Harmonic Modeling of a Cluster of ac/dc Converters

Accurate evaluation of current harmonics produced by a cluster of ac/dc converters requires accurate computation of overlap angles. The proposed approach, based on a hybrid time-frequency domain method, takes into account supply voltage unbalances and harmonics, transformer and commutation impedances and interactions among converters. The accuracy and speed of execution of the proposed algorithms is shown by comparing simulation results to those obtained with a commercial time domain simulation package. It is shown that attenuation, diversity and supply voltage unbalance are important aspects that must be taken into account to accurately predict the amplitudes and angles of current harmonics