Improved Direct Torque Control Method of Brushless Doubly-Fed Reluctance Machines for Wind Turbine

Direct Torque Control (DTC) method is an excellent technique for torque and flux control for a brushless doubly-fed reluctance machine (BDFRM). The advantages of the DTC method are simple implementation, fast response and little dependence on the machine parameters. However, the conventional DTC method has high torque and flux ripple and variable switching frequency problems. This paper proposes an improved DTC method for the BDFRM when used in wind power generation systems. The Space Vector Modulation (SVM) method is used for reducing the torque and flux ripple, and also for holding constant the switching frequency of the inverter. The control method is implemented in SIMULINK (R)/MATLAB (R) and the results show that the proposed DTC method can overcome the issues and problems associated with the conventional DTC method and improve the system operation performance.