笼型感应电动机电磁噪声控制方法与效果

总结、论述了作者在研制低噪声笼型感应电动机—塑料注射机专用笼型三相感应电动机过程中采用的控制电磁噪声的主要方法及其试验结果.文章还介绍了对有关试验数据的统计分析方法和结果.给出了一些有益的结论.     

单相供电的双笼转子三相感应电动机瞬态仿真研究

在缺乏三相电源而只有单相电源供电的地区,也许会用到双笼转子的三相感应电动机,如煤矿风机中的隔爆型双笼转子三相感应电动机用单相电源供电。本文对双笼转子三绕组单相电容电动机的瞬态特性进行仿真研究,具有理论意义和实际工程价值。为了得到瞬态特性,建立了双笼转子三相感应电动机在单相电源供电时的ABC相坐标系下的瞬态数学模型,应用对称分量法,根据双笼转子三相感应电动机稳态等效电路,导出移相电容的计算式,编写计算机仿真程序,通过实例对电动机带通风机负载时的瞬态过程进行仿真计算,给出了仿真特性曲线。仿真结果与理论分析相一致。     

基于FPGA的电磁金属探伤系统及其微弱信号处理

本文介绍了一种基于FPGA的电磁金属探伤系统,该系统用于研究电磁无损检测技术在金属板损伤探测上的应用.在该电磁金属探伤系统中,传感系统提供的测量感应信号为强噪声背景下的微弱信号.为了提高信号的检测精度,本文采用信号调理电路结合FIR数字滤波的方法,将基于FPGA的电磁成像金属探伤系统中微弱的测量感应信号从噪声中提取出来,仿真实验证明,该方案能为后续信号处理环节提供一个低噪声背景下的较强的感应信号.     

基于 FPGA 的电磁金属探伤系统及其微弱信号处理

本文介绍了一种基于FPGA的电磁金属探伤系统,该系统用于研究电磁无损检测技术在金属板损伤探测上的应用。在该电磁金属探伤系统中,传感系统提供的测量感应信号为强噪声背景下的微弱信号。为了提高信号的检测精度,本文采用信号调理电路结合FIR数字滤波的方法,将基于FPGA的电磁成像金属探伤系统中微弱的测量感应信号从噪声中提取出来,仿真实验证明,该方案能为后续信号处理环节提供一个低噪声背景下的较强的感应信号。     

机械结构动态改进技术在电动机振动噪声防治中的应用

本文介绍了结构实验模态分析、灵敏度分析和局部结构改进分析等先进的结构动态改进技术的基本原理,并由此对Y112M-4型电动机的机座进行了计算和分析,确定出一个结构改进方案.经实际改进试验验证,这一改进可有效地抑制电动机电磁振动和电磁噪声的传递,具有明显的减振降噪作用.     

单片机在感应电动机控制系统中的应用

感应电动机又称异步电动机.因为电磁驱动力矩是靠转子与磁场问的转速差产生的,电机正常运转时转速约比磁场转速小百分之几。本文将主要分析单片机在感应电动机启动控制中的应用。     

谈小型异步电动机的径向电磁噪声问题

主要叙述小型异步电动机电磁噪声产生的原因,着重对径向电磁噪声进行介绍,并提出改进的基本措施。     

判断电动机端子接线的简易方法

判断电动机端子接线的简易方法徐斌（辽宁省工业设备安装公司）鼠笼型交流感应电动机在运转以前，除测定绕组的绝缘电阻外，还要检查定于绕组起尾端接线的正确性。如接线错误，电机不能启动或启动时电流特别大（近似短路电流），熔丝熔断。检查的方法较多，本文介绍最简单...     

MATLAB-GUI在笼型异步电动机仿真中的应用

利用MATLAB的M文件编程实现三相笼型异步电动机的通用仿真程序,然后利用MATLAB-GUI完成界面的设计,从而开发仿真软件,该仿真软件具有通用性好、运行速度快、美观大方以及便于二次开发等优点,为电机的电磁设计和加工制造提供帮助。     

L型往复式空压机进气口噪声特性及消声器的研制

往复式空气压缩机是一种应用广泛的通用机械,它不仅是工业噪声中的主要噪声源之一,亦是扰民的环境噪声主要污染源.其中L型活塞空压机是我国产量和用户最多的一种压气设备.这种空压机的噪声主要由进气口的空气动力性噪声、机体和管道系统机械噪声、电动机的电磁噪声、风扇噪声和贮气罐的共呜振动噪声所组成,如表1所示,其中影响最大的是进气口噪声.     

Optimal Slot Numbers for Magnetic Noise Reduction in Variable-Speed Induction Motors

Although many empirical rules have been established for correctly choosing the number of stator and rotor slots so as to limit the audible magnetic noise level radiated by induction machines, these rules never take into account the stator natural frequencies or the fact that the motor is run at variable speed. In this paper, we present a fast simulation tool for the variable-speed magnetic noise emitted by induction machines, based on fully analytical models. On the basis of these models, we derive and experimentally validate an analytical expression for magnetic vibrations due to slotting reluctance harmonics, confirming the prime importance of slot combination in magnetic noise radiation. We ran simulations on a 700-W squirrel-cage motor in order to quantify the noise emitted by all possible combinations of slot numbers in two- and three-pole pairs, including odd slot numbers. We thus obtained a database that efficiently replaces the old empirical rules for slot combination numbers and helps in designing quiet induction motors. Similar databases can be built for other power ranges.      

Effect of Magnetic Saturation on Static and Mixed Eccentricity Fault Diagnosis in Induction Motor

We have investigated the effect of magnetic saturation of core materials on the diagnosis of static and mixed-eccentricity faults in induction motors. We modeled the faults by using a modified winding function (MWF) and time-stepping finite-element (TSFE) methods to compute the stator currents of both healthy and faulty motors for processing. We then analyzed the stator signal spectra of the motors by the MWF and TSFE methods and estimated the amplitudes of sideband components attributable to the faults. The results obtained by TSFE agreed well with experimental measurements. However, there was considerable discrepancy between the MWF results and the experimental measurements. We investigated the reason for the discrepancy by analyzing the air gap magnetic field distribution in both healthy and faulty induction motors in order to determine their linear and actual magnetization characteristics. We found that, in a faulty motor, for fixed permeability, the analytic method yields a much larger magnetic flux amplitude than is actually the case. At the same time, the distribution of magnetic flux in the air gap is more asymmetric than the actual case. Here, we present our experimental results and those obtained with the MWF method, using the finite-element analysis package Opera2d 10.5, for two three-phase, four-pole, 60-Hz, 3-hp motors having 36 stator slots and 44 and 28 rotor slots, respectively.      

Analytical Prediction of Cogging Torque in Surface-Mounted Permanent-Magnet Motors

We present a new approach to computing cogging torque based on only one analytical field solution in surface-mounted permanent-magnet (PM) motors. We use conformal transformation to compute the magnetic field created by the permanent magnets in the air gap with a single slot. Then, we derive the cogging torque due to the single-slot effect at different rotor positions directly from the 2-D analytical field solution. The total cogging torque is synthesized from the contribution of each slot. We have applied our approach to predicting the cogging torque of two surface-mounted PM motors, one with 4 poles, 24 slots and the other with 42 poles, 36 slots. The predicted cogging torques for both applications agree well with those obtained from 2-D finite-element analysis.      

Determining the equivalent circuit parameters of canned solid-rotor induction motors

For designing canned solid-rotor induction motors, the conventional induction motor circuit is inadequate. Here we present an alternative equivalent circuit, one that reflects the eddy currents in all regions (cans and rotor body). The proposed model operates on a per-phase basis at a single frequency. We confirm the validity of the new equivalent circuit with numerical and analytical solutions. This analysis has shown that the classical equivalent circuit for conventional induction motors is not sufficient to obtain the circuit parameters for the canned solid rotor induction motors. We also consider certain assumptions that make the analytical approach simpler.     

Characterization and Reduction of Magnetic Noise Due to Saturation in Induction Machines

This paper derives the analytical characterization of Maxwell radial vibrations due to saturation effects in induction machines, and especially in traction motors. The number of nodes and the velocity of these particular force waves are experimentally validated by visualizing some operational deflection shapes of the stator. It is shown that according to the stator and rotor slot numbers, and stator natural frequencies, these forces can be responsible for high magnetic noise levels during starting and braking. A simple rule to avoid saturation magnetic noise is then proposed, and applied to an industrial motor. Simulation results show that the new proposed motor improves magnetic noise level up to 20 dB, whereas experiments give a 15 dB improvement.      

Detections of secondary current and torque of induction motors using amorphous microcore field sensors

New secondary-current sensors for squirrel-cage induction motors are presented using a multivibrator with two group amorphous microcores. The 8-pair micro cores are set near the both endrings of a rotor for cancellation of the influence of unstable rotor motion on sensing of the secondary current. Electromagnetic torque was detected as an output voltage of a multiplier for the secondary current and the main flux. The main flux was detected using a multivibrator-type flux sensor utilizing two stator teeth as two cores. A possible new control system for variable speed induction motors with a torque feedback loop is discussed, which stably works independently of variations of motor parameters.     

General Analytical Models of Inductance Matrices of Four-Pole Bearingless Motors With Two-Pole Controlling Windings

In this paper, after introducing the bearingless motor's working principle in brief, we analyze the magnetic field distribution principle of the bearingless motor. We then derive in detail the general analytical models of inductance matrices of a four-pole bearingless motor with two-pole controlling windings. The derived general analytical models are applicable not only to bearingless motors with a salient-pole rotor, but also to bearingless motors with a cylindrical rotor. By setting different values of salient-pole arc width parameter $rho$ in the general models of inductance, the analytical models of inductance of different types of bearingless motors, such as bearingless induction motors, bearingless synchronous reluctance motors, and bearingless surface-mounted permanent magnet (SPM) motors, can be derived.      

A fast method for determining electrical and mechanical qualitiesof induction motors using a PC-aided detector

A unique computer-aided detector is presented that determines the mechanical and electrical qualities of single-phase and three-phase induction motors. Measurements of voltage, current, power factor, active power, and reactive power as well as evaluations of centrifugal switch and airgap eccentricity, i.e., misalignment between rotor and stator, of induction motors can be rapidly conducted, and test results are available on the screen within a few seconds. The feasibility and usefulness of this detector are impressively demonstrated through application examples     

感应电机矢量控制系统仿真研究

针对基于空间矢量脉宽调制技术（SVPWM）和转子磁场定向控制原理的感应电机矢量控制系统,利用控制功能模块化的设计思想,在Matlab／Simulink中建立功能独立的子模块如矢量控制模块、速度控制模块、坐标变换模块、SVPWM子模块等,并将这些功能模块拼装组合,构建了电流、转速双闭环感应电机矢量控制仿真模型。仿真结果表明基于模块化设计的感应电机矢量控制仿真模型是有效可行的,为电机控制器的设计提供了一种途径。     

Mathematical rotordynamic model for lateral vibration analysis of induction motors with dynamic eccentricities regarding start-up

The paper shows a mathematical rotordynamic model for lateral vibration analysis of induction motors with dynamic eccentricities regarding start-up. With this mathematical model, different kinds of dynamic eccentricities—mass eccentricity, magnetic eccentricity and bent rotor deflection—can be analyzed. Beside the mechanical influences—e.g. the rotor mass, rotor shaft stiffness, oil film coefficients of the sleeve bearings, structural stiffness of the sleeve bearing housings and end shields—also electromagnetic influence—e.g. the electromagnetic field and magnetic eccentricity—can be analyzed for the start-up. The paper is based on the well-known theory of accelerated resonance passing and is an enhancement of the theory for induction motors, considering also electromagnetism during start-up. Based on this rotordynamic model, the absolute displacements of the shaft centre, the shaft journals and the sleeve bearing housings can be analyzed as well as the relative displacements between the shaft journals and the sleeve bearing housings. Additionally, also the vibration velocities at the sleeve bearing housings can be derived. The aim of the paper is not to replace a detailed finite-element-model by a simplified analytical model, but to show the mathematical coherences between rotordyamics and electromagnetics for a start-up of an induction motor, considering different dynamic eccentricities.