Sincap kafesli asenkron makinalarda doğrudan vektörel kontrol

Abstract

The induction machines also known as the asynchronous machines, are commonly preferred in industry. Both the squirrel-cage type which has short-circuited rotor and the slip -ring (wound rotor) type of induction machines are used in electrical drives. in recent years, especially the squirrel-cage induction machines take fırst place in industrial applications. in the past, de machines were preferred in varjable speed drives since their flux and torque can be controlled easily by the field and armatüre currents. However, de machines have a lot of disadvantages because of their collector and brushes. They need periodic maintenance and can not be used in working conditions having explosive ör corrosion. Also a de machine has limited comutator capability. Since ali these disadvantages, induction machines were replaced de machines. Especially the squirrel-cage induction machines have excellent features such as; - To be cheaper and lighter compare with another type of machines. - To have simple and rugged structure - Robustness, reliability and maximum speed - High effîciency and low maintenance costs - To be suitable for using in difficult working conditions - Several speed options - Standardized design in spite of these excellent features, the squirrel cage induction machines need complex control algorithms due to their non-linear dynamic model. However, as a result of progress in the field of power electronics and power converters the control of induction machines became more practical. On the other hand, the implementation of microprocessor in the digital control circuits has introduced a wide scope of possibilities to overcome the complex dynamics of the machine. Additionally, the development of processing integrated circuits is öne of the majör factor of the rapid evolution of induction machine control. As a result of these developments, when the control of an induction machine needs fast transient responses ör torque at standstill viii amplitude and frequency of supplied voltage is chosen as the subject of this thesis. The thesis consists of five chapters. The general contains of each chapter is given in the following. The first chapter deals with the general approach of the thesis. In this chapter, it is given some clues about the other chapters and mentioned about the development of vector control methods. In second chapter, firstly the squirrel-cage induction machine and its structure and principles are explained. Then, the mathematical model of the machine is obtained on abc phase axis. Since the model has highly nonlinearity, to make the analysis possible and easier two different transformations are applied. Thus, the new model is obtained in odq axis in terms of per-unit quantities. The model is expressed in many way by choosing different state variables. In computer simulation, d-q axis stator and rotor fluxes and rotor speed are chosen as independent state variables and d-q axis stator voltages and load torque are selected as input variables. In third chapter, by using the state space model and computer simulation, the machine's behaviors are analyzed when the amplitude or frequency of supply voltage or load torque is changed. In fourth chapter, the vector control methods and their specifications are introduced. Under the light of this knowledge, the direct vector control method is applied to the machine and the result of computer simulations are given. In the last chapter, the results obtained throughout the thesis and the comparison between the results of third and fourth chapters are given. Thus, the final conclusions are explained. XUl SUMMARY DIRECT VECTOR CONTROL İN SQUIRREL-CAGE INDUCTION MACHINES The induction machines also known as the asynchronous machines, are commonly preferred in industry. Both the squirrel-cage type which has short-circuited rotor and the slip -ring (wound rotor) type of induction machines are used in electrical drives. in recent years, especially the squirrel-cage induction machines take fırst place in industrial applications. in the past, de machines were preferred in varjable speed drives since their flux and torque can be controlled easily by the field and armatüre currents. However, de machines have a lot of disadvantages because of their collector and brushes. They need periodic maintenance and can not be used in working conditions having explosive ör corrosion. Also a de machine has limited comutator capability. Since ali these disadvantages, induction machines were replaced de machines. Especially the squirrel-cage induction machines have excellent features such as; - To be cheaper and lighter compare with another type of machines. - To have simple and rugged structure - Robustness, reliability and maximum speed - High effîciency and low maintenance costs - To be suitable for using in difficult working conditions - Several speed options - Standardized design in spite of these excellent features, the squirrel cage induction machines need complex control algorithms due to their non-linear dynamic model. However, as a result of progress in the field of power electronics and power converters the control of induction machines became more practical. On the other hand, the implementation of microprocessor in the digital control circuits has introduced a wide scope of possibilities to overcome the complex dynamics of the machine. Additionally, the development of processing integrated circuits is öne of the majör factor of the rapid evolution of induction machine control. As a result of these developments, when the control of an induction machine needs fast transient responses ör torque at standstill viii amplitude and frequency of supplied voltage is chosen as the subject of this thesis. The thesis consists of five chapters. The general contains of each chapter is given in the following. The first chapter deals with the general approach of the thesis. In this chapter, it is given some clues about the other chapters and mentioned about the development of vector control methods. In second chapter, firstly the squirrel-cage induction machine and its structure and principles are explained. Then, the mathematical model of the machine is obtained on abc phase axis. Since the model has highly nonlinearity, to make the analysis possible and easier two different transformations are applied. Thus, the new model is obtained in odq axis in terms of per-unit quantities. The model is expressed in many way by choosing different state variables. In computer simulation, d-q axis stator and rotor fluxes and rotor speed are chosen as independent state variables and d-q axis stator voltages and load torque are selected as input variables. In third chapter, by using the state space model and computer simulation, the machine's behaviors are analyzed when the amplitude or frequency of supply voltage or load torque is changed. In fourth chapter, the vector control methods and their specifications are introduced. Under the light of this knowledge, the direct vector control method is applied to the machine and the result of computer simulations are given. In the last chapter, the results obtained throughout the thesis and the comparison between the results of third and fourth chapters are given. Thus, the final conclusions are explained. XUl SUMMARY DIRECT VECTOR CONTROL İN SQUIRREL-CAGE INDUCTION MACHINES The induction machines also known as the asynchronous machines, are commonly preferred in industry. Both the squirrel-cage type which has short-circuited rotor and the slip -ring (wound rotor) type of induction machines are used in electrical drives. in recent years, especially the squirrel-cage induction machines take fırst place in industrial applications. in the past, de machines were preferred in varjable speed drives since their flux and torque can be controlled easily by the field and armatüre currents. However, de machines have a lot of disadvantages because of their collector and brushes. They need periodic maintenance and can not be used in working conditions having explosive ör corrosion. Also a de machine has limited comutator capability. Since ali these disadvantages, induction machines were replaced de machines. Especially the squirrel-cage induction machines have excellent features such as; - To be cheaper and lighter compare with another type of machines. - To have simple and rugged structure - Robustness, reliability and maximum speed - High effîciency and low maintenance costs - To be suitable for using in difficult working conditions - Several speed options - Standardized design in spite of these excellent features, the squirrel cage induction machines need complex control algorithms due to their non-linear dynamic model. However, as a result of progress in the field of power electronics and power converters the control of induction machines became more practical. On the other hand, the implementation of microprocessor in the digital control circuits has introduced a wide scope of possibilities to overcome the complex dynamics of the machine. Additionally, the development of processing integrated circuits is öne of the majör factor of the rapid evolution of induction machine control. As a result of these developments, when the control of an induction machine needs fast transient responses ör torque at standstill viii amplitude and frequency of supplied voltage is chosen as the subject of this thesis. The thesis consists of five chapters. The general contains of each chapter is given in the following. The first chapter deals with the general approach of the thesis. In this chapter, it is given some clues about the other chapters and mentioned about the development of vector control methods. In second chapter, firstly the squirrel-cage induction machine and its structure and principles are explained. Then, the mathematical model of the machine is obtained on abc phase axis. Since the model has highly nonlinearity, to make the analysis possible and easier two different transformations are applied. Thus, the new model is obtained in odq axis in terms of per-unit quantities. The model is expressed in many way by choosing different state variables. In computer simulation, d-q axis stator and rotor fluxes and rotor speed are chosen as independent state variables and d-q axis stator voltages and load torque are selected as input variables. In third chapter, by using the state space model and computer simulation, the machine's behaviors are analyzed when the amplitude or frequency of supply voltage or load torque is changed. In fourth chapter, the vector control methods and their specifications are introduced. Under the light of this knowledge, the direct vector control method is applied to the machine and the result of computer simulations are given. In the last chapter, the results obtained throughout the thesis and the comparison between the results of third and fourth chapters are given. Thus, the final conclusions are explained.