Extensible Z-Source Inverter Architecture: Modular Construction and Analysis

Z-source inverter (ZSI) can overcome some drawbacks of classical current- and voltage-source inverter, which have features such as high reliability and buck-boost capability of single-stage inverter. This article proposes an extensible ZSI architecture, abbreviated as EZSI. The proposed architecture provides high voltage gain at a small shoot-through duty ratio, which improves the output waveform quality. It inherits the advantages of continuous input current and low dc-link voltage overshoot of quasi-ZSI. The EZSI can be constructed with modularization, using low voltage components to construct a high-power single-stage inverter. A modular analysis method of EZSI is proposed, which divides the high-dimensional state equation of inverter into several independent low-dimensional state equations and simplifies the research of EZSI. A typical EZSI (n = 2) L-mSSCL validates the correctness and feasibility of the proposed theory. Compared with the conventional high boost ZSIs, the proposed EZSI (n = 2) L-mSSCL has advantages in the aspects of boost capacity, component stress, and inverter efficiency. The operating principle, characters design rules, and power dissipation of the components is analyzed in detail. A 1-kW prototype is used for experimental validation. The theoretical analysis results match with the experimental results.