Switching Loss Reduction in the Three-Phase Quasi-Z-Source Inverters Utilizing Modified Space Vector Modulation Strategies

Abstract

Several single-stage topologies have been introduced since kicking off the three-phase Z-source inverter (ZSI), and among these topologies, the quasi-ZSI (qZSI) is the most common one due to its simple structure and continuous input current. Furthermore, different modulation strategies, utilizing multiple reference signals, have been developed as well. However, prior art modulation methods have some demerits, such as the complexity of generating the gate signals, the increased number of switch commutations with continuous commutation at high current level during the entire fundamental cycle, and the multiple commutations at a time. Hence, this paper proposes two modified space vector modulation strategies, aimed at the reduction of the qZSI number of switch commutations at high current level for shorter periods during the fundamental cycle, i.e., reducing the switching loss, simplifying the generation of the gate signals by utilizing only three reference signals, and achieving a single-switch commutation at a time. These modulation strategies are analyzed and compared to the conventional ones, where a reduced-scale 1-kVA three-phase qZSI is designed and simulated using these different modulation strategies. Finally, the 1-kVA three-phase qZSI is implemented experimentally to validate the performance of the proposed modulation strategies and verify the reported analysis.