Carrier-Based Modulation Technique to Reduce Low Frequency Ripple at the Partial Dc-Link Voltages of a Three-Level/-Phase/-Wire NPC Converter Applied

摘要

This work proposes a modulation technique for a three-phase/-wire/-level Neutral Point Clamped converter (NPC) aiming to reduce low frequency (LF) neutral point current components in future dc bipolar distribution network applications. The technique is based on the analysis of three-level converters in the abc reference frame, where the ac measured currents and duty-cycle signals are used to calculate the 0-axis duty-cycle, which ensures that the capacitor dc-link LF current components are eliminated, even when loads/microgeration units inject LF currents to the network central line. Simulation results validate the proposed technique.