Fuzzy Based Stator Flux Optimizer Design For Direct Torque Control
  Direct Torque Control (DTC) is well known as an effective control technique for high performance drives in a wide variety of industrial applications and conventional DTC technique uses two constant reference value: torque and stator flux. In this paper, a new fuzzy based stator flux optimizer has been proposed for DTC controlled induction motor drivers and simulation studies have been carried out with Matlab/Simulink to compare the proposed system behaviours at vary load conditions. The most important feature of the proposed fuzzy logic based stator flux optimizer that it self-regulates the stator flux reference value using the motor load situation without need of any motor parameters. Simulation results show that the performance of the proposed DTC technique has been improved and especially at low-load conditions torque ripples are greatly reduced with respect to the conventional DTC. 
Fatih Korkmaz, M. Faruk Cakir, Yilmaz Korkmaz, Ismail Topaloglu
cs.SY