A twelve-pulse converter under unbalanced input voltages

This work introduces the relationship between the input/output voltage/current in a 12-pulse converter using the transfer junction approach. A 12-pulse converter although very successful in eliminating the characteristic low order harmonics, fails to do so when the supply becomes unbalanced or distorted. This is attributed to the generation of the new non-characteristic harmonics, which were totally absent under ideal supply conditions. Operation of the proposed converter is investigated under a standard 5% unbalance and a selected distorted input voltage conditions. Harmonic voltage/current propagation to the converter input/output and the dc link sides are analyzed and confirmed by the prototype results and some simple solutions are presented