A Single DC Link Four Level Multilevel Inverter with Increased DC Bus Utilization for Drives

The paper proposes a low switch count multilevel inverter topology having a four-level space vector structure. The proposed MLI demonstrates a reduced number of active switches in relation to the number of output voltage levels. This inverter has an increased DC bus utilization, reaching up to 0.637 times the DC link voltage compared to the conventional multilevel inverters limited to 0.577 times the DC link voltage.The proposed multilevel inverter configuration integrates a two-level inverter with a cascaded H-bridge (CHB) converter in each phase. The each CHB capacitor voltage are regulated to one third of dc link voltage. The enhanced utilization of the DC bus voltage is due to the space vector redundancies provided by the CHB units. Both simulation and experimental validation of the proposed scheme are conducted on an induction motor drive across for various operating conditions. Field-oriented control (FOC) is employed to control the speed of the induction machine, while examining capacitor balancing under various transient conditions.