Considerations for digital controllers targeted at conducted-noise spectrum-spreading in dc-dc converters

A substantial part of the manufacturing cost of power converters for telecommunication applications involves designing filters to comply with the EMI limits. This paper investigates the effect of several frequency modulation profiles on conducted-noise reduction in dc-dc converters with programmed switching controller. The converter is operated in variable frequency modulation regime. Twelve switching frequency modulation profiles have been studied. Some of the modulation data are prepared using MATLAB software, and others are generated online. Moreover, all the frequency profiles have been designed and implemented using FPGA and experimentally investigated. The experimental results show that the conducted-noise spreading depends on both the modulation sequence profile and the statistical characteristics of the sequence. Considering this investigation significantly reduces the filter size.