Single-Phase Z-Source\/Quasi-Z-Source Inverters and Converters: An Overview of Double-Line-Frequency Power-Decoupling Methods and Perspectives

In this article, we investigate power-decoupling methods used in single-phase Z-source/quasi-Z-source inverters (ZSIs/qZSIs) to handle inherent double-line-frequency (2ω) power by comparing their implementation approaches and performances. Passive methods can be used to suppress 2ω ripples within the range of engineering tolerance by designing impedance networks, modifying modulation methods, or using closed-loop damping controls. Active power-decoupling methods eliminate 2ω ripples from the dc side by employing an active filter that buffers the 2ω ripple power. After we address the pros and cons of all methods, we apply a typical active method to a single-phase qZSI and a single-phase qZS matrix converter to demonstrate their high performance, promising perspectives, and potential applications.