The basic idea of an electric motor is to generate two magnetic fields. In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction from the rotating magnetic field of the stator winding. Introduction linear induction motor lim, is basically an advanced version of motor that is in use to achieve rectilinear motion instead of rotational motion as in ordinary conventional motors. Design of a single sided linear induction motor slim using a user interactive computer program a thesis presented to the faculty of the graduate school university of missouricolumbia in partial fulfillment of the requirements for the degree master of science by sarveswara prasad bhamidi dr. Induction motors with rotor helical motion 253 difference is in the rotor slip, which for rotary linear motor depends on both rotary and linear rotor speeds. This is one of the best book dealing with the design and analysis of linear induction motor. Linear induction motors are suitable for applications that require rapid movement of large payloads. Lim is an advanced version of rotary induction motor which gives a linear translational motion instead of. The linear motor training system is a useful teaching tool for instructors who wish to demonstrate the basic principles of magnetism as applied to the operation of linear induction motors. A lim operates under the same principles as its ac rotary motor counterpart, typically powered by a threephase voltage scheme with a. Singlephase induction motor threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together.
Linear induction motors are quite an engineering marvel, to convert a general motor for a special purpose with more or less similar working. An induction motor can be used as an induction generator, or it can be unrolled to form a linear induction motor which can directly generate linear motion. In the last years, in the field of research on linear induction drives, a lot of efforts have been oriented to improve the dynamics performances of these. A polyphase linear induction motor comprising a primary member having magnetic material formed with a polyphase winding and, for cooperating with the primary member, a secondary member comprising electrically conductive material backed by further magnetic material is so arranged that the working flux passes in low reluctance paths lying substantially in planes directed transversely of the motor. The linear induction motor is one of the most promising propulsion systems for superhighspeed ground transportation. How an induction motor works by equations and physics.
Discusses constructions of linear electric motors and drives, areas of theoretical investigation and problems of practical application. Like cylindrical induction motor, lim also runs at speed less than synchronous speed. Ppt linear induction motor powerpoint presentation. Conversion to mechanical power by motors pumps, fans, hvac, refrigeration compressors. In this thesis, the analysis of the dynamic response of a linear induction motor as an electromechanical system is done, accounting for all the governing equations implied in the process which are used to develop the corresponding simulation models. Simulation results have shown fem was a good method, but little test results exited. Each primary is installed along the entire length of the launch structure, but is divided into sections. This paper explores the construction process of a linear induction motor lim, the basic concepts behind key aspects of linear induction machines construction and the testing process of a working prototype. A linear induction motor has a polyphase energizing winding formed of groups of generally flat bobbintype windings arranged in two or more winding layers, the windings in each winding layer being generally coplanar with one another. Normally lim is used to make a motion frictionless absolutely. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. The linear induction motor is designed for high speed operation. Equivalent circuit of induction motor with rotatingtravelling magnetic field. The technology is not new but merely designed in a.
In this type of motor, the stator and rotor are called primary and secondary respectively. In this work, a flux and speed observer for doublesided linear induction motor applications is presented and experimentally validated. Linear induction motor induction launc hers feasible within the scop e of a small undergraduate pro ject. In a traditional electric motor, the rotor rotating part spins inside the stator static part in a linear motor, the stator is unwrapped and laid out flat and the rotor moves. In this paper the speed control method of lim, which lead to optimal control characteristic of motor such as thrust, flux and current, is proposed. Take a conventional rotary servo motor and unwrap it. Induction motor seminar ppt, pdf report study mafia. Pdf this paper explores the construction process of a linear induction motor lim, the basic concepts behind key aspects of linear induction machines. In a conventional round rotor induction motor the behavior of the machine is only needed to be calculated ov er one pole pi tch. Each aircored linear induction motor has a primary winding consisting of a linear array of coaxial circular coils, and a secondary which is a cylindrical conductive sleeve concentric with the primary.
One, two, and threedimensional solutions of the field equations have been obtained along with numerical solutions for the electromagnetic field in. Jul 15, 2019 a linear motor is effectively an ac induction motor that has been cut open and unwrapped. Nov 03, 2019 an induction motor also known as an asynchronous motor is a commonly used ac electric motor. Characteristically, linear induction motors have a finite primary or secondary length, which generates endeffects. The lims 3phase coil assembly can be directly connected to the ac line for single speed applications or to an adjustable frequency drive for variable speed control. Here are the design notes from a welldocumented lim coilgun in 1937. The aim this researc h pro ject is to dev elop a linear induction motor system capable of op erating at 400 v olts with an initial energy of 25 j to in v estigate the lo w feasibilit y op erating concept and erify design pro cedure used in. The voltage and current is induced in the rotor circuit from the stator circuit for the operation. The performance of the proposed dtfc method is analyzed with considering endeffect. The most important advantage of an induction motor is that its construction is quite simple in nature. Generally, induction motors are categorized based on the number of stator windings. A linear induction motor lim is a specific type of alternating current ac motor designed to produce motion in a straight line. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions.
With this design, the load is connected directly to the motor. In traditional designs of 60 hz linefed induction machines, skin effect is represented by correction coefficients k r and k x for bar resistance and slot leakage inductance. Each winding group is formed of two or more of the windings one within the other. It can also be used by students for determining the basic electrical characteristics of a linear induction motor and studying the dynamic behavior tractive force, acceleration, top speed of a linear. The generating mode for induction motors is complicated by the need to excite the rotor, which begins with only residual magnetization. The method is very accurate and often has been used for validating the fem computer software. Vivek brahmbhatt already has explained very nicely the construction of lim. The stator is laid out in the form of a track of flat coils made from aluminum or copper and is known as the primary of a linear motor. The 3phase set of currents, each of equal magnitude and with a phase. The shape and operation of a linear induction motor can be visualized as depicted in the figure by making a radial cut in a rotating induction machine and flattening it out. More in detail, from a doublesided linear induction motor. Stator poles rotate at the synchronous speed ns when fed with a three phase supply. Induction motors are the commonest type of motor and account for a very large proportion of heavy duty motors.
The rated single or 3phase ac voltage is applied to the vfd. This is the basic linear induction motor working principle. May 31, 2019 a linear induction motor or lim is a special type of induction motor used to achieve rectilinear motion rather than rotational motion as in the case of conventional motors. Ac induction motor high performance linear induction motor baldor provides industry with the widest range of linear motors, linear stages and controls. However, a slip ring is required to feed dc supply to the rotor in the case of a synchronous generator. He built several models in the lab, and designed on paper a coilgun for a trip to the moon.
Similarly to the conventional rotary motors, the secondary resistance can be split into two. Pdf the equipment and data acquisition system for testing linear induction motors lims has been described. Characteristics of linear induction motor considering. Dec 04, 2018 how does an induction motor work how it works 3 phase motor ac motor duration. Linear induction motors can achieve speeds in excess of 1800 per second 45 ms and accelerations in the range of 34g. So now what was the stator is now a forcer and the rotor becomes a coil or magnet rail. Mec design and construction of a pulsed linear induction motor. Linear induction motor a linear induction motor lim is an advanced version of rotary induction motor which gives a linear translational motion instead of the rotational motion. The construction of the stator is similar in both synchronous motors as well as induction motors. May 22, 2017 used in many industrial and hightech fabrication applications, linear motors are an invaluable part for the fastest and most efficient processes. In the rotary induction motor the stator and the rotor area are same whereas in the lim the one of the two is shorter than the other. The lim operator shall consist of a control unit, one or more linear induction motors and reaction fin sections. Pdf construction of three phase linear induction motor.
Ppt linear induction motor powerpoint presentation free. The result is a flat stator, or upper section, of iron laminations. Theory of linear induction motors 2nd edition nasaads. The linear induction motor science publishing group. A linear induction motor or lim is a special type of induction motor used to achieve rectilinear motion rather than rotational motion as in the case of conventional motors. Pdf fuzzy logic control of linear induction motor emre. The principle of the linear induction motor can be easily under. A linear induction motor lim is an alternating current ac, asynchronous linear motor that works by the same general principles as other induction motors but is typically designed to directly produce motion in a straight line. They are capable of speeds up to 1800 insec 45 ms and are typically used in applications where accurate positioning is not required. Characteristically, linear induction motors have a finite primary or secondary length, which generates endeffects, whereas a conventional induction motor is arranged. Electric motor electric motor linear induction motors.
Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. Innovia metro systems run on conventional metal rails and pull power from a third rail, but are powered by a linear induction motor that provides traction by pulling on a fourth rail placed between the running rails. Pdf fuzzy logic control of linear induction motor emre ozkop. Linear motors are electric induction motors that produce motion in a straight line rather than rotational motion. The rotor will constantly be turning to align its magnetic field with that of the stator field. A linear induction motor lim is a noncontacting, high speed, linear motor that operates on the same principal as a rotary, squirrel cage, induction motor. Linear induction motor lim is an asynchronous motor, working on the same principle an induction motor works, but is designed to produce the rectilinear motion, unlike the rotary movement produced by a motor. Standard lims can produce forces in the range of 720lbs 3200n at a 3% duty cycle. Apr 29, 2018 linear induction motor lim is an asynchronous motor, working on the same principle an induction motor works, but is designed to produce the rectilinear motion, unlike the rotary movement produced by a motor. The complete linear induction motor application tree is illustrated in figure1. The rotor takes the form of a moving platform known as the secondary. The premier electrothermic engineer and father of the induction heating industry, edwin finch northrup, foresaw the application of induction motor design to coilguns.
Instead of producing rotary torque from a cylindrical machine it produces linear force from a flat one. This book is a report on the results of particular research activities and is not intended as a comprehensive reference work. I would just like to add some practical applications of lim. The rated single or 3phase ac voltage is applied to the linear induction motor. Free download induction motor seminar ppt, pdf report. Innovia metro stylized as innovia metro is the current name given to an automated rapid transit system manufactured by bombardier transportation. Linear induction motor working principle your electrical guide.
The pulsed linear induction motor concept for highspeed trains b. Difference between synchronous motor and induction motor. Soft starters are used for induction motor drives having fan, pump and. Like permanent magnet linear motors commonly designated as ironless and iron core types linear induction motors consist of a primary part analogous to the stator in a rotary induction motor and a secondary part analogous to the rotor in a rotary version. Basically a special purpose motor that is in use to achieve rectilinear motion rather than rotational motion as in the case of conventional motors. A linear induction motor provides linear force and motion rather than rotational torque. Reasons are the same that are in the case of a cylindrical induction motor. If a rotary induction motor is compared with the linear induction motor, the lim requires a larger air gap and hence, the magnetising current is greater and the power factor and efficiency of the motor are lower. Linear motors complement todays linear motion technologies. Ac voltage controllers are used as soft starters for smooth starting of induction motors. Sizes vary from fractional horsepower to several thousand horsepower used for such applications as dieselelectric locomotives. Power lab project application of three phase linear induction motor duration. A linear induction motor is a type of linear motor based on a rotary ac induction motor.
The development of the technology started in 1975 and resulted in the implementation of five transit systems with the lim on board with a. The pulsed linear induction motor university of edinburgh. The rotor of an induction motor can be a squirrel cage rotor or wound. An induction motor can be defined as the ac electric motor device in which a power source fed by the alternating current with the help of a primary winding. Zimmerman pulsed power sciences center sandia national laboratories, albuquerque, nm 87 185 abstract the seraphim segmented rail phased induction motor concept is a linear induction. American journal of electrical power and energy systems. Theory of linear induction motors by sakae yamamura. If done so, the rotor poles get magnetically coupled with the rotating stator poles, and thus the rotor starts rotating at the synchronous speed. Linear induction motors are quite an engineering marvel, to convert a general motor for a special purpose with more or less similar working principle, thus enhancing its. This is quite an engineering marvel, to convert a general motor for a special purpose with more or. The linear induction motor will start from zero speed and accelerate to the rated velocity based on frequency and mechanical load. What is a linear induction motor and how does it work.
As a result, they often require forced air or watercooling to achieve published specifications. Baldor linear motors and stages steven engineering. Nov 11, 2011 the linear induction motor is designed for high speed operation. Advantages and disadvantages of induction motor electrical4u.
Singlesided linear induction motors slim 1 3 are electromagnetic devices of directly converting electrical energy into mechanical energy to realize linear motion without any mechanical converters, which have been applied in various industries. Linear induction motors fall into the category of special electrical machines in which the electric energy is converted directly into mechanical energy of translatory. How an induction motor works by equations and physics introduction. Fuzzy logic control of linear induction motor emre ozkop adem sefa akp. Linear induction motors are less efficient than permanent magnet linear motors, and thus produce more heat for a given continuous force output.
Such an induction motor with integrated brake is shown on figure 1. An induction motor is based on the principle of induction of voltages and currents. Bombardier transportation is a world leader in applying linear induction motor lim technology to urban transit systems. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Being a leader in linear motor design and manufacturing, baldor continually develops advanced products and innovations to meet a variety of linear motion applications. Pdf experimental tests on linear induction motors researchgate.
Making use of three phase systems, fundamental devices are used to produce. Pdf linear induction motor at present time semantic scholar. A linear induction motor lim is an advanced version of rotary induction motor which gives a linear translational motion instead of the rotational motion. The rotor needs to be rotated at a speed near to the synchronous speed during starting. Based on vfd settings, a unique voltage and frequency is applied to the linear induction motor. This paper presents fuzzy logic control for a singlesided linear induction motor slim.
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