employing fast switching components to supply low voltage asynchronous motors may be detrimental to their reliability in some cases. The premature failures of the insulating materials are often attributed to the existence of partial discharges (PD) in the windings. Nevertheless, a clear evidence of any PD existence in such systems is far from being established. Also, their location may not be in the turn-to-ground or phase-to-phase insulation but in the turn-to-turn insulation due to the voltage waveforms, and as such, the classical AC test is no longer applicable. The aim of this paper is to present an off-line test procedure capable of overcoming this problem. The results of the test carried out on the representative population of different motors are presented.     

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     

双绕组电机在电力系统中的发展

与传统笼型感应电机相比，双绕组电机具有降低电机谐波损耗、杂散损耗及转矩脉动的性能。综述了双绕组电机的研究状况，预测了双绕组电机的应用前景。     

Cost-effective motor surge capability

The use of surge capacitors to protect medium voltage induction motor windings from steep-fronted power surges has long been an accepted industry practice. Claims have been made that motor reliability would be improved without the use of surge capacitors if added interturn insulation were incorporated within the motor winding. This paper explores the surge-withstand ability of motors and the surge standards that have emerged. It presents a survey of industry practices and studies related to current motor applications, and provides the motor user with an economic evaluation to arrive at a cost-effective selection of motors with or without external surge protection     

高频脉冲下牵引电机绝缘的局部放电特性

变频牵引电机定子绝缘承受来自变流器的连续高压方波脉冲,可能导致绝缘过早失效,其老化机理与工频交流电压作用下差异很大。局部放电是导致变频调速牵引电机绝缘失效的主要原因之一。研究高频方波脉冲下的局部放电特性为牵引电机绝缘材料的改进和优化提供理论基础,试验分析了普通和聚酰亚胺纳米复合薄膜制成的电磁线寿命,结果发现纳米试样的寿命得到很大提高。针对普通和聚酰亚胺纳米复合薄膜研究了不同脉冲频率、上升时间和温度对放电起始电压、平均放电量和放电次数的影响。结果表明,频率的增加、上升时间的缩短和温度的增加加剧了局部放电活动,普通薄膜试样的局部放电活动更强,其原因是纳米粒子的添加导致纳米复合薄膜存在大量界面区和电导率增加,电荷的迁移速率增大,空间电荷累积效应减弱。     

高压紧凑型防爆电动机电加热带的选择

加热带是高压紧凑型防爆电动机的重要组成元件,它在电动机停止工作时开始工作,防止电动机在停机时因绕组潮湿、电气绝缘性能下降而引发电气故障。文章介绍了加热带的选型方法,提出了加热带应具备的技术要求。     

Computer Analysis of 3-Phase Induction Motor Operation on Rural Open-Delta Distribution Systems

Open-delta/open-delta and open-wye/open-delta transformer banks are often used as an economic means of supplying simultaneous single-phase and 3-phase loads in rural areas. If the 3-phase load is an induction motor, the inherent voltage unbalance causes increased losses and uneven heating that may lead to motor failure. often these motors are submersible or deep well pump motors located in remote unattended areas or air conditioning motors which may not have sufficient over-design to handle the voltage unbalance. The theory analyzing the open-delta distribution system has existed for many years, however, because of the tedious and almost infinite differences in distribution topology, the problem has been neglected. The purpose in this endeavor is to present a simple general approach to the solution of the problem by utilizing existing motor and network concepts and theories. Two previously published theories are used to predict motor heating and the motor derating that is necessary to prevent insulation failure due to the unbalanced voltages. A general motor model has been developed. Motor heating and derating are obtained from the model through a generalized digital computer program.     

变频异步电动机绝缘结构设计

通过对变频异步电动机绝缘结构的组成、材料的要求等进行分析,阐述了绕组线间或绕组线对地间可能发生的电击穿火花,但绝缘本身并未击穿,为局部放电（PD）等现象。在电磁线、浸渍树脂、槽绝缘、相间绝缘与层间绝缘、槽楔、引线方向应用H级绝缘材料,使变频电机的绝缘有耐冲击电压性能、耐局部放电性能和耐热、耐老化性能,从而提高了变频电机的可靠性,保障电机的稳定运行。     

航空电反推用永磁同步电机余度设计与仿真分析

本文以航空发动机电动反推力装置为应用背景,对永磁同步电机进行了余度设计,采用双绕组电机来代替两个独立的电机,既保证了高可靠性,又大幅度减轻了体积和重量。该电机的特点是只有一套转子,定子铁心上嵌绕着两套独立绕组,形成并联余度设计。控制器部分也采用余度思想,设计为双通道结构,热备份工作模式。基于航空发动机电动反推力装置的实际工况,考虑电机的四象限运行状态,并设计了相应的制动电路。结合控制策略,利用MATLAB/Simulink对整个系统热备份工作模式进行了仿真,整体上验证了余度设计的可行性。     

不饱和聚酯亚胺/少胶粉云母带绝缘及VPI工艺在高压电机中的应用

论文介绍了不饱和聚酯亚胺／少胶粉云母带绝缘体系及真空压力浸渍（VPI）电机工艺技术，对模拟线棒进行了常规电气性能，电热老化试验，检测结果和模拟线圈的检测在电机上应用的结果表明绝缘完全可以满足电机的绝缘性能要求。