Efficient Bi-Directional Digital Communication Scheme for Isolated Switch Mode Power Converters

An efficient high-speed bi-directional data transmission scheme for isolated AC-DC and DC-DC switched mode power converters is presented. The bi-directional scheme supports fast, efficient and reliable transmission of digitally encoded data across the isolation barrier and enables primary side control, allowing effective start-up and a simple interface to system controllers. Another key feature is that the bi-directional communication is independent of coupler gain and degradation and only the minimum number of couplers is required. The digital interface can also be used to transmit auxiliary signals between both sides. For test purposes, the scheme has been implemented on FPGAs and verified using a custom-built SMPC board.