This method of trying to control the speed is best suited. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. Induction motor drives with closedloop control are used in similar applications to d. Speed control of three phase induction motor electrical4u. Explain starting methods of 3 phase induction motor. By varying the frequency, the speed of the motor can be varied. Therefore the efficiency of three phase induction motor is reduced by this method of speed control. By default, the block sets the simulation type parameter to continuous to use a continuous sample time during simulation. This makes constant vf the most common speed control of an 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.
As its name indicates stator is a stationary part of induction motor. The base speed, at which the constant power region starts, does not usually coincide with the. Induction motor fault detection, protection and speed control. It also exhibits good self starting capability and high efficiency 1, 2. Speed control of a three phase induction motor fed from a single. More than 90% of motors used in industries are squirrel cage induction motor due to its rugged and maintenance free design. Starting of 3 phase induction motors, high starting torque motors, speed control, rheostatic method, pole changing method, cascade control of speed, double cage induction motor, cogging an d crawling of induction motor, induction generator. Before discussing the methods to control the speed of three phase. Simulation of 3ph induction motor in matlab with direct. Ges charles proteus steinmetz greatly developed application of ac complex.
The singlephase induction motor is not self starting. Read more methods of speed control of induction motor. Free download induction motor seminar ppt, pdf report. The method which can be used for the speed control of induction motor from stator side is. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed. Speed control of induction motor using vf technique phase i a thesis. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. However, recently, it has been increasingly used as variable speed motors driven by an inverter. Speed control of induction motor is possible in two sides. The singlephase ac induction motor best fits this description. Therefore, by varying the voltage and frequency by the same ratio, flux and hence, the torque can be kept constant throughout the speed range. Because the shadedpole motor lacks a start winding, starting switch or capacitor, it is electrically simple and inexpensive.
Oct 26, 2015 induction motor starting methods star delta starter motor should be brought with all 6 leads. You should also make a dc measurement of stator winding linetoline resistance using a dmm. Speed control of induction motor detailed explanation. This will reduce the need for additional motors because the same motor may be used to drive different devices. Threephase variables in the induction motor can be represented by space vectors in the cartesian coordinate set, dq, affixed to stator stator reference frame. Accordingly, two values of the capacitor may be used, one for starting and the other for running conditions. There are two basic reasons for the use of singlephase motors rather than 3phase motors. Speed control of induction motor 7 ways to control induction. The main methods employed for speed control of induction motors are as follows. Different characteristics of each speed control method will be.
Speed control of a three phase induction motor by stator voltage variation is straightforward. The most common efficient way to control asynchronous motor speed of many loads is with. The speed control of induction motor is done at the cost of decrease in efficiency. We do not require to give external starting torque for starting induction motor but the starter is provided with an induction motor for limiting starting current. They run at a constant speed from noload to the full load. Pdf speed control of induction motors kamakhya basumatary. Speed control of 3phase induction motor microchip technology. The induction motor is made up of the stator, or stationary windings, and the rotor. The system also involves the use of a speed control system which can adjust the speed to desired value.
Dec 23, 2017 the speed control of induction motor by considering to control on rotor side can subdivide into several speed controlling methods such as. Speed control of vector controlled induction motors using. The most commonly used controller for the speed control of induction motor is traditional proportional plus integral pi controller. Dec 17, 2019 when the speed control of three phase induction motor is done by adding resistance in rotor circuit, some part of power called, the slip power is lost as i 2 r losses. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. The motor is mounted in a test rig that allows one to control the torque applied to the motor shaft and to measure both rpm and torque. Controlling 3 phase ac induction motors using the pic18f4431. Starting induction motors on isolated or weak systems is a highly dynamic process that can cause motor and load damage as well as electrical network fluctuations. Pdf this paper gives the comparative study among various techniques used to control the speed of three phase induction motor. Three phase induction motor is a generally self starting motor. Mechanical damage is associated with the high starting current drawn by a ramping.
The motor is started under different loads in two methods. There are various methods of speed control for an induction motor. Induction motors have been traditionally used as constant speed motors supplied by the ac power source. The block uses the threephase input voltages to regulate the individual phase currents, allowing control of the motor torque or speed. Generally an induction motor operates at almost constant speed as the load is varied. Controlling 3 phase ac induction motors using the pic18f4431 pdf this application note describes how the pic18f4431 may be used to control an acim using open and closedloop vf control strategies.
Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. We can change the speed at the stator by, changing the supply frequency, changing the supply voltage and changing the number of stator poles. There are different methods of starting of 3phase slipring induction motor. The induction motor block implements a threephase induction motor. Speed control of induction motors the speed of an induction motor is given as n 120fp 1s. Compared to dol starting current is reduced by 1v3 i. Oct 11, 2014 hello friends, i am posting version3 project of single phase induction motor direction control. 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. The operating point is the intersection of the two characteristics and we can fix for a given load and motor parameters. Methods of speed control of induction motor electrical.
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. The rotor speed of an induction motor is given by the equation shown below. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. The 3phase set of currents, each of equal magnitude and with a phase. Speed control of an induction motor there is a various method of speed control of an induction motor. Most industries use squirrel cage induction motor with a starter for starting purpose. In this paper, indirect vector method is used to control the speed of induction motor.
Out of all the electrical machines, induction motor is the most used machine in industries. A stator winding is placed in the stator of induction motor and the three phase supply is given to it. Expired lifetime application number inventor benjamin g lamme. Single phase induction motor speed control this project is designed to control the speed of a singlephase induction motor by using operating knob, which is commonly used in home automation applications. An induction motor or asynchronous motor is an ac electric motor in which the electric current. Speed control at the rotor side we can change the speed at the rotor by,by adding some external resistance in the rotor circuitby cascade connection of the motor.
This slip power loss can be recovered and supplied back to improve the overall. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. The rotor will constantly be turning to align its magnetic field with that of the stator field. 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. 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. Nehrir, speed control of threephase induction motor by stator voltage control ieee transactions on industrial electronics and control instrumentatio n, may 1975. Speed control of induction motor ac motor speed control. If the motor slip is known, the rotor speed can be expressed by the equation. Figure 3 shows the relation between the voltage and. Pdf the applications of induction motors in various fields are. The induction motor can be isolated from the supply in case of any of the faults with relays. Already has done this project using relay circuit and microcontroller. Each method is studied and discussed using supporting simulation of currents, torque, speed, efficiency and power factor curves.
Space vectors of the stator voltage and current and magnetic fluxes flux linkages are commonly employed in the analysis and control of induction motor adjustable speed drives. Ppt induction motor powerpoint presentation free to. Record all nameplate information for the induction motor. Single phase induction motor direction control using plc v3. Induction motor control is complex due to its nonlinear characteristics. Lecture 6 three phase induction motors cairo university. Induction motor fault detection, protection and speed. Induction motor seminar ppt, pdf report study mafia. 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. It is widely used in industry due to low cost and rugged construction. Disadvantages of 3 phase induction motor induction motor has low inherent starting torque draw large starting currents, typically 68 x their full load values speeds not easily controlled as dc motors operate with a poor lagging power factor when lightly loaded induction motor components an induction motor has two main parts. To reduce the relative speed, the rotor starts rotating in the same direction as that of flux and. Initially motor winding is arranged in star and when the motor attains a speed of 7080% of rated speed, winding is rearranged in delta.
Speed control in three phase induction motor mcqs with answers q1. Thus, even if a given voltage level is sufficient for achieving the running torque, the machine may not start. Adding an external resistant into rotor side circuit. Starting torques can be 3 times higher to overcome the starting conditions, causing mechanical stress on the components in the motor. However, the conventional pi controller has some demerits such as. A comparison of induction motor starting methods being. Speed control in three phase induction motor mcqs with answers. In all singlephase induction motors, the rotor is the squirrel cage type. So electronic soft starters use a control system to reduce the torque by temporarily reducing the voltage or current input until the induction motor reaches its synchronous speed. The aim behind the development of the project is to limit the current at starting of motor and to develop the high starting torque. Jun 30, 2015 a three phase induction motor is basically a constant speed motor. An843, speed control of 3phase induction motor using pic18 mcus. Pdf speed control of induction motor by using intelligence. An887, ac induction motor fundamentals microchip technology.473 40 24 858 487 43 41 1250 1026 1250 558 939 71 92 635 1575 48 865 760 1466 247 1182 1020 1231 1488 107 572 1604 526 1370 1415 642 1025 1343 814 341 1406 1044 150 171 1291