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FLC-Based DTC of Induction Machine with Variable Amplitude Control of Torque Hysteresis Band to Improve Dynamic Performance

Anet Jose, ShanifaBeevi S.

This paper focuses on the direct torque control (DTC) of induction motor drive (IMD) using multiple Fuzzy Logic Controller (FLC). In DTC the torque and flux of an induction motor can be controlled directly by applying a suitable voltage vector to the stator of an induction motor. But the major drawback with the conventional DTC scheme is the presence of high torque ripples along with stator flux ripples. The deviation of electromagnetic torque from its set value causes vibrations and noise which reduces the efficiency of motor. Thus, the fuzzy logic controller (FLC) is used to adjust the bandwidth of the torque hysteresis controller in order to reduce the torque and flux ripples and, hence, to improve motor dynamic response. Also in conventional DTC, PI controller is used in the speed controller. PI controller is more suitable in steady state condition and for linear system. But since DTC along with IM is mostly nonlinear, fuzzy controller will be more suitable. Fuzzy controller performs well in nonlinear systems than PI controller. In this paper the DTC principle and its formulation is discussed and a Simulink model of fuzzy logic controlled DTC drive is developed. Finally the simulation results of conventional DTC drive and FLDTC drive are compared.