Conducted Electromagnetic Interference Modelling of an Automotive Printed Circuit Board

The prediction of electromagnetic interference (EMI) for products in the testing environment has always been a key concern for auto parts manufacturers. This paper proposes a fast and accurate simulation method for conducted EMI interference based on the CISPR25 standard for printed circuit board (PCB). To strictly comply with the testing process, a program is developed using the FFT algorithm to simulate the measurement receiver for conducted interference. The main sources of EMI noise in gear and warning light indicators are analyzed. To simplify the EMI model, the physical PCB model is replaced with an equivalent SPICE model, which greatly reduces the number of the mesh grids, but still reckons the trace impedance in the PCB. In case the parasitic parameters between the PCB and the testing table are left out, the high-frequency parasitic parameters are deduced theoretically and modeled for the gear and warning light system. The resonance frequencies of the multi-wire's impedance are derived and validated. Combining the LISN, high-frequency wire model, testing table, and circuit model, a conducted interference simulation model for the gear and warning light indicators is constructed. The simulation results show high correlation with the measured results.