Investigation of AC/DC converter harmonics by an analytical based time-discrete approach

By investigating AC/DC converter harmonics in more detail, the interaction of AC and DC side as well as nonideal conditions have to be considered. This paper proposes a time discrete approach, which allows one to calculate analytically the steady state DC currents at the firing points of each thyristor, if voltage harmonics or asymmetries disturb the ideal operation conditions. This forms the basis for an effective and accurate evaluation of AC/DC converter harmonics, especially for the investigation of parameter dependencies and for the application in harmonic distortion studies. Selected examples demonstrate particularly the analytical description of the discrete DC currents.