This paper proposes a generalized method for the generation of space vector pulse width modulation (SVPWM) signals for multilevel inverters. In the proposed method, the actual sector containing the tip of the reference space vector need not be identified. A method is presented to identify the center of a sub hexagon containing the reference space vector. Using the center of the sub hexagon, the reference space vector is mapped to the innermost sub hexagon, and the switching sequence corresponding to a two-level inverter is determined. A new technique is proposed in this paper, by which these two-level vectors are translated to the switching vectors of the multilevel inverter by adding the center of the sub hexagon to the two-level vectors. The proposed method can be extended to any n-level inverter, and a generalized algorithm is proposed. The scheme is explained for a five-level inverter, and experimental results are presented for a three-level inverter and seven level Inverter.
Using space-vector PWM with variable modulation frequency in multilevel inverters of precision electric drive systems
