DC harmonic distortion minimization in series connected converters with AC filters under unbalanced power supply

In converters system, the supply voltage can be in unbalanced condition for some reasons, and noncharacteristic harmonics will be produced in both DC and AC side. This paper proposes an analytical method for calculating the harmonic currents in series connected converters under unbalanced supply conditions. Then a minimization method used asymmetrical firing angles for the noncharacteristic harmonics in DC side is presented, it is solved by the numerical method. With the adaptive firing angles, the quality of DC side current will be improved. The validity of the proposed method is confirmed by results of simulation.