Design of a speed controller for a squirrelcage induction motor. Dec 10, 2015 watch this video and learn basics of squirrel cage induction motor. Pdf in a motor control, voltage saturation is a serious problem as a motor speed increases. From the equation 1 it is clear that the motor speed can be changed by a change in frequency f, a number of poles p, and slip s. Squirrel cage induction motor the engineering projects. The speed of the rotor will depend on the ac power, and the speed can be controlled by changing the input supply power. Pdf speed control of induction motors kamakhya basumatary.
Recall that leakage reactance is the reactance due to the rotor flux lines that do not also couple with the stator windings. How we measure reads a read is counted each time someone. 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. Consequently, mathematically it is possible to impose also two reference values in the control system of the sqcim. Design of speed controller for squirrelcage induction motor. It may be used where, the induction motor is supplied by a dedicated generator so that frequency can be easily varied by changing the speed of prime mover. The above three methods are most commonly used for the speed control of squirrel cage induction motors. Watch this video and learn basics of squirrel cage induction motor.
Some of the main advantages, why you should go for this motor include the following. Electric motors and machines, squirrel cage ac induction motor. Based on your location, we recommend that you select. Consider a three phase squirrel cage induction motor whose stator has. Once the motor is loaded the speed of the rotor will drop to a point where the rate of flux cutting induces rotor currents of sufficient strength to produce enough motor torque to support the load. Fieldoriented control foc is a technique whereby the complex nonlinear structure of a squirrelcage induction machine scim can be controlled to behave in. Control of motorcharacteristics by squirrelcage rotordesign. 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. Advantages and disadvantages of squirrel cage induction motor. An induction motor can therefore be made without electrical connections to the rotor. Jul 25, 2019 squirrel cage induction motor working principle. This reduction in motor speed with increasing motor load is known as slip.
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. The stator construction is the same in both motors. The squirrel cage induction motor is the most commonly used motor in industry. 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. The voltage and frequency being increased up to base speed. For any motor load application, it is imperative to know the torque speed characteristic of the motor. A squirrel cage i nduction motor sqim are the most common motors used in. At base speed, the voltage and frequency reach at the rated values. In this chapter, we shall focus our attention on the construction, working and characteristics of commonly used singlephase motors. The rotor is same as that employed in 3phase squirrel cage induction motor. The user can quickly start evaluating the performance of the vhz system with this method. Speed control of a three phase alternating current induction. A three phase squirrel cage induction motor rated at 3 horsepower, 220 v, 60 hz, 1725 rp m is fed by a three phase mosfet two level inverter.
Choose a web site to get translated content where available and see local events and offers. Control of motorcharacteristics by squirrelcage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. Pdf speed control of squirrel cage induction motor sqim. Speed control of three phase squirrel cage induction motor ijert. The squirrel cage induction motor is the electrical motor motor type most widely used in. An843, speed control of 3phase induction motor using pic18 mcus. Section 2 presents internal dynamics of the induction motor in state space form. Speed control of induction motors the speed of an induction motor is given as n 120fp 1s. A theoretical background on scalar motor control principle. A 3 phase ac induction motor photoed by hordu motor. Speed control of squirrel cage induction motor sqim based on voltage angle. Speed control is not possible in squirrel cage induction motor. The main methods employed for speed control of induction motors are as follows. Induction motor is now called the racehorse of the industry 1.
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. In this system, the scalar control vhz of induction motor experiments with and explores the use of speed control. Internet based speed control and torque analysis of a 3phase. Polyu bse induction motors principle operation and torque speed. An introduction there are various methods for the speed control of an induction motor. One motor is the called the main motor, and another motor is called the auxiliary motor. Thus, the rotor will feel the torque that rotates the rotor in the direction of the rotating magnetic flux.
For a squirrelcage motor, the rotor as represented in figure 2 is constituted by a system of bars in copper or aluminum, which are coaxial to the rotation axis and directly diecast in the slots made along the external periphery of the ferromagnetic. These are some of the methods which are commonly used for the speed control of squirrel cage induction motors. General electric and westinghouse signed a crosslicensing agreement for the squirrelcage design of the induction motor, and by 1900, it was all set to. The frequency can be varied using a manual input to the controller. Why is the rotor resistance method of speed control not. There is uniform air gap between stator and rotor but no electrical connection between them. Squirrel cage motor almost 90% of induction motors are squirrel cage motors. Firstly, i am going to tell you about the structure of squirrel cage induction motor. The total energy loss during starting of squirrel cage motor is more compared to slip ring motors. Former is cheaper and broadly used as it requires less maintenance than later one.
It is very important to control the speed of induction motors in. Hence, the synchronous speed changes with change in supply frequency. This makes constant vf the most common speed control of an induction motor 1. Pdf improving squirrel cage induction motor efficiency. The design of the basic inverter is covered in chapter 2. Speed control using variable frequencyvariable voltage supply speed control characteristics of a squirrel cage induction motor, pdf file. Squirrel cage construction, the rotor winding consists of a number of rotor bars, shortcut by rings from both side, see figure below. In a motor control system usually a loop is dedicated to the mechanical quantities. The torque developed in this method is proportional to the square of the supply voltage. Also lets get to know the methods which are used to control the speed of squirrel cage. The rotor bars are not insulated from the rotor core because they are made of metals having less resistance than the core. This is one of the major diadvantages of squirrel cage induction motors. Due to high input frequency from laboratory supply, the analysis of power loss made by hysteresis and eddy current become very important.
This paper describes a simplified method for the speed control of a three phase ac drive using. Mainly we discuss a threephase squirrel cage induction motor. Jan 10, 2019 the rotor conductors of the scim is shortcircuited by end rings. Different methods of speed control of threephase asynchronous motor.
A survey of speed and flux control structures of squirrel. Advantages of three phase squirrel cage induction motor. The rotor connections are not brought out at the outside, it is shortcircuited inside of the motor. Actual speed of an induction motor is given as n ns 1 s.
To drive three phase squirrel cage induction motor with a constant speed, vector control technique is used. May 20, 2015 the threephase induction motor the squirrel cage induction motor the woundrotor induction motor 3 4. Speed control of squirrel cage induction motor sqim based on voltage angle article pdf available april 2015. In squirrel cage induction motor starting torque is very low. Speed control of three phase induction motor electrical4u. A 1phase induction motor is similar to a 3phase squirrel cage induction motor in physical appearance. Working principle of 3 phase squirrel cage induction motor.
In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i. The fig 1 shows the relationship between the voltage versus frequency. 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. Torquespeed characteristics of squirrel cage induction motor iitbee. Polyu bse induction motors principle operation and torquespeed.
Speed control of induction motor using vf technique phase i a thesis. Know how the speed control is easily achieved by changing the number of stator poles. The rotor speed of an induction motor is given by the equation shown below. Oct 09, 2016 a 3 phase induction motor has two types based on the rotor construction, named as. High speed im with appropriate squirrel cage can reach circumferential speed up to 200 ms, see in 2. Various induction motor speed control methods advantages. Solid state speed control of a squirrelcage induction motor. This rotating magnetic field has a speed which is known as the synchronous speed. An induction motor or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.
Speed control of induction machines speed control by changing applied voltage, rotor resistance control, cascade control, stator frequency control, pdf file. Speed control system of induction motor by using vector. In section 3, the different speed control techniques of an ac motor are discussed. In normal conditions, the slip ring motor functions like a squirrel cage motor. Pdf speed control of induction motor using foc method. Also the rotor bars are usually not quite parallel to the rotor shaft but are mounted in a slightly skewed position. Jan 09, 2017 this method is applicable to squirrel cage induction motor only. 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 an induction motor there is a various method of speed control of an induction motor. Therefore an induction motor produces no torque at the synchronous speed. 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. Induction motor types based on the construction of the rotor, induction motors are broadly classified in two categories. Speed control of three phase squirrel cage induction motor. 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.
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