Modeling and Mitigation on Conducted Emission for Switch Mode Power Supply

The switch mode power supply (SMPS) have been widely used in the electrical and electronics systems for AC-DC and DC-DC power conversion, which can generate a lot of electromagnetic interference (EMI), especially conducted emission (CE) from 9kHz to 30MHz. The traditional CE models and mechanisms have been present for three line systems, including live, neutral and ground lines, while a novel CE models and mechanisms have been proposed in the paper for two line SMPS. Moreover, two methods have been designed to reduce the CE of SMPS, such as the capacitor shunt between the source and drain electrodes of MOSFET and the capacitors matrix. The experiment results show that the CE of the power concentrator can be suppressed well and pass EN 55022 class B, thus realize the proposed approaches good validation.