Study of Quasi-Z-Source Cascaded H-Bridge Multilevel Inverter with Voltage-Lift Cell

Background/Objectives: Quasi-Z-source based multilevel inverters have attracted much interest in recent research works due to its valuable merits when evaluated with conventional voltage source inverters and Z-source Inverters. The objectives of this research work is to provide lower power rating of power devices, continuous input current, higher boosted output voltage and reduced current stress for dc source. Methods/Statistical analysis: A new quasi-Z-source Cascaded H-Bridge multilevel inverter with voltage-lift cell (VL-qZS-CHB-MLI) is analysed in this research paper. The performance of the VL-qZS-CHB-MLI is verified through simulation results obtained using multicarrier PD-PWM technique with simple boost control strategy. Shoot-through states are introduced in generated pulses by utilizing the simple boost control technique. Extended boost operation of the proposed topology is provided by the shoot-through states. Findings: In this new proposed topology, the presence of voltage-lift cell significantly strengthens the boost capability for the equal shoot-through duty ratio as in traditional qZS-CHB-MLI. The proposed topology involves lower shoot-through duty ratio as in the qZS-CHB-MLI for achieving the same boost gain. This advantage of the proposed topology makes possible the larger improvement in the output voltage. Application/Improvements: The proposed topology can be popularly utilized for high-power applications requiring good quality boosted output and low voltage stress. Also, the proposed topology offered abundant merits over traditional Cascaded H-Bridge (CHB) multilevel inverter in distributed power generation applications like PV power system and wind energy system.