Methods for the Investigation and Mitigation of Conducted Differential-Mode Electromagnetic Interference in Commercial Electrical Vehicles

One of the main challenges as the market for fully commercial electrified vehicles quickly expands is predicting the electromagnetic interference (EMI) in traction voltage systems (TVSs) in differential mode (DM) and common mode (CM). The number of subsystems connected to vehicle TVSs is increasing, and thus, so are the electromagnetic compatibility (EMC) requirements. These requirements should make sure that neither the function nor lifetime of any source or load is affected by another, but experience shows that they are often insufficient. The purpose of this article is to show how circuit simulations can complement these requirements and that a generalized artificial network/line impedance stabilization network (LISN) is insufficient to correctly predict the EMI situation of a real vehicle. This article presents a method for complexity reduction in TVS DM simulations and a comparison with the usage of LISN to predict the EMI between subsystems; the article also addresses how to mitigate the EMI with DM filters for the subsystems. The proposed method creates a foundation for a faster and safer development process. The simulation model’s development includes a traction battery and TVS subsystems. It is found that a standardized LISN does not reflect the behavior of a commercial TVS and cannot be used solely to judge if a subsystem will operate as intended within a TVS without creating EMI. A change in switching frequency in the DUT can cause severe resonance between TVS subsystems, but this is not seen with a LISN. The conclusion of the article is that LISN can provide a false sense of security and that calibrated simulation models of a complete TVS are necessary to predict the behavior in that TVS; this study also highlights the importance of using DM filters to ensure protection against resonance frequencies.