SPLIT-WINDING STARTING OF A SINGLE-PHASE INDUCTION MOTOR

Abstract

Results of investigation of starting a single-phase induction motor having a single stator winding and using normal stator and rotor punchings are presented in this paper. Theoretical and experimental studies show that the motor requires less copper for its stator winding compared to a split-phase motor and the overall starting performance is very satisfactory.     

SPEED AT BREAKDOWN TORQUE OF A SINGLE-PHASE INDUCTION MOTOR

ABSTRACT

The purpose of this paper is to present an “exact” analytical expression to calculate speed at breakdown torque and the breakdown torque of single-phase induction motors. From the theoretical expression for torque developed by a single-phase motor, a sixth order polynomial in speed at breakdown torque is obtained, and solved, using a well known method. A real root for per unit speed, i.e. the ratio of speed to the synchronous speed, that lies between 0 and 1 is selected and the actual breakdown torque is determined by substituting it in the torque equation. The breakdown torque, also termed as maximum torque, so obtained has been found to yield better correlation between the predicted and the tested results than the only existing empirical relation. Steps to calculate speed at maximum torque are also suggested. For an arbitrarily selected single-phase induction motor, a curve of speed at breakdown torque as a function of r₂/X is also included for the purposes of illustration and understanding.     

AN ANALYSIS OF SHADED POLE INDUCTION MOTORS WITH INCREASED STARTING TORQUE

ABSTRACT

A method of analysis of shaded pole induction motors with ununiform airgap is described. For the analysis, a dq model of a generalised machine theory with any number of stator windings arranged in an arbitrary way on the stator and ununiform airgap is chosen. The analysis involves resolution into a harmonic series, together with complex matrix inversion. Results of computational study of the effect of changes of airgap profile on the performance characteristics are presented. It is shown that by increasing the airgap under the part of a pole which la opposite to the shading coils, an increased starting torque can be obtained.     

复合实心转子磁阻电动机起动性能分析

运用状态变量法,建立磁阻电动机暂态性能的数学模型,导出了磁阻电动机状态方程的直接表达式,并采用定步长四阶龙格-库塔法对复合实心转子磁阻电动机的起动性能进行数字仿真计算,所得结果与试验值较为一致。与凸极实心转子磁阻电动机相比,复合实心转子磁阻电动机转矩、转速脉动小,暂态过程短。     

电机启动过程信号的周期域分析

在简单介绍过程信号周期域分析方法之后,结合1台异步电动机启动、空转、关断过程信号的实际取样数据,通过周期域分析,获得了众多时、频域参量的周期域特性曲线,并分别对它们进行了必要的解释。周期域分析方法将会在过程信号分析中得到了广泛地应用。     

SINGLE-PHASE MOTOR INDUCTION-RUN PERFORMANCE

ABSTRACT

Based on the rotating-field theory and the ‘exact’ equivalent circuit of a single-phase induction motor operating on its main winding only, accurate solutions are derived for the salient features of its torque to speed performance at pull-out and zero torque, to enable the torque-speed plot to be readily compiled with sufficient accuracy for preliminary-design purposes. The torque, current, power factor and efficiency at any speed are also derived for use in the final-design stage, again on the assumption that the airgap mmf is sinusoidally distributed. However, in order to be strictly applicable to many modern designs, the analysis is extended to cover in a simple manner the general case of significant space-harmonic mmfs being present in the airgap.     

采用自抗扰控制器的高性能异步电机调速系统

矢量控制技术已被广泛地应用于高性能异步电机调速系统中,然而,由于在实时控制中存在严重的外部干扰,参数变化和非线性不确定因素,基于精确电机参数的准确解耦很难实现,并且磁通和转矩的动态性能也受到严重的影响,为了提高调速系统的动态性能,该文提出了一种可以取代经典PID控制器用于异步电机调速的非线性自抗扰控制器。自抗绕控制器由三部分组成;跟踪微分器,扩张状态观测器和非线性状态误差反馈控制律,利用扩张状态观测器,自抗绕控制器可以估计出系统状态变量及其广义导数,从而实现异步电机的精确解耦,此外,上述控制录需要精确电机参数就可以实现干扰补偿,这使得自抗绕控制器的设计能够独立于异步电机的精确数字模型。仿真和实验结果表明,相对于经典PID控制器,自抗绕控制器在较宽的调速范围内具有更好的动态性能以及对负载扰动,电机参数变化都具有更好的鲁棒性。     

ANALYSIS AND CONTROL OF TORQUE PULSATIONS IN CURRENT FED INDUCTION MOTOR DRIVES

ABSTRACT

Three types of feedback compensation schemes are described which can be used to reduce the torque pulsations which normally occur when induction machines are supplied from a current source inverter. The approach is verified both by a detailed computer simulation and also by test results from an actual system. Limitations of the method near zero slip frequency (no load) is discussed and a means suggested for elimination of the problem.     

PERFORMANCE STUDY OF A CHOPPER-CONTROLLED INDUCTION MOTOR

Abstract

In this paper, the speed of an induction motor is controlled using a chopper circuit on the rotor side. Analysis of transient, including switching power supply and changing in duty cycle of chopper, and steady-state performance of the chopper-controlled induction motor are predicted-Analysis and simulation consider the induction motor equations from the rotor side where a diode bridge is connected. Experimental results are obtained to verify predicted behaviour based on this digital simulation.     

SINGLE-PHASE INDUCTION MOTOR WITH ASYMMETRICAL STATOR

ABSTRACT

This paper describes a single-phase single-winding induction motor which is self-starting without the use of a shading winding. Starting torque is produced by a combination of several stator asymmetries: an airgap under the main pole which is-tapered down in the direction of rotation, poles without windings in the quadrature axis with solid iron flux bridges to the lagging sides of the main poles, and yoke sections which are larger on the leading than on the lagging sides of the main poles. A qualitative explanation of the action of these asymmetries is presented using equivalent circuits.     

OPTIMIZATION OF AN ELECTRONICALLY CONTROLLED CAPACITOR FOR A SINGLE-PHASE INDUCTION MOTOR

ABSTRACT

In this paper the performance of a single-phase induction motor with an electronically controlled capacitor is examined. The capacitor in series with the auxiliary winding is controlled with an electronic circuit and different optimization criteria are applied in order to determine the optimum capacitance of subsequent performance of the motor.     

ANALYSIS OF A SPHERICAL INDUCTION MOTOR

Abstract

The advent of robotics and automated manufacturing processes has brought about an urgent need for novel electromechanical transducers with unusual design and performance characteristics. Operating flexibility, ruggedness, size, force to weight ratio, and robust control capabilities are design attributes which place a heavy burden on conventional machines used for manipulation purposes. The spherical induction motor introduced in this paper is an electromechanical drive which holds considerable promise in these application areas. A general analysis of both the fields and resultant forces generic to the spherical induction motor is presented. The analysis properly accounts for the diffusion of the magnetic field with changing frequency and motor speed. To aid in the prediction and conceptualization of the torque and commensurate motor losses, normalized plots of these parameters are given for various limiting values of skin depth ratio to conductor thickness. The analysis concludes with a prediction of terminal relations for a typical 3-phase winding. After predicting stator phase inductances (self, mutual, and rotor speed components), a mechanism for predicting rotor speed is discussed. Results indicate that the device is capable of continuous speed control and efficient torque production.     

复合笼条转子感应电动机不同转子材料特性对起动性能的影响

利用电磁场理论和变分法建立了复合笼条转子感应电动机起动时二维电磁场的数学模型，给出了利用有限元法求解正弦时变场的方法。在计算过程中，以定子端电压为约束条件，对定子起动电流进行了迭代计算，得到了额定电压下的起动电流和起动转矩。以此为基础，改变转子槽形，计算转子不同材料时不同转子结构电机的起动性能。通过方案比较，选取合理的转子槽形和材料，进行样机的加工和试验，把计算结果与实测结果进行对比，表明复合笼条转子感应电动机起动性能的计算结果满足工程实际的需要。同时，将计算结果与普通感应电动机起动性能进行比较，证明复合笼条转子感应电动机具有良好的起动性能。     

ROLE OF TORQUE ANGLE IN INVERTER-FED INDUCTION MOTOR DRIVES

ABSTRACT

It is shown from the induction motor differential equations that changes in load torque, speed reference and torque angle are accompanied by a transient change in the speed of the air-gap mmf. The time constant associated with the torque angle change is different for a voltage source and a current source inverter-fed induction motor. This aspect throws light on the instability of current source inverter-fed induction motor on open loop operation. Evidently, the solution to overcome this instability is to use the torque angle for feedback control. It is proved that torque angle feedback alone is not sufficient for stabilization of the current source inverter-fed induction motor.     

PERFORMANCE ANALYSIS OF LOAD COMMUTATED INVERTER FED CAGE INDUCTION MOTOR DRIVE

ABSTRACT

An approach, to analyse the performance of a variable speed cage induction motor drive fed from load commutated inverter (LCI), is presented. Induction motor with an appropriate capacitor across its stator terminals constitutes the load on the inverter. A fully controlled bridge converter, supplied by a variable dc voltage source, commutated with the back emf of the motor, acts as an inverter. An algorithm to compute the motor performance, is developed using equivalent circuit representation of the system. Strategies for the selection of control variables, in order to achieve the desired speed range for satisfactory performance of the drive are given. The performance of a 3-hp, cage induction motor fed from LCI is computed, using the developed algorithm for wide range of speed; and is verfied experimentally.     

A COMPARISON OF THE SINGLE-PHASE INDUCTION MOTOR WITH AN ASYMMETRICAL STATOR YOKE TO THE SHADED-POLE MOTOR

Abstract

The single-phase induction motor with yoke asymmetries can be calculated by means of the same computer program as the shaded-pole motor and compared with it, if some reluctances are substituted by additional windings. The influence of many different parameters on the performance is demonstrated     

三相异步电机在单相电源供电时稳态运行性能的分析和计算

基于分析和单相电机稳态运行的等效电流法。结合近代电路理论中网络图论的有关内容,推导了三角形接法三相异步电机在单相电源供电时,以矩阵形式表示的性能计算公式。将计算值和实验值进行比较的结果表明,两者是比较接近的。     

CALCULATION OF PITCH TORQUE FOR AN ARC-TYPE LINEAR INDUCTION MOTOR

Abstract

An adaptation of Parseval's theorem is used to compute the pitch torque produced in an arc-type single-sided linear induction motor, directly from the Fourier transforms of the air gap magnetic field components. Results predicted through this approach are shown to agree favourably with measurements made on a 2-m diameter test wheel facility.     

异步电动机直接转矩控制系统的改进方案

针对基于直接转矩控制的异步电动机运行时存在较大的电流及转矩脉动问题，该文提出一种新的控制方案。该方案是在原来两电平逆变器的基础上增加一个Boost电路，以使异步电动机的电流及转矩脉动减小，并且使变频器开关频率降低。仿真结果表明该方法案能有效地解决电流及转矩脉动的问题。     

ANALYSIS OF A SERIES-DELTA CONNECTED TANDEM INDUCTION MOTOR

Abstract

A tandem induction motor comprised of two independently housed stator windings, one housing stationary and the other able to be physically rotated, and a squirrel-cage rotor common to both stators is described. When the motor is fed from a single source, altering the position of the moveable stator changes shaft speed in a similar manner to operating a normal induction motor at variable terminal voltage

This paper presents an equivalent circuit model of the tandem induction motor for series-delta connected stator windings. Using the equivalent circuit stator current, power factor, and torque are calculated and then compared to laboratory test results obtained from a 3 kW tandem motor test rig