A comparative study of four bidirectional sparse matrix converter topologies for wind power applications

Recently, sparse matrix converters are gaining the researchers´ attention as an improved alternative to traditional matrix converters thanks to the advantages they offer by reducing their number of semi-conductor switches. Three major solutions are found in the scientific literature to increase the voltage transfer ratio limited so far to 0.86; the reverse operation of the matrix converter, the over-modulation of the matrix converter and the introduction of a Z-source network in the dc stage of the converter. In this paper, the Very Sparse Matrix Converter (VSMC) is adopted since it presents the smaller number of switches in the family of bidirectional matrix converters. It is simulated in three configurations designated to increase the voltage transfer ratio while improving the overall performances of the converter in order to facilitate its implementation in the wind conversion systems. First, the VSMC is simulated in normal operation, then in reverse operation. Second, it is simulated with the cascaded Z-source network and finally with the series Z-source network. All four configurations are compared in terms of voltage transfer ratio improvement and output voltages and currents waveforms. Then, further analysis is carried out for the cascaded and series Z-source configurations in order to compare both arrangements. The series Z-source VSMC presents better performances in terms of output current THD and Z-source components reduced constraints.