A comparative investigation on the use of random modulation schemes for DC/DC converters

A comparative investigation on the use of random modulation schemes for dc/ dc converters is presented. The modulation schemes under consideration incl ude randomized pulse position modulation, randomized pulsewidth modulation (PWM), and randomized carrier-frequency modulation with fixed and variable duty cycle. The paper emphasizes the suitability and applicability of each scheme in dc/dc converters. Issues addressed include the effectiveness of r andomness level on spreading the dominating frequencies that normally exist in constant-frequency PWM schemes, and the low-frequency power spectral de nsity (PSD) of each scheme. The validity of the analyses is confirmed exper imentally by using a dc/dc buck converter operating in continuous conductio n mode. The PSD of the output under each scheme will be presented and compa red.