Common Mode Noise Sources Analysis and Volume Optimized CM-EMI Filter Design for a TM-PFC

Electromagnetic interference (EMI) analysis for the grid and the connected equipment is essential to ensure that the defined EMI standards are not violated. In this paper, the common mode (CM) noise sources of low power boost power factor correction (PFC) converters operating in transition mode (TM) are investigated. The main portions of the propagated CM noise are due to the bridge rectifier diodes and the transformed differential mode (DM) noise to CM noise. Identifying these noise sources reveals noise reduction solutions. By applying these considerations, the maximum amount of noise at the critical frequency is determined. Passive filters tend to be bulky and their volume reaches up to 30% of the entire system volume. Thus, using an optimized approach, the filter with the minimum volume is dimensioned. A single-phase 80W TM-PFC with an exact model of operated controller IC is also simulated in LTspice to show the validity of the presented investigations.