High-Frequency Interactions Among Power Converters in Built-in dc Networks

This article discusses the occurrence of high-frequency interactions among power electronics converters in dc distribution grids. Dc grids are becoming common also in aircrafts and ships. The main reason is the ease of interconnection of energy sources and storage devices and the fact that the vast majority of electronic loads operate on dc. The analyzed phenomena can occur in dc distribution networks, either in low voltage (usually in airplanes and buildings) or medium voltage (in ships). The interactions depend on the front-end filters that connect the converters to the dc bus, resulting in resonances that, under certain conditions, may coincide with the converters switching frequencies. In such a situation there is an amplification of voltage or current, affecting the voltage along the feeder, resulting in a large circulation of current at high frequency. This is an issue that can affect loads and converters connected to the grid and that is difficult to identify since it occurs in frequencies beyond the frequency range usually identifies by the power quality analyzers. Simulation and experimental results are shown, based on typical converter values used in low voltage dc microgrids.