感应电机直接转矩控制系统仿真

研究了异步电机直接转矩控制的方法,利用MATLAB／SIMULINK仿真工具对直接转矩控制系统进行了建模和仿真．结果表明：直接转矩控制具有鲁棒性强、转矩动态响应速度快等优点．     

On-line broken-bar fault diagnosis system of induction motor

Induction motor faults including mechanical and electrical faults are reviewed. The fault diagnosis methods are summarized. To analyze the influence of stator current, torque, speed and rotor current on faulted bars, a time-stepping transient finite element (FE) model of induction motor with bars faulted is created in this paper. With wavelet package analysis method and FFT method, the simulation result of finite element is analyzed. Based on the simulation analysis, the on-line fault diagnosis system of induction motor with bars faulted is developed. With the speed of broken bars motor changed from 1 478 r/min to 1 445 r/min, the FFT power spectra and the wavelet package decoupling factors are given. The comparison result shows that the on-line diagnosis system can detect broken-bar fault efficiently.     

基于定子电流的感应电动机MRAS转速估计

提出了一种新的模型参考自适应系统（MRAS）感应电动机转速估计模型.以感应电动机本身为参考模型,以可直接测量的定子电流为状态变量,以定子电流-电压方程为可调模型,根据Popov超稳定理论提出满足全局渐进稳定的转速自适应律估计转速.利用Matlab进行仿真,仿真结果说明了模型的有效性.     

Single neuron network PI control of high reliability linear induction motor for Maglev

The paper deals with a new model of linear induction motor (LIM) to improve the reliability of the system. Based on the normal equation circuit of LIM considering the dynamic end effect, an equivalent circuit model with compensation of large end effect is constructed when the end effect force at synchronism is of braking character. The equivalent circuit model is used for secondary-flux oriented control of LIM. Single neuron network PI unit for LIM servo-drive is also discussed. The effectiveness of mathematical model for drive control is verified by simulations.     

Study on Rotor IGBT Chopper Control for Induction Motor Drive

Rotor chopper control is a simple and effective drive method for induction motor.This paper presents a novel IGBT chopper topology,which can both adjust rotor resistance and protect IGBT efficiently.Investigation on the quasi-transient state of the rotor rectifying circuit is made,and a nonlinear mapping between the equivalent resinstance and the duty cycle is deduced.Furthermore,the method for determining the magnitude of the external resistor is introduced.     

Novel torque ripple minimization algorithm for direct torque control of induction motor drive

To elucidate the principles of notable torque and flux ripple during the steady state of the conventional direct torque control (DTC) of induction machines, the factors of influence torque variation are examined. A new torque ripple minimization algorithm is proposed. The novel method eradicated the torque ripple by imposing the required stator voltage vector in each control cycle. The M and T axial components of the stator voltage are accomplished by measuring the stator flux error and the expected incremental value of the torque at every sampling time. The maximum angle rotation allowed is obtained. Experimental results showed that the proposed method combined with the space vector pulse width modulation(SVPWM) could be implemented in most existing digital drive controllers, offering high performance in both steady and transient states of the induction drives at full speed range. The result of the present work imphes that torque fluctuation could be eliminated by imposing proper stator voltage, and the proposed scheme could not only maintain constant switching frequency for the inverter, but also solve the heating problem and current harmonics in traditional induction motor drives.     

基于预测控制的直接转矩控制系统的研究

针对异步电动机直接转矩控制（DTC）系统在低速时由于开关频率不稳定而引起转矩脉动较大的缺点，提出了一种预测控制方法。该方法根据转矩和定子磁链的误差来确定应该施加的参考电压矢量，最后利用空间矢量脉宽调制（SVPWM）方法来合成该矢量，这样即保证了逆变器的开关频率恒定，从而大大降低转矩脉动。仿真结果表明，在低速下定子磁链轨迹近似为圆，转矩脉动不明显。     

螺旋形线圈感应电池的专用电动机

介绍了一种无机械转换机构，把电能直接转换为机械振动的螺旋形感应电池专用电动机，提高了电机与使用工艺对象联系的可靠性，并通过分析得到数字模型．     

Diagnosis of stator faults in induction motor based on zero sequence voltage after switch-off

To improve the accuracy of the stator winding fault diagnosis in induction motor, a new diagnostic method based on the Hilbert-Huang transform （HHT） was proposed. The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic, which could effectively avoid the influence of the supply unbalance and the load fluctuation, and directly represent the asymmetry in the stator. Using the empirical mode decomposition （EMD） based on HHT, the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted. Then, the fault characteristic can be acquired. Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.     

Analysis of a new 5-phase bearingless induction motor

This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.     

伺服电机测试实验平台设计与实现

设计并实现了伺服电机测试实验平台,该平台是以计算机为核心组成的数字化测试系统。电机的各类信号通过PCI数据采集卡I、SA采集卡和串口传送给计算机。该测试系统能够模拟实现变负载摩擦、变间隙和变转动惯量等多种功能,并对特定的伺服系统以控制精度和速度为主要指标,在测试实验平台上进行了测试。     

感应钢包炉结构与电磁特性的改进

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2+1维两分量BKP系列方程的对称和代数结构

本文利用形式级数对称理论,给出2＋1维两分量BKP系列方程的无穷多截断对称，并求出它们的李代数关系，表明构成一个广义的W∞代数．     

浅析镜像对称结构在汉语中的表现及应用

本文对汉语中的镜像对称结构进行了界定,并通过这种结构在汉语中字词句篇的具体表现,说明了镜像时称结构在汉语中的广泛存在.在大量的实例列举下,总结了镜像对称结构具有新颖性、趣味性、艺术性、实用性四个特点,并认为如果能将这些特点应用到无论是中小学的汉语教学还是针对外国人的对外汉语教学,都是大有裨益的.     

广义Birkhoff系统的对称性与守恒量（英文）

研究了广义Birkhoff系统的3种对称性及其相应的守恒量.首先,基于Pfaffian作用量在无限小变换下的不变性,建立了广义Birkhoff系统的Noether理论;其次,基于微分方程在无限小变换下的不变性,建立了广义Birkhoff系统的Lie对称性的定义和判据,给出了由系统的Lie对称性直接导致的Hojman守恒量;最后,基于力学系统运动微分方程中出现的动力学函数在经历无限小变换后仍然满足原来方程的一种不变性,建立了广义Birkhoff系统的Mei对称性的定义和判据,给出了由系统的Mei对称性直接导致的Mei守恒量.举例说明了结果的应用.     

分形对称图案生成方法及其应用

探讨了实验相空间的非线性映射和保守系统准规则斑图的能量画法。利用可视化语言编制了非线性映射和对称图案的计算机生成程序，可生成各种分形艺术图案，该图案可用于地毯设计、室内装饰设计以及产品外形表理纹理图案设计等方面。     

贵州省城市体系等级结构分析

对贵州城市体系等级结构特征及其城市规模结构的优化进行了初步的探讨,首先运用齐夫（Zipf)模型计算出城市规模分布的分维值,根据分维值得出贵州城市人口分布不平衡,首位城市垄断性强,大城市发展速度快于中小城市的结论,其二,分析发现城市分布属于集聚型,城市职能结构层次偏低,第三,今后贵州应加快城市经济建议步伐,提高经济效益,扩大城市规模,增强城市的辐射能力,形成等级完整、城市职能结构合理的城市规模体系。     

Form Invariance, Noether and Lie Symmetry of Non-conservative Hamiltonian Systems in Phase Space

For the non-conservative holonomic Hamiltonian systems in phase space, the definition and criteria of the form invariance of the generalized Hamilton canonical equations were given. The relations among the form invariance, Noether symmetry and Lie symmetry were studied. The theory of the form invariance for the conservative holonomical systems was worked out. An example was given to illustrate the results.     

三相感应电动机的教学辅助系统设计

以三相感应电动机电磁设计的课程教学为研究对象,通过图形用户界面设计了一款集电机设计和课程教学演示功能于一体的人机交互教学辅助系统.给出了该系统的设计思路、基本功能.将抽象概念以图形方式演示,加深学生对感应电动机设计过程的理解,提高教学质量.     

变频电动机的起动特性

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