Reserch On Asynchronous Motor Rotor Field Oriented Control System Baed On Three-Level Inverter

With the rapid development of power electronic technology, modern control theory, and microcomputer control technology, induction motor drive has also made a breakthrough, and is gradually developing to the direction of high-voltage and high power. Field oriented control is one of the most widely used speed control methods. Three-level inverter which can achieve higher voltage rating, output less harmonic content has been widely used in high voltage high power inverter occasions. Therefore, the study of the field oriented control of Asynchronous motor based on the three-level inverter has practical significance.This paper introduces the topological structure, switch status, and the working principle of the three-level inverter, analyses the SVPWM control strategy which suitables to the three-level inverter, studies the specific steps and methods of SVPWM control, including reginal judge,the calculation of vector time,vector sequence and the allocation of vector time, use the method of allocation vector sequence and time for decreasing the voltagetoneutral shift. This paper introduces the mathematical model of Asynchronous Motor in the three phase stationary frame and the method of coordinate transformation, according to the principle of magnetic field equivalent infers mathematical model of asynchronous motor in the voluntarism Reference Frame and the Synchronous Reference Frame. The coordinate transformation offers the condition for the field oriented control which imitates the DC Motor; analyzs the fundamental principles of the field oriented control, the model of rotor flux, uses the indirect method of observing the rotor flux. Infers the voltage reconstitution formula for three-level inverter on account of the direct method of observing the rotor flux; devises the asynchronous motor rotor field oriented control system based on three-level inverter, including flux closed cycle, rotate speed closed cycle, voltage feed forward compensation. This paper models and simulates the system by the MATLAB/Simulink, the results indicates:the output voltage of the three-level inverter is right, the rotor flux wave is correct, the voltage reconstitution method is right, the system has well dynamic performance when driving heavy load and pop-inload. The final, this paper designs the system hardware.