Operation, Control and Verification of Seven-Level Quasi-Z-Source-Based T-Type Inverter

Abstract

In this paper, a novel seven-level Quasi-Z-Source-based [Formula: see text]-type inverter (7L[Formula: see text]qZST[Formula: see text]) is proposed. The proposed inverter is an upgrade of Quasi-Z-source (qZs) network and seven-level [Formula: see text]-type inverter. The 7L qZST[Formula: see text] comprises of three qZs-based impedance networks, two bidirectional switches and an [Formula: see text]-bridge inverter. It owns the advantages of reduced switch count, improved output voltage gain, enhanced reliability and better quality of output voltage and current. The performance of the proposed topology is tested for two different pulse width modulation techniques based on shoot-through control. The first technique offers simple control and operated at a fixed shoot-through duty cycle for realizing output voltage level. The second technique facilitates independent control of each qZs network dc-link voltage and they can be operated at different shoot through duty cycle which overcomes the limitation of first technique with better quality in output voltage. The detailed operation of the proposed topology and control schemes have been elaborated for different switching states for each output voltage level generation. Extensive simulation and experimentation are performed for both the switching schemes to verify their performance under steady state and dynamic conditions. Furthermore, a brief comparison is constructed to highlight the merits of the proposed inverter with conventional topologies.