An Enhanced Control Strategy for AC–DC Matrix Converters Under Unbalanced Grid Voltage

Under unbalanced grid voltage conditions, an ac-dc matrix converter (MC) induces ripple on the dc side, as well as severe grid current harmonics. To overcome these problems, an enhanced control strategy for an ac-dc MC based on an independent control scheme for the active and reactive powers is proposed in this paper. The generated current reference is directly synthesized from instantaneous power analysis in a stationary frame, and a constant dc voltage and current and sinusoidal grid current are obtained. Moreover, the input power factor (IPF) becomes almost unity due to the reactive power control, in spite of unbalanced grid voltage conditions. There is no need to extract grid voltage components such as the positive and negative sequences, and a controller for the grid current is not required, in contrast to previous methods. Thus, the proposed control method can be implemented easily without a large storage requirement. Simulation and experimental results are presented to verify the effectiveness of the proposed control strategy.