Characterizing noise source and coupling path in Flyback converter for common-mode noise prediction

This paper characterized the CM noise generation and coupling mechanism to predict the CM noise in Flyback converter. The spectrum of noise sources are analyzed using bandwidth-effects-FFT and the CM noise coupling paths are identified to build up a new CM noise analysis method. With this CM noise analysis method, the total CM noise and the contributions of all the coupling paths in the converter can be predicted. The performance of CM noise suppression measures can also be diagnosed before practical implementation. This method can provide EMC designers with a costless and time saving solution to design the converter. Experimental illustrations are also included to verify the validity of the proposed CM noise analysis method. Comparison between the measured and predicted results shows that this CM noise modeling method can provide adequate prediction of the CM noise feature for the converter.