Parameter estimation and indirect vector control of AC induction motor

Abstract

Industrial motor drive applications are usually complex and expensive. Most industries invest time and effort to implement drives which are low-cost, reliable, energy efficient and require low maintenance. In this field, the Induction motor (IM) is popular for its superior performance compared to its counterparts. There are two types of IM- squirrel cage IM and wound rotor IM both widely used. The popularity of the squirrel cage induction machine is attributed to its ruggedness (high output power to size ratio) and simplicity of construction. Recent advances in power electronics such as the Voltage Source Inverter (VSI) based drives have enabled variable speed control of IM's. VSI based drive converts DC voltage into three phase voltage of variable magnitude and frequency based on requirements for motor control. Well established knowledge in the fields of Digital Signal Processing (DSP), high performance microcontrollers, and analog sensors has aided the growth of motor controllers. This thesis has its foundation on a certain form of control called Indirect Vector control based on frame transformations, estimators and error based controllers. Chapter 1 discusses the basics of frame transformations, its advantages and modeling the IM in a new frame called the dq-frame. Chapter 2 examines the indirect vector control on the dq- frame and lays the foundation for simulation study. Chapter 3 deals with the method used to arrive at motor parameters and discusses the importance of accuracy of these values. It also expands on the vector control foundation by building a mathematical model of some of the components of the control used for simulation studies. Chapter 4 discusses in detail the design of error based controllers and presents a simple comparative study between different controllers. Chapter 5 talks about the simulation and hardware setup and provides the respective results.