A Novel Line Frequency Chopper-Based Rectifier With Input Filter for Enhanced Power Quality

We have previously proposed a hybrid rectifier that consists of a diode rectifier and a series chopper that operates at the line frequency with the input current total harmonic distortion (THD) of 16.4% and 28% at the primary and secondary side, respectively, of a balanced three-phase transformer. This paper focuses on further reduction of the input current THD using an input LC filter. Generally, an LC filter at the input of a diode rectifier reduces the input current THD, however, it introduces a lagging phase as well resulting in a reduced power factor. To mitigate the lagging power factor, the proposed rectifier can be operated with a leading phase controllable through the switching angle of the series chopper. Hence, an appropriate design of an input LC filter reduces the input current THD without degrading the input power factor. The proposed approach is presented with simulations and hardware results showing a significant reduction in the input current THD to 7% with a displacement factor close to unity.