Level vector pulse width modulation for multilevel inverters

In this paper, a novel method named as level vector pulse width modulation (LVPWM) is proposed for multilevel inverters. Similar to the conventional space vector pulse width modulation (SVPWM), the proposed method is a vector-based method in the & alpha;-& beta; frame. Unlike the SVPWM, the variables of each of the & alpha; and & beta; axes are considered separately. Instead of space vectors, level vectors are considered for the synthesis of the reference vectors. There is no need to consider multiple switching states, vectors, and large lookup tables in the algorithm. The appropriate switching states for the synthesis of the reference vectors are determined using simple computations at each sampling time. Generality for different inverter topologies, online implementation, simplicity of the algorithm and computations, independency of the algorithm complexity from the number of switching states, and easy extension to overmodulation region are the advantages of the proposed method. Implementation of the LVPWM in different inverter topologies is studied. The validation of the proposed modulation strategy is carried out by simulation and experimental results.