Modeling and Reduction of Radiated EMI due to Ground Impedance in a High-density Active-clamp Flyback Power Adapter

The article firstly reviewed the modeling and prediction techniques for radiated electromagnetic interference (EMI) in active-clamp Flyback (ACF) power adapters. Second, developed an improved radiated EMI model of the ACF power adapter based on circuit topologies, PCB parasitics, working voltage waveforms, antenna/converter impedance, and transfer functions. Third, the improved radiated EMI model was quantified and experimentally verified. Fourth, proposed two techniques for radiated EMI mitigation based on the improved radiated EMI model: optimizing PCB layout and adding a cross capacitor for resonance. Experiments verified the analysis and techniques. The techniques were also extended to other isolated power converter topologies.