Application Of Induction Motors Research Articles

Closure to discussion of "Flammable vapor ignition initiated by hot rotor surfaces within an induction motor: reality or not?"

In this article, the authors reaffirm the recommendations and conclusions of their original paper (see ibid., vol. 35, no. 1, p. 100-11, 1999). They do not recommend a change in the present industry practices regarding induction motor application in Division 2 locations, only that caution be exercised for those applications involving the relatively few flammable materials with autoignition temperatures (AITs) below 200/spl deg/C. Further testing, as discussed, is planned during 1999 to further determine the safe limits of induction motor operation in areas of potential low-AIT material releases.

Torque Characteristics and Application of 2-phase Induction Motor Driven by Two Power Supplies with Near-by Frequencies

Torque Characteristics and Application of 2-phase Induction Motor Driven by Two Power Supplies with Near-by Frequencies

A speed identifier for induction motor drives using real-time adaptive digital filtering

A novel sensorless speed identifier for real-time application in induction motor drives under steady-state and transient conditions is proposed. It is based on the calculation of rotor slot harmonic (RSH) frequencies using an adaptive digital filter. It outperforms other analog or spectrum-based RSH speed identifiers in terms of accuracy and speed of response. The new identifier measures the speed with less than 0.1% error by processing the stator current on a sample-by-sample basis. It is also capable of tracking speed transients of high slew rates with high accuracy. The authors believe this to be the first effective tracking of RSHs during transients ever reported. The proposed algorithm is computationally very efficient and requires only a single processor for its real-time implementation. Simulated and experimental data were used to validate the algorithm.

Regulatory impact on the application of AC induction motors

This article identifies the impact of current and future laws, regulations, codes, standards, and recommended practices affecting the specification, design, operation, and maintenance of electric motors. The intent is to provide the engineer with a user's guide to assure compliance. The purpose of the article is to identify existing and anticipated to the application of AC induction motors. Those areas where no apparent restrictions exist are also explored. It is important to understand that these constraints are, for the most part, in a constant state of review and possible change.

Pulse converters in traction applications

After over a century of electric traction, the virtual monopoly of the commutator motor is drawing to a close. Major advances in devices and techniques have made the application of polyphase induction motors to traction units a viable proposition. The authors describe how the use of pulse power converters in these units can improve the electrical performance even further.

Five-level GTO inverters for large induction motor drives

The development of large induction motor drives with low torque ripple and fast dynamic response for new or retrofit applications has been limited by the device ratings and problems of series connections. This paper investigates the use of a five-level GTO voltage-sourced inverter for large induction motor drives. The advantages of such a drive are that single GTO thyristors may be used at each level, thereby avoiding the need for series connection of the thyristors. The thyristors are well protected from overvoltages by the clamping action of the DC supply capacitors. The disadvantages are that each DC level requires a separate supply, four in the case of the five-level inverter, and that the devices are not equally loaded. This paper reviews the basic operation of the five-level inverter and possible PWM voltage/frequency control techniques for the specific application of induction motor drives. The simulation results clearly show the unequal loading of the devices and the need for independent voltage supplies for the five levels. It is shown that a combination of several PWM techniques offers the best solution for the drives application. The conclusions indicate that large induction motors with ratings up to 22 MVA, 7.46 kV may be supplied by the five-level inverter using available 4.5 kV, 3.0 kA GTO thyristors. The recommended supply for such an inverter with full regenerative operation over the complete speed range is four, four-quadrant converters in a quasi-24-pulse configuration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Study on the feasibility of application of linear induction motor for vertical movement

Numerical studies on the linear induction motor with a short stator are carried out to evaluate its feasible maximum payload ratio, considering its application for an actuator with vertical movement. The dependency of the ratio on a set of machine parameters is obtained. The payload ratio higher than three is shown to be realizable. >

Unstable Self-Excitation of Torsional Vibration in AC Induction Motor Driven Rotational Systems

The most common NEMA Design Classes of AC induction motors have speed-torque characteristics that can give rise to unstable self-excitation of torsional vibration in rotational systems during start-up. A torsional vibration computational model for start-up transients has been developed as a design tool for induction motor applications. Torsional instability can occur at speeds in the positive sloping segment of the motor’s speed-torque curve and is particularly acute when the mass moment of inertia of the load device is more than two times the mass moment of inertia of the motor rotor. The computational model is compared with an exact solution method and with a laboratory test of a motor-driven inertial load. Applications of the computational model to electric submersible pump (ESP) design cases are discussed.

Safety considerations for the application, installation, operation, and maintenance of industrial AC induction motors

Safety considerations for the application, installation, operation, and maintenance of industrial AC induction motors

Start-Up Torque Limitation of Induction Motors by Asymmetrical Starting Connections

ABSTRACT Smooth acceleration during the start-up is important in some industrial applications of induction motors. An example is given by texile machines, where the breaking fibre threas during the start-up must be avoided. An asymmetrical starting scheme, implemented by means of an external resistance inserted in one of the motor phases, can provide a simple, but elective, solution to this problem; the value of the resistance Mill depend on the assigned value of the maximum torque developed. To compute the transient behavior during the start-up, a dynamical motor model, effective also of describe asymmetrically connected machines has been used to study the torque control problem. The present paper reports the results obtained with reference to a 70 W induction motor supplied by a frequency converter. A comparison between experimental data and simulation is presented.

Torsional vibration resulting from adjustable-frequency AC drives

Torsional vibrations are a problem for the rapidly growing population of induction motor applications utilizing adjustable-frequency AC drives. The concepts used in analyzing torsional vibration are presented. Its effects on various system components are examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Variable Frequency Drives and Power Factor

Variable frequency drives are being used in many applications which were previously fixed speed induction motor applications. The predominant ones are centrifugal pumps and fans where substantial energy savings can be realized with adjustable speed operation. The power factor of variable frequency drives when applied to centrifugal pumps and fans is discussed. The power factor characteristics of the three most commonly used controllers-variable voltage input (VVI), current source input (CSI), and pulsewidth modulated (PWM)-will be reviewed in detail. Also application guidelines on selection and installation of power factor correction capacitors will be reviewed.

Non-Deadband Reversing Control of Linear Induction Motor

There are numerous applications of Linear Induction Motors (LIM) in industry. More recently, linear positioning servo systems employing LIMs have attracted some interest. This paper describes a method for controlling such motors bydirectionally without deadband. For this purpose, advantage is taken of the double sided construction, which allows separate excitation for each primary. Hence at low speed, two flux waves of opposite direction can be excited, which produce two counteracting forces. At high force levels the mode is shifted to supporting waves, which allows full utilization of the power capability. The LIM is fed through two Thyristor three-phase a.c. controllers. Test results are presented and compared with theoretical considerations. Finally, the plant transfer curve and the control system are briefly analyzed.

AC Induction Motor Torsional Vibration Consideration - A Case Study

Much has been written on the application of high-speed (3600 r/min) motors to pumps and compressors relative to vibration and lateral critical speeds. A reciprocating compressor coupled to an induction motor is a complex torsional system and can present a more complex set of problems to the equipment suppliers because of the wider range of forcing frequencies present. The problems encountered on a specific application with the objective of developing guidelines to be used to avoid similar system torsional problems on the application of induction motors to reciprocating equipment are discussed.

Applications of linear induction motors in industry

Applications of linear induction motors in industry

Applications of linear induction motors in industry

Numerous papers have been published in the Proceedings IEE on theoretical aspects of linear-induction-motor design. There are now large numbers of these motors used in practical applications, and the paper describes many of these. Four basic types of linear induction motor are currently in use: single sided, double sided, disc and tubular, using 3-phase or single-phase supplies. These types and their speed-control gear are dealt with in the paper.

Application of linear induction motors to high-speed transport systems

The linear motor has been chosen as the method of propulsion for the full-scale prototypes of several high-speed transport systems currently being developed. The paper sets out the problems of the electrical design of such systems, showing its interdependence with the mechanical and thermal designs. Attention is then concentrated on the double-sided flat linear, motor with conducting-sheet secondary, which is thought to offer the greatest advantages for long tracks. Considerations of power supply, thrust and speed control and methods of braking are included. It is shown that a steel plate cannot be used as secondary conductor on economic grounds. The particular requirements of vehicles which are suspended on air cushions are considered throughout the paper and a concluding section discusses the possibility of using electromagnetic current collection for such vehicles.

Paper 6: Application of the Linear Induction Motor to High-Speed Transport

High-speed ground transport (150 m/s) to be effective over limited distances also requires high acceleration. Were the power required to overcome air resistance and achieve adequate acceleration provided by conventional means, bulk and mass would be excessive. The linear induction motor offers considerable advantage at high speeds, it is not limited by centrifugal force and is independent of adhesion. A high overhead rating is possible as heat is left behind in the reaction rail. Output of a double-sided machine may be expected to reach 7 lb/in2 (44 500 N/m2) of effective pole face and the system is equally effective in braking. The principle of operation is described. To be efficient the current which is ‘in phase’ with the applied voltage must be made as large as possible compared with the magnetizing current, operation must be at low values of slip and the surface speed of the travelling field should be high. Thus a quantity known as the ‘goodness’ of a machine may be described by the expression where μ0 is permeability of free space; ρr is surface resistivity of rotor; p, pole pitch; g, total effective air gap in the magnetic circuit; and Vs is surface speed of travelling field = synchronous speed of vehicle. Because of the simplicity of the construction, g is necessarily larger than would be the case for a conventional machine and ρr is less favourable. However, these can be compensated for by increasing p with a suitable adjustment of frequency and the effect of the term Vs is such that the linear motor becomes better the higher the speed at which it is required to operate. Tests on a linear motor at Gorton are described and some of the mechanical problems of applying linear propulsion to railways are discussed.

The application of linear induction motors to conveyors

The principal advantage in using linear induction motors to drive conveyor belts is that force can be applied uniformly to the belt over a wide area without mechanical contact. The drive is therefore independent of the coefficient of friction between belt and rollers and belt stretch is less likely to occur. The main problem in designing a linear motor for such a drive arises from the fact that the speeds required are low, and it is shown that efficient systems are possible only if the motor is supplied with low-frequency power.Two systems are investigated, the first using a woven copper belt and the second a series of solid plates connected to chains along each side. The effect of end-ring resistance and of contact resistance between weft and warp is investigated in the case of the woven belt. The action of the plate conveyor involves the behaviour of discontinuous rotors, and a theoretical investigation of this problem included. The findings are substantiated by experimental results obtained from a fairly large model. Other applications which could utilize the short rotor effect are suggested.

Discussion on “The application of linear induction motors to conveyors”

Discussion on “The application of linear induction motors to conveyors”