基于预前控制异步电机直接转矩控制方案的研究

在传统异步电动机直接转矩控制方案中，由于负载的变化规律不可预测，因此其常会带来较大的开关频率的变化，为此提出了一种基于预前控制的异步电动机直接转矩控制的方法。该方法依据前一个周期的磁链和转矩误差，对下一个开关周期所应施加到异步电动机的定子电压矢量进行预测，然后借助空间矢量PWM的方法，合成此开关电压矢量。样机实验结果表明，该方案不但能维持逆变器的开关频率基本恒定，而且还具有比传统直接转矩控制更为优良的动静态特性。     

交流电动机矢量控制变压变频调速系统（二） 第二讲 异步电动机在静止坐标系上的数学模型

本文首先介绍了异步电动机空间矢量的概念，对异步电动机的各种坐标系进行了定义，在此基础上，根据电磁感应定律得到了异步电动机在静止坐标系上的数学模型，最后分析了异步电动机数学模型的性质。     

电梯专用矢量控制变频调速器设计

简要介绍了一种电梯专用的、矢量控制变频调速器的原理和技术方案。该变频调速器采用转差频率型矢量控制，在电动机转子磁通的旋转坐标上，对电动机进行运算控制，使交流异步电动机具有直流电机的调速性能，即使在零速时，也能输出额定转距，此外，由于功率因素始终接近于１，比普通调压调速方式节能３０％以上。     

浅谈单相异步电动机的反转

单相异步电动机是由单相交流电源供电的旋转电机，其定子绕组为单相。当接入单相交流电时，它在定转子气隙中会产生一交变脉动磁场，所以单相异步电动机不能自启动。为了使单相异步电动机自启动，就要在启动时产生一个旋转磁场。本文以电容分相式单相异步电动机为例，介绍单相异步电动机的反转。要使单相异步电动机反转，关键在于改变旋转磁场的旋转方向，但又不能像三相异步电动机那样靠掉换两根电源线来实现。本文结合电容分相式单相异步电动机的具体电路形式，讨论了使其反转的三种方法，经实验验证。确实可行。     

中压电动机采用固态软起动器与变频器起动的比较

本文简述了交流异步电动机定子调压和变频调压的工作原理和机械特性，并以6KV 2000KW交流异步电动机为例，对中压固态软起动器和中压变频器起动二种方案作为了技术经济比较，认为对于起动转矩要求不大的风机、泵和压缩机类负载，从技术经济指标和可靠性来考虑以采用固态软起动器为宜。     

煤矿大功率防爆异步电动机软启动技术研究

针对煤矿大功率防爆异步电动机的启动特性需求,提出一种基于数字信号处理器的软启动控制方案,解决起动过程电流过大、能耗高的问题。在分析软启动技术和煤矿大功率防爆异步电动机启动过程上,从软启动器的电气结构出发,设计基于TMS320F2812A的数字式控制系统,实现电动机起动过程端子电压、电流和输出转矩的调节。     

软启动器在轴流螺旋桨式风机上的应用

本文介绍和分析了STRB软启动器在160kW异步电动机上的应用，它能有效限制异步电动机的起动电流，减少对电网、电动机、负载机械设备的冲击。软启动器是传统的星／三角转换、自耦降压、磁控降压等降压起动设备的理想换代产品，是异步电动机起动的新一代技术。     

采用上下位机方案实现异步电动机调压节能

文章介绍的节能装置采用上下位机方案，三相交流调压和特定消谐的PWM斩波控制方式。它根据异步电动机负载变化自动改变电动机的端电压，使电动机工作在最佳状态，达到降低损耗，节约能源的目的。     

基于ADSP-BF518开环估计转速的矢量控制系统设计

在高性能的交流异步电机矢量控制系统中,速度传感器的高成本和困难的安装条件限制了交流异步电动机的应用,因此无速度传感器的控制技术成为发展趋势。本文阐述了以数学模型的开环估计转速控制算法为核心,采用ADSP-BF518芯片设计了三相交流异步电动机无速度传感器矢量控制系统,具有一定的实用价值。     

异步电动机故障实时在线监测系统的研制

针对异步电动机故障诊断的特点,研制了一种异步电动机故障实时在线监测系统。该系统对所采集异步电动机的各种电压、电流、绕组温度等进行数据预处理后,通过TCP/IP数据采集通信模块传输给上位机,再结合信息融合技术和神经网络技术,判断系统状态,实现对异步电动机实时、可靠的在线故障诊断。通过以太网,基于LabVIEW界面对该系统进行了实验,结果表明其故障诊断快速、有效。     

干膜选择对夹膜短路的改善

通过对夹膜短路的现象进行分析,确定改善对策,并对改善措施进行跟踪评估。评估结果发现干膜的正确选用对改善夹膜短路产生明显效果,而且能降低总生产成本,提升良品率。     

Semi-active and active magnetic stabilization of supercritical rotor dynamics by contra-rotating damping

High speed rotors are usually operated above the critical speed to achieve a good self-centring and to reduce the reactions of bearings. Damping associated to the rotating parts induces some dynamic instability, when the system rotates faster than an angular velocity defined as ‘instability threshold’. To increase the range between the critical speed and the instability threshold the designer usually applies to the stator a suitable amount of non-rotating damping, being always stabilizing. In some application there is no stator available (spacecrafts, satellites) and in rotors suspended on active magnetic bearings the control current may be fairly large, if the dynamic stability has to be assured at a high spin speed. A new kind of active magnetic stabilisation is therefore proposed to overcome those limits. The damping action of the stator is here rotating, but its vector and the rotor spin speed are just opposite. Therefore that action appears as ‘contra-rotating’. This approach provides an asymptotic dynamic stability of both the forward and backward whirling motions, even in the high supercritical regime. Design issues, implementation and results obtained in case of a semi-active system based on permanent magnets as well as of an active magnetic device are herein discussed.     

圆柱-球体三自由度超声电机的研究

从实现圆柱-球体多自由度超声电机的运动原理和提高其输出性能的角度出发，提出了该种电机设计的基本要求。在此基础上，设计了一种新的电机定子结构，并用有限元法对该定子进行了模态分析和设计计算。依据设计结果，制作了样机。实验结果表明，定子的工作模态基本上满足其设计要求，电机的输出性能较以前有了大幅度的提高。同时也证明所采用的设计方法是正确的。     

行波型杆式超声电机定子模态干扰的研究

行波型杆式超声电机定子模态干扰会造成电机工作效率低下,不稳定,难以控制等问题。首先利用有限元法和Hamilton理论,建立行波型杆式超声电机定子的动力学有限元模型;其次进行模态分析,求解各模态频率对定子结构参数的灵敏度,以此为依据进行结构参数调整,实现定子工作模态与干扰模态分离;最后制作了定子样机。其模态试验结果表明达到了模态分离的目的:定子工作模态频率至少在2 kHz范围内不存在其他干扰模态,从而验证了该方法的有效性。     

A New PWM Strategy Based on a 24-Sector Vector Space Decomposition for a Six-Phase VSI-Fed Dual Stator Induction Motor

This paper presents a new space vector pulsewidth modulation (SVPWM) technique for the control of a six-phase voltage source inverter (VSI)-fed dual stator induction machines (DSIM). A DSIM is an induction machine which has two sets of three-phase stator windings spatially shifted by 30 electrical degrees and fed by two three-phase VSIs. Despite their advantage of power segmentation, these machines are characterized by large zero sequence harmonic currents, and in particular those of order 6 k plusmn 1, which are due to the mutual cancellation between the two stator windings. The proposed SVPWM scheme, while easy to implement digitally, reduces significantly these extra stator harmonic currents. Experimental results, collected from a 15 kW prototype machine controlled by a digital signal processor, are presented and discussed.     

大型发电机检运中出现的问题分析及处理

我国大型电机近年来发生的性质严重、影响较大且在一定程度上带有普遮性的运行故降和事故进行分析.结合现场工作实践,对大型发电机定期检运中现的定子、转子等常见问题以及漏氢现象,并提出了最适用和最有效的手段和预防措施.     

Influence of the motor load inertia and torque in the fault diagnosis of rotors in induction machines

During the last decades, non-invasive techniques have been proposed to carry out the fault diagnosis in electric machines. When these techniques are employed in the fault detection of the induction machine's rotors, they exhibit a strong dependence on factors such as the motor load inertia or the opposed torque. In order to develop automatic diagnostic systems or the diagnosis assistance over the rotor state, such as expert systems or knowledge based systems, it is necessary to have available further information to weigh up the influence of these factors. This work presents a study done, based on induction motor's mathematical models, about the incidence of the motor inertia and the opposed torque in some non-invasive fault detection technique employed more frequently. The model takes into account in an independent way each of the rotor bars and then allows to represent different faulty situations. These techniques with non-invasive features do not require sensors directly over the motor and thus allow a diagnosis even on-line when the machine is running. Particularly the study of the following techniques was approached: power spectral analysis, torque spectral analysis, stator current spectral analysis and Park's current vector behaviour. Therefore the diagnostic may be based in the measurement of motor's external variables such as applied voltages and stator currents.     

改善影响激光对潜通信系统通信质量的几个因素的研究

从激光对潜通信的能量传递模型出发讨论改善接收机性能的方法,分别针对背景辐射、光脉冲时域和空域的扩展和光斑强度的随机变化引起的信号衰减、畸变、起伏等影响通信质量的因素展开分析。本文对上述因素提出了改善措施,并且提出了将动态自适应调节系统应用到分集接收系统中,提高接收机的性能。     

微型压电超声马达定子表面振动特性分析

微型压电超声马达定子表面的振动幅度是难以检测的动态微小量。定子振动状态将直接关系到压电马达的实现与否。首镒分析了采用均分电极结构的微型压电超声行波马达的定子表面的振动振幅。通过影响定子振幅相关因素的分析，表明要获得最佳表面振动效果，压电薄膜与弹性体的厚度必须相匹配。     

Bearing Fault Detection Via Stator Current Noise Cancellation and Statistical Control

This paper proposes a new approach to detect in situ bearing faults via stator current monitoring. For in situ bearing faults, the characteristic bearing fault frequencies may not exist, particularly at an early stage. In addition, the bearing fault signatures are usually subtle compared to the dominant components in the sampled stator current. Therefore, in this paper, a noise cancellation technique is used to suppress those dominant components that are not related to a potential bearing fault. The remaining components, i.e., the noise-cancelled stator current, are then closely related to the health condition of the bearing. Furthermore, it is observed that under the presence of a bearing fault, the noise-cancelled stator current displays a significant amount of degrees of uncontrolled variation in its magnitude. The uncontrolled variation is detected by observing the samples falling outside the three-sigma limits on Shewhart's control charts. Therefore, it is possible to detect in situ bearing faults by detecting the variation in magnitude of the noise-cancelled stator current, as verified by online experiments performed in this paper.