Auxiliary Pulse Tripling Circuit with Low kVA Rating to Reduce Input Current Harmonic Distortion in 12 Pulse Rectifier

In recent years, to increase the number of pulses in 12-pulse autotransformer rectifiers (12-PARs) and reduce the input current total harmonic distortion (IC-THD), without increasing the cost and complexity, the technique of pulse multiplication circuit has been proposed. With this approach in this paper, to upgrade the rectifier structure from 12 pulses to 36 pulses, an auxiliary pulse tripling circuit (APTC) with a very small kilovolt ampere rate (a kilovolt ampere equal to 1.34% of the rated load power) is presented. The proposed APTC consists of an unconventional interphase transformer (UIPT) with two diodes in the primary winding and a single-phase diode bridge rectifier connected to the secondary winding. Also, the 12-phase autotransformer used in the proposed structure is based on a polygon connection with a very low kilovolt-ampere rate. As a result, the total kilovolt-ampere rate of the proposed 36-pulse autotransformer rectifier (36-PAR) is about 24% of the rated load power, which is much less compared to similar structures. Also, according to the simulation results, the IC-THD in the proposed rectifier is less than 3%.