Experimental validation of a Space Vector Modulation method for a 4-leg Matrix Converter

Most variable speed AC generation systems use back-to-back converters to supply electrical energy, with fixed electrical frequency and voltage, to a stand-alone load or grid. Matrix Converters (MCs) are a good alternative to back-to-back converters because they have several advantages in term of size and weight. Therefore MCs can be advantageously used in any variable speed generation system where high efficiency, reliability, small size and low weight are considered important factors. Possible applications are mobile power supply systems, variable speed diesel generation schemes and wind energy conversion systems. Nevertheless, to interface a MC-based generation system to unbalanced 3Φ stand-alone loads, a four-leg MC is required to provide a path for the zero sequence load current. However, the conventional Space Vector Modulation (SVM) algorithm used with 3×3 MCs cannot be applied to a four-leg matrix converter. Therefore, in this paper a SVM algorithm, adequate for the operation of a 3×4 MC is presented. The proposed modulation scheme is mathematically analysed and experimental results, obtained with an experimental prototype, are discussed.