Know about the different winding slots, lamination of the stator and its construction. This method is applicable to squirrel cage induction motor only. Induction motors are used in applications requiring fast and precise control of torque, speed, and shaft position. Three phase induction motors used in explosive atmospheres w60 line squirrel cage rotor horizontal date. This type of speed control is not possible for the squirrel cage induction motor. Although they are energy efficient while running at full load. The torque developed in this method is proportional to the square of the supply voltage. Figure 3 shows the relation between the voltage and torque versus frequency. Squirrel cage induction motors menzel elektromotoren. At us american market 2pole and 4pole squirrelcage induction motors with increased.
The main methods employed for speed control of induction motors are as follows. Squirrel cage construction, the rotor winding consists of a number of rotor bars, shortcut by rings from both side, see figure below. Frequency controlled motors refer to motor series that are invariably used together with a. More than 90% of motors used in industries are squirrel cage induction motor due to its rugged and maintenance free design. Speed control system of induction motor by using vector. Almost 90% of induction motors are squirrel cage motors.
List and describe the more commonly used equipment in an electric substation. Threephase induction motor squirrel cage rotor customer. In all singlephase induction motors, the rotor is the squirrel cage type. Also appreciate the rugged construction of squirrel cage rotor and know the spectacular reasons for the skewed arrangements of the rotor conductors.
How an induction motor works by equations and physics. Low voltage threephase squirrelcage induction motor. A squirrelcage rotor is the rotating part of the common squirrelcage induction motor. Review on efficiency improvement in squirrel cage induction motor by using dcr technology subramanian manoharan. Bnspem04 specification for for a squirrel cage induction. Difference between cage rotor and slip ring rotor a woundrotor is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Various induction motor speed control methods advantages. Physical layout of induction motor in an induction motor induction refers the field in the rotor is induced by the stator currents and asynchronous refers that the rotor speed is not equal to the stator speed. 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. Determination of the torquespeed characteristic of.
What are the parts of a squirrelcage induction motor. May 20, 2015 the threephase induction motor the squirrel cage induction motor the woundrotor induction motor 3 4. Speed control is not possible in squirrel cage induction motor. Squirrel cage induction motors are very widely used in both fixedspeed and. Speed control of 3phase induction motor using pic18 microcontrollers. It can be used both for squirrel cage and slip ring motors and enables monitoring and. Typical torquespeed curve of a squirrel cage induction motor given in figure 1 provides information about the operation of induction motor. The construction of stator of the induction motor is almost the same as other motors. The relative motion between this field and the rotation of the rotor induces electric current in the conductive bars. Faculty of engineering tobruk, faculty of engineering benha2 1, 2. Know how the speed control is easily achieved by changing the number of. The induced torque of the motor is zero at synchronous speed.
Very large motors sometimes have a portion of the ends of the rotor windings externally connected through brushes so you can control the effective resistance of the rotor. The singlephase ac induction motor best fits this description. Difference between cage rotor and slip ring rotor basic. Squirrel cage induction motor requires significantly less maintenance as it does not contain brushes, commutators, slip rings. The rotor connections are not brought out at the outside, it is shortcircuited inside of the motor. The sinusoidally distributed flux density wave is moving at slip speed inducing in the rotor cage voltages of magnitude indicated by the blue vertical lines. In slip ring induction motor slip rings are provided with the rotor. A metal housing, with ribs designed for natural cooling. Induction motors with integrated condition monitoring ethercat. Search wegthreephaseinductionmotorstlinesquirrelcage. Types of ac induction motor rotors there are twotypes of rotor windings.
In this work a conventional three phase squirrel cage type induction motor with specifications 10 hp, 415v, stardelta connected and 4 poles is chosen for comparison with our motor, which is designed for good efficiency. So the main idea behind motor maintenance is to prevent breakdown rather than repairs them. Stator fundamental field induces rotor cage loops with rotor frequency. Almost 80% of the mechanical power used by industries is provided by three phase induction motors because of its simple and rugged construction, low cost, good operating characteristics, the absence of commutator and good speed regulation. Torquespeed characteristics of three phase squirrel cage induction motor aim to obtain the torquespeed characteristics tn r of a three phase squirrel cage induction motor using 1. Also lets get to know the methods which are used to control the speed of squirrel cage. Speed control of induction motor detailed explanation. Pdf speed control of a squirrel cage induction motor. So obviously the speed of an induction motor can be controlled by varying any of three factors namely supply frequency f, number of pole p or slip s.
Speed control of induction motors the speed of an induction motor is given as n 120fp 1s. Different speed control methods of induction motor are explained below. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. The squirrel cage induction motor was designed for an extended service life under very demanding conditions. Thus a continuous speed control system is achieved, corresponding to a frequency range of from 2. This is because the squirrel cage motor has a simple and rugged construction. Oct 09, 2016 a 3 phase induction motor has two types based on the rotor construction, named as. Sensorless field oriented control of 3phase induction motors using control law accelerator cla manishbhardwaj abstract this application report presents a solution to control an ac induction motor using the control law accelerator cla which is a small foot print coprocessor present on some of the microcontrollers from the c2000 family of. The goal of this paper is to study the speed control of the squirrel induction machine with a double cage model, by usingconstant vf control strategy. Direct torque and flux control of squirrel cage induction motor. Menzel squirrel cage motors are available in all standard motor cooling and protection types for lowvoltage from 75 kw as well as medium and high voltage up to 25,000 kw. However, should the motor require service, this manual includes a section that assists the. Efficiency classes of singlespeed threephase cage induction motors.
Stator winding spreading the coil in this manner creates a sinusoidal flux distribution per pole, which improves performance and makes the motor less noisy sound and electrically. There are two basic reasons for the use of singlephase motors rather than 3phase motors. Squirrel cage wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. Control of motorcharacteristics by squirrelcage rotordesign. How are squirrel cage induction motors constructed. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. The squirrel cage induction motor is the most commonly used motor in industry.
This motor should be mounted on the motor bench, wherein the motor shaft may be coupled to the dynamometer for taking the measurements. Generally an induction motor operates at almost constant speed as the load is varied. This is because, with vector control, it is possible to achieve high dynamic transient performance, equalling that of the separately excited dc motor, in variable speed ac drives. Reaction of a squirrel cage rotor in a 2pole field in the rotor reference frame. The proposed procedure for determining the efficiency of the squirrel cage induction motor powered by a vfd allows obtaining the efficiency curves of all the equipment under test and the overall system in a simple and practical way, in order to make a future efficiency rating of the whole induction motor variable frequency drive. When the supply voltage is reduced, induction motor draws more current. Know how the speed control is easily achieved by changing the number of stator poles. Deivasahayam gopalakrishnan ranganathan induction motors account for approximately 50% of the overall electricity use in industrialized countries. Nov 18, 2015 induction motor torquespeed characteristics. Out of all the electrical machines, induction motor is the most used machine in industries. Modelling and analysis of squirrel cage induction motor. Torquespeed characteristics of three phase squirrel cage.
To drive three phase squirrel cage induction motor with a constant speed, vector control technique is used. Well the shortest and the simpest answer would be the stator and the rotor. The speed control through vf drive is the best method. What are the advantages of a squirrelcage induction motor. Control and measuring method for three phase induction motor with.
Horizontal squirrel cage mediumvoltage induction motor. Studying and improving of squirrel cage induction motor scim efficiency is a continuous area of interest not only among the researchers but also the industry, manufacturer and government. This paper presents a mathematical model of 3phase squirrel cage induction motor accounting for a very high number of space harmonics in which, due to application of a special transformation of voltages and currents, a differential equation system with constant coefficients is obtained. Differentiate between the various types of generating electric power stations. The rotor of the squirrel cage three phase induction motor is cylindrical in shape and have slots on its periphery. Therefore, this thesis proposes an efficiency optimization method of the induction machine im through the variation of the control parameters. It consists of a cylinder of steel laminations, with aluminum or copper. The model of the threephase squirrel cage induction motor can be. In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i. Working principle of 3 phase squirrel cage induction motor. Model repair specifications for low voltage induction motors these model repair specifications are intended to cover routine repair and rewind of lowvoltage randomwound threephase ac squirrel cage induction motors.
The reason for the name squirrel cage is because of the type of rotor used in these motors. Flux adjustment by choosing number of turns per phase. Vfd controlled induction motor efficiency measurement. Starting of squirrel cage induction motors485 an induction motor can be regarded as a transformer with a small air gap in the magnetic circuit. The field windings in the stator of an induction motor set up a rotating magnetic field through the rotor.
Lecture 6 three phase induction motors cairo university. Since here we are talking about maintenance of induction motor, and it is of two types. Third international conference on advances in control and optimization of dynamical systems march 15, 2014. Read more methods of speed control of induction motor. During voltage surges, increase in voltage saturates the magnetic components of the squirrel cage induction motor. In first comparison, motor was supplied from laboratory source. Squirrel cage definition and meaning collins english dictionary. The variable torque command is generated from the speed loop using a conventional pi controller which has been implemented in experimental work to validate the simulation results. The stator winding is assumed to be yconnected with the access to the phase terminals.
An induction motor or asynchronous motor is an ac electric motor in which the electric current. The curve is nearly linear in normal operating conditions which are between pullout speed and synchronous speed 6. Advantages and disadvantages of squirrel cage induction motor. Which is the best method of speed control of a squirrel. Kanpur, india design of a three phase squirrel cage induction motor for electric propulsion system ravi prakash,mohammad junaidakhtar, r.
These motors are tested to strict quality control for routine and type tests at every stage of production and are ideally suitable for various industrial applications. This is why the commonest induction motors are called squirrel cage motors since the structure looks like what might be used to entertain a small animal in captivity. Model repair specifications for low voltage induction motors. Sensorless field oriented control of 3phase induction. Squirrel cage induction motors are more sensitive to the supply voltage fluctuations. Recall that leakage reactance is the reactance due to the rotor flux lines that do not also couple with the stator windings. Squirrel cage induction motor and wound rotor induction motor. The magnetization current im flowing in the motors equivalent circuit fig. Premium gold motor low voltage threephase squirrel cage induction motor. Solid state speed control of a squirrelcage induction motor. Construction of three phase induction motor electrical4u.
Lets start with the parts that are visible to us when we look at an induction motor. Jan 10, 2019 the rotor conductors of the scim is shortcircuited by end rings. Firstly, i am going to tell you about the structure of squirrel cage induction motor. The implementation is done using a rectifier and an inverter, where the pwm triggering pulses were generated by using pic micro controller for switching the igbts of the inverter. A synchronous motor may have a squirrel cage winding embedded in its rotor, used to increase the motor starting torque and so decrease the time to accelerate to synchronous speed. Delivering full text access to the worlds highest quality technical literature in engineering and technology. Modelling and analysis of squirrel cage induction motor with leading reactive power injection 101 accommodate a system with any number of phases which might be useful in the case of the machine having an auxiliary winding as proposed in this work.
Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. An equipment is presented for speed control of threephase squirrel cage induction motors supplied through a thyristor converter directly from the mains the european 50hz system by controlling the frequency and voltage magnitude. Know about the most popular and almost unbreakable construction of squirrel cage induction motor. In this paper, the development of speed control system for three phase squirrel cage induction motor using a vector control method is presented and simulation for proposed system is done with the help of matlab simulink. The design of the basic inverter is covered in chapter 2. Vector control, also described as field oriented control, is being increasingly used for the speed control of induction motors. Design of a three phase squirrel cage induction motor for. The slip ring motor has very little application in industries.
Mainly we discuss a threephase squirrel cage induction motor. Former is cheaper and broadly used as it requires less maintenance than later one. Jul 25, 2019 squirrel cage induction motor working principle. The major divergence between calculated and measured results are because of input power. Why is the rotor resistance method of speed control not. Pdf in a motor control, voltage saturation is a serious problem as a motor speed increases.
The squirrel cage induction motor may be modeled with a double cage model in order to predict well starting current and torque 2. An887, ac induction motor fundamentals microchip technology. The present study emphasizes speed control by using an external speed loop with dtc controller. The speed control can be achieved through two modes of vfd operation. The squirrel cage winding of a synchronous machine will generally be smaller than for an induction machine of similar rating. For motors falling outside this description, the more comprehensive model specifications below are recommended. This rotating magnetic field has a speed which is known as the synchronous speed this rotating magnetic field induces the voltage in rotor bars and hence shortcircuit currents start flowing in the rotor bars. Designing of three phase squirrel cage induction motor for. Vf control of squirrel cage induction motor drives. Cage induction machines institut fur elektrische energiewandlung.
This paper deals with analysis of high speed squirrel cage induction motor. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. Energy efficiency improvement of a squirrelcage induction motor. On a mathematical model of squirrelcage induction motors. We can add external resistance in rotor circuit through a slip ring in the induction motor. Direct torque control dtc is the simplest method meant for torque control of a threephase induction motor. This rotating magnetic field has a speed which is known as the synchronous speed. Control of motorcharacteristics by squirrel cage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. Squirrel cage induction motor the engineering projects. Construction of squirrel cage induction motor explained. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. Pdf speed control of squirrel cage induction motor sqim. Bnspem04 specification for for a squirrel cage induction motor with control panel for stepless speed control variable speed driver control. Dec 10, 2015 watch this video and learn basics of squirrel cage induction motor.
Pdf improving squirrel cage induction motor efficiency. Parida department of electrical engineering national institute of technology, silchar,assam, india email. Now let us discuss in detail, the most common form of induction motor, the squirrel cage induction motor. This paper analyzes the concepts of a wellbalanced capacitor voltage fed multilevel diode clamped converter driving a three phase squirrel cage induction motor at a varying load. But the rotor construction differs with respect to the type of motor. Speed control of three phase squirrel cage induction motor using vf method is implemented.
Widerange speed control of threephase squirrelcage. Indirect vector control of multi cage induction motor. Studies on direct torque controlbased speed control of. Test motor was tested on bench to experimentally verify the results. Normally, we use the motors in industrial drives because they are rugged, reliable and economical. Easier method of controlling to rque for squirrel cage induction motor is proposed based on. Variable voltage variable frequency vf control theory an induction motor compared to a dc motor has some major advantages such as. As induction motors are widely being used, their speed control may be required in many applications. Menzel squirrel cage induction motors are manufactured for various industries and industrial applications of all kinds. An open loop inverterthreephase squirrelcage induction motor drive system that provides constant maximum torque or increased maximum torque and reduced.
Speed control of three phase squirrel cage induction motor. Control of motorcharacteristics by squirrelcage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. Methods of speed control of induction motor electrical. The speed of induction motor can be varied by changing supply voltage. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. Some disadvantages of squirrel cage induction motors are. This type of speed control is only possible for slip ring induction motor.
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