Common-mode EMI noise reduction for grid-interface converter in low-voltage DC distribution system

More attention to the electromagnetic interference (EMI) issues arises in grid-interface converter system where the radio frequency (RF) conducted emissions have to be considered on both dc and ac-side, such as in the application of photovoltaic (PV) system, dc distribution system, and charging system in electric vehicles (EVs). This paper presents a brief overview of the recent EMI research activities in such applications as well as the EMI filter design and measurement considerations. The common-mode (CM) conducted EMI noises pose more challenges of filter design in the grid-interface converter system due to the noise propagation paths are coupled between dc and ac side through the grounding capacitors. This paper presents a discussion on an ac EMI filter structure in the single-phase grid-interface converter for low-voltage dc distribution system, which helps reduce the coupling between dc and ac-side, and thus simplifies the CM EMI filter design process.