AC-DC smoothing capacitor current coupling for improved powerline signal reception

The proliferation of Switch-Mode Power Supplies (SMPS) has led to a significant size decrease in step-down transformers for PC power supplies, moving away from the traditional linear power supplies which are heavier and bulkier than their modern counterparts. Step-down transformers are becoming more and more redundant in AC-DC converters due to higher blocking voltages of MOSFET´s and the need for reducing the size and the power efficiency of power supplies for mobile equipment. Still, an integral part of any PC power supply is the AC-DC conversion stage. A diode bridge, smoothing capacitor and a load resistor is the very least number of components any power supply requires to be classified as an unregulated power supply. This paper presents live results showcasing a specialized coupling technique of signal coupling for Power-Line Communications. This technique improves signal reception, for the AC-DC smoothing capacitor charging intervals of the mains cycle, as compared to that of a standard PLC receiver during the same intervals. This paper investigates the insertion of a special coupling transformer in the parallel capacitor branch of the rectification stage of a typical AC-DC convertor, for the case where no step-down transformer is present. The technique shows time-domain diversity in signal coupling and utilizes the capacitor charging mechanism which occurs twice during the mains cycle. Frequencies in the CENELEC bands are used for the study.