AC side equivalent circuit-based method for harmonic analysis of a converter system

A new method that can be used in the calculation of characteristic harmonic components generated by a converter system is described. This is based on modulation theory and an AC side equivalent circuit for a converter is derived. The effects of the commutation overlaps and impedance are correctly represented providing that the overlap angles are known. Using this method, the entire harmonic calculation can be performed at the 4C side of the converter, thus substantially simplifying the harmonic analysis process. This method is particularly useful when information on the DC link is not needed. A new understanding into the mechanism of harmonic generation in converter systems is also provided.