The Research Of Variable Frequency Speed Regulate Technology Based On Three Level Direct Torque Control

Recent years, multilevel inverters as a hot pot of high voltage and high power application of converter technology are widely used in high voltage variable frequency speed regulate technology and flexible AC transmission systems. The method of high-voltage converter technology combined with direct torque control (DTC) and three-level inverter made it lower harmony and switches with small voltage. So it is meaningful.This paper analyzed three level direct torque control and space vector pulse wide modulation based on many domestic and foreign literatures about induct motor DTC and high voltage inverters. This paper established three level mathematical model in dq coordinate system and three level induction motor united mathematics model. Another, paper analyzed signal space vector method and composed victual vector method of three level DTC. A new vector select method composed of fuzzy control and victual vector control was introduced and used in three level DTC field. At last, Simulation model are established by use of Matlab/Simulink toolbox. This method optimized the effect of three level DTC and solved the inherent problem of mid-point voltage balance in three level inverter, lowered the harmony of inverter. This paper completed the main circuit and control circuit. Software algorithms and flow charts are given.