Modeling And Simulation Of Vector Control For Three Phases Induction Machine

In order to obtain the high dynamic response, the high precision magnetic torque control of AC machine is essential. As we know the DC regulating speed system has its limitation since the existence of brush, while the AC machine is widely used with the rapidly development of computer technology and power electric technology. After over ten year's development, the performance of variable frequency speed regulation control of asynchronous motor has excelled the performance of DC speed regulation control. The purpose of this dissertation is to establish a model of three phase inductive machine, based on the model, we can study various control theory.Vector control method is a new variable frequency speed regulation technology, which is more effective than SPWM technology. The basic ideal of vector control is to simulate the three phase inductive machine as a DC motor. The process depends on the analysis and studying on the mathematic model of inductive machine. In this thesis a mathematic model of three phase inductive machine is presented firstly, the model is established with MATLAB/SIMULINK. Then after doing the vector transform to the inductive machine model, we can get the decoupled model in two phases synchronous revolving reference frame. In the two phases synchronous revolving reference frame, the vector of stator current is decomposed into two components: the excitation parts which is overlapped to vector of rotor flux linkage and the torque parts which is vertical to vector of rotor flux linkage. By control the position and value of stator current vector in revolving reference frame, namely by control the field current part and the torque current part respectively, realizing the decoupled control of flux and torque just as the DC motor control.In this paper, a detailed analysis and depiction of three phase inductive machine model is presented. Through the analysis of dynamic electromagnetic relationship and the introduction of coordinate transform method, the mathematic model of three phase inductive machine in different reference frame was established. The typical characteristic of AC inductive machine is a multi-variable system featuring time-variant, nonlinear and strongly coupled parameters. In this paper, the particular of vector control principle and vector transform approach is presented and the uncoupling of three phase inductive machine model is also explained.In the thesis, a design of Rotor flux orientation control of three phase inductive machine is given, including the analysis and design of magnetic flux observer, magnetic flux PI regulator, torque PI regulator and speed PI regulator etc. In the end, the simulation research using the MATLAB/SIMULINK software is given. The simulation result show the model and the control method established in the paper is ideal.