Improved Direct Torque Control of DFIG with reduced torque and flux ripples at constant switching frequency

Abstract

This paper presents a modified hysteretic controller to improve Direct Torque Control (DTC) of the Doubly-Fed Induction Generator (DFIG) to achieve constant switching frequency and reduced torque and flux ripples. The proposed controller generates appropriate voltage vector with variable magnitude and angle, in order to reduce those ripples. The Space Vector Modulation is employed to apply the reference voltage vector to rotor windings. Other advantages of DTC methods such as fast dynamic response and simple coordinate transforms are preserved. The experimental results verify the advantages of this method compared to conventional DTC.