When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. Kanpur, india design of a three phase squirrel cage induction motor for electric propulsion system ravi prakash,mohammad junaidakhtar, r. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. A motor rating of 10 horse power, 415 volts with 1440 rpm and 4pole is selected for design problem and an equivalent circuit model is developed to find out the various. 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. Normally with motors beyond 5 hp, starters are provided. Model repair specifications for low voltage induction motors. So the rotor always lags behind the rotating field in the stator. List and describe the more commonly used equipment in an electric substation. The synchronous speed of an induction motor is a function of the number of stator poles. Pdf speed control of multiple induction motors of electromagnetic. Speed of a dc shunt motor can be varied very easily with good efficiency, but in case of induction motors, speed reduction is accompanied by a corresponding loss of efficiency and poor power factor. Speed control of wound rotor induction motor using rotor. The speed of the rotating magnetic field is referred to as synchronous speed.
This work is introducing the designing of new three phase squirrel cage induction motor with an objective of getting good efficiency. The above three methods are most commonly used for the speed control of squirrel cage induction motors. In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i. Torque speed characteristics of induction motor slip. Reaction of a squirrel cage rotor in a 2pole field in the rotor reference frame. Squirrel cage induction motor an overview sciencedirect topics. Speed control of squirrel cage induction motor sqim based on voltage angle. Electric vehicle speed control using three phase inverter. Methods of speed control of induction motor electrical.
It is low cost and requires low maintenance in comparison with. It supplies an induction motor ich has a full load speed of 144wh 0 rpm. The squirrel cage induction motor was designed for an extended service life under very demanding conditions. Working principle of 3 phase squirrel cage induction motor. By doing a set of measurements, the students will determine parameters of the induction. Differentiate between the various types of generating electric power stations. Normally, we use the motors in industrial drives because they are rugged, reliable and economical. Know about the different winding slots, lamination of the stator and its construction. The torque of the induction motor depends on the rotor resistance. Squirrel cage induction motor the losses in the induction motor due to supply and control of the variable frequency drive are evaluated at steady state.
Also appreciate the rugged construction of squirrel cage rotor and know the spectacular reasons for the skewed arrangements of the rotor conductors. Firstly, i am going to tell you about the structure of squirrel cage induction motor. The squirrel cage induction motor drive with vector or fieldoriented control. Energy efficiency variations in fluxspeed plan at 0. Lecture 6 three phase induction motors cairo university. In the vhz control, the speed of induction motor is controlled by the adjustable magnitude of stator voltages and frequency in such a way that the air gap flux is always maintained at the desired value at the. For motors falling outside this description, the more comprehensive model specifications below are recommended. Design of a speed controller for a squirrel cage induction motor using fieldoriented control g. Electrical motor electric motor electromagnetic induction. Speed control of 3phase induction motor using pic18 microcontrollers. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Speed control of induction motor part 1 by, supply. Speed control of induction motor using vector control.
Typical nema design b induction motor speedtorque curve. Energy efficiency improvement of a squirrelcage induction motor. Construction of squirrel cage induction motor explained. Full voltage is only applied when the motor picks up speed. The ruggedness and simplicity of the squirrel cage induction motor usually makes it the first choice for a driver.
The hardware includes squirrel cage induction motor, bridge inverter, isolation card, digital signalprocessor dsp, speed sensor, potentiometer for speed desired adjustment, and switches for user interface. Designing of three phase squirrel cage induction motor for. The ac squirrel cage induction motor is essentially a constant speed device. A 1phase induction motor is similar to a 3phase squirrel cage induction motor in physical appearance. Can a squirrel cage induction motor be considered a constant. In this video i describe about the speed control of inductuon motor by using different methods like, 1.
Pdf methods for varying speed in squirrel cage induction. Observation of no load test i o amp v o volts pin watts stator cu loss. The fig 1 shows the relationship between the voltage versus frequency. 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. These motors fill most generalpurpose, constant speed drive requirements. Know how the speed control is easily achieved by changing the number of stator poles.
Out of all the electrical machines, induction motor is the most used machine in industries. An induction motor is practically a constant speed motor, that means, for the entire loading range, change in speed of the motor is quite small. At no load the motor will turn closer to synchronous speed as there is little load on the rotor. Modelling and analysis of squirrel cage induction motor. The speed of the rotor will depend on the ac power, and the speed can be controlled by changing the input supply power.
Parida department of electrical engineering national institute of technology, silchar,assam, india email. Thus, the rotor will feel the torque that rotates the rotor in the direction of the rotating magnetic flux. Recall that leakage reactance is the reactance due to the rotor flux lines that do not also couple with the stator windings. At base speed, the voltage and frequency reach at the rated values.
Faculty of engineering tobruk, faculty of engineering benha2 1, 2. Losses in an inverter fed squirrelcage induction motor system. More than 90% of motors used in industries are squirrel cage induction motor due to its rugged and maintenance free design. Field oriented control and direct torque control of three.
Oct 10, 2017 it can be considered as constant speed motor. Polyu bse induction motors principle operation and torque speed. Methods for varying speed in squirrel cage induction motors. The relative motion between this field and the rotation of the rotor induces electric current in the conductive bars. Control of motorcharacteristics by squirrelcage rotordesign. The principle of working of squirrel cage and slip ring induction motor is based on faradays law of electromagnetic induction. Vfd controlled induction motor efficiency measurement. Pdf induction motors do not run at synchronous speed, they are.
Find the percentage slip and number of poles of the induction motor. Squirrel cage induction motor and wound rotor induction motor. Squirrel cage rotor squirrel cage rotor consists of copper bars, slightly longer than the rotor, which are pushed into the slots. One motor is the called the main motor, and another motor is called the auxiliary motor. Due to high input frequency from laboratory supply, the analysis of power loss made by hysteresis and eddy current become very important. This is because the squirrel cage motor has a simple and rugged construction. A squirrelcage induction motor is one in which the secondary circuit consists of a. Design of a speed controller for a squirrelcage induction. The desired speed is entered by the user via the potentiometer. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. Abstract induction motor im control is a difficult and complex engineering problem due to multivariable, highly nonlinear, timevarying dynamics and unavailability of measurements.
This rotating magnetic field has a speed which is known as the synchronous speed. How are squirrel cage induction motors constructed. Squirrelcage induction motor objectives and overview. The squirrel cage winding of a synchronous machine will generally be smaller than for an induction machine of similar rating. Torque speed characteristics of three phase squirrel cage induction motor aim to obtain the torque speed characteristics tn r of a three phase squirrel cage induction motor using 1. The reason for the name squirrel cage is because of the type of rotor used in these motors.
The field windings in the stator of an induction motor set up a rotating magnetic field through the rotor. 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. Squirrel cage construction, the rotor winding consists of a number of rotor bars, shortcut by rings from both side, see figure below. Three phase induction motors used in explosive atmospheres w60 line squirrel cage rotor horizontal date. In the project has been done an analysis of the mathematical equations of the whole system, separating the mechanical system turbine and gearbox and the electrical generator and. Modeling and control of squirrel cage induction generator. Also lets get to know the methods which are used to control the speed of squirrel cage. 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. These are some of the methods which are commonly used for the speed control of squirrel cage induction motors. During voltage surges, increase in voltage saturates the magnetic components of the squirrel cage induction motor they have high starting current and poor starting torque the starting current can be 59 times the full load current.
Our article all about induction motors explains the specifications for all types of induction motors and is a good place to see all the different induction motor characteristics. Generally an induction motor operates at almost constant speed as the load is varied. Almost 90% of induction motors have squirrel cage rotors. A 3 phase induction motor can be used for different applications with various speed and load requirements. May 20, 2015 the threephase induction motor the squirrel cage induction motor the woundrotor induction motor 3 4. Essentially a squirrel cage induction motor can never keep up with the synchronous speed due to a few physical factors. Squirrel cage induction motors scim are more widely used than all the rest of the electric motors as they have all the advantages of ac motors and are cheaper in cost as compared to slip ring induction motors.
Multispeed control of cage induction motor electrical. Teco totally enclosed fan cooled squirrel cage induction motors are designed, manufactured and tested to meet or exceed the latest nema, ieee, csa and other international standards. What are the specific applications of squirrel cage and. Speed control of induction motor detailed explanation. Improving motor and drive system performance department of. Almost 90% of induction motors are squirrel cage motors. Former is cheaper and broadly used as it requires less maintenance than later one.
The main reasons being friction and drag from load. Know about the most popular and almost unbreakable construction of squirrel cage induction motor. A modified approach to induction motor stator voltage and. Singlephase ac induction squirrel cage motors index aerovent. This makes constant vf the most common speed control of an induction motor 1. Direct torque and flux control of squirrel cage induction motor.
Our test motor with squirrel cage has a circumferential speed of 40 ms. The rotor is same as that employed in 3phase squirrel cage induction motor. If the slip ring induction motor is started with all the slip rings or the rotor. The motor is supplied from an inverter that provides an instantaneously controlled set of phase currents that combine to form. Squirrel cage induction motor the engineering projects. Solid state speed control of a squirrelcage induction motor. The operating point is the intersection of the two characteristics and we can fix for a given load and motor.
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. The voltage and frequency being increased up to base speed. For reduction in the starting current, a lower voltage is applied to the stator, especially for the squirrel cage induction motors. In squirrel cage induction motor starting torque is very low. Design of a three phase squirrel cage induction motor for. Starting of squirrel cage induction motors485 an induction motor can be regarded as a transformer with a small air gap in the magnetic circuit. 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. This method cannot be used for squirrel cage induction motor. Pdf improving squirrel cage induction motor efficiency. Speed control of wound rotor induction motor using rotor resistance control aim to use variable resistance in the rotor circuit to control wound rotor induction motor speed theory polyphase induction motors are mainly of two types by construction, squirrel cage and woundrotorwith sliprings. A threephase induction motor is essentially a constant speed. There is uniform air gap between stator and rotor but no electrical connection between them. Oct 09, 2016 a 3 phase induction motor has two types based on the rotor construction, named as.
The change in the number of stator poles can be achieved by having two or more number of. An843, speed control of 3phase induction motor using. The design of the basic inverter is covered in chapter 2. External resistance can be connected to the rotor circuit to control the motor speed.
Combining an inservice motor with a vfd provides facil. Torquespeed characteristics of three phase squirrel cage. To drive three phase squirrel cage induction motor with a constant speed, vector control technique is used. Pdf speed control of squirrel cage induction motor sqim. Pdf in a motor control, voltage saturation is a serious problem as a motor speed increases. Mathematical modeling and speed torque analysis of three phase squirrel cage induction motor using matlab simulink for electrical machines laboratory now all the measured values in no load test of 3o squirrel cage induction motor is tabulated in table 3. These motors are suitable for all general applications where an open machine is not applicable due to severe environments such as excessive dirt, dust andor moisture. Now let us discuss in detail, the most common form of induction motor, the squirrel cage induction motor. On a mathematical model of squirrelcage induction motors. The speed of a threephase induction motor driving a given load is determined by matching the torque speed characteristics of the motor and load, as shown in fig. High speed im with appropriate squirrel cage can reach circumferential speed up to 200 ms, see in 2. Variable voltage variable frequency vf control theory an induction motor compared to a dc motor has some major advantages such as.
Steady state equivalent circuit of a squirrel cage induction motor for constant flux control a. This article will focus on what needs to be specified for squirrel cage induction motors, which involves phase, speed, torque, and current. Speed control of three phase induction motor electrical4u. Items that present losses are the micro variable speed controller, the vfd display, the communication bus, the control system, vfd control panel. It is not desirable to start large motors direct on line giving full voltage to the stator. Horizontal squirrel cage mediumvoltage induction 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. The ends are welded to copper end rings, so that all the bars are short circuited. Third international conference on advances in control and optimization of dynamical systems march 15, 2014. Jul 25, 2019 squirrel cage induction motor working principle.
As we know the speed of induction motor, torque of induction motor, so, the speed of induction motor can be changed by changing synchronous speed or by changing the slip of induction motor and then parameter r2 and x2 are changed then torque remain constant and change in slip is affected in speed control. In normal conditions, the slip ring motor functions like a squirrel cage motor. 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. Mainly we discuss a threephase squirrel cage induction motor. Speed control system of induction motor by using vector. Search wegthreephaseinductionmotorstlinesquirrelcage.
What is a squirrel cage motor and how does it work. Control of motorcharacteristics by squirrelcage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. In previous articles i have discussed the construction, operation, starting, speed control, and classes of squirrel cage induction motors this article is devoted to slip ring induction motors as discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator pol 247 online. However, should the motor require service, this manual includes a section that assists the. Dec 10, 2015 watch this video and learn basics of squirrel cage induction motor. Analysis and design of ac induction motors with squirrel cage rotors. Speed of an induction motor the magnetic field created in the stator rotates at a synchronous speed.
The slip ring motor has very little application in industries. 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. Characteristic curves related to speed threephase induction motor squirrel cage rotor. Speed control of three phase squirrel cage induction motor. The squirrel cage induction motor is the electrical motor motor type most widely used in. Harley university of natal, king george v avenue, durban 4001 south africa received october 23, 1989 abstract fieldoriented control foc is a technique. Speed control of induction motor 7 ways to control. Slipring induction motors have better starting characteristics compared to squirrelcage motors. In this paper vector control for speed control of threephase squirrel cage induction motor has been developed and analyzed. This method of speed control is suitable for squirrel cage type of induction motors. The squirrel cage induction motor is the most commonly used motor in industry. In this method of speed control of three phase induction motor, the two threephase induction motors are connected on a common shaft and hence called cascaded motor. As the motor speed and the voltage are increased in proportion, constant vf, the rated flux.
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