A Five-Level Torque Controller Based DTC Scheme for Open-End Winding Five-Phase IM Drives With Single DC Source and Auxiliary Plane Harmonic Elimination

This article presents a new five-level torque hysteresis based direct torque control scheme for dual inverter fed five-phase induction motor drives with open-end stator windings. Three voltage levels required to implement the five-level torque hysteresis controller are generated by combining the appropriate voltage vectors of the two inverters. The proposed scheme ensures that the harmonic voltages in the nontorque producing auxiliary plane are nullified in every switching period. Since the switching voltage vectors are realized using adjacent and nonadjacent line voltages, the magnitude of the voltage appearing across the windings is much higher compared to the conventional star connected five-phase drive, for the same dc link voltage. This feature reduces the dc link voltage requirement substantially for a given motor voltage. The switching scheme employed prevents circulation of common mode currents even when a common dc source is used for feeding both inverters. The proposed scheme is experimentally verified on a five-phase induction motor drive with open end stator windings. The control scheme is implemented using TMS320F28335 digital signal controller.