Study on voltage distribution in windings of an inverter-fed traction motor

Voltage distribution in windings is important for inverter-fed traction motors.The analysis on voltage distribution characteristics is significant to the study of insulation failure mechanisms and structure design.First,a distribution parameter model has been developed according to the winding structure of an inverter-fed traction motor.Based on the model,finite element differential method was employed to determine voltage distribution characteristics.Simulation results were compared with actual voltage distribution.Moreover,the influence of pulse rise time and cable was discussed.The results show that the shorter the pulse rise time is,the more uneven the voltage distribution is.In addition,cable length has little influence on voltage distribution characteristics.However,the amplitude of voltage would also increase by 40%in coils and turns.

Cooling System Design Optimization of an Enclosed PM Traction Motor for Subway Propulsion Systems

This paper presents the design optimization of a self-circulated ventilation system for an enclosed permanent magnet(PM)traction motor utilized in the propulsion systems for subway trains.In order to analyze accurately the machine's inherent cooling capacity when the train is running,the ambient airflow and the related heat transfer coefficient(HTC)are numerically investigated considering synchronously the bogie installation structure.The machine is preliminary cooled with air ducts set on the motor shell,and the fluidic-thermal field distributions with only the shell air duct cooling are numerically calculated.During simulations,the HTC obtained in the former steps is applied to the external surface of the machine to model the inherent cooling characteristic caused by the train movement.To reduce the temperature rise and thus guarantee the motor's working reliability,an internal self-circulated air cooling system is proposed according to the machine temperature distribution.The air enclosed in the end-caps is driven by the blades mounted on both sides of the rotor core and forms two air circuits to bring the excessive power losses generated in the heating components to cool regions.The fluid flow and temperature rise distributions of the cooling system's structural parameters are further improved by the Taguchi method in order to confirm the efficacy of the internal air cooling system.

Dynamic analysis of traction motor in a locomotive considering surface waviness on races of a motor bearing

The traction motor is the power source of the locomotive.If the surface waviness occurs on the races of the motor bearing,it will cause abnormal vibration and noise,accelerate fatigue and wear,and seriously affect the stability and safety of the traction power transmission.In this paper,an excitation model coupling the time-varying displacement and contact stiffness excitations is adopted to investigate the effect of the surface waviness of the motor bearing on the traction motor under the excitation from the locomotive-track coupled system.The detailed mechanical power transmission path and the internal/external excitations(e.g.,wheel–rail interaction,gear mesh,and internal interactions of the rolling bearing)of the locomotive are comprehensively considered to provide accurate dynamic loads for the traction motor.Effects of the wavenumber and amplitude of the surface waviness on the traction motor and its neighbor components of the locomotive are investigated.The results indicate that controlling the amplitude of the waviness and avoiding the wavenumber being an integer multiple of the number of the rollers are helpful for reducing the abnormal vibration and noise of the traction motor.

Wide speed range for traction motor in braking force of electric braking control system

A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient is controlled by estimating the load torque of motor, thereby traction motor is not rotated after stop. In addition, coasting operation and brake test are performed from normal-opposite operation and start using a small-scale model comprising the inertial load equipment and the power converter. Further, traction motor is made to be equipped with a suspension torque. Pure electric braking that makes traction motor stop by an air brake at the time of stop is also implemented. Constant torque range and constant power range are expanded during braking so that braking force is secured with the electric brakes even in high speed region. Therefore, vehicle reduction effect can be expected by reducing parts related with an air brake which is not used frequently by using a pure electric brake in the M car in wide speed region. Further, maintenance of brake system can be reduced. Besides, ride comfort of passenger in the electric rail car, energy efficiency improvement, and noise reduction effect can be additionally expected. Further, an improved brake method that uses only an electric brake till motor stop is proposed by comparing those in the blending brake that uses an air brake while reducing brake torque at vehicle stop.

Evaluation of Environmental Impacts of Traction Motor Production and Disposal

By the application of life cycle assessment(LCA) methodology, this paper estimates the environmental impacts of production and disposal of traction motors used in electric vehicles in China. The results show that the total energy use, the criteria emissions and the greenhouse gases(GHG) emissions of a traction motor production and disposal are about 2,899,MJ, 4.5,kg and 259.5,kg per motor, respectively. Among the regulated emissions, the SOxemission ranks first by total mass, followed by CO, PM10, NOx, PM2.5, and volatile organic compound(VOC). The motor material production stage accounts for most of the energy consumption and emissions, followed by the assembly stage and the end-of-life disposal stage. In this study, the environmental performance analysis is extended to the comparison between the use of secondary material and primary material for the material production stage. It is found that using 100% secondary material results in a 52.9% reduction in energy consumption, a 49.8% reduction in regulated emissions, and a 49.3% reduction in GHG emissions compared with the use of 100% primary material.

Improved Dynamics Model of Locomotive Traction Motor with Elasticity of Rotor Shaft and Supporting Bearings

The locomotive traction motor is described as a rotor-bearing system coupling the kinetic equations of the traction shaft and its support bearings with the determination of their elastic deformations in this study.Under the effect of excitations induced by the dynamic rotor eccentric distance and time-varying mesh stiffness,the elastic structure deformations of the shaft and support bearings are formulated in the vibration environment of the locomotive.In addition,the nonlinear contact forces between the components of the rolling bearing,the lubricating oil film,and radial clearance are comprehensively considered in this study.The results indicate that the elastic deformations of the shaft and bearings can change the dynamic responses of the traction motor and its support bearings.There are large differences between the ranges of the rotor motion calculated by the rigid and the flexible traction motor models when the intensified wheel-rail interaction is considered.With the increase of the rotor eccentricity,the results underscore the role of the elasticity of traction shaft and support bearings in dynamic researches of the traction motor.The critical value of the initial eccentric distance for the rub-impact phenomenon decreases from 1.23 mm to 1.15 mm considering the flexible effect of the shaft and bearings.This dynamics model of the traction motor can provide more accurate and reasonable simulation results for correlational dynamic researches.

Research and improvement of leakage protection system in traction motor

Because the leakage protection circuit in traction motor of coal mining machine is impacted by frequency converter devices,malfunctions appear frequently.This paper makes an in-depth analysis,proposes a solution of using the subtraction circuit to offset interference signals and conducts a simulation analysis.The above scheme,which is simple and easily realized,can improve the reliability of leakage protection device in traction motor.

Design of Axial-Flux Motor for Traction Application

This paper deals with the design of high power – low dimensions axial-flux permanent-magnet motor intended for trac-tion application. First, two motor configurations are analytically designed and compared using finite element calcula-tion. Then, the configuration yielding the best performances is integrated and modelled with the whole traction chain under MATLAB/SIMULINK environment in order to demonstrate the motor operation on a large speed band.

Performance Evaluation of a 60kW IPM Motor for Medium Commercial EV Traction Application

This paper presented the design and performance analysis of a 60kW interior permanent-magnet(IPM)synchronous motor used as traction drive in a medium commercial electric vehicle(EV),according to the traction requirements of the electric vehicle under the rated operating conditions and overload conditions.The key dimensions were calculated on the basis of the permanent-magnet(PM)motor theory,and the 2D finite element method(FEM)simulation model of the IPM motor was built by using 2D Maxwell software.The influence geometric structures of the IPM motor including the PM dimensions and skewed PMs on electromagnetic torque were investigated,and the temperature distribution of the motor under rated operating condition and the condition of maximum speed were calculated.Finally,the simulation results of the IPM motor running in various operating modes were compared with the experimental results,which demonstrated that the designed IPM motor can match all requirements of the medium commercial electric vehicle driving applications.

Study of Traction Motor Feedback Testing SystemControlled by Microcomputer

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Analysis of Temperature Rise in High-Speed Permanent Magnet Synchronous Traction Motors by Coupling the Equivalent Thermal Circuit Method and Computational Fluid Dynamics

To solve the problem of temperature rise caused by the high power density of high-speed permanent magnet synchronous traction motors,the temperature rise of various components in the motor is analyzed by coupling the equivalent thermal circuit method and computational fluid dynamics.Also,a cooling strategy is proposed to solve the problem of temperature rise,which is expected to prolong the service life of these devices.First,the theoretical bases of the approaches used to study heat transfer and fluid mechanics are discussed,then the fluid flow for the considered motor is analyzed,and the equivalent thermal circuit method is introduced for the calculation of the temperature rise.Finally,the stator,rotor loss,motor temperature rise,and the proposed cooling method are also explored through experiments.According to the results,the stator temperature at 50,000 r/min and 60,000 r/min at no-load operation is 68℃ and 76℃,respectively.By monitoring the temperature of the air outlets inside and outside the motor at different speeds,it is also found that the motor reaches a stable temperature rise after 65 min of operation.Coupling of the thermal circuit method and computational fluid dynamics is a strategy that can provide the average temperature rise of each component and can also comprehensively calculate the temperature of each local point.We conclude that a hybrid cooling strategy based on axial air cooling of the inner air duct of the motor and water cooling of the stator can meet the design requirements for the ventilation and cooling of this type of motors.

轨道交通能量互馈式交流牵引传动综合测试系统的设计

针对轨道交通牵引传动系统性能测试与特性试验需求,设计一种列车交流牵引传动测试系统。系统由四象限整流器、DSP控制单元、牵引变流器、负载变流器、牵引电机与负载电机组成。牵引变流系统采用全新的“双变流器--交流电机负载反馈”方案,能量通过直流侧在牵引电机与负载电机之间互馈,避免试验过程中能量的大量消耗。系统可实现牵引变流器的牵引/制动工况性能测试,牵引电机性能测试、特性试验与功率测量,具有高智能化与自动化、安全可靠、测试准确度高、能量利用率高的优点。

CRH5动车组牵引脉冲整流器自适应优化控制方法研究

针对CRH5动车组牵引主回路脉冲整流器在牵引网压波动下的稳定性问题,提出一种基于自抗扰算法的参数自适应优化控制策略。在CRH5动车组牵引脉冲整流器现采用的dq双环控制结构基础上,针对电流内环采用最速综合fal函数实现控制响应及控制量大小随误差变化自适应调整,基于状态空间方程构建一阶线性自抗扰电压外环控制器以实现对系统扰动的观测及跟踪。由此改善控制器对外部扰动的估计及补偿能力,增强控制器对车网耦合特性变化的适应能力。通过Matlab/Simulink仿真对比分析了基于PID控制和基于参数自适应优化控制的dq电流控制器性能,仿真结果表明,基于参数自适应的dq电流优化控制策略下的整流器直流侧输出电压在启动过程中超调量更小,且在应对网压波动时输出电压波动恢复后的稳态误差小于指标值的1/6,抗干扰能力更强。为进一步验证该控制器应对网压低频振荡的抗扰动效果,在RT-LAB半实物实验平台上搭建动车组-牵引网级联耦合模型对比分析2种控制策略下的牵引网网压波形。结果表明:基于参数自适应的dq电流优化控制更能适应多列动车组同时接入而引发的扰动,抑制牵引网网压大幅度振荡;fal电流环的参数自适应特性能改善控制器动态特性,可根据瞬态误差及时调整控制器响应,且其控制参数适应范围较宽,易于整定。

齿轨车辆牵引电机布置模式及系统耦合振动特性

为探究牵引电机布置模式对齿轨车辆动态特性及齿轮-齿轨啮合特性的影响,在考虑齿轮-齿轨非线性啮合行为及其动态时变激扰和轮轨非线性接触关系的条件下,分析了不同电机布置模式下的车辆动力学特性。以Strub齿轨系统为原型,建立了齿轨车辆-轨道垂纵耦合动力学模型,研究了三种不同电机驱动形式对齿轨车辆动态特性的影响规律,并在此基础上提出了适用于齿轨车辆的牵引电机布置方案。研究表明:牵引电机双置工况下齿轮啮合力和垂向、纵向振动加速度更小;其中电机双置时齿轮齿轨啮合力约为电机后置和前置时的50%,平直段齿轮垂向和纵向加速度的最大幅值差分别为4.04和6.01 m/s^(2),爬坡段电机后置时齿轮振动加速度最大,其垂向、纵向加速度幅值比电机双置时大45%;平直线路上电机后置与前置时齿轨车辆的舒适性较好,而爬坡段牵引电机双置模式下更好;鉴于齿轨车辆主要应用于爬坡线路,且爬坡时电机双置齿轨车辆的动力学指标最好,因此建议牵引电机双置为最优布置模式。

基于电机振动的动车组牵引逆变器故障诊断研究

牵引逆变器的安全性和可靠性对高速动车组车辆的稳定运行至关重要,为了对逆变器工作状态进行识别,文章结合车辆系统动力学,提出了一种基于电机振动信号分析的故障诊断方法。将电机振动信号作为监测对象,通过检测逆变器故障时电流畸变引起电机异常振动的特征信号来进行判断。以CRH2型动车组牵引传动系统为例,建立了基于空间矢量脉宽调制策略下的三电平牵引逆变器电路仿真模型,对逆变器结构故障模式进行仿真。仿真结果表明,逆变器故障会显著影响交流侧输出电流谐波含量,尤其是5倍频、7倍频、11倍频、13倍频电流谐波;而这些谐波电流输入到牵引电机后转化为6P(1-s)倍频、12P(1-s)倍频的脉动转矩,并作用于电机,使得其输出振动中含有相应频率的谐波成分。通过对高速动车组实际运行过程中的牵引电机振动信号进行分析可发现,在正常情况下振动信号不明显含有此类谐波频率成分,而当逆变器存在故障时,则会导致在振动信号中该频率信号含量非常明显。因此,文章所提出的基于振动信号分析法能够有效地监测并诊断牵引逆变器工作状态,并具有一定的工程应用价值。

基于卷积神经网络的牵引电机定子绕组匝间短路故障诊断

为实现牵引电机定子绕组匝间短路故障诊断,提出一种基于一维卷积神经网络(one-dimensional convolutional neural network, 1D-CNN)的故障诊断方法。首先对电机健康状态、不同相发生匝间短路故障及不同故障严重程度下的定子电流进行三层小波分解,得到小波分解高频系数和低频系数;求取小波分解系数的二范数,作为电机电流的特征;设计并训练1D-CNN,将训练好的1D-CNN作为分类器,实现牵引电机定子绕组匝间短路故障“端到端”的智能诊断。设计并搭建异步电机定子绕组匝间短路故障诊断实验平台。实验结果表明:所提方法可以准确有效诊断出轻微的匝间短路故障。在闭环控制下,电机发生1匝短路故障时,诊断正确率达到90.5%,并能够有效区分故障相。

基于定子槽结构优化的交流牵引电机电磁降噪设计方法

针对交流牵引电机存在电磁噪声过大的问题,提出一种基于定子槽结构优化的电磁降噪设计方法。在分析交流牵引电机产生电磁噪声机理的基础上,针对其定子槽底部开槽降噪的具体设计方法及其开槽位置与槽口参数优化展开了研究。通过技术验证,同时对开槽处理前后进行了对比分析,结果表明:采用所提出的交流牵引电机定子槽结构优化方法在保持效率不变的情况下对电磁降噪具有显著效果。

基于阶跃激励响应的牵引电机定子早期匝间短路故障诊断方法

为了实现对牵引电机定子绕组匝间短路早期故障的可靠诊断,文章提出了一种基于阶跃激励稳态响应电流的故障诊断方法。首先根据牵引电机三相定子绕组匝间短路模型,对定子绕组任意两相施加阶跃激励,推导出3种情况下的响应电流表达式,并依据响应电流稳态值的变化特征提出新的故障特征分量;然后,搭建故障电机仿真模型,分析短路电阻和短路故障严重程度对响应电流的影响,研究故障特征分量对早期匝间短路故障诊断的有效性与可靠性;最后搭建试验平台,分析当电机固有不对称时,匝间短路故障对故障特征分量的影响。仿真与试验结果表明,该故障特征分量可以表示早期的匝间短路故障及其严重程度,并且能滤除电机固有不对称的影响。基于阶跃激励稳态响应电流的诊断方法操作便捷,结果可靠性高,对保护牵引系统的安全具有极大意义,且具备极大的工程应用价值。