The Study Of Doubly-fed Induction Motor Based On Direct Torque Control Technology

As the excellent performance in speed adjustment, doubly-fed electric motor have broad application prospects. Especially in terms of fan and pump load, doubly-fed motor control system is a more reasonable program., which widely used in water and wind power generation system because of its more reliable and more effective characteristic.Direct Torque Control technology (DTC) has been widely used in the case of cage rotor induction motors and the good results are obtained. Direct torque control technology is a efficient AC motor control method which bases on space voltage vector and direct optimum control the inverter switching state to achieve the high-dynamic performance of torque.In this paper, Direct Torque Control technology is applied in a doubly-fed electric motor speed adjustment system and the detailed blue print is designed based on the analysis of the model of motor and stationary coordinate transformations, the torque and electromagnetic equation can be gained in the rotor coordinate system. The mathematical model of grid-side converter is analyzed, then the control model of converter is achieved. After studying the DTC technology, the approximate circle flux control method is adopted. Based on this method, the simulation has been done by MATLAB/Simulink the simulation result verify that the method of approximate circle flux control is feasible.The experimental system for doubly-fed motor speed adjustment is constructed. The experiment is based on simulation done before, the experimental results and analysis are given which all prove the theory, obtained expectant effect.