In this project, compensation of the dc-side voltage harmonics of a medium-voltage (MV) 12-pulse ac/dc converter is achieved using a series active power ﬁlter (APF). The output voltage harmonics are dependent on the converter ﬁring delay angles and, consequently, on the speciﬁc power locus followed by the ac/dc converter. This power locus ensures minimum ﬁfth and seventh harmonics (total rms) in the input current which provides minimum input current total harmonic distortion when the reactive power is less than 0.5 p.u.
The series APF is connected between the load and the converter output via a magnetic ampliﬁer to eliminate the dc current from the APF inverter, thus reducing inverter losses. Voltage harmonic compensation using a series APF,with and without a magnetic ampliﬁer, is examined with both resistive and inductive loads.