Generalized Synchronous Optimal Pulse Width Modulation for Multilevel Inverters

With the growing interest of the industry in high-power medium-voltage multilevel inverters and the technological limitation in high voltage power semiconductors switches, synchronous optimal pulse width modulation techniques, originally developed for two-/three-level inverters, became again a topic of interest, now to optimize multilevel waveforms. This work proposes a novel formulation for the problem of optimizing the modulation pattern of multilevel converters, including in a single optimization problem the decision of the directions for each step transition in addition to the switching angles and, thus, completely defining the optimized multilevel waveform at a given modulation index. In addition, experimental results are presented in order to demonstrate the effectiveness of this optimized modulation technique exemplar applied to a five-level NPC H-bridge feeding a permanent magnet synchronous motor.