Purpose

Voltage fluctuation (flicker) is a power quality disturbance that can produce several undesirable effects on industrial equipment. This paper aims to present the methodology and results of investigations undertaken to examine the speed and torque of an induction motor (IM) under voltage fluctuation conditions.

Design/methodology/approach

The IM response to different characteristics of voltage fluctuations is presented. It will be shown that under a special condition the IM torque can even reach two times the rated torque. To show how this occurs, a qualitative discussion is given on the motor response by linearized equations.

Findings

The small-signal analysis was used to determine the frequency which leads to maximum speed fluctuations. It was shown that, if the motor is excited with a modulation frequency (resonant frequency) which is one of its natural frequencies (modes), the mode will act as a fluctuating amplifier and greatly increase the amplitude of torque and speed fluctuations. Sensitivity analysis is also carried out to evaluate the influence of motor parameters on the resonance frequency. The results show that the resonance frequency is not affected at all by the changes in magnetizing reactance. This has been shown that magnetic saturation does not have any impact on the resonance frequency. The most effective parameters are rotor and stator resistances.

Originality/value

With the increasing popularity and use of arc furnace loads in the metallurgy industry and due to the wide application of large IMs in the industry, it is possible that the frequency of torque pulsation locates near a natural frequency and then will create an oscillation with a large magnitude, potentially leading to accelerated fatigue or severe damage of shaft. However, if this phenomenon occurs in industries, the resonance frequency must be filtered from the input voltage. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole IM are used to validate the accuracy of simulation results.

中文翻译：

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特殊电压波动条件下感应电机的高转矩和过度振动

目的

电压波动（闪烁）是一种电能质量干扰，会对工业设备产生多种不良影响。本文旨在介绍在电压波动条件下检测感应电机 (IM) 速度和扭矩的研究方法和结果。

设计/方法/方法

给出了对不同电压波动特性的 IM 响应。结果表明，在特殊条件下，IM 扭矩甚至可以达到额定扭矩的两倍。为了说明这是如何发生的，通过线性化方程对电机响应进行了定性讨论。

发现

小信号分析用于确定导致最大速度波动的频率。结果表明，如果电机以调制频率（谐振频率）作为其固有频率（模态）之一进行激励，则该模态将充当波动放大器并大大增加转矩和速度波动的幅度。还进行了灵敏度分析，以评估电机参数对共振频率的影响。结果表明，谐振频率完全不受磁化电抗变化的影响。这表明磁饱和对谐振频率没有任何影响。最有效的参数是转子和定子电阻。

原创性/价值

随着电弧炉负载在冶金行业的日益普及和使用，以及由于大型电机在行业中的广泛应用，扭矩脉动的频率可能位于固有频率附近，然后会产生较大的振荡。量，可能导致加速疲劳或轴的严重损坏。但是，如果在工业中出现这种现象，则必须从输入电压中滤除谐振频率。在 1.1 kW、380 V、50 Hz、2 极 IM 上的实验结果用于验证仿真结果的准确性。