Modeling and Reduction of Radiated EMI in Non-isolated Power Converters in Automotive Applications

This paper develops modeling and reduction techniques of the radiated electromagnetic interference (EMI) in non-isolated power converters in automotive applications. In modeling investigations, noise source models and the antenna models are developed to reveal the generation of the common mode (CM) noise and the radiated EMI in the investigated buck-boost power converter. The developed models can predict the radiated EMI with clear physical meanings of the switching noise, the power converter topology, and the PCB parasitics. The influences of the PCB ground layer parasitics on the radiated EMI are first revealed. In noise reduction investigations, several techniques are proposed including 1) PCB layout improvement for reducing the parasitics of the ground layer and 2) circuit topology improvement including the addition of a capacitor across the input and output nodes and improvement of the PCB traces connecting the cross capacitor. Experimental verifications of the radiated modeling and reduction techniques are conducted on a buck-boost power converter in automotive lighting applications.