Conducted EMI Suppression by Random Carrier Frequency Modulation Techniques

摘要

Random Carrier-Frequency (RCF) control mode is a new control scheme. When applied to DC/DC converters, it reduces conducted EMI significantly. However, limited theoretical studies about RCF control mode are available. In this paper, the analytical expression of the amplitude of voltage power spectra density in the RCF mode is deduced. The level of randomness is defined .The effects of the level of randomness on reducing the peak level of the power spectra density are analyzed .Theoretical predictions are confirmed with experiment. Finally special attention is given to the output voltage ripple under different spread spectrum modulation techniques.