Transient Stability Analysis of Three-Phase Reluctance Motors

ABSTRACT

Lyapunov's direct method has been applied extensively to the stability analysis of nonlinear systems. The method enables one to directly judge stability without solving the nonlinear differential equations representing motor involved.

In the paper, the effect of important parameters on trasient stability of a three-phase reluctance motors have been assessed from the data obtained for load and applied voltage changes by applying the Lyapunov's direct method.     

变频调速三相异步电动机发展趋势分析

笼型异步电动机由变频器供电时 ,同由恒压、恒频电源供电时相比 ,在性能参数上有显著差别。因此 ,多年来 ,尤其是 2 0世纪 90年代以来 ,从事变频调速电动机研究的广大科技人员在广泛试验研究的基础上 ,通过优化设计、改进转子槽形、增强绝缘结构、采用绝缘轴承等一系列措施 ,对各种变频调速异步电动机进行改进和更新换代 ,以提高产品性能、使用寿命和可靠性 ,使变频调速异步电动机在产品应用范围、产品系列和品种、产品技术水平等方面有了明显的发展和进步 ,产品试验日趋完善 ,科研工作也日益受到重视和加强。下面将扼要叙述国内变频调速异…     

三相异步电动机绝缘强度测试解析

阐述了三相异步电动机绕组绝缘试验的项目,包括绝缘电阻试验、绝缘耐压试验、绕阻匝间绝缘试验的原理、方法和测试标准,并说明了注意事项和具体的考核指标,从而为电机出厂试验、维修和用户提供绝缘测试考核的依据.     

Analysis of Winding Failures in Three-Phase Squirrel Cage Induction Motors

Every motor user is faced with the fact that someday his motor will fail. Due to the destructive nature of most failures, it is not easy to determine the cause. The purpose of this paper is to introduce a procedure for analyzing these failures and determining the cause so that further steps can be taken to eliminate them.     

隔爆型三相异步电动机的应用

隔爆型三相异步电动机是应用于存在有爆炸性气体环境的重要电气设备,作为传动机的原动力工具.它的正确使用直接关系到工矿企业的安全生产和人身安全,是企业经济效益的保证.作者阐述了隔爆型电动机的防爆要点,正确的使用方法和电机的维护、检修事项,同时列表说明了电动机常见电气和机械故障的处理方法.     

浅谈三相异步电动机的保护措施

主要阐述了三项异步电动机在实际运行当中的几种保护措施。     

三相异步电动机断电重合闸瞬态分析

分析和研究了三相异步电动机断电和重合闸的瞬态过程及危害。运用直接相量法建立了三相异步电动机的数学模型,并利用Ansoft语言建立了仿真模型。以一台三相异步电动机为例,仿真了电源断电后不同时间段重合闸时的电机瞬态过程,并给出了定子电流、转矩的瞬态曲线。通过仿真与理论相结合进行分析,得出在断电重合闸过程中,电机定子电流和转矩波动趋势。     

Controlled Starting of AC Induction Motors

As the demand for electrical energy continues to increase, increasing restrictions will be placed on full-voltage starting of ac induction motors. Inrush is the problem. The utilities are tending to enforce more rigorously the historical limits on the amount of inrush allowed. Reduced-voltage starters have traditionally been used to reduce the impact of motor starting inrush. All traditional starters have reduced the amount of inrush, but none have eliminated it. The type of driven load must be taken into consideration in order to provide motor torque sufficient to start the load while eliminating the starting current inrush. The Ultra Torq is a motor plus solid-state starter combination which provides a solution to the problem. The Ultra Torq controls the rate-of-change of kVA with respect to time, thereby eliminating the problem of inrush. A successful start is assured by matching the motor, starter, and controller to the torque requirements of the load and to the kVA limits of the system. The match makes the difference.     

大型高压异步电动机的瞬态运行方式分析

随着电力电子技术的日臻完善,用软起动方式起动异步电动机已受到人们广泛重视,这就要求提供电机完整的动态特性曲线.本文首先建立了异步电动机的瞬态模型,然后给出了完整的动态特性曲线,并且从电磁基本理论出发对动态特性进行了讨论,对软起动器的设计有着重要意义.     

Analysis of the Audible Noise of Three-Phase Squirrel-Cage Induction Motors Supplied by Inverters

One of the major problems in inverter-fed motors is the high level of audible noise produced by harmonic current and voltage components. To analyze these phenomena the field in the machine airgap is calculated using the rotating field theory together with the Maxwell stress theorem. This analysis yields a way for predicting the spectrum components produced by the motor and for relating it to the airgap flux density distribution time harmonics caused by the nonsinusoidal supply. The theoretical approach is used for calculating the airgap flux density distribution and the frequency spectrum components of a small three-phase squirrel-cage induction motor fed by a six-step voltage source inverter (VSI) and by a pulsewidth-modulated (PWM) inverter. The theoretical results are compared with experiments.     

多绕组多速三相异步电动机环流问题分析

针对多绕组多速电动机经常遇到的环流问题进行了分析，总结产生的原因，并通过８／６极绕组的实例分析得消除环流的一般性结论。     

双三相感应电动机故障状况下有限元仿真

双三相感应电动机在电动机气隙磁动势不变的基础上,保持多相电机每相激磁电流幅值相等.但当双三相感应电动机出现故障时,基波磁动势由圆形变为椭圆形的旋转磁动势,导致六相电动机不能正常运行.对双三相感应电动机各种故障状况进行有限元仿真分析,找出可容错运行的工况.     

变频调速对三相感应电动机的影响

通过对三相感应电动机变频调速转矩特性的分析,提出了变频调速系统对三相感应电动机的设计要求,并根据分析的结果对电机进行了设计,与实验结果吻合。     

A Novel Method of Multistage Dynamic Braking of Three-Phase Induction Motors

An effective braking system suitable for three-phase induction motor drives is discussed. Braking is achieved in four stages using an electronic switching circuit. Initially, a single capacitor is connected across two of the motor terminals allowing single-phase self-excitation. Following a certain speed drop, a second capacitor is added across the same terminals to sustain self-excitation and reduce the speed further. In the third stage magnetic braking is achieved by short circuiting the third terminal. Finally, the motor is brought to a standstill by dc injection. A method of determining minimum capacitor requirements is presented for both single-phase and symmetrical application. Experimental results are included, demonstrating the validity of theoretical results regarding capacitor requirements, and indicating the effectiveness of the proposed braking scheme.     

三相异步电动机T-n特性测试的一种尝试

针对感应电动机机械特性传统测试方法复杂、精度低、重复性较差等缺陷，介绍了一种能自动精确测取感应电动机机械特性的“动态”测试方法。该方法以动力学定律为基础，用转矩转速传感器和惯性电气自动补偿器分别测取负载转矩和加速转矩，从而得到被试电机的“动态”输出转矩、简单介绍了测试装置工作原理和测试结果，并讨论了扫描时间对测量度的影响。     

电压骤降时三相感应电动机瞬态分析

考虑主磁路饱和时三相感应电动机在d—q静止坐标系下的状态方程，通过实例对瞬时电压骤降引起电动机的瞬态运行过程进行了计算机仿真计算，得到了一些结论。     

Converter Propulsion Systems with Three-Phase Induction Motors for Electric Traction Vehicles

Three-phase induction machines have a number of advantages compared with collector type machines which make them particularly suitable for traction purposes. These advantages, which were recognized long before, could only be used in praxis by means of the progress, which the development of static power converters has made in the last decade. Primarily having been used in diesel-electric traction vehicles inverter-fed three-phase induction motors are now going to be applied in large scale to line-fed electric vehicles. In this field of application the induction machine has some additional advantages; e.g., the motor torque versus speed curve declines much less with increasing speed than that of the common series wound ac machine. Consequently, for the first time in history universal electric locomotives can be built, which are equally suited for hauling high-speed passenger trains as well as heavy freight trains. Converter systems are described, which do not drain reactive power from the supply line or even feed reactive power into the line, if necessary, and produce only a small amount of harmonics. Hence these systems are very well suited for high-power electric traction vehicles as well as for smaller vehicles, which are in service simultaneously in one district (e.g., rapid transit vehicles), and for industrial locomotives. Finally, some test and production vehicles with three-phase induction motors, test data, and experiences in service of such vehicles are described.     

A Speed and Power Factor Controller for Small Three-Phase Induction Motors

A form of controller/compensator is suggested for the speed control of small induction motors. This controller uses pairs of thyristors in each supply line, incorporated into a resistance/capacitance network. Smooth speed control may be realized over a wide speed range, and the motor current remains substantially sinusoidal. For a small laboratory type motor, the current was reduced by up to 30 percent, and high power factor was maintained over the whole speed range. The overall efficiency of the compensated system increased by about three percent over that of the uncompensated motor.     

降低笼形三相异步电动机电磁噪声的探讨

分析总结降低笼形转子三相异步电动机电磁噪声的方法,完成了YSKF低噪声专用电机设计和试制.     

Analysis of Unstable Phenomenon of Three-Phase Synchronous Motors

ABSTRACT

The unstable phenomenon, which is known as the hunting, often occurs under certain conditions in a light loaded operation of the synchronous motor. This paper analyzes these conditions affected by-machine parameters. Lyapunov's direct method is adopted for the stability analysis. This method can be obtained information about both the stable and unstable domains in simple calculations.