A New Space Vector Modulation Strategy to Enhance AC Current Quality of Isolated DC-AC Matrix Converter

The isolated dc-ac matrix converter is a promising option to connect dc system and ac system, performing directional power conversion and providing galvanic isolation. Due to the absence of the bulky dc-link capacitor, the converter can be compact. However, when a conventional modulation method is applied to the converter, the coupling of H-bridge and matrix converter will result in numerous harmonics in ac current. This article proposes a new space vector modulation (SVM) strategy for isolated ac-dc matrix converter. It improves the duty cycle calculation to reduce the harmonics in ac current while the number of switching actions remains low. Furthermore, considering the essential commutation process of matrix converter can also impact waveform quality, two-step commutation and optimized zero vectors are adopted to reduce narrow pulsewidth modulation pulses, ensuring the gating signals are always long enough to finish commutation. Simulation and experimental results are provided to verify the performance of the proposed SVM strategy.