A Multilevel Inverter Configuration for an Open-End-Winding Pole-Phase-Modulated-Multiphase Induction Motor Drive Using Dual Inverter Principle

This paper presents a multilevel inverter (MLI) configuration for open-end-winding pole-phase-modulated-multiphase induction motor (PPMMIM) drives. The proposed MLI configuration consists of one nine-phase two-level inverter and three 3-Φ two-level inverters. In pole-phase modulation, increasing the number of poles decreases the number of phases that increases the space harmonics in air gap flux. Moreover, in high-pole mode of PPMMIM drives, two-level voltage supply causes the high torque ripple that degrades the performance of the drive. Usually, conventional MLIs are not preferred for reducing torque ripple, due to the capacitor-balancing issues and more number of semiconductor devices. To address these issues, the proposed MLI configuration effectively utilized the inherent availability of the three identical voltage coils in the high-pole mode for reducing the torque ripple. The 3-Φ carrier phase-shifted space vector pulse width modulation (SVPWM) is used for generating the multistep voltage across the effective phase in high-pole mode as well as for shifting the lower order harmonics to higher order frequencies. Moreover, in low-pole mode, the dc-link voltage utilization of the proposed MLI configuration is improved by 13.8% with third harmonic injected SVPWM as compared to conventional 9-Φ SVPWM. Another important feature of the proposed MLI configuration is its ability to supply the two-level voltage under fault conditions. This feature notably improves the reliability of the PPMMIM drive. The finite-element method model of 5-hp nine-phase PPMMIM is designed in ANSYS Maxwell 2-D and is cosimulated with the proposed MLI configuration in Simplorer environment. The effectiveness of the proposed MLI-fed 5-hp MIM drive is experimentally verified for the entire modulation range.