Direct torque control of multilevel SVPWM inverter in variable speed SCIG-based wind energy conversion system

Direct torque control (DTC) theory has been successfully used in a variety of high performance industrial AC drives. This paper presents the application of DTC space vector modulation (DTC-SVM) to two and three level voltage source inverter (VSI) to improve the energy efficiency of a variable speed wind energy conversion system. Three different topologies are proposed to control the torque and flux of a squirrel-cage induction generator (SCIG) driven by a variable speed wind turbine. The main objective of this study is to improve the quality of energy of the wind energy conversion system by reducing torque ripples in the SCIG. Simulation results have shown that the proposed DTC-SVPWM with two or three levels inverter produced improved transient responses and reference tracking performance of the voltage in the generator and grid sides as well as the DC link. The overall simulation models have been implemented using Simulink and SimPowerSystems toolboxes.