Fuzzy logic speed control and adaptation mechanism-based twelve sectors dtc to improve the performance of a sensorless induction motor drive

Abstract

The direct torque control (DTC) was proposed as an alternative to vector control. This strategy uses as a base the direct determination of switching states of the inverter and provides a simpler scheme and less sensitivity to machine parameters. However, the variable switching frequency of DTC engenders high flux and torque ripples which conduct to an acoustical noise and degrade the performance of the control, especially in low-speed regions. In the objective of improving the DTC performance for the induction motor operation, this paper inscribes a modified version of DTC by increasing the number of sectors and inserting a nonlinear fuzzy regulator in the speed regulation loop, in order to ensure a robust control contra different uncertainties and external disturbances. The goal is to achieve a significant reduction of the high ripples of the conventional DTC, which are the major drawbacks. Furthermore, the sensorless control can increase reliability and decrease the cost of the control system. Therefore, a Luenberger observer-based fuzzy adaptation mechanism is implemented to improve speed and flux observation.