A unity power factor forward converter

A novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented. The converter is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage. A detailed analysis of the operation is presented. A constant frequency current mode control provides excellent transient performance at the output and sinusoidal input currents at the input. Various tradeoffs involved in the design of the converter elements and control parameters are discussed in depth. All the results are backed up by experimental waveforms from a laboratory converter