Calculation and Distribution of Losses in EMC Filters in the High-Voltage Power Train for an Electric Vehicle

Noise currents in high-voltage power trains of electric vehicles place significant strain on the EMC filters used to mitigate conducted and radiated emissions. The power loss caused by the resistive properties of the filter components is a key factor in determining the temperature behavior and lifetime of the filter. A validated numerical EMC model of an electric vehicle power train is used to investigate the losses of a single-stage LC filter for the high-voltage DC path. The losses of the inductive and purely resistive components are calculated directly from the time domain signals, while the loss in the capacitors is calculated in the frequency domain to include the frequency dependence of their parasitic resistance. A parametric study of the influence of the capacitance and the serial damping resistance on the losses and the conducted emissions is carried out. Finally, the effect of asymmetry of the capacitors within common tolerance ranges is investigated.