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.

Experimental research of traction motor system for electric vehicle base on sound tensity

The traction motor of electric vehicle is differing from the general industry traction motor completely. Not only frequently start, parking, accelerate, decelerate and low speed, but also high torque in climbing slope, low torque in high speed and wide range speed are requested. Base on the theory of sound intensi- ty, the experiment of noise are study through the measurement at discrete points. The sizing grid is 10mm × 10mm, The sound intensity map of traction motor are protracted at 1000r/min and the result show that the main noise sources are fan, gear-box and the traction motor in turn.

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.

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.

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.

Modern Predictive Diagnostic Method of Induction Traction Motor Based on FEM, BEM

The paper presents a mathematical model of special construction induction traction motor. On the base of predictive filtering, analytical studies, fuzzy logic control, relying on the virtual data generated by FEM （Finite Element Method） and BEM （Boundary Element Method） is detected faults of induction motor. Digital predictive filter is used to separate a fundamental harmonic from spectrum current and voltage harmonics. Fuzzy logic control is used to identify a motor state. Magnetic fields distribution in the traction motor, of the wheel vehicle is presented in the paper. Modem diagnostics method has been used for faulty motor simulation and shows results of motor fault effects. Some computer programs were applied in calculation of magnetic fields distribution. On the base of magnetic field distributions were analyzed different failures situations. Some laboratory experiments realized for induction traction motor were verified by results of computer calculations.

Study of Traction Motor Feedback Testing SystemControlled by Microcomputer

this paper describes the design of a feedback testing system for locomtive tractionmotor. The structures and features of the software and hardware of themicrocomputer control system have been studied. This testing system hasalready been put into operation successfully in several locomotive depots inChina.

Surface wear evolution of traction motor bearings in vibration environment of a locomotive during operation

Wear is a major cause of bearing failure,however,compared with other impact failures,smooth wear is often neglected because of its slow gradualness.In a locomotive,under the effect of the intensified wheel-rail interaction and gear mesh,the surface wear can increase the radial clearances of motor bearings,trigger abnormal vibration and noise,and adversely affect the efficiency and safety of the traction motor.In this study,considering the mechanical structure of the traction motor,a locomotive-track spatially coupled dynamics model with traction power transmissions(LTMM)is adopted to provide accurate dynamic loads and obtain the dynamic responses of the system.From the perspective of contact stress and relative skidding at the roller-race interface,the causes and evolution of motor bearings surface wear are analyzed.The results indicate that the wear of inner races of motor bearings is uniform.The outer races of the driving/non-driving end bearings(DB or NDB)are worn in the loaded/main loadbearing regions.The increasing surface wear can increase the internal dynamic forces(e.g.,the centrifugal force of rotor and unbalanced magnetic pull)induced by the instantaneous eccentricity of the rotor,intensify the interactions between the roller and races,and deteriorate the vibrations of the traction motor and its neighboring components in the locomotive.In addition,the effects of the friction coefficient at the roller-race interface and track random irregularity are analyzed.This study offers a theoretical basis in service life prediction and design of the motor bearings.

Configurations and Control of Traction Motors for Electric Vehicles:A Review

In recent decades,worldwide global warming and reduction in petroleum resources have accelerated researcher’s attention to produce alternative sustainable and environmentally clean transportation systems.Electrification of vehicular technology is capable of curbing the environmental pollution problem in an efficient and effective way,due to high efficiency electric motors,development and advancement in the field of power electronic devices,digital signal processing and advanced control techniques.This article presents a comprehensive review on different configurations/architecture of electric vehicles(EVs)and hybrid electric vehicles(HEVs),traction motors for electric propulsion system and high performance speed sensorless control of traction drive.The basic architecture key components of hybrid vehicle and different power train configurations with respect to applications and limitations are discussed.The integral part of electric propulsion system,traction motor classes for desired operational characteristics and limitations are summarized from a system perspective with the latest improvements.High performance traction motor control techniques are discussed with respect to automotive applications.Finally,speed sensorless control techniques research trends as well as an extensive review on rotor speed estimation techniques for robust and efficient sensorless traction drive control are highlighted.This article provides state of the art key global trends and tradeoff of various technologies with future trends and potential areas of research.

Analytical modeling and simulation on lateral mechanical characteristics of high-speed train traction motor hanging leaf spring

In this paper,using the theoretical analysis method,according to the actual structure of the hanging leaf spring of the traction motor mounted on the frame,the lateral force model of the hanging leaf spring of the traction motor was established.Then,through theoretical deduction,the deformation analytical calculation formula and the stress analytical calculation formula of the hanging leaf spring were established.The correctness of the leaf spring’s lateral force model was established and its deformation and stress analytical formulae were verified using ANSYS finite element analysis software.Based on this,according to the deformation analytical formula and the stress analytical formula of the leaf spring established,the influence of the main structural parameters on the mechanical characteristics of the leaf spring was discussed,and the reliability of the analytical analysis method of the lateral mechanical characteristics of the traction motor hanging leaf spring was verified by the loading–unloading test.The results show that the deformation and the load of the leaf spring change linearly.The changes of leaf spring’s stress at different positions can be considered as being composed of three sections:a linear change section in the root,a nonlinear change section in the middle,and a nonlinear change section in the end.In the structural parameters,the end thickness h2 has the greatest influence on the stiffness and the stress of the leaf spring,and the maximum thickness of the leaf spring eye h1 has the least influence on the stiffness and the stress of the leaf spring.The influence degree of other parameters on the stiffness of the leaf spring is h_(3),L_(1),L_(3),L_(2) in order,and the influence degree on the stress of the leaf spring is h_(3),L_(1),L_(2),L_(3) in order.In addition,when the root thickness h_(3) is greater than a certain value,the maximum stress point of the leaf spring appears at the end position L_(2).This study can provide a useful reference for the intelligent forward design and the rapid analysis of the mechanical characteristics of high-speed train traction motor hanging leaf spring.

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 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.

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。

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.

共母线开绕组永磁同步牵引电机级联模型预测电流控制

为抑制共母线开绕组永磁同步牵引电机传动系统转矩脉动和由共模电压以及三次谐波反电动势作用于零轴回路产生的零序电流,提出一种自抗扰级联模型预测电流控制方法。首先,在第1级采用第1个有效电压矢量使得q轴电流增加,第2个有效电压矢量使得q轴电流减小,这一新的筛选组合规则将2个有效矢量根据对q轴电流作用效果分组寻优和作用时间分配;其次,在第2级对第1级所选有效电压矢量的零轴分量局部寻优,在第3级对第1级和第2级优化后系统产生的零轴电流分量采用极性相反的零矢量进行矢量分类寻优抑制,并精确分配作用时间;然后,在第4级对前3级所选电压矢量进行开关状态局部寻优,确定最优电压矢量的低开关频率状态组合作用于逆变器。最后,引入自抗扰控制减少电机启动加速过程中的调速超调,并对所提策略和双矢量模型预测电流控制进行稳态和动态仿真对比。结果表明:所提策略对转矩脉动、零轴电流、总谐波畸变率、开关频率和调速超调都具有很好的抑制效果,避免了传统模型预测控制的多目标代价函数中权重系数整定,对系统的控制性能有明显的提升作用。研究结果为进一步对共母线开绕组永磁同步牵引电机传动系统弱磁控制进行究,以及将驱动控制系统应用于机车牵引提供参考。

基于信息图-MCKD的高速列车牵引电机轴承故障诊断算法研究

高速列车牵引电机轴承故障特征微弱且干扰噪声强,为解决电机轴承故障特征难以提取的问题,文章提出了一种基于谱负熵信息图与最大相关峭度解卷积(MCKD)的电机轴承故障诊断方法。首先,对故障轴承振动信号进行基于谱负熵的信息图处理,确定最佳中心频带和带宽,从而对轴承振动信号进行带通滤波;然后,对滤波后的信号采用MCKD方法进行故障特征增强;最后,对故障特征增强后的信号进行包络分析,识别出电机轴承的故障特征。经仿真信号和台架试验数据验证,结果表明,信息图-MCKD方法对牵引电机轴承故障诊断具有良好效果。