DC-link Voltage Balancing Algorithm Using a Space-Vector Hysteresis Current Control for Three-level VSI Applied for Wind Conversion System

One of the most inherent problems of the multi-level NPC topology is to maintain the neutral point voltage in a narrow band around the half of the DC voltage. This paper presents a DC-link voltage balancing algorithm for three-level voltage source inverter using a new space-vector based on hysteresis current control (SV-HCC). The proposed SV-HCC controls the active and reactive power delivered to the grid by the doubly fed induction generator (DFIG) by means of controlling its rotor currents. In addition, it controls the neutral point voltage using the redundant inverter switching states. Simple look-up tables are required for areas and sectors detection and also for vectors selection. The performance of the proposed control technique has been verified by simulation.