Applying FM control to PFP converters

The basic DC-DC converters (boost, forward, flyback, Zeta, Sepic and Cuk) can work as power factor preregulators (PFP). These converters can be designed to obtain unity or near unity power factor (PF) values. In this paper, a method for high frequency electromagnetic interference reduction using the frequency modulation (FM) approach is described for all these converters. Results show that a reduction of the conducted electromagnetic interference (EMI) generated by these converters is possible using the FM technique. The price to pay for this EMI attenuation is a mean reduction in the power factor, except for the boost converter which works as an ideal PFP in FM mode.