Identification Method of EMI Sources Based on Measured Single-Channel Signal and its Application in Aviation Secondary Power Source Design
A single-channel mixed and complicated nonlinear electromagnetic interference (EMI) signal generally can only be measured in the electromagnetic compatibility test for an electrical system. Based on the single-channel signal, this paper describes a novel identification method of EMI sources. The method applies the ensemble empirical mode decomposition (EEMD) for channel expansion. The number of main EMI sources is evaluated by the principal component analysis, and the main expanded channels are sifted by the correlation analysis to solve the underdetermined problem of single-channel blind source separation. This paper also describes an effective method to identify the interference strength among the main EMI sources: the amplitude ratios of main EMI sources are extracted by combining the frequency characteristics with intrinsic mode functions (IMFs), in which the frequency characteristics are obtained by fast independent component analysis and the IMFs are achieved by EEMD. When this method is applied for conducted EMI identification in switching power converters of aviation secondary power source, experimental results show that it can evaluate the number of main EMI sources and identify the main EMI sources accurately.