Harmonic pollution and low power factor in power systems caused by power converters

Harmonic pollution and low power factor in power systems caused by power converters have been of great concern. This investigation aims to identify a low cost, small size, efficient, and reliable AC to DC converter to meet the input performance index of Uninterruptible Power Supplies (UPS). The study examines the performance of single phase and three phase AC to DC converters alongside various control techniques. A novel AC/DC converter based on a quasi-active power factor correction (PFC) scheme is proposed, improving power factor using an auxiliary winding coupled to the transformer of a cascade DC/DC flyback converter. The auxiliary winding creates a high frequency pulsating source which extends the input current conduction angle, thereby reducing input current harmonics. The design incorporates a single inductor, substantially lowering costs and enhancing system efficiency. Furthermore, a buffer capacitor is employed to maintain a constant power factor by compensating for the inductive components, eliminating the need for active switches and control circuits for PFC. Simulation results are presented with an R-load to validate the proposed circuit's effectiveness.