EMI Source Modeling Method Considering the Accurate Model of the Voltage Probe Based on CISPR25 Conducted EMI Testing

The electromagnetic compatibility standards for electric vehicles are often more stringent than other electronic equipment, which are reflected in two aspects: a lower emission limit and a wider frequency range of concern. Thus, the applicability and accuracy of the current electromagnetic interference model are facing challenges. In the frequency range of 45MHz to 108MHz specified in the CISPR25 electromagnetic compatibility standard, the non-ideal characteristics of the oscilloscope measurement system will affect the accuracy of electromagnetic interference modeling. In response to this problem, an accurate model of the oscilloscope measurement system and the corresponding parameter extraction method is proposed in this paper. At the same time, the Probe Effect Elimination Algorithm is proposed to obtain a more accurate noise source model. A vehicle-mounted Buck-type DC-DC converter electromagnetic interference emission platform is built in this paper, and a link budget simulation based on MATLAB and Simulink is compared with the EMI emission value in the experiment. Combined with the electromagnetic interference model based on impedance measurement, the proposed method calculates the CISPR25 Class 5 conducted emission value with an error of less than 1.12dBμV between 150kHz and 108MHz.