An efficient method to calculate optimal pulse patterns for multi-level converters

Optimal Pulse Patterns (OPPs) permit setting the switching frequency of power converters to a low value without compromising on Total Harmonic Distortion (THD). The optimization, which is performed offline, is a slow procedure. For instance a normal PC might need up to several weeks to calculate OPPs for a five-level converter. This paper presents a general algorithm for calculating OPPs for multi-level converters. Where calculation time is highly reduced via reformulation of optimization problem and choosing proper initial values. The calculation procedure is explained in detail and compared with standard optimization algorithm for a five-level inverter.