DC Dynamic Braking Performance of Linear Induction Motors

Abstract

Polyphase double-sided flat linear induction motor with non-magnetic conducting wide secondary operating in the dc dynamic braking mode is analyzed using field theory techniques. One-dimensional, One-dimensional space harmonic, Two-dimensional in the secondary plane, and Three-dimensional models are employed and performance is predicted. Predicted braking thrusts are compared to experimental results obtained elsewhere.     

A Novel Method of Multistage Dynamic Braking of Three-Phase Induction Motors

An effective braking system suitable for three-phase induction motor drives is discussed. Braking is achieved in four stages using an electronic switching circuit. Initially, a single capacitor is connected across two of the motor terminals allowing single-phase self-excitation. Following a certain speed drop, a second capacitor is added across the same terminals to sustain self-excitation and reduce the speed further. In the third stage magnetic braking is achieved by short circuiting the third terminal. Finally, the motor is brought to a standstill by dc injection. A method of determining minimum capacitor requirements is presented for both single-phase and symmetrical application. Experimental results are included, demonstrating the validity of theoretical results regarding capacitor requirements, and indicating the effectiveness of the proposed braking scheme.     

三相异步电动机阻容制动瞬态过程仿真研究

根据三相异步电动机在α-β静止坐标系下的变参数动态数学模型,编写了一个适合于三相异步电动机阻容制动瞬态过程的实用仿真计算程序,通过实例对三相异步电动机阻容制动运行过程进行仿真计算和分析;根据三相异步发电机稳态等效电路,用最优化方法得到了励磁电容临界值,计算结果与实测结果基本吻合.并对仿真结果进行比较分析,得出了一些有用的结论.     

Brushless DC Motors Using Unsymmetrical Field Magnetization

The prevalent types of brushless dc motors have evolved from the classical synchronous machine structures, using two-phase, three-phase, or four-phase stator windings and symmetrical N-S field magnetization patterns. The popular two-phase two-pulse brushless motor requires auxiliary means for starting and for ensuring relatively constant torque with rotor position. Three methods are used: 1) skewed stator poles, which introduce unsymmetrical air-gap reluctance and the resultant unsymmetrical air-gap magnetic field, 2) the Wessels design, which uses a rotor pole pattern of north-south-zero (N-S-0) and auxiliary stator poles, and 3) a combination of N-S-0 rotor pattern and 1200 electrical (el) pitch stator coils to produce an unsymmetrical air-gap magnetic field. The electromagnetic torque produced by motors using each of these methods is calculated using the coenergy method.     

六相感应电动机电源反接制动瞬态仿真研究

对六相感应电动机电源反接制动的瞬态过程进行了仿真分析。为了得到瞬态特性,建立了六相感应电动机在静止dq0坐标系下的混合磁链瞬态数学模型。编写计算机仿真程序,通过实例对六相感应电动机的电源反接制动的瞬态过程进行仿真计算,对仿真结果进行分析,得出了一些有用的结论。     

基于脉冲注入法的无刷直流电动机转子位置检测研究

提出了一种采用脉冲注入来检测无刷直流电机在静止状态时转子位置的方法。基于此方法依次向定子绕组注入一系列的脉冲,通过脉冲电流的变化对转子位置进行估算。实验结果表明：该方法不但具有较高的位置检测准确性,同时对电机的参数依赖性小,可以省去电机内部的检测元件,又可以应用到其它电机。     

无刷直流电动机的动态边界层鲁棒控制

非线性鲁棒控制技术适用于像无刷直流电动机这样的快速运动对象的控制,在提高控制精度的同时,会引发系统颤振.设计了一种具有动态边界层的非线性鲁棒控制器,分析了闭环系统的控制性能.在控制器作用下,被控系统可以较好地跟踪速度参考输入信号.不仅速度跟踪误差最终能够收敛到边界层内,而且在消除颤振现象的同时,通过减小边界层宽度提高控制精度.仿真结果验证了所提出的控制方法的有效性.     

A DC Signal Injection-Based Thermal Protection Scheme for Soft-Starter-Connected Induction Motors

This paper proposes a remote and sensorless thermal protection scheme for soft-starter-connected induction motors. A dc signal injection-based method is used to estimate the stator winding resistance and, thus, the stator winding temperature. Based on continuous monitoring of the stator winding temperature, a thermal condition monitoring and protection scheme is proposed using only the motor's input voltages, currents, motor nameplate information, and the ambient temperature. An adaptive Kalman filter is designed to reduce the stator winding temperature estimation error. In addition, the influence of the cable resistance was investigated, and a compensation method is suggested to improve the accuracy of the estimated temperature. The requirements of the data acquisition system, such as sampling frequency and analog-to-digital conversion resolution, and their affects on the accuracy of the estimated temperature are also discussed in detail. The proposed thermal monitoring scheme has been validated from the experimental results of a 7.5-hp TEFC induction motor under various load conditions. The importance of this new thermal monitoring scheme lies in its remote and sensorless nature.     

基于Maxwell的单相无刷直流电动机分析与设计

以一款2000 r/min、6极、200 V、100 W单相无刷直流电动机为例,给出了设计这种单相无刷直流电动机的思路,完成了电磁方案设计,并试制了样机,进行了有关性能测试.利用Ansoft/Maxwell建立了这款电动机的二维有限元仿真模型,对其静态和动态性能进行仿真.仿真结果与样机试验结果各项性能指标误差在8％以内,验证了仿真模型和仿真分析的准确性.     

感应电动机非线性解耦控制的动态性能分析

在借鉴国内外相关研究的基础上,对感应电动机非线性解耦控制系统的动态性能进行了深入分析.经过分析发现,在非线性解耦控制器的作用下,感应电动机的转速、磁链控制误差及转子磁链估计误差可以指数收敛至零,但负载力矩估计误差只能是渐近有界的.对感应电动机的仿真结果表明,上述理论分析是正确的.     

感应电动机动态特性与电压骤降的相互影响

基于不对称电压骤降推导了感应电动机电磁和机械回路方程,并结合电压骤降过程,分析了感应电动机动态特性和电压骤降的相互影响。运用电力系统计算机辅助设计和电磁暂态模拟程序软件（power systemcomputer aided design and electric magnetic transient in DC system,PSCAD/EMTDC）建立仿真模型来计算感应电动机的动态特性对电压骤降波形、电压骤降幅值和持续时间等特征参数的影响,以及不对称和对称电压骤降对感应电动机的母线电流、转速和电磁转矩等特性的影响。仿真结果表明感应电动机动态特性与电压骤降之间是一种动态的关系：感应电动机的动态特性会使电压骤降波形发生畸变,造成电压骤降幅值和持续时间等特征参数发生变化,而电压骤降也会造成感应电动机母线电流、转速和电磁转矩等特性发生变化。     

2.3 kW高速永磁无刷直流电机转子动力学分析

高速永磁无刷直流电机具有功率密度高、体积小、效率高等优点,在很多领域有着广泛的应用.转子动力学分析是高速无刷直流电机面临的主要问题之一.结合所研制的2.3 kW,150 000 r/min高速无刷直流电机,设计了单端式轴承支撑结构和两端式轴承支撑结构两种不同的转子,并对两种结构进行了转子动力学分析,表明双端式结构的电机在100 000 r/min下运行平稳.     

Performance Equations for DC Commutatorless Motors Using Salient-Pole Synchronous-Type Machines

A large volume of research has been done to analyze commutatorless dc motors using salient-pole synchronous-type machines. These studies have not resulted in clear design-oriented expressions relating performance to machine geometry. The development of design-oriented algebraic expressions of machine performance measures in terms of machine inductances is described. Speed independent equations for commutation angle, commutating current, critical angle, safety angle, average and instantaneous torques, and instantaneous damper currents are developed. Shunt- and series-type machines are analyzed, and numerical examples of both are included.     

BP网络在无刷直流电机参数辨识与控制中的应用

在无刷直流电机控制系统中，采用基于熵类误并准则学习算法的BP网络，克服了传统BP算法收敛速度慢，易收敛于局部极小值的缺点，避免了“过学习”的现象，实现了控制系统中电机参数的实时辨识，从而提高了控制系统的性能。     

自适应陷波滤波器在异步电动机故障诊断中的应用

本文应用自适应陷波滤波器对异步电动机定子电流信号进行处理，其结果有利于转子故障特征的提取。实测结果表明，这种方法可以提高故障诊断的灵敏度。     

DC Kiln Drive Motors

The most important considerations in applying dc drive motors and thyristor power supplies to a cement kiln are their procurement, maintenance, and operating costs; and equipment reliability in the cement plant environment. Drive requirements and their effect on motor size are discussed. Efficiency comparisons at several speeds for three different designs of dc drive motors are made. Two motor kiln drives with motors connected in series and also in parallel are discussed. Recommendations for applying each connection with regard to drive horsepower and voltage are made. Included is a brief discussion on applying dc motors by taking a part of the total speed range as constant horsepower rather than taking the entire speed range as constant torque.     

自适应模糊双模无刷直流电机速度调节器的设计

研究了基于模糊逻辑的无刷直流电机的控制方法。讨论了无刷直流电机速度调节器的设计,并将模糊控制器与传统的P ID控制器有机结合,组成高精度的自适应双模速度调节器。仿真结果表明此方案具有较好的动态性能。     

Constant Torque Operation of Induction Motors Using Chopper in Rotor Circuit

A novel control scheme is investigated for operating induction motors in the constant torque mode. The basic control schemes and analysis of the steady-state performance of the system are presented. Circuit models are used to predict the performance characteristics. A new dc dynamic braking method is proposed and studied that provides very fast braking. Experimental results are presented to verify the theoretical predictions and demonstrate the feasibility of the control schemes.     

直流电机换向有限元仿真模型的研究

电刷换向是直流电机的特有现象,换向将引起电弧火花、换向噪声、电磁干扰等诸多问题。由于换向过程非常复杂,目前的解析数学计算难以准确计算换向电流。该文采用一种由开关元件构成的电路模拟直流电机的换向过程,在有限元软件Ansoft Maxwell对直流电机进行仿真分析,从而获得传统解析计算难以计算的换向数据,提供了一种简单快捷的预测换向电流的方法。换向电流的解决,也给解决换向相关问题指出了一条捷径。     

感应电动机动态效率优化的自抗扰解耦控制

针对感应电动机系统具有强耦合、不确定性、干扰因素多、非线性等特点,针对感应电机最大转矩每安培控制策略,应用自抗扰控制(ADRC)静态解耦和扩张状态观测器(ESO)动态解耦技术,给出一种适用于感应电机效率优化控制的ADRC解耦设计方案。为了提高系统的响应速度,减少计算量,设计了一种去掉跟踪微分器(TD),并且ESO和NF采用线性函数的ADRC。仿真结果表明,该控制方案不仅能提高轻载时电动机的运行效率,而且具有良好的转速跟踪效果,并且具有较好的鲁棒性和抗干扰能力。