A 480v, 60 hz, 50hp, three phase induction motor is drawing 60 a at 0. This document is highly rated by mechanical engineering students and has been viewed 429 times. Mar 12, 2020 torqueslip speed characteristics of induction motor im threephase induction motor mechanical engineering notes edurev is made by best teachers of mechanical engineering. The behavior of a squirrelcage induction motor in the case of opencircuit noload and short circuit with math equations. Synchronous and asynchronous electromechanicalsystems dr. Torqueslip speed characteristics of induction motor nptel. The torque the motor produces is also a function of slip. Vf so for constant vf ratio a constant torque can be achieved. Torque speed characteristics of induction motor slip. In addition, we clearly need to know what perform ance is required. The magnetization current i m flowing in the motor s equivalent circuit fig.
Torqueslip speed characteristics of induction motor im. Torque speed characteristics of the induction machine. Variations in induction motor toque speed characteristics control of motor characteristics by cage rotor design. Induction machines can now be used in high performance applications where precise movement is required. Synchronous and asynchronous electricmotors the electric motor is an electromechanical continuous energy conversion equipment that converts electrical energy into electrical energy mechanical energy. Will have two or more sets of motor poles installed about the stator, for each motor winding.
However, this control scheme focus to ensure that any particular torque can be obtained at the same flux as operating at normal frequency and voltage. Record all nameplate information for the induction motor. Torque speed characteristic of an induction motor torque speed characteristic is the curve plotted between the torque and the speed of the induction motor. This file calculates the equivalent circuit of a three phase induction motor from the data of open circuit test and blocked rotor test. Torquespeed characteristic of induction motor in order to estimate the speed torque characteristic let us suppose that a sinusoidal voltage is impressed on the machine. Difference in maximum torquespeed characteristics of. Variable voltage variable frequency vf control theory. You should also make a dc measurement of stator winding linetoline resistance using a dmm.
The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the machine. As we have already discussed the torque of the induction motor in the topic torque equation of an induction motor. What is the difference between the speed and the torque of. Induction motor torque speed characteristics all about. In this work, the performance of a closedloop adjustable speed drive for singlephase induction motor using voltage amplitude control. 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. The torquespeed characteristics of a singlephase induction motor is illustrated in figure. Torque slip characteristics of three phase induction motor the torque slip curve for an induction motor gives us the information about the. Speed is the rate at which the engine spins thats why the unit rpm rotations per minute torque is how much twisting force the engine generates at its shaft for a particular speed of rotation torque force x perpendicular distance unit. Different methods of speed control of threephase asynchronous motor. Performance characteristics and double revolving theory of. Jul 11, 2019 torque slip characteristics of three phase induction motor the torque slip curve for an induction motor gives us the information about the variation of torque with the slip. It also calculates the thevenin equivalent circuit parameters, maximum torque induced, starting torque and slip for maximum power or torque. 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.
Jan 06, 2016 load requirements torquespeed characteristics the most important things we need to know about the load are the steadystate torquespeed characteristic, and the effective inertia as seen by the 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. Machine model and algorithm have been developed for calculation the motors characteristics at variation of the voltagefrequency reference and the load. The stator copper losses are 2 kw, and the rotor copper losses are 700 w.
B running characteristics of induction motors the stators. The rotor will constantly be turning to align its magnetic field with that of the stator field. This curve is called the torque speed characteristic curve. The friction and windage losses are 600 w, the core losses are 1800 w, and the stray losses are negligible. Electrical engineering assignment help, torquespeed characteristics of 3phase induction motors, torquespeed characteristics of 3phase induction motors because the torqueslip characteristic is one of themost important aspects of the inductionmotor, we will now develop an expression for torque as a function of slip and other equivalent cir. Variable voltage variable frequency vf control theory an induction motor compared to a dc motor has some major advantages such as absence of brushes. The speed regulation of a motor expresses how much its speed varies between noload and full load.
The equation of the torque is given as shown below. Induction motor torque speed curveinduction motor torque. The actual or running speed of an induction motor is influenced by the applied load and the resultant slip. The rotor speed of an induction motor is given by the equation shown below. Speed control of an induction motor there is a various method of speed control of an induction motor. Read about more of the powerful features of pdfmachine merge here. Therefore the efficiency of three phase induction motor is reduced by this method of speed control. S 1, the two rotating fields have the same strength and generates equal and opposite torques resulting in net starting torque of zero value. The speedtorque curves of induction motors are usually determined from a set of their. This paper explains the reason for the difference in maximum torque speed characteristics and power factor of im between the motor and generator operation modes and investigates the influence of machine design parameters on the difference, such as stator resistance, rotor resistance and iron loss etc. What is the difference between the speed and the torque of a. The torque slip curve for an induction motor gives us the information about the variation of torque with the slip. Figure 1 shows the speed torque curve for a 30hp, 1800 rpm induction motor in an. Equivalent circuit of an induction motor and torque speed.
Torque speed characteristics of three phase squirrel cage induction motor aim to obtain the torque speed characteristics tn r of a three phase squirrel cage induction motor using 1. Different loads will have different torque speed characteristics. To obtain the torquespeed characteristics tnr of a three phase squirrel cage induction motor using. It finally plots torque speed characteristics of induction motor. The speed regulation is expressed in percent of full load speed. A04 induction motor speed control home department of. Torquespeed characteristics of a single winding singlephase induction motor.
Induction motor torque speed curveinduction motor torque speed characteristics the torque slip curve for an induction motor gives us the information about the variation of torque with the slip. Nov 18, 2015 induction motor torquespeed characteristics. Figure 1 showed a plot of induction motor torque vs speed from zero to synchronous speed. As described in chapter 1, the synchronous speed of a rotating magnetic field type motor is determined by the following formula. Induction motor torque speed characteristics sumit maitra. Analytical approach to determine speedtorque curve of induction. Running characteristics of induction motors the stators magnetic field of an induction motor revolves at the synchronous speed.
Control of induction motor drive using artificial neural network. Various induction motor speed control methods advantages. Different loads will have different torquespeed characteristics. An induction motor can therefore be made without electrical connections to the rotor. The summation of all torques acting on the motor shaft comprises the mechanical model. Induction motor torquespeed characteristics figure 6.
The magnetization current im flowing in the motors equivalent circuit fig. Jun 05, 2016 induction motor torque speed characteristics sumit maitra. Torque speed characteristics of induction motor electrical. Torquespeed characteristics of the induction machine. Analytical approach to determine speedtorque curve of. Pdf control of induction motor drive using artificial. Induction motor speed so, the im will always run at a speed lower than the synchronous speed the difference between the motor speed and the synchronous speed is called the slip where n slip slip speed n sync speed of the magnetic field n m mechanical shaft speed of the motor n n n slip sync m 3192014.
We can derive an equation from the equivalent circuit that allows the calculation of the torque for a given value of slip. Jul 25, 2017 induction motor torque speed curve induction motor torque speed characteristics the torque slip curve for an induction motor gives us the information about the variation of torque with the slip. With both motor types, it is important to match the compressor torque versus speed requirements with motor torque versus speed capabilities as discussed in sections 6. The speed of an induction motor depends on the mechanical load. A nema design b motor generally operates at 3% slip, or 50 rpm of slip. Torque slip characteristics of induction motor electrical4u. Characteristics of a three phase and single phase induction motor.
Induction motor aim to obtain the torquespeed characteristics tn r of a three phase squirrel cage induction motor using 1. Speed control of vector controlled induction motors using integralproportional controller. Torquespeed characteristics, single phase induction. There are more than one methods to control the speed of induction motor, you can choose one depending on your resources, efficiency required etc. Induction motor torque speed characteristics youtube. Our pdf merger allows you to quickly combine multiple pdf files into one single pdf document, in just a few clicks. Figure 1 shows the speedtorque curve for a 30hp, 1800 rpm induction motor in an. 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. Speed control of vector controlled induction motors using. Characteristics of induction motors nidec corporation. A which in turn means that speed of induction motor has. Recalling that the equivalent circuit is the perphase representation of the machine, the current drawn by the circuit is given by. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the. Pdf performance characteristics of induction motor under.
In this post let us see what are the various methods to control the speed of induction motor. All we need to do is to keep daxis stator current constant. As this field is cut by the short circuited rotor winding, current is induced in the rotor circuit. It is a common practice to plot speed versus torque to investigate the motors characteristics.
Torquespeed characteristics of squirrel cage induction motor. Torque slip characteristics of three phase induction motor. At one extreme, for example, in a steelrolling mill, it may be necessary. How to control the speed of an induction motor quora. The speed control of an induction motor requires more elaborate techniques than the speed control of dc machines.
Torque speed characteristics of induction motor as induction motor follow the relation t. Performance characteristics and double revolving theory of single phase induction motor. Pdf performance characteristics of induction motor under v. Jan 09, 2017 speed control methods of induction motor. Speed control of three phase induction motor electrical4u. As long as the load torquespeed characteristic lies inside the motor torquespeed envelope then normal operation is possible. Load requirements torquespeed characteristics the most important things we need to know about the load are the steadystate torquespeed characteristic, and the effective inertia as seen by the motor. Torquespeed characteristics of 3phase induction motors. Torqueslip characteristic stability analysis for induction motor. We know that t he speed of the induction motor is given by, from the above equation, the speed of the motor can be controlled by changing supply frequency and by changing number of poles in the stator. Pdf the induction motor drive is a dynamic nonlinear system with uncertainty in the machine parameters. Speed control of induction motor induction motor speed control by pole changing. Fall 2005 ee595s electric drive systems 36 the plan continued achieving 14.
A new v f relation that improves the speed response of the single squirrel cage induction motor is presented and is defined by a frequency factor. However, the slip at which the maximum torque occurs changes with rotor resistance. Consider a 2pole 50hz motor with synchronous speed 3,000 rpm, noload speed 2,950 rpm, and fullload speed 2,750 rpm. Fall 2005 ee595s electric drive systems 8 voltsperhertz control. The important performance characteristics in the steady state are the efficiency, power factor, current, starting torque, maximum or pullout torque. Introduction squirrelcage threephase induction motors are widely used for most industrial and commercial applications since their constructions are very simple 1.
As described in chapter 1, the synchronous speed of a rotating magnetic fieldtype motor is determined by the following formula. Torque slip characteristic stability analysis for induction motor. Themotorisallowedtorunatnoload,andissuppliedwithvarious voltages at nofcmal frequency,rangingfrom 25 percentabove normaltoa value at which the motorwill just continuerunning. The equivalent circuits derived in the preceding section can be used to predict the performance characteristics of the induction machine. Torque speed characteristic of an induction motor circuit globe.
Torquespeed characteristics of three phase squirrel cage. As long as the load torque speed characteristic lies inside the motor torque speed envelope then normal operation is possible. The 3phase set of currents, each of equal magnitude and with a phase. In the electrical model, the voltage, v, and the slip, s, determine the rotor current. Performance characteristics of three phase induction motor. Induction motor, speedtorque curve, induction machine. Load torque will depend on the type of load be it a pump or fan etc. The basic idea of an electric motor is to generate two magnetic fields.
For motor speeds below the nominal value, the torque capacity of the motor is preserved with the proposed relationship. New relation to improve the speed and torque characteristics. A microcontroller m68hc11e9 has been used to implement such. An analysis of steadystate operation and performance characteristics of an induction motor with volt per hertz speed control is presented in this paper. Torquespeed characteristics of three phase squirrel cage induction motor aim to obtain the torquespeed characteristics tn r of a three phase squirrel cage induction motor using 1. An induction motor is normally sized for the anticipated full load torque. An induction motors rotor can be either wound type or squirrelcage.
The curve is also useful for different kinds of electrical machine analysis. Both induction and synchronous motor types can be coupled with a vfd for variable speed operation. Department of electrical and electronics engineering, federal university of technology, pmb 65, minna, nigeria. Motor analysis block diagram induction motor starting can be analyzed using electrical, mechanical, and thermal models which interact as diagrammed in figure 1. Torqueslip speed characteristics of induction motor im threephase induction motor mechanical engineering notes edurev notes for mechanical engineering is made by best teachers who have written some of the best books of mechanical engineering. The rotors magnetic field caused by this current interacts with the stators field to produce torque on the rotor. Torque speed characteristic of induction motor in order to estimate the speed torque characteristic let us suppose that a sinusoidal voltage is impressed on the machine.