Effect of frequency modulation on input current of switch-mode power converter

Comprehensive theoretical analysis of the effect of switching frequency modulation (SFM) on input current of DC/DC switch-mode power converters (SMPC) operating in discontinuous conduction mode (DCM) is presented. Theoretical and SIMULINK simulation results are verified experimentally. Peak input and power components currents increase and low-frequency harmonics appear in the input current due to the use of SFM. Some considerations on the right choice of modulation parameters to reduce the negative effects considering also output voltage ripples and electromagnetic interference attenuation are proposed. The analysis performed can be very useful for a design of DC/DC SMPC with SFM in DCM.