Study On Direct Torque Control Of Induction Motor Fed By Three-level Voltage Source Inverter

In recent years,the multilevel inverter has already become the modulation domain in the high voltage frequency conversion field. It has significant advantages,such as less distorted output,lower switching frequency,etc,and It has reality energy conservation significance in application of the high- voltage and high-power. Direct Torque Control (DTC) has attracted popular interest because of its high performances.In this thesis,a direct torque control of induction motor based on a three level inverter is to be proposed.Theoretical analysis, simulations and experiments are made to prove the validity of the proposed algorithm.By the analysis of a three level inverter and direct torque control, the mathematic models of both induction motor and a three-level inverter are built and the direct torque control algorithms are analyzed. At last give the simple project to choose the voltage vector between low and high speed. According to the different influence for low and high speed at the same voltage vector.Some simulations have been made by the MATLAB/SIMULINK software package. And a self-made set has tested the platform,and take the diode three level invertors of clamping type as the foundation frequency conversion velocity modulation,including:Main power electric circuit,cushion circuit,electro-optical isolation driving circuit, electric current,voltage sampling circuit,protection circuit and so on,and through the familiar of DSP algorithm, a control system has been designed with digital signal processor TMS320LF2407 as the core. through a series of experiments to the principle prototype,the invertor control policy, the frequency conversion velocity modulation and so on,and the experiment profile has been given,simultaneously the feasibility of the system has also been proven .