The optimal control strategy for rectifier side of low switching frequency back-to-back converter

The industry application of High-power medium-voltage drives converter is an appealing spot in Power electronics technology in recent years. In this paper, an optimal control strategy for rectifier side of three-level NPC back-to-back converter under low switching frequency conditions have been presented. First, the power feed forward is applied for enhancing the dynamic characteristics in the circumstance of bidirectional energy flow. And the demand of three-level DC neutral point control is solved by using a modified asymmetrical regular sampling SVPWM whenever the energy is being used or feed backed. Simulation and experimental results based on a rectifier side of a 75 kVA three-level NPC back-to-back experimental prototype converter with a 400 Hz device switching frequency constraint show satisfactory performance.