平衡大惯量转动体运动过程中产生的角动量分析

针对传统平衡角动量方案只能消除转动体住匀速运行状态时系统角动量的缺点，介绍了一种利用转动惯量小、转速快的转盘，其瞬时速发对也于转动体瞬时速度的方法柬平衡角动量。利用单片机控制两个步进电动机来分别驱动转动体和转肋的硬件系统，并设计了主要软件实现程序。     

基于独立分量分析的电力系统瞬时电压畸变信号判别方法

提出一种基于独立分量分析(independent component analysis,ICA)的瞬时电能质量扰动信号检测与判别方法。利用ICA可将相互独立的源信号从其线性混合信号中分离出来的特点,以负熵作为衡量信号独立性的目标函数,通过优化此函数,得到一种固定点算法：FastICA算法,用此算法对包含瞬时电能质量扰动信号的电网电压信号进行计算,可分离出与扰动相对应的信号。对于不同类型的扰动,分离出的信号具有不同的波形特征,根据这一特点,可对扰动进行判别并确定其位置和持续时间。仿真试验结果表明,该方法对瞬时电压跌落、瞬时电压上升、瞬时脉冲、瞬时电压中断、谐波等多种瞬时电压畸变信号有较好的检测与判别效果。     

基于工业互联网和多传感器数据的电机故障诊断方法

提出了一种基于工业互联网和多传感器数据的电机故障诊断方法。通过各类传感器在线实时得到电机的电压、电流、振动、温度等信号的瞬时值,并转化为表征电机状态的各个特征参数。根据各个特征参数在各个故障模式下的变动情况,得到各个故障模式下故障特征及其隶属度。把故障特征与故障模式之间的关系分为充分条件和必要条件关系。按照充分条件和必要条件分类后,对每个故障模式对应的2类条件下的故障特征的隶属度进行融合,最后得出每个故障模式的隶属度,为远程运维系统决策服务。该方法既可以部署在电机远程运维工业互联网的边缘设备中,也可以部署在云平台服务程序中,实现快速而可靠的电机故障诊断。     

一种基于AT89C2051的多路舵机控制方案设计

研究了舵机的控制原理,在比较已有舵机控制方案的基础上,提出了一种基于AT89C2051的多路舵机控制方案.给出了舵机控制器的硬件设计方案框图,研究了多路PWM控制信号的产生方法,介绍了舵机控制器的软件设计方案,并给出了多路PWM信号的程序流程图.     

基于变分模态分解的电能质量扰动检测新方法

为了更加准确地提取扰动信号特征,提出了基于变分模态分解(VMD)的电能质量扰动检测新方法。该方法由VMD和希尔伯特变换(HT)2个部分组成。首先,对扰动信号进行傅里叶变换以确定VMD的预设分解尺度;然后,利用VMD将扰动信号分解为系列调幅-调频函数之和;最后,对每个调幅-调频函数进行HT,求取瞬时幅值和瞬时频率,进而确定扰动信号特征。较之希尔伯特-黄变换和局部均值分解方法,VMD方法不仅可分析不同时间支集的扰动信号,处理复合扰动和频率相近的奇数次谐波,也不存在模态混叠,获取的瞬时幅值和瞬时频率更加准确。仿真信号和变电站电容器组投入时的电压信号分析结果证明了所提方法的可行性和有效性。     

Realization of instantaneous torque control of an induction motor considering secondary flux as a parameter

Recently, many researches aiming at the realization of high‐performance and high‐precision control of induction motors have been reported, and instantaneous torque control of an induction motor can be regarded as one of the most important topics in this field. In previous works, the authors developed a new method to realize instantaneous torque control of an induction motor with a voltage‐source inverter, and demonstrated both its numerical simulations and experimental results. Unfortunately, the mathematically complicated derivation of the control method made it difficult to understand intuitively, and hindered us from analyzing the detailed characteristics of motor speed changes. In this paper, the authors propose a new method to realize instantaneous torque control of an induction motor, which differs from the concept of vector control. The proposed method is a two‐degree‐of‐freedom control which considers the instantaneous torque command and secondary flux command as parameters. The analytical solution reported here is a particular solution of the differential state equation of an induction motor, and can be expressed as a simple explicit function of the instantaneous torque command, secondary flux command, and motor speed. The authors show the validity of the proposed method through numerical simulations and experimental results. This paper aims the realization of high‐performance control of an induction motor. The authors propose a new method to realize instantaneous torque control without transient torque with a voltage‐source inverter. © 2001 Scripta Technica, Electr Eng Jpn, 137(1): 48–56, 2001     

并联运行电动机短路故障仿真及保护对策

2台并联运行的异步电动机,当一台电动机发生三相或两相短路故障被电流速断保护装置切除时,会引起另外一台正常运行的电动机电流增大,超过其额定电流4倍以上,导致正常运行电动机的速断保护误动作而跳闸。基于Matlab建立2台异步电动机并联运行时短路故障的仿真模型,研究分析了产生上述情况的机理、不同类型故障的影响程度及故障信号特征,并提出了带方向元件的电流速断保护的新方案,该方案既防止了正常运行电动机电流速断保护的误动作,又不影响故障电动机电流速断保护的正确动作。动模试验证明了该方法的正确性。     

用于多分量信号分析的自适应广义S变换算法研究

时频分析是处理非平稳信号强有力的工具,S变换作为传统的时频分析方法之一,其窗函数的尺度可以随频率改变。但是,其时频窗函数尺度变化是固定的,无法适用不同信号的局部特性,导致能量聚集性较差。本文提出了一种自适应的广义S变换算法,设计了由4个调节参数控制的广义高斯窗函数,采用浓度测量自适应优化调节参数,以寻求最佳的时频表征效果。并针对时频分析结果,采用瞬时频率重组和分量重构方法,得到各个分量的瞬时频率,同时进行平滑处理,最终实现多分量信号的参数估计。仿真实验说明,本文提出的自适应广义S变换算法,结合瞬时频率重组和分量重构信号方法,极大地提升了多分量信号的时频分辨率和信号分离的准确性。     

Instantaneous power as a medium for the signature analysis ofinduction motors

Preventive maintenance of electric drive systems with induction motors involves monitoring of their operation for detection of abnormal electrical and mechanical conditions that indicate, or may lead to, a failure of the system. Intensive research effort has been for sometime focused on the motor current signature analysis (MCSA). The MCSA techniques utilize the results of spectral analysis of the stator current. Reliable interpretation of the spectra is difficult, since distortions of the current waveform caused by the abnormalities in the drive system are usually minute. In this paper, an alternate medium for the motor signature analysis, namely the instantaneous power, is proposed. By theoretical analysis, computer simulations, and laboratory experiments, it is shown that the instantaneous power carries more information than the current itself. Utilization of the instantaneous power is thus enhancing the reliability of diagnostics of induction motor drives     

A Method of Sensing Line Voltages for Parameter Adaptation of Inverter-Fed Induction Motor Servo Drives

Most high-performance inverter-fed induction motor drive systems require signals corresponding to the input voltages of the motor for parameter adaptation. Low-performance systems require the signals for stabilization. The voltage signals are used in the controller circuit and therefore require isolation. Isolation of the voltage signals is not a cost-effective solution in low-power motor drive systems. The fact that the base drive signals to the transistor inverter are isolated makes them the ideal choice for the reconstruction of the motor line voltages. A method of sensing line voltages from the base drive signals of the transistor inverter circuit is described. A step-by-step derivation of the voltage sensing algorithm is given which leads to a simple realization. The synthesized voltages are used in parameter adaptation for inverter-fed induction motor drives. The sensing scheme has been implemented on a laboratory prototype, providing experimental results which are presented.     

Combined compensation structure of a static Var compensator and an active filter for unbalanced three-phase distribution feeders with harmonic distortion

A combined reactive power compensation method of a static Var compensator (SVC) and an active filter is described in this paper for unbalanced three-phase distribution feeders with harmonic distortion. The SVC acts as a classic reactive power compensator for load balancing and power factor correction. The small rating active filter is used to improve filtering characteristics of the passive filter in SVC and suppress possible resonance between the system impedance and the passive filter. The control signals are derived from the calculation of instantaneous active and reactive powers of the distribution feeder. Simulation results carried out by the electromagnetic transients program (EMTP) show that the proposed reactive power compensation configurations can effectively balance currents, correct power factor, and eliminate harmonic currents.     

Compressed and Distributed Sensing of Neuronal Activity for Real Time Spike Train Decoding

Multivariate point processes are increasingly being used to model neuronal response properties in the cortex. Estimating the conditional intensity functions underlying these processes is important to characterize and decode the firing patterns of cortical neurons. This paper proposes a new approach for estimating these intensity functions directly from a compressed representation of the neurons' extracellular recordings. The approach is based on exploiting a sparse representation of the extracellular spike waveforms, previously demonstrated to yield near-optimal denoising and compression properties. We show that by restricting this sparse representation to a subset of projections that simultaneously preserve features of the spike waveforms in addition to the temporal characteristics of the underlying intensity functions, we can reasonably approximate the instantaneous firing rates of the recorded neurons with variable tuning characteristics across a multitude of time scales. Such feature is highly desirable to detect subtle temporal differences in neuronal firing characteristics from single-trial data. An added advantage of this approach is that it eliminates multiple steps from the typical processing path of neural signals that are customarily performed for instantaneous neural decoding. We demonstrate the decoding performance of the approach using a stochastic cosine tuning model of motor cortical activity during a natural, nongoal-directed 2-D arm movement.     

Short circuit protection of energy efficient motors

Many years ago, the National Electrical Code established a maximum setting for this instantaneous trip breaker of seven times motor full load amperes (FLA), the theory being that that value was just above the typical 6X locked rotor current. In a 1986 IEEE IAS paper Scheda noted that the two most commonly encountered problems in applying high-efficiency motors are (1) replacing a standard motor with a high-efficiency motor, and (2) the need to use thermal sensors on larger machines since higher settings for electronic control would violate the NEC. His paper concludes: “It is suggested that work be done in the industry and standards organizations to serve the needs arising from the use of electronic detection of instantaneous currents for motor protection.” This article addresses some of the work done in the industry to serve these needs and, in particular, how the use of an “electronic detection” inverse time circuit breaker can be appropriately applied when an instantaneous trip breaker would nuisance-trip     

基于DSP的永磁直线同步电动机初级故障检测装置

为了消除由于永磁直线同步电动机结构和电源电压不对称对瞬时功率造成的影响,采用了TMS320F243型DSP作为永磁直线同步电动机初级故障检测装置,并采用了瞬时功率补偿的方法,对已补偿的瞬时功率纹波进行辨识,用以表征初级绕组中的短路和断路故障信息,完成了对信号的转换、滤波和变换。实验和仿真表明,该装置对初级故障的检测具有较好效果。     

Time–frequency higher‐order spectra with adjustment to the instantaneous frequency variation

Novel time–frequency techniques are proposed: the short time instantaneous higher‐order spectra (HOS) with adjustment to measured or known a priori time variation of the instantaneous frequency of transient signals. It is shown that the proposed transforms are more effective than the non‐instantaneous HOS (i.e. without adjustment to time variation of the instantaneous frequency) in recognizing a non‐stationary nonlinearity. Copyright © 2008 John Wiley & Sons, Ltd.     

海洋采油平台直流配电网瞬时负载的适应性评估

在海洋石油工程中,电动机是主要的电气负载,其起动过程可能会产生瞬时冲击,影响直流配电网的系统性能。文中基于降阶解析的思想,对此特殊场景下瞬时负载的影响开展研究。首先在一定条件下简化系统动态微分代数方程,推导直流母线电压的近似解析表达式;然后研究瞬时有功负载对海洋采油平台直流母线电压的影响;最后在PSCAD/EMTDC中搭建四端柔性直流配电网模型并设置不同的瞬时负载进行仿真,分析不同瞬时负载情况下的直流母线电压,验证文中所提解析表达式的正确性。结果证明,文中的解析表达式可以有效反映海洋采油平台直流配电网对瞬时负载的适应性。     

空载起动运行三相感应电动机突加负载及其瞬间断电时的动态仿真

首先利用三相感应电动机的运动方程,推导出它的状态方程,并结合实际电机参数利用Matlab语言对空载起动运行的三相感应电动机突加负载及瞬间断电时的动态过程进行了仿真。仿真结果符合三相感应电机的动态过程的特性。     

基于DITC的开关磁阻电机转矩脉动最小化研究

转矩脉动是开关磁阻电机较为突出的缺点.本文基于直接瞬时转矩控制(DITC)的概念,直接控制瞬时转矩跟随参考转矩,并结合转矩滞环控制器,阐述了减小转矩脉动的控制原理.针对一台3相12/8极开关磁阻电机,建立了Matlab环境下SRM系统的仿真模型.仿真结果和实验结果如实地反映了开关磁阻电机的运行特性,验证了本文所用的直接瞬时转矩控制能有效地减小转矩脉动.     

Analysis of atmospheric electric field variation signals using digital natural observation method

As the atmospheric electric field always fluctuates, its observed waveforms are very complicated. It is important to detect the characteristic variation from the observed signals and determine its cause. The natural observation method is adequate for analyzing such nonperiodic signals as the atmospheric electric field signals. In this method the aspectum is proposed as the quantity to estimate the instantaneous power. In this study signal processing by the aspectum was applied to signals of atmospheric electric field variation. It was clarified that a strong correlation exists between the instantaneous fluctuations of atmospheric electric field and the wind speed in the convenient meteorological environment. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 27–34, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20302     

Performance of a 10-Hp switched reluctance motor and comparisonwith induction motors

A comparison of computed and measured performances of a 10 hp Oulton switched reluctance motor (SRM) and a comparison with the performance of induction motors are presented. The instantaneous current and torque waveforms are computed for the SRM using the results of finite element method (FEM) analysis. The SRM calculated and experimental locked rotor torque, instantaneous current, efficiency, and losses when pulsed voltage excitation is applied to the motor windings were compared. In all cases, there is quite good agreement between the theoretical and experimental results. In addition, the measured total losses, efficiency, and temperature rise for a 10 hp SRM and different induction motors of the same rating are presented. The SRM has a higher efficiency and a lower temperature rise than the induction motors tested