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MODELING AND SIMULATION OF INDUCTION MACHINE AND ITS APPLICATION IN ELECTRIC DRIVES

MODELING AND SIMULATION OF INDUCTION MACHINE AND ITS APPLICATION IN ELECTRIC DRIVES. PRAJOF P edited by Sarath S Nair www.technologyfuturae.com. CONTENTS. Introduction Dynamic d-q modeling Synchronous and stationary reference frame equations Simulation of induction machine Vector control

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MODELING AND SIMULATION OF INDUCTION MACHINE AND ITS APPLICATION IN ELECTRIC DRIVES

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  1. MODELING AND SIMULATION OF INDUCTION MACHINE AND ITS APPLICATION IN ELECTRIC DRIVES PRAJOF Pedited by Sarath S Nair www.technologyfuturae.com www.technologyfuturae.com

  2. CONTENTS • Introduction • Dynamic d-q modeling • Synchronous and stationary reference frame equations • Simulation of induction machine • Vector control • Simulation of vector control • Sensor less control • Simulation of sensor less vector control • Conclusions www.technologyfuturae.com

  3. INTRODUCTION • Motion control is required in large number of industrial and domestic applications like transportation systems, rolling mills, machine tools, fan, pumps, robots, washing machines etc. • Electric drives are used for motion control. • AC and DC machines used in drives • AC motors have several advantages- high robustness, reliability, low price and high efficiency. • Latest ac machine drive technology –VECTOR CONTROL and sensor less control. These are studied with the help of dynamic d-q modelling. www.technologyfuturae.com

  4. DYNAMIC d-q MODEL OF INDUCTION MACHINE • In an adjustable speed drive transient behavior has to be taken into consideration • The conventional mathematical modeling are complex • In d-q modeling 3-φ machine parameters can be represented by an equivalent 2-φ (d-q) • A change of variables can be used to reduce the complexity of machine differential equations. www.technologyfuturae.com

  5. CONTD… The following assumptions are made to derive thedynamic model: • Uniform air gap. • Balanced rotor and stator windings, with sinusoidal distributed mmf. • Saturation and parameter changes are neglected. www.technologyfuturae.com

  6. AXES TRANSFORMATION • It is used to transform the machine variables to a frame of reference that rotate at arbitrary angular velocity www.technologyfuturae.com

  7. SYNCHRONOUSLY ROTATING REFERENCE FRAME–DYNAMIC MODEL (KRON EQUATION) • Voltage equation of an induction machine can in synchronously rotating reference frame can be written as follows: www.technologyfuturae.com

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  9. STATIONARY FRAME–DYNAMIC MODEL www.technologyfuturae.com

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  11. SIMULATION OF MODELING OF INDUCTION MACHINE www.technologyfuturae.com

  12. Rotor reference frame is used • Electrical equations for squirrel cage induction motor is given by • But for MATLAB simulation we use www.technologyfuturae.com

  13. The electromagnetic torque and mechanical speed is given by • Rotor speed and position is given by • Magnetizing current, im is defined as www.technologyfuturae.com

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  17. VECTOR CONTROL- PRINCIPLE • Vector Control is similar to control of separately exited DC motor, with independent control of flux and torque and with superior dynamic response. • Vector control is done by resolving stator current • The magnitude of iqs should be controlled to adjust the torque and the magnitude of ids should be controlled to adjust the rotor flux www.technologyfuturae.com

  18. CONTD… • Assumption made - the position of the rotor flux linkage phasor, ƛr , is know • The current phasor is produces rotor flux ƛr and the torque Te www.technologyfuturae.com

  19. Classification of vector control Vector control is classified on according to how the field angle is acquired. They are as follows: • Direct vector control • Indirect vector control www.technologyfuturae.com

  20. INDIRECT VECTOR CONTROL • Field angle is generated in feed forward manner • This method uses the model equations of the machine with easily measurable quantities as inputs • Derived from synchronously rotating reference frames www.technologyfuturae.com

  21. The resultant rotor flux linkages, ƛr,, is assumed to be on direct axis • The field, stator and slip angles can be obtained as follows θf = θsl + θr θs = θf + θT www.technologyfuturae.com

  22. INDIRECT VECTOR CONTROL SCHEME • The command values are given by as follows www.technologyfuturae.com

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  24. SIMULATION OF VECTOR CONTROL- INDIRECT VECTOR CONTROL www.technologyfuturae.com

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  26. SENSORLESS CONTROL • Meaning-Control without any speed sensor • Speed sensor - Incremental shaft mounted speed encoder • Speed encoder is undesirable in a drive because it adds cost and reliability problems, besides the need for a shaft extension mounting arrangement www.technologyfuturae.com

  27. CONTD… • Estimate the speed signal from machine terminal voltages and currents with help of a DSP • Estimation is normally complex and heavily dependent on machine parameters • Parameter variation problem particularly near zero speed imposes a challenge in the accuracy of speed estimation. www.technologyfuturae.com

  28. Induction motor speed estimation techniques • Slip calculation • Direct synthesis from state equations • Model referencing adaptive system (MRAS) • Extended Kalman filter • Slot harmonics • Injection of auxiliary signal on salient rotor www.technologyfuturae.com

  29. DIRECT SYNTHESIS FROM STATE EQUATIONS • The q and d stator voltages in the stator reference frame are obtained from the phase voltages as • Similarly, the current are obtained in the same way www.technologyfuturae.com

  30. CONTD… • From equation (I) and (II) we can find ƛdrs and ƛqrs www.technologyfuturae.com

  31. CONTD… • The field angle can be calculated as www.technologyfuturae.com

  32. SIMULATION OF SENSORLESS SPEED ESTIMATOR www.technologyfuturae.com

  33. Actual speed of the machine www.technologyfuturae.com

  34. Speed from machine parameters www.technologyfuturae.com

  35. CONCLUSION • The d-q modeling of induction machine was explained • MATLAB simulation of induction machine modeling was done and the variations in speed and torque was observed • Two applications of d-q modeling ,namely – vector control and sensor less control was discussed • Vector allows direct control of flux and torque, making torque limiting and field weakening possible. • Decoupling between flux and torque is effective even under dynamic conditions. • It was seen from MATLAB simulation that Vector Control provides excellent dynamic response. • It is very complicated and requires the usage of powerful processors • The controllers process dc quantities in the steady state www.technologyfuturae.com

  36. Precise and smooth speed operations and used obtain high performance drives • The basic principle of Sensor Less vector control of induction motor was explained • MATLAB simulation was done on sensor less estimation of speed and compared with actual speed of the machine www.technologyfuturae.com

  37. REFERENCES • M. Satyendra Kumar Shet and Uday Kumar R. Yaragatti, ‘’Design of computer application for 3 phase vector control induction motor drive’’, IET-UK International Conference on Information and Communication Technology in Electrical Sciences (ICTES 2007),Dr. M.G.R. University, Chennai, Tamil Nadu, India. Dec. 20-22, 2007. Pp.315-322. • G. R. Slemon, “Modeling of induction machines for electric drives, “IEEE Tram. Onlnd. App. Vol. 25, No. 6, pp. 1126-1131, 1989. • Tsugutoshi Ohtani, NoriyukiTakada and Koji Tanaka, ‘Vector Control of Induction Motor without Shaft Encoder,’’ IEEE Transaction on Industry Applications, Vol. 28, No. 1, Jan-Feb 1992. • B.K. Bose. “Modern Power Electronics and AC Drives”. Upper Saddle River, NJ: Prentice Hall Pvt ltd, 2002. www.technologyfuturae.com

  38. 5. R.Krishnan.”Electric Motor Drives Modeling, Analysis and Control” PHI Learning private limited New Delhi-110008, 2008. • Gopal. K. Dubey, ‘Fundamentals of Electric Drives’, 2nd Ed. Narosa Publishing House, New Delhi, 2007 • V. T. Ranganathan, ‘Induction Motors’, Course Notes on Electric Drives, IISc, Bangalore. • Krause, P.C.: Analysis of Electric Machinery, New York, McGraw-Hill, 1986. • Yen Shin Lai, “Modeling and vector control of induction machine- A new unified approach’’, IEEE Tram. Onlnd. App. 0-7803-4403-01, 1998. www.technologyfuturae.com

  39. Technical Presentations, Research Reviews, New designs & Developments Log On to www.technologyfuturae.com TechnologyFuturae

  40. THANK YOU www.technologyfuturae.com

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