Research On Direct Torque Control Technique For Asynchronous Induction Motor

Direct Torque Control (DTC) is a high dynamic performance speed control system developed after Vector Control Technology in two decades. DTC is a novel control technique which is quite different from field-oriented control, which allows the precise and quick control of the flux linkage and torque without calling for complex control algorithms.The paper analyzes systemically and completely the existing problems at low speed of DTC, analyzes the reasons, system based on analyzing some important parts,such as the arithmetic model of asynchronous motor inα?βcoordinates, the choice of voltage vectors and flux-linkages models, etc.This paper proposes a new strategy, and this method is indirect stator quantities control (ISC). This method analyzes the reasons reducing torque ripple under indirect stator quantities control. The effect is very obvious to reduce torque ripple. Adopting voltage vectors to synthesize the voltage we need, and this method is simple.In the environment of Matlab, uses the power system block to build a simulink model. Compared the traditional DTC and indirect stator quantities control (ISC) based on the simulink results, the results shows that the breadth of flux linkage is steady, and control the shape of flux linkage in round. The improved DTC has a good performance, which proves the validity of the method put by the paper.