Robust QFT-based control of DTC-speed loop of an induction motor under different load conditions ?

摘要

Electric AC drives in manufacturing processes are well known and extensively studied. Speed loops can be commonly constructed through a decoupling method like Direct Torque Control (DTC) or Field Oriented Control (FOC) and a PID controller, which lacks of robustness towards torque variations. In this work a robust speed controller is incorporated to a DTC; its robustness is applied to the settling time of the speed when the system is subjected to different load conditions, which vary from a low value to nearly its maximum. DTC-speed loop is linearly modeled through least squares identification method and its uncertainties are overcome through Quantitative Feedback Theory (QFT). Control objectives are achieved and simulated results are presented together with a traditional PI controller perspective.