A new low cost AC-DC converter with high input power factor

This paper presents a new topology to improve the power factor in noncontrolled three-phase AC-DC converters. The technique consists of the addition, between each two lines, of a switch capable of conducting current in both directions, along with the inductive filter to the DC side. The switches operate during the intervals which the diodes do not conduct, allowing an alternative path for phase currents to circulate during these intervals. The conduction time of the switches is reduced compared to the operation period of the converter. So, the switches process little power which means a low increase in the converter cost. The converter principle of operation and its characteristics are described. Simulations results and an experimental laboratory set-up are presented to assess the performance of the technique