异步电动机变频调速与节能

风机、泵类设备电力拖动系统采用变频调速技术可获得良好的节能效果。     

异步电动机变频调速与节能

风机、泵类设备电力拖动系统采用变频调速技术可获得良好的节能效果。     

初探变频调速异步电动机的频率响应极限

变频调速已成为异步电动机实现转速调节的主要方法之一。目前的通用变频器还不能满足较低频率调速的要求。本文推导出了变频调速及软起动的频率最低限。发现了软起动的最佳起动频率。     

交流变频调速异步电动机节能计算方法探析

异步电机的电流大小和电机消耗的功率随负载的轻重而改变,利用电磁调速、恒转矩负载等节能方法,对变频异步电动机节能进行了估算,分析采用变频器对交流异步电动机进行调速控制,可以节省可观的电能.     

恒转矩变频调速对三相异步电动机损耗、效率的影响

本文从理论上分析了恒转矩变频调速对三相异步电动机的效率及各项损耗变化、影响,提出了自己的观点。     

异步电动机调速变频器容量的选择

<正> 近几年来,异步电动机变频调速技术得到了较广泛的应用。为保持在变频调速时电动机的最大转矩不变,需要维持磁通恒定。这就要求在改变电源频率f_1的同时,对定子端电压U_1也要作相应的调节。因此,对给电动机供电的调速变频器一般都要求兼有调频和调压两种功能,这种变频器通常简称为VVVF型变频器。     

变频调速技术在我司水泥生产中的应用

近年来 ,随着电力电子技术与自动控制技术的发展 ,大功率半导体器件变流技术的成熟 ,不少新颖的电动机调速装置进入工矿企业 ,采用变频调速技术对异步电动机进行交流调速控制已被广泛地应用在各个拖动和节能领域中 ,这对节约能源、提高经济效益具有重要意义。在水泥生产中 ,立窑罗茨鼓风机是中小型水泥厂的主要耗电设备之一 ,过去采用异步电动机拖动 ,基本上恒速运转 ,当需要调节风量时 ,实际采用的方法是通过蝶阀放风对风量进行调节 ,这种调节方式当然简便 ,但从节省能源的观点来看 ,不是一种好的控制方法。通常风机是根据生产中可能出现的…     

对异步牵引电动机试验项目和试验方法的探讨

对IEC349—2标准中规定的试验项目和试验方法与相关的国标和铁标进行了对比,指出了这些标准在试验项目的规定、要求、试验方法等方面存在的差异,并结合目前国内机车动车用异步牵引电动机研制时在试验中存在的问题,提出了一些建议。     

两相电机的合成电压矢量变频调速

从理论上论述了两相电机通过控制合成电压矢量实现变频调速的可行性。对运用该方法的控制系统和电机运行特征进行了仿真。仿真结果表明该方法具有良好的调速效果 ,在调速范围内 ,两相电机可实现对称运行     

高压变频调速技术在转炉除尘风机上的应用研究

本文介绍了高压变频调速技术在莱钢转炉除尘风机上的研究与应用概况、设计原理和应用后的效果。     

A comparison of ANSI and IEC standards for power station polyphaseinduction (asynchronous) motors

The Institute of Electrical and Electronics Engineers (IEEE) is encouraging the comparison of American and offshore standards and documentation of the comparison findings. At the 1994 IEEE Winter Power Meeting, the Electric Machinery Committee Working Group on Standards Comparison met on February 2, 1994, to assign specific documents for comparison. Task forces were established for nine categories of electric machinery. The subject of this paper is the comparison of ANSI C50.41-1982, “Polyphase induction motors for power stations”, with the IEC 34 series standards covering “Rotating electrical machines”, which was performed under the auspices of the large asynchronous machines task force. The paper is based on the comparison issued on August 4, 1994     

DF4A型机车有级调速的无级改造

提出了DF4A型机车有级调速在段修范围内进行无级调速的改造方案。分析了有极调速进行无级调速改造相关的重要环节,还提出了改造方案的注意事项。     

变频调速技术在旋流井系统中的节能应用

近几年来,随着科技的不断进步,电气技术取得了突飞猛进的发展,淘汰低性能、高能耗设备已迫在眉睫,某公司为降低生产成本、提高服务质量,不断加大设备自动化改造升级。由于变频器的使用可以降低电能消耗和操作简单,以及免维护、控制精度高等优势。因此,该公司对新区旋流井供水系统中4台水泵控制系统进行了变频节电改造,采用了先进的变频控制技术,改变了原系统生产设备落后的面貌,达到了节能的目的。     

Steady-state performance of DC motors supplied from photovoltaicgenerators with step-up converter

A simple step-up converter circuit consisting of a single power transistor and an inductor is used as an interface between a PV (photovoltaic) generator and a shunt DC motor driving a centrifugal water pump. The step-up converter allows maximum power output from the PV generator to the motor at all insolation levels. Steady-state performance of the motor is vastly improved as its input voltage and current are stabilized by the regenerative action of the converter. The PV generator operates at maximum power regardless of insolation variations. The converter duty ratio can be set at a fixed optimal value which is valid for all insolation levels. This remarkable property makes this device economically attractive since it is easy to build and does not require any insolation-dependent control as compared to other peak-power tracking devices     

Labview implementation of speed detection for mains-fed motors using motor current signature analysis

The speed of an induction motor (IM) can be extracted from the motor currents of an induction motor with a Labview implementation of motor current signature analysis (MCSA). The implementation is applied to an IM driven by the 60 Hz mains. The estimation system consists of data acquisition, demodulation and FFT spectrum analyses. The above estimation algorithms are implemented in Labview for Windows, with the Labview output being compared to measurements from a tachometer, with acceptable results.     

Efficiency testing of motors powered from pulse-width modulatedadjustable speed drives

This is a report of efficiency testing of an induction motor powered from three different pulse width modulated adjustable speed drives. The motor was operated at a range of speeds and torques, and each drive was operated at the highest, lowest, and an in-between carrier frequency. The motor was a typical NEMA design B motor, and the drives were typical, industrial scalar drives using the default volts/Hz setting. The testing showed that the drive efficiencies remained above 90% until torque was lowered to below 20% of rated torque. Combined motor and drive efficiencies remained above 80% until speeds or horsepower loads were lowered to below 20% of rated torque. The test was performed using a unique data acquisition scheme that permitted acquisition of a large number of torque settings for each speed selection