An Improved SVM Strategy to Reduce DC Current Ripple for AC–DC Matrix Converter

The ac-dc matrix converter can facilitate the bidirectional interconnection between the utility grid and relatively low-voltage dc source/loads. To fulfill the grid codes and dc source/loads requirements, the ac-dc matrix converter shall produce low ripples in dc current and low total harmonic distortion (THD) in ac current. To improve the ac and dc current quality, this article proposes a new nine-segment space vector modulation (SVM), which optimizes the duty cycle of zero vector. Compared with the conventional nine-segment SVM strategy, lower THD of ac current and smaller dc current ripple can be achieved in the improved SVM strategy under any voltage condition with arbitrary power factor. To address the commutation problems, which is an important challenge to safely operate ac-dc matrix converters, a two-step voltage-based commutation strategy is applied to reduce commutation time. Simulation and experimental results are provided to verify the effectiveness of the improved SVM strategy.