Comparative performance analysis of decoupled SVPWM techniques for a four — level open end winding induction motor drive

Multilevel Inverters (MLIs) are extensively being used in high-performance AC drives owing to their increased efficiency and improved harmonic performance. MLIs also facilitate the use of semiconductor switching devices of lower voltage rating for high DC bus voltages. Several MLI topologies are in use to which the dual-inverter fed Open-End Winding Induction Motor Drive (OEWIMD) is a recent addition. A four-level OEWIMD is implemented with two unequal DC - link voltages, which are in the ratio of 2:1. In this power circuit configuration, the DC-link capacitor of the inverter operating with lower voltage is susceptible to the problem of overcharging. It was shown in earlier literature that the Decoupled Space Vector PWM (SVPWM) schemes, namely, the Equal Duty SVPWM (EDSVPWM) and the Proportional Duty SVPWM (PDSVPWM) can avoid this unwanted phenomenon. In this paper, with the aid of an improvised loss model, the thermal performance of the OEWIMD using these two SVPWM schemes is critically compared. Simulation results indicate that the EDSVPWM is effective for the reduction of the power loss of the overall OEWIMD system, which includes the dual-inverter system and the motor. In contrast, the PDSVPWM scheme results in the reduction of the power loss in the dual-inverter system only.