Analysis and Experimental Validation of Control Systems for Four-Leg Matrix Converter Applications

Matrix Converters (MCs) have some advantages when compared to conventional back-to-back PWM voltage source converters. The converter may be considered more reliable and it can be smaller because the bulky dc capacitors are eliminated from the topology. For ac to ac power conversion, the size and weight of the whole generation system can be much reduced when back-to-back converters are replaced by MCs. To supply electrical energy to an unbalanced 3F stand-alone load, a fourth leg is required to provide a path for the zero-sequence load current. To regulate the load voltage, closed-loop control is required. In this paper, the application of d-q controllers and resonant controllers to four-leg MCs is addressed. The design and performance issues of the controllers, for operation with balanced, highly unbalanced loads and nonlinear loads are discussed in this paper. Experimental results obtained from a small prototype are presented and analysed in detail.