共查询到20条相似文献，搜索用时 140 毫秒
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本文分析了直线感应电动机存在的特有问题，介绍了基于ANSOFT软件的直线感应电动机的瞬态特性仿真方法。提供了仿真实例。 相似文献
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HUANG Jin YANG Jia-qiang NIU Fa-liang 《浙江大学学报(A卷英文版)》2007,8(8):1320-1329
A new rotor broken bar fault diagnosis method for induction motors based on the double PQ transformation is pre-sented. By distinguishing the different patterns of the PQ components in the PQ plane,the rotor broken bar fault can be detected. The magnitude of power component directly resulted from rotor fault is used as the fault indicator and the distance between the point of no-load condition and the center of the ellipse as its normalization value. Based on these,the fault severity factor which is completely independent of the inertia and load level is defined. Moreover,a method to reliably discriminate between rotor faults and periodic load fluctuation is presented. Experimental results from a 4 kW induction motor demonstrated the validity of the proposed method. 相似文献
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研究异步电机转子断条、动态偏心这两种状态下的故障特征,并通过实验室的鼠笼式异步电机转子故障实验系统,对采集的定子电流信号首先通过FFT变换,进行归一化处理,提取出定子电流特征向量;对采集的电机机壳X-Y振动信号则通过db3小波包分析进行去噪处理和频域能量特征向量的提取,实现了故障的分类 相似文献
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Because brushless direct current (BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces (back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated. 相似文献
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基于群灰色关联度分析方法的电力变压器绝缘故障诊断 总被引：2，自引：0，他引：2
基于变压器油中溶解气体分析,提出了一种基于群灰色关联度分析的变压器绝缘故障诊断新方法.首先根据故障类型与灰色参考序列构造,选择变压器典型故障样本构造多组参考序列,这些参考序列组构成一个灰色参考序列群.其次根据给出的新的关联系数计算方法,计算个体关联系数和关联度.然后根据给出的群灰色关联度计算方法,计算群灰色关联度和构造群灰色关联度矩阵.最后根据关联序识别变压器绝缘故障诊断.通过大量变压器绝缘故障诊断实例分析,所提方法诊断准确性与可靠性优于三比值法和传统的灰色关联分析方法,具有较好的分类诊断能力和可靠性. 相似文献
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A new fault isolation and restoration technique employing local Ethemet network for the looped MV circuit is presented. It can isolate all short circuit faults in the loop within 300 ms and restore the supply of healthy sections in less than 1.2 s. A reliable fault location method of isolating the single phase-to-ground fault （SPGF） in the non-effectively earthed network, which makes use of the fault generated transient signals, is also proposed. And the method locates the SPGF by examining transient zero-mode current correlation, which is not influenced by the neutral grounding mode and need no additional device. Laboratory test and simulation results show the proposed techniques are feasible, and significantly improve the supply reliability. 相似文献
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从系统工程可靠性出发,引入联系数的和、点积与积的概念以及相应的定理与性质,并利用联系数的点积对同异反可靠性系统中故障问题进行分析,从而探讨了系统工程中串联与并联的可靠度中故障问题的计算方法,解决了系统工程中有关串联与并联的可靠性的问题. 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｔｒａｄｉｔｉｏｎａｌｍｅｔｈｏｄｔｏｓｔｕｄｙｔｈｅｐｅｒｆｏｒｍａｎｃｅｓｏｆｉｎｄｕｃｔｉｏｎｍｏｔｏｒｓｉｓｂａｓｅｄｏｎｔｈｅｃｏｎｃｅｐｔｏｆｅｑｕｉｖａｌｅｎｔｃｉｒｃｕｉｔ.Ｔｈｅｐａｒａｍｅｔｅｒｓｉｎｔｈｅｅｑｕｉｖａｌｅｎｔｃｉｒｃｕｉｔａｒｅｕｓｕａｌｌｙｏｂｔａｉｎｅｄｂｙｍａｇｎｅｔｉｃｃｉｒｃｕｉｔｃｏｍｐｕｔａｔｉｏｎ .Ｉｎｒｅ ｃｅｎｔｙｅａｒｓｉｔｈａｓｂｅｃｏｍｅｐｒａｃｔｉｃａｌｔｏｕｓｅｆｉｎｉｔｅｅｌｅｍｅｎｔｍｅｔｈ… 相似文献
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永磁电机具有效率高、功率密度高以及可靠性高等优点,目前已成为我校运动控制课程的重要教学内容之一。区别于传统的直流电机或者感应电机教学实验平台,永磁电机控制系统要求位置、转速和电流的闭环控制系统。为适用实验教学的要求,设计开发了一套基于数字信号处理器(DSP)的永磁电机实验教学平台,并给出了实验项目实例。该实验平台为相关专业学生提供良好的实践环境。 相似文献
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基于粗糙集理论的电力电子电路故障诊断 总被引：1，自引：0，他引：1
基于粗糙集理论，提出了一种电力电子电路故障诊断的新方法：粗糙集方法。简单介绍了粗糙集理论，详细叙述了利用粗糙集理论诊断电力电子电路的过程。文章以三相可控整流电路为例，利用粗糙集理论，对故障信息中样本的故障征兆进行处理，通过知识约简，删除多余的征兆属性，形成诊断的确定性规则，实现故障分类。仿真实例表明，与以往的诊断方法比较，该方法不仅准确可靠，而且直观方便。 相似文献
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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. 相似文献
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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. 相似文献
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文章提出通过USS现场总线将西门子S7-1200和G120变频器连接起来,组成多台异步电动机变频调速监控网络,并在HMI上实现人机交互。该控制系统成本相对较低、电缆数量减少、多台电动机可同时分别控制、电机运行状态实时显示,控制系统稳定性、可靠性、灵活性大大提高。 相似文献
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本文从分析现有网格用户验证技术入手,提出了一种基于多重口令的验证方法并应用于网格用户的验证中,从而实现对网格用户验证过程性能的优化。多重登录口令技术基于阀值验证思想,极大地方便了用户的登录,本文同时借鉴拜占庭传输算法,对多重登录口令的可靠与容错性能进行了初步的实验和研究,结果表明多重口令登录方法提高了网格验证的可靠性。 相似文献
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To investigate the robust fault detection(RFD) observer design for linear uncertain systems,the H_ index and H ∞ norm are used to describe this observer design as optimization problems.Conditions for the existence of such a fault detection observer are given in terms of matrix inequalities.The solution is obtained by new iterative linear matrix inequality(ILMI) algorithms.The RFD observer design over finite frequency range in which D f does not have full column rank for a system is also considered.Numerical example demonstrates that the designed fault detection observer has high sensitivity to the fault and strong robustness to the unknown input. 相似文献
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研究一类线性离散时变系统的故障估计问题.首先,通过引入一种规则化最小二乘标准来作为故障估计问题的性能指标;进而,应用最小二乘固定滞后平滑算法,得到了估计问题可解的充要条件,给出了故障和状态的一步滞后平滑估计器和两步滞后平滑估计器.算例验证了本文所提方法的有效性. 相似文献