A repetitive control system for four-leg matrix converters feeding non-linear loads

Abstract

Generators working with variable speed, rather than fixed speed, have many advantages, which are well documented in the literature. Higher efficiency, better power to size ratio and less mechanical stress in the system are some of the characteristics of variable speed generators. In particular, variable speed diesel generators can be used to provide small highly portable generation systems for emergency vehicles and military/aerospace applications. Such systems can be used to feed stand-alone linear/non-linear loads if an adequate power converter interface is provided. Four-leg matrix converters can be used as the power electronic interface between variable speed generators and stand-alone loads. The fourth leg provides a neutral point for single phase loads and a path for the circulation of zero sequence currents. When non-linear loads are connected to the matrix converter output, relatively high harmonic distortion can be produced in the load voltage unless an appropriate control system is provided. In this paper the application of a repetitive control system to improve the quality of the load voltage is presented. Experimental results obtained from a prototype are shown and fully analysed.