Design And Research On Three-Level Inverter Based On Rotor Field Oriented Vector Control

W With the continuous innovation and development of power electronics technology, computer technology and automatic control technology, DC speed control is being replaced by AC variable speed. AC variable speed was identified as one of the main development direction of the modern electrical transmission. AC variable speed technology has been selected as the power-saving, to improve product quality and improve the environment, promoting technological progress. Diode-clamped three-level inverter has been widely used, due to the simple structure of the main circuit, simple control method, small size, low cost, high reliability. This thesis is mainly research on three-level inverter based on rotor field oriented vector control theory.First, this thesis summarizes the development status of the three-level inverter and vector control technology. It introduces main circuit topology and operating principle of diode-clamped three-level inverter, analysis of the three modes of operation of the circuit. Based on the traditional three-level Space Vector Pulse Width Modulation (SVPWM) algorithm, it introduces the three-level SVPWM algorithm on coordinate of60-degree with more suitable for digital control implementation. And it also analyzes the three-level inverter midpoint potential imbalances and control strategies. The theory is proved to be correct by Matlab/Simulink simulation analysis. Secondly, it introduces the model of the induction motor on the three-phase stationary reference frame, by coordinate transformation, derives the model of the induction motor on the two-phase rotating coordinate frame, two-phase stationary reference frame, two-phase synchronous rotating coordinate frame and two-phase synchronous rotating coordinate frame based on rotor field oriented. It introduces the basic principles of vector control through analyzing the magnetic field equivalence principle. Thus it introduces vector control based on rotor field oriented. Thirdly, the thesis designs the current control loop and the speed control loop of the control system, and the result of simulation in the Matlab/Simulink proves the control system has a very quick dynamic response and high steady state accuracy. The control system is shown to have a good dynamic response and steady state accuracy by the Matlab/Simulink simulation analysis. At last, the thesis introduces the hardware circuit design of the three-level inverter control system based on TMS320F28335, and experimental study. SVPWM algorithm is proved to be correct, midpoint potential balance control strategy is proved to be effective, by the result of the experiment. The control system is also shown to have a good dynamic response and steady state accuracy by the result of the experiment, and achieves the purpose of decouple control on the flux and torque of the induction motor.