Modulation of three-level Z-source indirect matrix converter

Abstract

This paper proposes an actively controlled three-level Z-source matrix converter with capability of performing output voltage buck-boost, and producing sinusoidal input-output quantities. The converter is in principle realized by inserting a Z-source impedance network to the dc-link of the otherwise voltage-buck only indirect matrix converter (IMC), formed by cascading a front-end current source rectifier and a rear-end three-level inverter together. Topology wise, the proposed converter is therefore not distinctly different. Rather, the focus is on its modulation control, whose hidden details, different from those of traditional IMC, must be unveiled before voltage buck-boost and sinusoidal input-output quantities can be produced simultaneously, together with a lower commutation count and narrow pulse avoidance. This theme of investigation is now pursued in the paper with the converter operational modes and optimal modulation possibilities discussed extensively to bring forth its attractiveness for ac-ac buck-boost energy conversion, as validated in simulation.