Random PWM for minimization of conducted EMI in flyback switching converters and FPGA based implementations

This paper presents Field Programmable Gate Array (FPGA)-based controller for conducted-noise reduction in ac-dc converters using random PWM. The PWM signals are implemented for parallel single-phase AC-DC flyback converters. The switching noise produced by the converter has been reduced by randomly varying the switching frequency of the converter. Among various PWM techniques, this design uses sinusoidal PWM. Experimental results show that the conducted noise spectrum has been significantly improved and the noise level has been effectively reduced.