Three-dimensional space vector modulation for a four-leg three-level inverter

The trend toward deploying inverters in interfacing distributed generation (DG) systems to the grid has raised the importance of control and power quality aspects of inverters. Using multilevel inverters in DG systems, one can achieve high power quality outputs with realistic switching frequency. The four-leg three-level inverter topology is proposed for DG applications in three-phase four-wire systems, for its full DC-link utilization and low voltage ripple on the DC-link capacitors. A novel algorithm for three-dimensional space vector modulation (3D-SVM) is proposed for controlling a four-leg three-level inverter. The issues of vector selection and switching sequence determination are described. Simulation results are compared with those of a three-leg three-level inverter to assess the effectiveness of the proposed 3D-SVM and to establish the advantages of the four-leg three-level topology over conventional three-leg three-level one