Enhancement of Power Factor using Converters

New recommendations and future standards have increased the interest in power factor improvement circuits. There are multiple solutions in which line current is sinusoidal. In addition, in the recent years, a great number of circuits have been proposed with non sinusoidal line current. In the proposed circuit, the power factor is improved by using an auxiliary winding coupled to the transformer of a cascade dc/dc fly back converter. The auxiliary winding is placed between the input rectifier and the low-frequency filter capacitor to serve as a magnetic switch to drive an input inductor. The proposed approach is primarily based on the concept of inductive effect, from which PFC cells composed of energy buffers and high-frequency signals are introduced. Since the dc/dc fly back converter is operated at high-switching frequency, the auxiliary windings produce a high frequency pulsating source such that the input current conduction angle is significantly lengthened and the input current harmonics is reduced. Properly selecting an eligible PFC cell and inserting it in between input rectifier and dc-link capacitor can yield an SSC which can improve the input power factor significantly.