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 deri
ved. The effects of the commutation overlaps and impedance are correctly re
presented providing that the overlap angles are known. Using this method, t
he entire harmonic calculation can be performed at the AC side of the conve
rter, thus substantially simplifying the harmonic analysis process. This me
thod 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.