An Interface for Renewable Energy Sources using a Multilevel Rectifier with Enhanced DC Link Control

This paper the control of the neutral point current in a Neutral Point Clamped Rectifier. This control ensures that the voltages across the DC link capacitors remain equal, even in the presence of unbalanced loads or sources in the DC side. The method employs an offset which is added to each of the inverter modulation waves. This offset causes a zero sequence voltage in the rectifier which can drive the desired neutral point current to counteract the unbalanced capacitor currents. Simulation and experimental results confirm the method.