Identification of essential coupling path models for conducted EMI prediction in switching power converters

Essential coupling path models means that from a circuit theoretic viewpoint, the simplest models contain the dominant noise sources and the dominant noise coupling paths, which can provide a full feature of the EMI generations. This work presents a modeling approach to investigate the conducted EMI in switching power converters. Three modes of conducted EMT noise: the mixed-mode (MM), the intrinsic-differential-mode (IDM), and the common-mode (CM) are identified by time domain measurements associated with the switching actions. The derived models assume lumped parameters circuits represent the noise generation and propagation paths that allow easy physical interpretations. The experimental results show good agreement in the comparison of measured and predicted MM, IDM and CM noise emissions with filter included. The proposed method is easy to apply in practice for understanding, diagnosis, and evaluation EMI behaviors.