基于简单占空比调节的异步电机直接转矩控制

针对异步电机传统直接转矩控制(DTC)存在的转矩脉动大、开关频率不固定等问题,已经提出了一些通过优化有效电压矢量占空比来减小转矩脉动的方法。然而,这些方法不仅计算复杂而且对参数依赖性大。本文在比较三种经典占空比控制方法性能的基础上,提出一种简单有效的占空比确定方法。该方法能同时减小转矩和磁链脉动,并且尽可能保持了传统DTC结构简单和鲁棒性强的优点。仿真和实验结果验证了本文所提方法的有效性。     

异步电机新型占空比直接转矩控制方案

传统的基于矢量表的异步电机直接转矩控制(ST-DTC)存在较大的稳态误差以及转矩脉动等问题。目前已经提出了一些通过优化有效电压矢量占空比来减小转矩脉动的方法,然而,这些方法不仅计算复杂而且严重依赖电机参数。通过深入分析每个电压矢量引起的转矩和定子磁链变化率的基础上,提出一种简单且非常有效的占空比控制方法。该方法在占空比的计算中考虑了电机转速的影响,能同时减小输出转矩脉动及其稳态误差,并且尽可能保持了传统DTC结构简单和鲁棒性强的优点。仿真和实验结果验证了所提方法的有效性。     

Selecting and Applying Mini-Computer Control for Textile Industry Applications

Some control problems in textile processes require or can justify a control computer in lieu of conventional type of control. How then should the typical user approach the selection and implementation of a system. The user must evaluate 1) buying the mini and applying it himself, 2) buying the mini from one vendor and system application from a ``software house,' and 3) buying the computer and programming as an engineered control system from one vendor at what may initially appear to be a premium price. He will soon learn that the ``mini' price tag balloons as he decides to actually do something with the basic box. Considerations of hardware, control oriented software and process-computer interface are discussed. Flexibility, reliability, and expandability of hardware and software as well as vendor experience and services offered are key features which should be evaluated as related to user's current needs.     

Sensorless Direct Field-Oriented Control of Three-Phase Induction Motor Drives for Low-Cost Applications

A sensorless direct rotor field-oriented control (SDRFOC) scheme of three-phase induction motors for low-cost applications is presented in this paper. The SDRFOC algorithm is based on a sensorless closed-loop rotor flux observer whose main advantages are simplicity and robustness to motor parameter detuning. The whole algorithm has been developed and implemented on a low-cost fixed-point digital signal processor controller. Experimental results are presented for a 0.5-kW induction motor drive for a primary vacuum pump used in industry applications.     

AC Drives in Traction Applications

DC motors and drives have previously been the choice for traction applications. The desire to use an induction motor in similar applications has been unfulfilled due to the absence of a suitable ac drive controller that could fully exploit the economical, rugged, and simple ac induction motor. AC drives using vector-control techniques are available to gain the high-performance operation in precise-torque and four-quadrant applications. This paper describes the use of such a drive for locomotion of large coal-handling equipment.     

Application of Sectional Drives and PLC's to Textile Ranges

The textile industry requires complex drive and control systems in the areas of bleaching, finishing, and dyeing processes. Electrical system designs associated with the use of this equipment are, in general, overly traditional. It will be shown in this paper that for little extra, cost, current technology can be applied in the form of programmable controllers (PC's) and electronic drive regulators in such a way as to improve the reliability and operating efficiency of the range drives.     

Encoders for Simultaneous Sensing of Position and Speed in Electrical Drives With Digital Control

Speed and position sensing in servo drives is an issue that is still not completely understood. Expressions like ldquoaccuracyrdquo and ldquoresolutionrdquo still get mixed up when engineers talk about encoders. These words, however, do describe different characteristics and should not be confused. The introduction of digital control has made this issue much more important for servo drive applications than before. This paper presents some general explanations of speed and motion sensing as well as different encoder technologies available today and their characteristics, particularly with respect to digitally controlled servo drives.     

Interfacing Modern Drives with Mill Distributed Control Systems

Present-day drive systems are all-digital and have taken on the characteristics of a drive-level distributed control system with a high-speed communications system encompassing the master, drives, and operator's controls. The interface with the next higher level in the mill control hierarchy, the distributed control system, must reflect these characteristics. The speed of response required for direct manipulation of the drive system is very fast. Consequently the slower distributed control system is used primarily to monitor and perform relatively long-term control functions on the drive system. Local machine operator controls are required for safe direct command control of the sections. An adequate communications link may be established through conventional programmable controller highway protocol and hardware.     

Control Strategies for PWM Drives

The majority of pulsewidth modulation (PWM) drives operate in three distinct modes: pure PWM at the lower speeds, pure six-step at the higher speeds, and quasi-PWM at the intermediate speeds. The pure PWM stage can be operated with a constant frequency, unsynchronized carrier. The transitional quasi-PWM stage, because of the operation of the minimum dwell time protection system, must be synchronized. The phase of the carrier relative to the signal then becomes important. Under these circumstances it is advisable that the carrier to signal frequency ratio be an odd multiple of three and the phase of the carrier be such that, at a signal zero, the carrier and signal have slopes of opposite sign.     

交流传动系统的控制策略

从控制原理和电机数学模型出发 ,结合实用的系统 ,论述交流传动系统的控制策略。全文分基于稳态模型的控制策略、基于动态模型的控制策略和不依赖于对象数学模型的控制策略三个层次。在最后一个层次上 ,强调了智能控制的发展前景。     

Eddy Current Adjustable-Speed Drives for Central Fan Applications

Growing concerns over the availability and cost of energy have prompted engineers to seek methods of conservation through reduction of operating costs of supply and return fans in typical air distribution systems. Traditional methods of attaining variable air volume typically utilize thermostatically controlled volume dampers and variable inlet vanes as a compromise to achieve system balance at the expense of energy consumption. The reduction of direct power costs on central fan systems through electrical speed control of eddy current drives is examined. In addition, several facets of the drive system will be evaluated in terms of centrifugal fan load applications. Simple payback analysis is also considered.     

电动汽车异步电动机驱动系统的在线效率优化

提高电动汽车异步电动机驱动系统的运行效率是十分必要的.研究了用于电动汽车异步电动机驱动系统在线效率优化的方法.如何有效地检测系统的输入功率和调整磁通,是该方法用于实际系统时的难点和关键问题.分析了异步电动机驱动系统逆变器直流侧电压电流的特性,根据这些特性,设计了相应的多阶滤波方法,准确得到了系统的输入功率,结合适当的磁通调节方法,实现了整个驱动系统的在线效率优化.实验结果证明,整个优化方法是快速和有效的.     

基于容错逆变器的永磁同步电动机矢量控制

研究了一种容错逆变器和在该逆变器不同桥臂故障时的永磁同步电动机矢量控制系统容错运行策略。分析了一种容错逆变器的工作原理,并由无中线引出的永磁同步电动机电流特性分析可以知道,三相定子电流之和等于零,通过两相定子电子就可以实现电机的电流控制。在此基础上提出了基于容错逆变器的永磁同步电动机矢量控制系统容错运行方案,该方案简单可行,并通过仿真实验验证了策略的正确性和有效性。     

无位置传感器的全数字化开关磁阻电机驱动系统

在数字电机控制专用ＤＳＰ芯片ＴＭＳ３２０Ｆ２４０的基础上,以电机自行车用ＳＲＭ为研究和试验对象,探讨了包含数字电流控制和间接位置检测两项关键技术的全数字化驱动控制,并结合电动自行车具体工况进行了电机、功率变换器及控制器的系统设计和试验。试验结果验证了理论分析和方案的正确性。     

Textile Machine Noise Control

An approach to noise control by a textile machine manufacturer is outlined. The means of identifying noise sources are discussed. The results of applying some noise reduction techniques are presented.     

一种新的内置式永磁同步电机弱磁调速控制方法

提出了一种新的内置式永磁同步电机弱磁调速的电流调节算法。该算法能够保证电机在整个弱磁调速区以最大的转矩电流比运行。其d轴电流根据外部转矩、转速给定和母线电压值的变化来决定,q轴电流分量则由d轴电流值和转速值来决定。文章通过系统仿真验证了该算法具有动态反应快、调速区间转换平稳的特性。     

电动车异步电机驱动技术的应用和发展

本文讨论了电动车异步电机驱动技术的应用和发展,提出了需解决的几个方面问题.     

数字视频远程监控系统在变电站应用的故障分析

以盐城供电公司远程视频监控系统为例,着重介绍了视频监控系统在实际应用中的系统结构、功能以及系统特点,并对系统运行进行了详细分析。这对于电力企业创建无人值班通信站、提高通信自动化的管理水平具有一定的借鉴作用。     

多相永磁同步电机多维控制技术

多相电机控制是一个多维控制问题,但目前大多数多相电机的控制方法仍然是三相电机控制方法的简单推广,导致了谐波电流不可控、系统性能低等问题.在详细分析了多相电机数学模型和多相空间电压矢量分布特征的基础上,本文采用基于正交矢量空间的多维控制方法,实现了多相电机电流的多维调节.全文以五相永磁同步电机驱动系统为例,仿真和试验结果表明了该方法的有效性.     

超临界机组的水燃比控制研究与应用

结合邹县1000MW超超临界机组调试过程中出现的问题,探讨了超临界机组水燃比控制的特点和存在问题,分析了水燃比控制在超临界机组控制中的重要性,研究了制粉系统对水燃比控制的影响和工程应用情况,以及RB功能中水燃比控制问题,并提出了相应的控制方案。