Conducted EMI Noise Modelling for DC–DC Converters Based on the Time-Domain Measurements

Switch mode power supplies (SMPSs) are the source of radiated and conducted EMI noise. The radiated part is usually mitigated by adding proper shielding. The conducted part propagates through the input and output terminals to the power lines and loads. The most common approach to attenuate the conducted noise is benefiting the EMI filter. Implementation of an EMI filter needs to have some information about the source of noise, such as its impedance and amplitude. This information could be obtained by applying proper approaches, categorised into lumped or behavioural methods. In this paper, a behavioural method (spectral analysis) is used to model the conducted EMI noise, generated by a DC–DC converter. The proposed method can estimate the transfer function of both common mode (CM) and differential mode (DM) noise separately. Time domain data is used to identify model, utilising an uncomplicated setup. The experimental results are presented to verify the theory of the suggested method. The results show, there is less than a 5 dB deviation between the obtained model and the verification data set. Also, an EMI filter and a notch filter have been implemented based on the extracted model to show the effectiveness of the suggested method in practice.