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1 ISSN X,VOLUME 3 ISSUE 2,1/4/215 STUDY THE PERFORMANCE CHARACTERISTIC OF INDUCTION MOTOR Niranjan.S.Hugar*1, Basa vajyoti*2 *1 (lecturer of Electrical Engineering, Dattakala group of institutions, Bhigwan. Pune, India) *2 (student of Electronics Engineering, Srinivas School of Engineering, Mukka. Mangalore, VTU, India) niranjanhugar@gmail.com*1,basavajyotifulare@gmail.com*2 Abstract:- The study of induction motor performance characteristic provides a greater understanding of design and control of induction motor. The aim of our work is to draw the performance characteristic of induction motor by using simulink model. Further this simulink model is used for constant v/f ratio the graphs are plotted for above variation and are compared. By the knowledge of these performance experience with the real system, to test the controllers graphs, further enhancement in closed loop is adopted with proper feedback control technique, induction motor model is obtained and this model is motor characteristic of speed- torque is used for wide range of application. Induction motor has high starting torque, zero steady speed error for any frequency. [2]. Simulation tools play a fundamental role in today s engineering educational projects. The three-phase electric machine model is complex and nonlinear, and some small impact simplifications and linearization are made. Thus, after gaining some experience with the simulation, we should have an they have designed and simulated, during the experimental activities using the proposed set-up. Some of the machine parameters used in the helpful in practical design of induction motor. simulation is got from the real machine. Keywords: - Computer-controlled systems, The MATLAB implementation is adopted because of computerized monitoring, Matlab Simulink, induction Motors Control. 1. Introduction 1.1 Introduction:- The induction motor is most widely used motor type in industries because of its self starting capacity, simple, rugged structure, low its inherent integration of vectorized system, and is analyzed using numerical analysis methods. It s a simple implementation of functionality of controllers and power electronic excitations. This approach provides a powerful design tool because of ease in observing the effects of parameter modification and of cost and reliability induction motor are used in many changes in system configuration and control adjustable speed application. The dynamic model equations are complex and these are of many different forms. The modeling depends on choice of reference frame. All the rotor parameters and variables are not actual quantities but are quantities referred to stator frame. The circuit parameters are determined by no load test and locked rotor test [1]. The induction strategies. The magnetic coupling is expressed in terms of an induction matrix which is a function of position θ. The next step is to transform the original stator and rotor abc frames of reference into a common k or dq frame in which the new variables for voltages, currents, and fluxes can be viewed as 2-D space vectors. Among the possible choices of dq 1

2 ISSN X,VOLUME 3 ISSUE 2,1/4/215 frames is most suitable for finding performance characteristics [3]. 2. Literature survey 2.1. Literature survey The stator resistance and frequency compensation technique required minimum knowledge of machine parameter. The measuring quantity is stator current only by vector ally adding it to commanded voltage both in-phase and quadrature component of stator current. The frequency compensation is based on the air gap power and a nonlinear relationship between slip frequency and air gap power [2].The induction motors have gained extremely wide application by the large number of advantages compare to other type of motors. The difference in speed is dependent on the radius of curvature and spacing between them [4] Excitation and controllers The simulation of the inputs to the machines involves the mathematical representation of programmed time sequence of events such as the sudden application or removal of mechanical loads. This results in the ramping of the magnitude and frequency of the applied voltages. [3] System architecture The most of the machines used now a day s are induction machines. Due to availability of these induction machines in all ratings. The main advantage of using induction machine is controlling factor. We can control various performance characteristics such as speed, torque, rotor current, stator current etc with respect to time. Thus the controlling factor of these parameters is one of the most advantages. An AC induction motor has a fixed stator windings and rotating rotor windings. A threephase AC induction machine is the only type of machine where the rotating magnetic field is created by induction, similar to that of transformer. 3. Mathematical modeling 3.1. Modeling This section describes many of the issues which need to be addressed and resolved before attempting to devise a complete model for improving reliability in motor control. In order to model the solution it needs an analysis of the characteristic curves with respect to time. The requirement of initial condition, in the matrix form, is used to model of induction machine. [3] 3.2. Assumption and approximate The Assumptions are made for improving efficiency and reliability of the induction motor the following assumption is listed below: (a) All the machine parameters should be in SI unit. (b) Approximate the initial conditions (c) Specify the final time of the machine Constitutive flux-current relation The flux linkage of induction motor is a product of current and inductance or in terms of the current of the induction motor is inductance by flux linkage is λ=l*i (3.3.1) 3.4. Torque: The Torque of the induction motor in terms of mechanical speed ω m and angular position is Te= ( ωm)/ m (3.4.1) The torque of induction motor in terms of poles, current and dl / d is given in the (3.4.2) Te = p/4*i *dl/d *I (3.4.2) 3.5. Electrical system equations: In electrical system equation the voltage of the induction motor is given in terms of resistance, current and change in linkage flux is given by (3.5.1) V=R*I+dλ/dt (3.5.1) 2

3 ISSN X,VOLUME 3 ISSUE 2,1/4/215 The voltage of the induction motor in terms of inductance (L), angular velocity (ω m ) current (I) and change in current dl/dt is given in (3.5.2) [3] Fig Simulink models Fig shows the three phase induction machine phase variable model. The expression for voltage is V=(R+ωm*dL/d )*I+dI/dt (3.5.2) given by V=(R+W (3.25) m *dldtheta)*i+l*di/dt, which is 3.6. Mechanical system equations: The mechanical system equation of torque in known as electrical system of developed state model, where L is the inductance matrix of order (6x6) and terms of load torque (Tl), [3] moment of inertia (J), dldtheta is the derivative of inductance matrix L frictional co-efficient (B m ), angular speed and change in angular speed (dω m /dt) is given in (3.6.1), (3.6.2) w.r.t theta (θ). This electrical system is used to Te=J*dωm/dt+TL+Bm*ωm (3.6.1) obtained electrical torque equation given by ωm = d /dt (3.6.2) Te=p/4*I *dldtheta*i. The model developed using Te=P/4*I *dldtheta*i (3.6.3) equation (known as torque model) is shown in The change in current is given by (3.6.4) di/dt=l\ (V-R+ωm *dldtheta)*i (3.6.4) Fig.4.7. This torque is compared with load torque to obtain desired torque. The change in speed is given by (3.6.5 [3] dωmdt=p/2*(te-tl)/j-bm*ωm/j (3.6.5) dthetadt= ωm ; dxdt= [di/dt;dωm dt; dtheta] 4. Simulation 4.1. Simulation block diagram model The above mathematical equations are used to create a Simulink model as shown in Fig.4.1.These equation are in matrix/vectorized form. The Simulation is carried out with the induction motor Model provided In Fig to and waveforms of rotor current, speed and torque w.r.t time are observed using scopes Fig Three-phase induction machine (phase variable model) The expression for modeling inductance matrix is given in the inductance square matrix of order (6x6) and is a function of. These are represented in their vector/matrixes form using horizontal and vertical concatenation. The developed inductance matrix model is 3

4 ISSN X,VOLUME 3 ISSUE 2,1/4/215 given load conditions. The characteristics graphs obtained by using simulink are shown in Fig to Fig Frequency: 6Hz Voltage: 22v rotor current vs time Iar Ibr Icr Fig Concatenation used to assemble the inductance matrix L as a function of θ The derivative of inductance matrix is also a square matrix of order (6x6) as a function of. These are represented in their vector/matrixes form, using horizontal and vertical concatenation. The expressions are evolved and are used for modeling of dl/dt.. Fig shows Concatenation used to assemble the matrix dl/dθ as a function of θ 4.2. Graphs obtained from simulink The simulation results are the output of out coming, these can be realized using scope, display, workspace and by writing a plot command. In this the results are analyzed by writing a plot command and these plotted graphs are useful in studying the induction motor performance under the rotor current Fig The graph shows Rotor current vs. time. speed(n-m) speed vs time Frequency: 6Hz Voltage: 22v 15 Fig shows the graph of Speed vs. time. N 4

5 ISSN X,VOLUME 3 ISSUE 2,1/4/ Torque vs time T Frequency: 4Hz Voltage: 126.8v rotor current vs time Iar Ibr Icr Torque(N-m) Frequency: 6Hz Voltage: 22v rotor current Fig shows the graph of torque vs. time V/F control method for frequency of 5Hz and 4Hz The performane characteristics of the induction motor is obsrved by maintaining the V/F ratio conatant for different values. First, the votage/frequecy = 22/6 =3.667 is selected and then to keep this ratio a constant at frequency of 5Hz, the corresponding voltage value of V=5*3.667=183.5V is selected. and for 4Hz the voltage value of V=4*3.667=126.8 is selected. The variation in graphs is shown in below figures. rotor current rotor current vs time Frequency: 5Hz Voltage: 183.5v Iar Ibr Icr -6 Fig.4.3.1b. shows the graph of Rotor current vs. time. speed(n-m) speed vs time 12 Fig.4.3.2a. shows the graph of Speed vs. time. speed(n-m) Frequency: 5Hz Voltage: 183.5v speed vs time Frequency=4HZ N N Voltage=126.8V Fig.4.3.1a. shows the graph of Rotor current vs. time. 9 Fig.4.3.2b. shows the graph of Speed vs. time. 5

6 ISSN X,VOLUME 3 ISSUE 2,1/4/ Torque vs time Frequency: 5Hz Voltage: 183.5v T are low. But the coincidence between the original and obtained graphs will be less with lower frequencies and voltages. Torque(N-m) The Fig.4.3.3a.shows the graph of torque vs. time Torque(N-m) Torque vs time Frequency: 4Hz Voltage: 126.8v -3 The Fig.4.3.3b.shows the graph of torque vs. time 5. Conclusion 5.1. Conclusion The induction motor performance is studied for different voltages and frequencies. The result of the simulations shows that the linear characteristic curves with respect to time. The values of the configured model are changed considering the ratio V/F constant to obtain different set of graphs and are compared. From these graphs it can be understood as V/F ratio is kept constant for lower values of frequencies and voltages then the original values the following conclusion are obtained, maximum peak value at initial time at t= during transient period are lower value, time required for transient to settle is decreases hence, transient in the waveform observed T 5.2. Future enhancements The performance characteristic graphs obtained from induction Simulink model are used to study the induction motor behavior for different value frequencies and voltage values, by the knowledge of this model, varies feedback models of induction motor can be developed, accordingly proper control strategies are adopted for better efficiency, linear behavior of performance characteristics to the applied input parameters. A number of additional modifications have been made in induction machine, the controlling and implementation through the software had made using MATLAB. With this information further enhance in implementation and design of induction motor can be carried out. 6. References [1] Marcos vinicius lazarini and Ernesto ruppest filho, Sensor less three phase induction motor direct torque control using sliding mode control strategy. IEEE-27, Coimbra, Portugal [2]Alfredo Mu noz-garc ıa, Thomas A. Lipo, A New Induction Motor V/f Control Method Capable of High-Performance Regulation at Low Speeds IEEE-25. [3] M.Riaz, simulation of electric machine and drive system. University of Minnesota `riaz [4] Rakesh parekh, Ac induction motor fundamentals. 23 microchip technology Inc DC887A 6