This induces an electric field in a coil or squirrel cage to drive a rotor. A low cost solu tion of this control can be implemented in a picmicro microcontroller. With the increase in stator voltage, the motor speed. Methods of speed control of induction motor electrical. Three phase induction motor or ac motor is started by itself but we require some starter or other methods for proper starting and controlling induction motor. There are different methods for controlling the speed. Speed control of three phase induction motor ppt play ppt. Speed control of 3 phase induction motor a 3 phase induction motor is practically constant speed motor provided that applied parameters supply, frequency etc. A principal aim of a starter on a three phase induction motor is to reduce the starting current as much as possible while at the same time providing adequate torque to meet the requirements of the load. This method is also called the tandem control and obsolete now. This article covers several starting methods of three phase induction motor along with their applications.
Induction motor control is complex due to its nonlinear characteristics. The method which can be used for the speed control of induction motor from stator side is a. Speed control methods of various types of speed control motors. In this paper, various methods of speed control of induction asynchronous motors such as variable rotor resistance, variable stator voltage, constant voltshertz. Stator voltage control is a method used to control the speed of an induction motor. The synchronous s peed of the motor at rated conditions is. Generally, speed control using pole changing method is restricted to two steps.
Stator voltage control of an induction motor circuit globe. Speed of 3 phase induction motor needs to varied according to requirement. The control methods for induction motors can be divided into two parts. A 3 phase induction motor uses current delivered in three phases in a sequence into the coils of a stator to create a rotating magnetic field.
Speed control techniques of induction motors can be broadly classified into two types. Our speed control motor packages include the motor, the driver controller, and a potentiometer which allows for easy speed control adjustment. Pdf different methods of speed control of threephase. In this method of speed control of three phase induction motor. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. In cumulatively cascade method for speed controlling. One single phase wattmeter plus miscellaneous apparatus as needed. Speed control of three phase induction motor electrical4u. Various induction motor speed control methods advantages. Today i will discuss very important topic speed control of induction motor. Nehrir proposed a technique for speed control of threephase induction motor by stator.
The ability of varying any one of the above three quantities will provide methods of speed control of an induction motor. There are three speed control motor product groups. Simulation results shows that space vector pulse width modulation which generates the voltage patterns at real time is able to control the speed of a three phase alternating current induction motor. It i ndicates the validity of space vector pulse width modulation in controlling the speed of a three phase alternating current induction motor acim. Variable voltage variable frequency speed control of. How to control the speed of three phase induction motor. While there are different methods for control, variable voltage variable frequency vvvf or v f is the most common method of speed control in open loop. Record all nameplate information for the induction motor. Variable voltage variable frequency control of three phase induction motor in closed loop is the significant feature of the thesis work.
Nehrir proposed a technique for speed control of three phase induction motor by stator voltage control 19. The three phase induction motor has following advantages. Circuit diagram for blockedrotor test on 3 phase induction motor. A three phase induction motor is basically a constant speed motor. Pdf microcontroller based speed control of three phase. A three phase induction motor is basically a constant speed motor so its somewhat difficult to control its speed. Speed control methods for a 3 phase induction motor. Pdf speed control of induction motors kamakhya basumatary. Speed control of induction motors the speed of an induction motor is given as n 120fp 1s. 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. For speed control of induction motor mainly three control methods are employed namely scalar control, field oriented control foc and direct torque control dtc. We will discuss a simple open loop method of speed control called, variable voltage variable. To control the speed of a 3 phase induction motor in open loop, supply voltage and frequency need to be varied with constant ratio to each other.
The main purpose of controlling the speed of three phase induction motor is to save unwanted energy. For slipring induction motors, rotor terminals are brought out and rheostats of suitable range can be connected in each phase. The change in speed depends upon both rotor circuit resistance and load. There are various methods which are used for the speed control of three phase induction motor such as stator voltage control. The purpose of the scalar control technique is to control the magnitude of the chosen quantities. You should also make a dc measurement of stator winding linetoline resistance. Vfd speed control of three phase induction motor by vf. An843, speed control of 3phase induction motor using. By introducing external resistance in the rotor circuit, the speed of the motor can be reduced. Speed controls from stator side as well as rotor side are also. Applications of three phase induction motor are for fixed speed.
Constant vf control of induction motor this is the most popular method for controlling the speed of an induction motor. Aspalli, speed control of three phase induction motor by vvvf method using g7a drive international journal of recent technology and engineering ijrte vol. We can vary the motor speed by varying the stator voltage. Changing the number of poles is not easy, so we do not use that method. Single phase induction motors are used extensively for smaller loads, such as household appliances like fans. The difference in speed between rotor, the synchronous speed and the rotating. The synchronous speed of the motor at rated conditions is. In pole changing method, the number of pole pairs is changed by changing the field connection.
Design and simulation of three phase induction motor at different load. Firstly three phase induction motor drive system is simulated in various modes using matlabxilinx, then. Induction motors are widely used ac motors in industrial area. Several various techniques are implemented to control the speed of three phase induction motor, namely vf speed control, rotor resistance control, frequency control, and stator voltage control 6. Different methods of speed control of threephase asynchronous. 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. In this method, the slip power of induction motor is utilized for speed control. Low cost, low maintenance, simple construction, reliability and high efficiency. Constant vf method is commonly used for constant and variable speed control of induction motor 6. Speed control of 3phase induction motor microchip technology. Vf speed control of 3 phase induction motor using space. Speed control of induction motor using vector control. The speed of a three phase induction motor driving a given load is determined by matching the torque speed characteristics of the motor and load, as shown in fig. Different speed control methods of induction motor are explained below.
As in above method, if the supply frequency is reduced keeping the rated supply voltage, the air gap flux will tend to saturate. Speed control of 3 phase induction motor electrical idea. 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. It certainly leads to the best performance and high efficiency of the induction motor.
Abstract speed control of three phase induction motor is important for industry. Stator voltage 3 phase motor speed control methods in this 3 phase motor speed control method, only stator voltage is varied to vary the speed of the motor, the stator frequency is kept constant. Speed control of three phase induction motor electrical. Vfd speed control of three phase induction motor by vf method using pic microcontroller. However, with the invention of solidstate devices, the frequency of the current fed to the synchronous motor can be varied. This method is applicable to three phase slipring induction motor only. The ac speed control motor unit that uses the most popular singlephase capacitorrun induction motor, the. In this method of speed control of three phase induction motor the original sinusoidal mmf wave is modulated by another sinusoidal mmf wave having the different number of poles. However, there is no restriction to the phase of injected emf. This maintains the speed regulation and efficiency of dc shunt motor. Speed control in three phase induction motor mcqs with answers q1. Pdf speed control of threephase induction motor based.
The main methods employed for speed control of induction motors are as follows. Scalar control is the term used to describe a simpler form of motor control, using nonvectorcontrolled drive schemes. Speed control of a three phase alternating current. For example, a stator is wound with two 3phase windings, one for 4. There are following methods of speed control of three phase induction motor.
Pole changing method speed control of induction motor. Speed control in three phase induction motor mcqs with. Three phase induction motor starting methods starting. Slip power in induction motor is the power dissipated in the rotor winding as ohmic loss. We can control the speed of the synchronous motor by changing the frequency of the supply to the motor. Speed control of wound rotor induction motor using rotor. Speed control of three phase induction motor using arduino. Other than this illustration of vector control strategy for an induction motor im drive using sinusoidal pulse width modulation technique has been efficient. It is necessary that voltage emf being injected must have same frequency as of the slip frequency. The proposed paper represents variable speed control application of. A variable frequency drive vfd is used to control the speed of motor with the primary voltage control method. Here we will see a detailed article related to the starting methods of three phase induction motor. The speed of a three phase induction motor can be varied by varying the supply voltage.
It is widely used in industry due to low cost and rugged construction. As we already know that the torque developed is proportional to the square of the supply voltage and the slip at the maximum torque is independent of the supply voltage. Before discussing the methods to control the speed of three phase. This application note also covers the basics of induction motors and. How to control the speed of 3 phase induction motor quora. Three phase squirrel cage induction motors are widely used in industrial drives because they are rugged, reliable and economical. In this application note, we will generate a third pwm in software, using a general purpose timer and an io pin resource that are readily available on the picmicro microcontroller. Speed control of induction motor 7 ways to control. But in the case of 3 phase induction motors very difficult to control speed smoothly. The different methods of speed control of induction motor can be broadly classified in to scalar and vector control methods. The three phase induction motor or synchronous motor is used as ac drive.
Scalar control method is generally not used in application, where accurate torque response will. In this paper, various methods of speed control of induction asynchronous motors such as variable rotor resistance, variable stator voltage, constant volts hertz. Scalar control is relatively simple method compared to vector control. Field oriented control and direct torque control of three. The speed of induction motor depends on various factors, like supplied voltage, frequency, number of poles. In this method, speed of an induction motor is controlled by injecting a voltage in rotor circuit. Explain starting methods of 3 phase induction motor. Pole changing method pole changing method is one of the main methods of the speed control of an induction motor. This method is most suitable for applica tions without position control requirements or the need for high accuracy of speed control.