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. Explain how the threephase induction motor develops starting torque. Starting code b plot of the voltagecurrent characteristic of a capacitor bank. Study of stator voltage control method for induction motor torque control using matlab simulation. The most commonly used controller for the speed control of. Before discussing, induction motor drives its important to understand and know about induction motors. Vfds control the motor speed and motor torque by controlling the frequency and magnitude.
Squirrel cage induction motor an overview sciencedirect topics. On the other hand, the voltage reference values, fed to the space vector modulator, could be used instead of the voltage measurements, thus avoiding the use of expensive measurement hardware. Explain why the induction motor slows down as the load is increased. The stator is composed of laminations of highgrade sheet steel. Stator voltage control of induction motor control by ac. In the electrical model, the voltage, v, and the slip, s, determine the rotor current. Speed control of induction motors linkedin slideshare. Induction electrical machine simulation at threephase stator. But the flux estimate, when estimated from the stator circuit variables, is dependent on the stator resistance of the induction motor.
In this model, speed of induction motor is controlled with proper firing angle of ac voltage controller. Pdf speed control of 3phase induction motor using volthertz. Induction motor drive based on the stator flux vector control. Out of the several methods of speed control of an induction such as pole changing, frequency variation, variable rotor resistance, variable stator voltage. The speed of a three phase induction motor can be varied by varying the supply voltage. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed.
Induction motor driving a centrifugal compressor advantages. The threestator windings develop a rotating magnetic flux rotating at. It is an ac motor in which current is induced in the rotor winding by the magnetic field of the stator winding, by electromagnetic induction. A novel prediction technique for the direct torque control dtc of an induction motor is presented in the paper. The laminations are insulated from each other usually by a varnish layer. Mcsa and zct are utilized to extract broken rotor bar information from recorded stator current signal. In very simple words induction motors can be described as a threephase, selfstarting constant speed ac motors. The content of this book is divided into three basic parts. The induction motor is made up of the stator, or stationary windings, and the rotor. The stator frame consists of laminations of silicon steel, usually with a thickness of about 0.
Speed control of three phase induction motor electrical4u. Vfd supplied induction motor torquespeed curve with voltage and frequency. 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. The alternating current ac induction motor is one of the most rugged and most widely used machines in industry. A number of control strategies about the voltagetofrequency ratio.
Nehrir, speed control of threephase induction motor by stator voltage control ieee transactions on industrial electronics and control instrumentatio n, may 1975. In a purely capacitive circuit, the current will lead the voltage by 90, while in a purely inductive one, the current will lag the voltage by 90 see fig. Speed control of induction motor 1 variable terminal voltage control 2 variable frequency control 3 rotor resistance control 4 injecting voltage in rotor circuit 20 1 variable terminal voltage control variable frequency control variable terminal voltage control wide speed range low speed range lower higher rated speed lower rated speed 21. Lamination is necessary since a voltage is induced along the axial length of the steel as well as in the stator conductors. In this thesis voltage model is used for the flux estimation. Singlephase induction motor threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together. Various methods of speed control 3phase induction motor. Induction motor speed controlled by using thyrister based 3phase ac voltage controller. Determine the impact of rewindingrepair on motor effi ciency. The speed of induction motor can be varied by changing supply voltage. Scalar control is the term used to describe a simpler form of motor control, using nonvectorcontrolled drive schemes. Speed control of vector controlled induction motors using.
The torque developed in this method is proportional to the square of the supply voltage. The conventional dtc method selects voltage vectors from switching table. How to control the speed of 3 phase induction motor quora. Induction motors horizontal and vertical weg electric machinery, wem, induction motors have been specifically designed and manufactured for the most severe industrial applications, such as heavy duty fans, pumps, refiners, compressors, crushers and grinding mill drives. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b.
It gets damaged frequently due to wear and tear and needs rewinding. Comment on the differences noted between using stator voltage control and adding rotor resistance, to control the speed of the motor. Abstract control of induction motor im is well known to be difficult owing to the fact the mathematical models of im are highly nonlinear and time variant. Speed of a 3 phase induction motor can be controlled by these methods. Some of the benefits of an induction generator technology are. Speed control of induction motor is possible in two sides. Contents nomenclature ix preface xv 1 dynamic model of the induction motor 1 1. Speed control of induction motors requires the accurate estimation of the fluxes in the motor.
Problems and premature failures often indicate input power system troubles, poor or deteriorating mechanical installations, or malfunctions in the driven machinery. The reason for describing induction motors as constant speed is because normally these motors have a constant speed depending on the frequency of. Abstract the paper deals with the vector control and predictive control of the induction motor. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type rotor as the name suggests it is a rotating part of an electrical machine, in which current is induced by transformer action from rotating magnetic field. Pdf explicit predictive voltage control for an induction. The summation of all torques acting on the motor shaft comprises the mechanical model. Pdf study of stator voltage control method for induction motor. 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.
By reducing stator voltage control of induction motor, speed of a highslip induction motor can be reduced by an amount which is sufficient for the speed control of some fan and pump drives fig. Blaschke presented a paper on vector control for induction motor. Ppt induction motor powerpoint presentation free to. For each sampling period, the value of the stator voltage is calculated to keep the stator flux equal to the reference vector, while the stator flux reference vector is calculated to keep the rotor flux amplitude constant at all operating conditions. It is logical that the least expensive, lowest maintenance type motor should be used most often. Motor analysis block diagram induction motor starting can be analyzed using electrical, mechanical, and thermal models which interact as diagrammed in figure 1. When the motor is up to speed the switch is moved to the run position which connects the supply directly to motor. The circuit simulated above is one of the topologies of 3phase ac voltage controllers whose output is fed to im for drive applications a pdf file is attached to best explain the operation of the circuit. We can change the speed at the stator by, changing the supply frequency, changing the supply voltage and changing the number of stator poles. In normal operation, the stator is excited by alternating voltage.
The rotor will constantly be turning to align its magnetic field with that of the stator field. Induction motor drive, lookup table, vector control introduction high performance induction motor drives require decoupled torque and flux control. 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. Therefore, motor troubleshooting involves the entire system, not just the. The influence of the most important parameter variations e. Speed control of induction motor detailed explanation. Diagnostics of rotor and stator problems in industrial. Record all nameplate information for the induction motor. Stator voltage control is basically a method to control the speed of an 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. This method is applicable to squirrel cage induction motor only. An induction motors rotor can be either wound type or squirrelcage. Stator voltage control frequency control stator voltage and frequency control i. Pdf direct torque control of induction motor with stator.
Vectorcontrolled induction motor drives the previous control strategies good steadystate but poor dynamic response oscillation resulted from the air gap flux vector control fieldoriented control is related to the phasor control of the rotor flux. Electric motor electric motor construction of induction motors. The advent of vector control techniques has solved induction motor control problems. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The control performance of field oriented induction motor drive greatly depends on the correct stator flux estimation. The paper aims to present an innovative predictive voltage control pvc approach for an induction motor im drive. This paper presents a new torque control algorithm for induction motors, based on the stator flux vector control. As a voltage and a current is applied to the stator winding terminals, a magnetic field is developed in the windings. Ppt 2 static rotor resistance control free download as powerpoint presentation.
The stator consists of a series of wire windings of very low resistance permanently attached to the motor frame. Various induction motor speed control methods advantages. The proposed control procedure is based on controlling the stator voltage. Vector control of induction motor using sophisticated look. A squirrelcage induction motor is one in which the secondary circuit consists of a.
Pdf on jan 1, 2017, arun kumar yadav and others published study of stator. Threephase to stator reference frame transformations 8 1. An induction 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. Electric motor construction of induction motors britannica. Stator voltage control is a method used to control the speed of an induction motor. Pdf on oct 1, 2016, sachin hegde and others published speed control of 3 phase induction motor using volthertz. Free download induction motor seminar ppt, pdf report. The field orientation principle in control of induction motors.
Asplitphase induction motor the stator of a splitphase induction motor is provided with an auxiliary or starting winding s in addition to the main or running winding m. The basic idea of an electric motor is to generate two magnetic fields. The 3phase set of currents, each of equal magnitude and with a phase. Online estimation of stator resistance of an induction. There are two major components of an ac induction motor. If the generator produces an unregulated voltage, it is possible to make some changes in the speed or load in order to get a desired. In a threephase induction machine, alternating current supplied to the stator windings energizes it to create a rotating magnetic flux. Induction motor, vector control, predictive control. Induction motor is a device which converts electrical energy into mechanical energy. Stator voltage control of three phase induction motor fed. Induction motor controlled by ac voltage controller file. An induction motor is presented as an electromechanical power converter, and basic relations between the electrical, magnetic and mechanical quantities in the motor will be explained. Design of a single sided linear induction motor slim using a user interactive computer program a thesis presented to the faculty of the graduate school university of missouricolumbia in partial fulfillment of the requirements for the degree master of science by sarveswara prasad bhamidi dr.
Induction motor seminar ppt, pdf report study mafia. Induction motor drives starting braking speed control of. The previous control strategies good steadystate but poor. While torque is proportional to voltage squared eq. This control is commonly provided through vector control 1. The inverter voltage is controlled up to a maximum value limited.
The stator is supplied by a balanced threephase voltage that drives a threephase. Stator voltage control of an induction motor circuit globe. Most of the cost will relay in the price of the magnet used to induce the electromotive force. An induction motor can therefore be made without electrical connections to the rotor. For the vector control, the rotor flux oriented one is pointed out, with highlight on the voltage source inverter type. You should also make a dc measurement of stator winding linetoline resistance using a dmm. Initially, when the motor is started, heavy current flows through the field winding of the stator because back emf has not yet been induced.