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.