Harmonic propagation in high power converter under unbalanced and distorted input voltages

This work analyzes the relationship between the input/output voltage/current in a 12-pulse converter using the transfer function approach. A 12-pulse converter although very successful in eliminating the low order harmonics, fails to do so when the supply becomes unbalanced. 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. It is demonstrated that a specially designed PWM converter should be able to minimize the effect of small degree of unbalance and distortion in the input voltage.