Novel modulation schemes and switching pattern for Z-Source ultra-sparse matrix converter

Abstract

The Z-Source networks are recently being employed in the matrix converters (MCs) to overcome their main drawback, which is the low voltage transfer ratio (VTR). In spite of several Z-Source topologies introduced for the direct and indirect matrix converters, some important issues such as their modulation, operational modes, existing challenges in practical implementation, the design of an optimal switching pattern, and so on, have not been fully addressed in the literature. This paper focuses on cascaded Z-Source ultra-sparse matrix converter (ZSUSMC), where the Z-Source network is inserted between the rectifier stage and inverter stage of an ultra-sparse matrix converter. Provided discussions can be extended to other indirect MC topologies, such as sparse and very-sparse MCs, though. Two space vector modulation (SVM) schemes, with and without considering the zero state in the space vector rectification, are proposed, and then, their advantages and disadvantages are discussed. In addition, an optimal switching pattern, which ensures minimum number of changes in the switches states over the entire switching period, is proposed. Hardware-in-the-loop studies are carried out and performance of the converter under the proposed modulation techniques is evaluated. The proposed modulations are compared with a recent study and its superior performance in terms of input and output currents quality is confirmed.