Starting Characteristics of Motor in Inverter-Motor Drive System

When the induction motor is fed from the PWM VSI inverter, with and without torque enhancing function, the variations of the starting torque and the starting current versus the starting frequency are analyzed, based on the steady state equivalent circuit of the induction motor.The corresponding expressions are derived, and the corresponding curves are also drawn, from which the initial starting frequency range can be determined properly and easily. The initial starting frequency range is the common range, in which the starting torque should be high enough and the starting current low enough.Some other useful formulas are also derived.These results are significant for electrical drive designers to make the starting schemes. The effects of the increase of the stator and the rotor resistances on the starting torque and the initial starting frequency range are also discussed, which is caused by the skin effects of the high order harmonics present in the PWM inverter output voltage.

Role of End-ring Configuration in Shaping IE4 Induction Motor Performance

The performance characteristics,particularly the starting performance of direct line-fed induction motors,which are mainly influenced by the design of the rotor,are crucial considerations for end-users.It is quite a challenging issue for motor manufacturers to enhance the starting performance of existing mass-produced motors with minimal modifications and expenses.In this paper,a simple and cost-effective method to improve the starting performance of a commercial squirrel-cage induction motor(SCIM)is proposed.The influence of geometric parameters of the end-ring on the performance characteristics,including starting(locked rotor)torque,pull-up and break down torque,starting current,rotor electric parameters,current density,power losses,and efficiency have been comprehensively investigated.It has been revealed that among the other end-ring design parameters,the ring thickness has a significant effect on the performance characteristics.An optimal end-ring thickness is determined,and its performance characteristics have been compared to those of its initial counterpart.Numeric and parametric analyses have been conducted using a 2D time-stepping finite element method(FEM).The FEM results were validated using experimental measurements obtained from an 11 kW SCIM prototype.

A Novel Part-Winding Starting Method for 4-Pole Squirrel Cage Induction Motor

the paper has been removed due to the authors' personal reason.

Torque Ripple Suppression Control Strategy for Brushless Integrated Starter/Generator Wound-Field Synchronous Motor

A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a brushless wound-field synchronous motor in its starting process. The starting process was analyzed and the model of wound-field synchronous electric machine was established. The change of field current of the electric machine was described mathematically for simplified exciter and rotate rectifier. Based on the traditional field control, the flux linkage compensation was introduced in d-axis current to counteract the flux ripple. Some simulation and preliminary experiments were implemented. The results show that the proposed method is feasible and effective.

Research on Startup Reliability of Ultrasonic Motors

作为一种在航空航天和武器系统有着广泛用途的新型微电机,超声电机的启动可靠性影响了其进一步的推广应用。该文通过理论分析将影响电机可靠启动的因素定位为定、转子摩擦界面阻力的增加以及定子的非线性振动,其中摩擦界面阻力增加包括摩擦材料嵌入定子槽中以及摩擦材料与定子的粘接。结合仿真分析和实验研究,证明超声电机定子振动的非线性是影响电机可靠启动的根本原因,越靠近共振频率非线性越严重,而定、转子接触界面的粘接以及摩擦材料嵌入定子齿使定子谐振频率升高,也就使原有工作频率更接近共振频率,从而导致电机定频启动困难。最后提出利用定子振动的非线性,采取降频启动的方法,可有效提高电机启动可靠性,为超声电机的推广应用打下良好基础。

Study of Steady-state Performances for a Novel Line-start Single-phase Permanent Magnet Synchronous Motor With Three Parallel-connected Windings

对于三相感应电动机的单相运行,学者们已经提出了多种实用的接线方式,比如Smith接法、SEMIHEX接法。然而,对于三相异步起动永磁同步电动机的单相运行,很少有合适的接法提出。将并联式接法应用于三相异步起动永磁同步电动机的单相运行,提出了一种新型三绕组并联式异步起动单相永磁同步电动机。分析了三相异步起动永磁同步电动机同步运行时以及起动瞬间的正序、负序阻抗,基于对称分量法,对该接法电机的对称运行条件进行分析,得出了电容的确定方法,并利用遗传算法对电容值进行优化。提出了该新型电机稳态性能的计算方法;设计了一台高功率因数和一台低功率因数三相异步起动永磁同步电动机作为样机,并分别将其改接为三绕组高效单相永磁同步电动机,进行实验研究。实验结果表明,低功率因数的异步起动永磁同步电动机更适合改接成新型三绕组并联式单相永磁同步电动机。由低功率因数三相永磁同步电动机改接成的单相异步起动永磁同步电动机在额定负载下运行时,具有与同容量三相永磁同步电动机相近的效率和更高的功率因数。

A Novel Soft Start Method of Super Large Capacity High Voltage Motor

The large current generated by starting directly of super large capacity and high voltage induction motor would have a huge impact on the grid as well as the motor itself.The variation of the power factor and electromagnetic torque during direct start of motors with different capacity and voltage levels are obtained.Aiming at the problem that the secondary impact of auto-transformer starter is too large and the cost of magnetic control starter is too high,the auto-transformer and magnetic control soft start method of super large capacity and high voltage motor is proposed and the basic working principle is analyzed.The calculation formula of cost for magnetic control soft starter and auto-transformer and magnetic control soft starter is deduced,and specific examples are analyzed and compared.It is concluded that the choice of auto-transformer with appropriate tapping ratio can greatly reduce the cost of auto-transformer and magnetic control soft starter compared with the other one.Finally,the simulation and experiment results show that the start method can effectively avoid secondary current impact and constrain the motor starting current to less than 2.5 times the rated current.

Research on Switched Reluctance Motor for Automobile Starter/Generator System

A self-designed and developed 12/10 switched reluctance motor(SRM)is chosen as the object of study and a prototype of 2.5?kW switched reluctance starter/generator with fly-wheel is designed based on the requirements of the selected engine (Changan Aotooc three-cylinder engine wagon) for the starter, generator and drive. The 36?V/42 V DC source system is applied to establishing the simulation-analyzing model of the motor. A finite-element (FE) analysis of its two-dimensional electromagnetic field is conducted to obtain the exact model of the motor. Systematic simulation is carried out combining with its power conversion circuit and control element. Meanwhile the starting process and performance of the system are studied and analyzed with special efforts. Satisfactory result is derived from the testing of the prototype: theoretical analysis is basically matched with the tested data, which proves the rationality and feasibility of the design procedures, systematic modeling and control strategies. Therefore, the new 12/10-structure scheme is put forward based on the development and analysis of various SRM and it meets the requirements of the researched motor in terms of the structural parameters.

考虑同步启动低频电流影响的蓄水电动机组继电保护配置方法

在蓄水电动机组继电保护配置过程中,因电动机组同步启动时参与同步振荡,导致低频电流幅值较大,影响电网运行的安全性。针对这一情况,提出考虑同步启动低频电流影响的蓄水电动机组继电保护配置方法。针对蓄水电动机组不同电压下的线路进行线路保护配置和整定,将保护装置与断路器相连,并制定一套阶段式保护,实现对蓄水电动机组线路的保护,在此基础上,根据电动机组的工作阶段采用两种不同的整定方式,实现对蓄水电动机组的过流保护,考虑同步启动低频电流的变化,改进低功率保护整定,自动调整低功率保护动作值。结果表明:提出的蓄水电动机组继电保护配置方法能够快速消除故障,及时调整机组工作状态。在该配置方法作用下,线路的连锁故障率比较低,进一步保障了蓄水电动机组的安全运行。

电动汽车增程器启动技术研究

增程器启动涉及到无刷直流电机和发动机两个部件的起动及相互之间的配合。针对无刷直流电机起动过程中需克服发动机变化阻转矩的特点,提出利用定子绕组电感随电机转子位置不同而变化的特点,通过施加脉冲电压矢量、再比较母线电流的方法实现无刷直流电机的初始定位和准闭环加速起动;针对发动机起动易受低温环境影响的特点,对增程器提出了有效的预热措施。实验结果表明,无刷直流电机准闭环起动方案方便有效,整机启动可靠性高。

基于动态磁网络法大型感应电机阻抗参数及起动特性计算

为提高大型感应电机动态阻抗参数及起动特性计算的准确性及计算效率,构建了考虑电机转子转速变化引起气隙磁导变化的非线性动态磁网络模型。以一台6.5 MW大型感应电机为例,分析起动电流变化对电机内各处饱和程度的影响机理,在此基础上,根据磁力线路径及电机内饱和程度确定动态磁网络模型中的非线性磁导的计算方法。将动态磁网络模型与转子趋肤效应模型相结合,提出计及漏磁并考虑转子转速变化及饱和偏移现象的电机动态阻抗参数的计算方法。推导并建立基于转子多回路法的大型感应电机的动态数学模型,根据电机瞬态过程中的电磁耦合关系,确定动态数学模型与磁网络模型的动态耦合求解方法,提出大型电机瞬态过程中考虑电流、转速、饱和及趋肤程度变化的动态阻抗参数及起动特性的计算方法。通过与有限元计算结果及实验结果对比,验证了所提出计算方法的正确性。

表贴式永磁同步电机无位置传感器零低速起动方法的比较研究

由于运行在中高速状态下的永磁同步电机无位置传感器控制方式大多是采用反电动势来估算角度位置和转速,这在零低速往往不适用。为了实现表贴式永磁同步电机无位置传感器零低速起动和平滑切换到中高速运行,分析了恒压频比控制、恒流频比控制、脉振电压信号高频注入法三种低速起动控制方法。开环恒压频比控制采用了新的V/F曲线和电压补偿,近似补偿定子阻抗压降防止起动失败;单闭环IF控制和双闭环脉振高频电压注入控制采用加权算法切换至滑模观测器。对某一表贴式永磁同步电机应用Matlab/Simulink进行了永磁同步电机无位置传感器控制系统的仿真分析,仿真结果验证了所提出方法的有效性。

大型可变速抽水蓄能机组SFC起动性能分析

大型可变速抽水蓄能机组在抽水工况下作为电动机运行,在起动过程中需要克服发电电动机和水泵水轮机的阻力矩,并且需要在一定的时间内将机组拖动到并网转速,所以采用有效的起动方式至关重要。大型可变速抽蓄机组电动工况起动方式包括静止变频器(SFC)起动、背靠背起动和自起动三种,其中SFC起动为抽蓄电站普遍采用的起动方式之一。变速机组也可采用定速机组配置的SFC进行起动,但变速发电电动机为绕线式异步电机,采用三相交流励磁技术,与定速机组在机型和励磁技术等方面完全不同,且目前国内外针对变速发电电动机SFC起动的相关研究成果较少,故亟需开展变速发电电动机、SFC装置和交流励磁配合的研究分析。自起动方式受到电机参数和变流器输出等限制,输出力矩的能力较小,而背靠背起动方式常作为备用起动方式,两者均不适用于400MW级及以上大型可变速抽蓄机组的起动。本文从分析可变速发电电动机SFC起动的原理入手,搭建了可变速发电电动机SFC起动的数值仿真模型,利用该仿真模型对一台440MW的抽蓄机组起动全过程进行了仿真分析,获得了主要物理量的变化规律,验证了数值模型的可靠性。

基于离线单相周期方波脉冲的三相异步电机启动转矩测试

为了克服三相异步电机启动转矩无载测试现有方法存在的测试精度较低、电网冲击等问题,提出一种基于离线单相方波脉冲的电机启动转矩测试方法。以Y160M-4型三相异步电机为研究对象,给出用于测试启动转矩的单相方波逆变电源结构、工作原理及关键参数计算方法,并利用二维瞬态电磁场数值计算方法,以研究不同激励模式下的启动转矩为目的,获取电机启动过程的电枢电流。结合电机数学模型和坐标变换理论,研究并给出单相正弦波激励下的电机等效电路模型和启动转矩理论计算模型。在此基础上,进一步给出单相方波激励下的启动转矩数据处理方法。经验证,依据所提出的单相方波激励下的电机启动转矩计算方法并结合二维瞬态电磁场数值仿真,启动转矩测试相对误差约为0.25%。研究结果表明,利用该方法计算三相异步电机的启动转矩,测试精度获得明显提高,从而证明了所提方法的正确性和可行性。

运动经验对短跑起跑过程中神经-肌肉控制策略的影响研究

目的:探究运动经验对起跑时肌肉协同特征的影响,分析不同运动经验下肌肉协同与姿态稳定性之间的关系。方法:采用三维动作捕捉系统、三维测力台和无线表面肌电采集设备同步采集11名高水平短跑运动员和14名短跑初学者在起跑时的运动学、地面反作用力和表面肌电数据。将2组受试者的表面肌电包络线映射至脊髓各节段的α−运动神经元池以获取脊髓水平的运动输出,采用非负矩阵分解和K-Means聚类获取2组受试者的肌肉协同特征。基于非受控流形分析建立各组肌肉协同变异性与质心横向位移波动之间的关系。结果:1)高水平组L1~L3节段的输出在起跑时与低水平存在显著差异(P<0.05),高水平组L4~S3节段的输出在起跑末期显著高于低水平组(P<0.05);2)高水平组的各组肌肉协同的空间结构较为合理,激活时间更为集中(P<0.05);3)高水平组在起跑时各组协同之间的协调程度较高,低水平组的各组肌肉协同仅在预备姿态时具有较好的协调。结论:运动经验可以优化各组肌肉协同间的协调及各协同内部的时空结构。合理调整预备姿态的肌肉激活策略并提高起跑器蹬离技术,有助于促进起跑的运动表现。

一种基于离散变频的三相异步电机软启动控制

针对传统三相异步电机软启动方式存在启动转矩不足,难以适用于部分需要重载启动电机场合的问题,采用一种离散变频的软启动控制方法,将离散变频的方式与传统软启动控制相结合,同时加入功率因数角补偿以提高电机在启动过程中的平稳性。实验表明,该控制方法可在抑制电机启动电流的同时,有效提升电机的启动转矩,同时抑制电机在启动过程中的抖动。

基于自适应零电压矢量三脉冲法的永磁同步电机带速重投策略

永磁同步电机运行过程中失电后,常因自身惯性或外界推动而处于高速旋转状态。若要带速重投,则需短时间内完成初始位置/转速观测。现有零电压矢量脉冲法的脉冲宽度和脉冲间隔不变,常使观测误差增大,严重时可能引起过电流。为此,研究一种自适应零电压矢量三脉冲法,可以根据零电压矢量脉冲所激励的电流矢量幅值自适应调节脉冲宽度,根据初始转速预估值自适应二次修正脉冲间隔,从而针对不同的电机参数或运行状态自动施加合理的零电压矢量脉冲。仿真结果表明,所研究的自适应零电压矢量三脉冲法脉冲宽度及脉冲间隔调节效果好,初始位置/转速观测和带速重投的可靠性高。

混动车起动异响分析与解决

本文总结了某款双电机构型混动车起动异响问题的解决方法和过程,对混动车起动异响产生机理和影响因素进行了深入分析。研究表明,起动过程中动力总成本体激励导致的传动系齿轮敲击是产生起动异响的主要原因。控制发动机起动时刻曲轴位置从而减小发动机本体激励,调整系统惯量或者控制发电机在转速爬升过程中施加补偿扭矩,可以改善动力总成的转速波动,达到提升起动工况动力总成声品质的目的。

同步电机静止变频软起动及其电枢电流谐波分析

同步电机软起动是由静止变频器(Static Frequency Converter,SFC)将同步电机从静止逐渐拖动至额定转速。但SFC短时和频繁起动会造成大量谐波,该谐波施加在同步电机电枢绕组对同步电机造成不可逆的危害。本文首先图解分析了同步电机软起动低速和高速阶段的换相过程,由此推导出各阶段电枢电流模型,从而分析得出电枢电流谐波特性。最后,搭建出同步电机软起动的Matlab/Simulink模型,验证本文推导的准确性。

大功率船用柴油机空气电机启动过程瞬态特性仿真

为提升大功率船用柴油机启动性能,采用GT-power软件建立船用柴油机稳态模型,增加空气电机启动系统模块,构建柴油机启动过程瞬态模型。基于仿真结果,分析环境排气背压、润滑油温度和压缩空气系统参数等对柴油机启动性能的影响规律。仿真结果可为基于空气电机启动的大功率船用柴油机的系统参数设计和性能评估提供依据。