A Novel Source Current Control Strategy and Its Stability Analysis for an Indirect Matrix Converter

Indirect matrix converter (IMC)'s source current may contain low-order harmonics caused by asymmetric modulation in a variable-speed-constant frequency generation system. However, without capacitor/inductor decoupling effect, IMC's source current depends on loads and cannot be controlled independently. In this paper, the expressions of source current harmonics in the synchronous rotating reference frame are analyzed first. It leads to the conclusions that the only uncontrollable part of the source current is its d-axis dc component, and the quality of the source current can be improved by suppressing the harmonics. On the basis of above analysis, a novel source current control strategy is proposed for an IMC with asymmetric modulation, which can improve the source current quality and correct the input power factor. Self-tuning resonant controllers and a proportional integral controller are employed to achieve above goals. The stability of the system is also analyzed considering the change of input impendence after adding the source current control, which can be used as the guidance for the selection of control parameters. Finally, the validity and the feasibility of the control strategy are verified via experiments.