Performance Enhancement of PPMIM Drives by Using Three 3-Phase Four-Leg Inverters

Abstract

In this article, a multilevel inverter (MLI) scheme is proposed for 9-phase pole phase modulated induction motor (PPMIM) drives. The proposed inverter scheme is realized with the help of three 3-phase four-leg inverters. In 3-phase 12-pole mode (3PH-12PO), the proposed MLI supplies a 3-level voltage for each phase winding of the PPMIM drive with an improved harmonic profile, which results in better torque ripple. In this mode, the PPMIM drive performance is analyzed with a level shifted as well as phase shifted carrier based space vector pulse width modulation (SVPWM) techniques. On the other hand in 9-phase 4-pole mode (9PH-4PO), with help of phase grouping concept a 3-phase SVPWM implemented for enhancing the linear modulation of the 9-phase PPMIM drives by 15.4%. The fourth leg present in each 3-phase four-leg inverter is used effectively for suppressing the circulating currents in phase windings during 9PH-4PO operation. The proposed MLI is efficient to operate the PPMIM drive in both normal as well as fault conditions with rated power/torque. The proposed MLI-fed PPMIM drive performance with open circuit/short circuit of switch and source fault conditions are analyzed. The proposed MLI scheme is validated with the Ansys Maxwell finite element method (FEM) as well as laboratory testbed on a 5-hp 9-phase PPMIM drive under normal as well as open circuit switch/source fault conditions.