A Fault-Tolerant 24-Sided Voltage Space Vector Structure for Open-End Winding Induction Motor Drive

This article proposes a method of generating 24-sided polygonal voltage space vector structure composed of 24 real active vectors and a zero vector. Each active vector is a real vector in contrast to switched average vectors in literature. Generation of real 24-sided vectors minimizes switching losses and improves quality of phase voltage compared to switched averaged vectors technique. An important feature of the presented scheme is elimination of lower order harmonics up to 19th order from motor phase voltage throughout the modulation range that gives reduction in torque pulsation and near sinusoidal phase current. The proposed scheme extends the linear modulation range till 99.42$\%$. Open-end winding induction motor is fed with primary and secondary inverters from either ends. Primary and secondary inverters are implemented by cascading two-level inverters. DC sources for both the inverters are realized using a simple star-delta transformer combination. The proposed concepts are verified with laboratory prototype and the respective results during the steady-state, transient, and fault scenario are presented. The supporting loss analysis and harmonic performance of the proposed drive is performed with existing topologies.