Changing rotor slip important to match the motor to the load ensure that a change in motor power gives a desired change in load speed load should have a substantial inertial components inertial torque can carry the load through brief periods when motor torque. For the operation of induction motor in constant torque region requires flux command to be maintained at its rated value. Ac drives or vfd can also use to control motor rotation direction and rotation speed of three phase induction motor. The rotor speed of an induction motor is given by the equation shown below. That is why it cannot be operated for continuous operation, it is used in the. The project is complete mathematical model of field orientation control foc induction motor is described and simulated in matlab for studies a 50 hp37kw, cage type induction motor has been considered. Mineo tsuji, shuo chen, shinichi hamasaki, xiaodan zhao, and eiji yamada,a novel vf control of induction motors 5. Therefore by changing the number of poles we can easily change the speed of three phase induction motor.
The speed of induction motor can be varied by changing supply voltage. Abstract this method is used to control the speed of the induction motor. Ahuja speed control of induction motor using vector or field oriented control international journal. By changing the frequency of the ac voltage supplied to the induction motor, the speed of the induction motor changes. If, n speed of the rotor, the slip, s for an induction motor is defined as s s. Pole changing method pole changing method is one of the main methods of the speed control of an induction motor. Epwm technique for speed control of induction motor.
Generally, induction motors are categorized based on the number of stator windings. This method of controlling the speed by pole changing is used mainly for cage motor only because the cage rotor automatically develops a number of poles, which is equal to the poles of the stator winding. Different speed control methods of induction motor are explained below. Vf is the most common method of speed control in open loop. The most popular type is the 3phase, squirrelcage ac induction motor. In this, the induction motor is connected to the frequency converter. It is widely used in industry due to low cost and rugged construction. This method of speed control of induction motor is easy, low maintenance cost and low initial cost but it has some limited use because with the large change in voltage relatively small change in speed.
Different method of starting of threephase squirrel cage induction. One called the direct or feedback method, and the other, the indirect or feed forward method. Pdf speed control of induction motor using foc method. All the required control or protection and motor performance data will be. 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. Line voltage control the torque developed varies with the square of the applied voltage. Puja talukder, prashant kumar soori, and benetta aranj, speed control of.
For detail of this method, please read vvvf speed control of induction motor. 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. Various methods of speed control 3phase induction motor. In this video i describe about the speed control of induction motor by different type methods like, 1. Thus, it can be one of the best available answers today for a broad class of. Speed control of an induction motor there is a various method of speed control of an induction motor. From the above formula, pole changing in induction machine can be done using a dahlander motor also known as a pole changing motor. The speed control by this method is simple and can be made economical by using different methods to control the operation of cycloconverter which in turn controls the performance of motor. Speed control of wound rotor induction motor using rotor. These techniques depend on varying the stator ac voltage to control the speed of threephase induction motor. Kelly electrical and computer engineering michigan state university east lansing. How to control the speed of 3 phase induction motor quora. Induction motor drives without direct speed sensor s h ave the features of low cost, high reliability and less maintenance requirements.
There are essentially two general methods of vector control. Speed of a 3 phase induction motor can be controlled by these methods. Here we have studied about the pole changing method of speed control of induction motor. A continuous trend in im drives is to increase the reliability of the drive system. Speed control of single phase induction motor using ac. In case of three phase induction motor torque produced is given by t. The block diagram of matrix converter fed direct vector control method for induction motor is shown in figure 4. Change in stator poles is achieved by two or more independent stator windings wound for different. Speed control of induction motor by pole changing method pdf. An induction motors rotor can be either wound type or squirrelcage type. It is hard to learn anything valueable from that page.
It is applied to a vector controlled induction motor drive and experimentally verified. Epwm technique for speed control of induction motor 1s. It has been more than a century since the principle of the operation of induction motors was discovered. Methods of speed control of induction motor electrical. One of the mature control systems of induction motor is the field oriented control method. A dahlander motor also known as a pole changing motor, dual or two speedmotor is a type of multispeed induction motor, in which the speed of the motor is varied by altering the number of poles. Since the number of pole pairs can only be changed in steps like from 2 to 4, this scheme provides stepped speed control of induction motor. Illustrate clearly how speed control of induction motors is achieved by the frequency adjustment. Sensorless control of induction motor drives at very low. If you want to control induction motor speed, save yourself a lot of grief and get a 3phase motor.
The control of a continuously operated polechanging induction machine j. Speed control of vector controlled induction motors using. Conclusion although the method of speed controlling of induction motor using this technology is efficient, but as we are using resistance to control the speed of the motor here also resistive losses occurs, which causes unnecessary heating effect on the motor and also reduces the efficiency in some extent. One solution is to decrease the amount of normally used sensors. 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 speed response of induction motor is checked for without controller, with pi controller and with pid controller which is shown in figure 6, 7 and 8. Speed control of three phase induction motor electrical4u. In pole changing method, the number of pole pairs is changed by changing the field connection. In this method, the number of poles of induction motor is changed by. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. Therefore, whenever stator frequency is changed to obtain.
Pdf speedsensorless control of induction motor drives. Continuous operation of a pole changing induction machine. An984, an introduction to ac induction motor control using. Some of the advantages like low cost, rugged design less complex, and easy to maintain ac motors results in many of the industrial operations are performed with the use of ac drives than dc drives. Conventional methods for starting and speed control of singlephase induction motor need often quite expensive external electrical equipment. Thus in this paper, ac chopper is implemented to control the speed of single phase induction motor by using 3 asymmetrical pwm method. Various induction motor speed control methods advantages. Speed control of induction motor detailed explanation. Sometimes theyre talking about induction motors, other times not, and they dont specify which is which, or even which induction motor type they are talking about. An introduction there are various methods for the speed control of an induction motor. This method is applicable to squirrel cage induction motor only.
Pole changing can be used to achieve different speeds in induction machine by switching the configuration of the electrical stator windings in the ratio of 2. An843, speed control of 3phase induction motor using. If the motor is an older 1, and dahlander motors usually are, then the windings will have a problem with the steep pwm edges and the ringing. An induction motor can therefore be made without electrical connections to the rotor. A three phase induction motor is basically a constant speed motor. One another method of speed control is by changing the number of poles of the induction motor. The control of a continuously operated polechanging induction. Speed control of an induction motor by using indirect. 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. To study the speed control of induction motor by varying supply. 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. Induction motor rewinding 36 slots 3 phase 6 pole with diagram. This method of controlling the speed by pole changing is used mainly for cage motor only because the cage rotor automatically develops a number of poles, which is. Abstracta new method is described which considerably improves the performance of rotor fluxmras based sensorless drives in the critical low and zero speed region of operation.
Speed response of induction motor on full load condition without any controller figure 7. Speed response of induction motor on full load condition with pi controller figure 8. Generally, speed control using pole changing method is restricted to two steps. The first industrial motors of this type were constructed at the end of the nineteenth century and soon gained the favor of users who appreciated their raggedness, simplicity and relatively low manufacturing cost compared to dc commutator motors. At high power levels, the inverter can switch only at low frequencies, and the harmonic distortion is quite high. Nehrir, speed control of threephase induction motor by stator voltage control ieee transactions on industrial electronics and control instrumentatio n, may 1975. How to control the speed of an induction motor quora. The motor may have fixed or variable torque depending on the stator winding. Indirect vector controlled ivc induction motor drives used in high. Speed control of induction motor using pi and pid controller.
The hbridge inverter circuit could also be used to drive a shadedpole motor with a single winding. In this method of speed control of three phase induction motor rheostat is added in the stator circuit due to this voltage gets dropped. In this scheme, the number of pole pairs is changed by changing the field. Pole changing method speed control of induction motor. Ac induction motor is a special type of electric motor having its own typical characteristics and performance in terms of starting, speed control, protections, and so on. Vf speed control of three phase induction motor by using. Another way to drive a splitphase motor or a shadedpole motor uses a voltage doubler circuit with an hbridge inverter, as shown in figure 6. Speed control of induction motor 7 ways to control. This method of controlling the speed by pole changing is used. Therefore, there is a great inte rest in the research community. Variable frequency control vf of induction motor 1. An induction motor can be used as induction generator, or it can be unrolled to form the linear induction motor which can directly generate linear motion.
The performance evaluation of the motor under the different switching strategies. Speed control of single phase induction motor using triac. In this method, the number of poles of induction motor is changed by changing the connection of stator winding. Induction motor is now called the racehorse of the industry 1. Pole changing method for speed control of 3 phase induction motor. There are more than one methods to control the speed of induction motor, you can choose one depending on your resources, efficiency required etc. The variable frequency method consists of the following three methods.
It is named after its inventor robert dahlander 1870. Sensorless speed control of an induction motor drive using. Comparative study of speed control of induction motor using pi and fuzzy logic controller doi. The control of a continuously operated polechanging. Changing the line frequency with solidstate motor drives has become the preferred method for induction motor speed control. But please keep in mind that this method is applicable for squirrel cage rotor as here number of poles change with and are always equal to the number of stator. The torque developed in this method is proportional to the square of the supply voltage. This method is therefore called variable voltage variable frequency vvvf method. Speed control of induction motor part 2 pole changing. Speed control of induction motor using cycloconverter. In case of salient pole machine, the magnetizing circuit is more saturated and the armature. Pole changing method is one of the main methods of the speed control of an induction motor.