Hybrid space vector pulse width modulation based direct torque controlled induction motor drive

The major disadvantage of the conventional DTC drive is the steady state ripples in torque and flux. The implications are, increase in acoustical noise, harmonic losses and incorrect speed estimation. Using space vector modulation (SVPWM) technique it is possible to reduce the mean square flux ripple up to base speed. In this paper a new hybrid SVPWM based adjustable-speed DTC drive is proposed. This hybrid modulator utilizes the zero voltage vector redundancy that leads to clamping sequences. This improves the performance of the drive compared to that using conventional sequence used in SVPWM technique at higher speeds. Simulation results show that the ripples in flux, torque and current are reduced over the entire speed range.