Wiring Harness Cable Input Impedance Verification For Electromagnetic Compatibility Pre-Compliance Testing

Electromagnetic compatibility (EMC) is an important but challenging requirement in electric vehicles (EVs). Engineers often work on pre-compliance testing before full-scale EMC testing. Solving potential problems before costly EMC product testing not only saves overall design cost, but also reduces the time needed for product development. This work focuses on characterizing the input impedance of a cable connected to the low-voltage system inside the motor control unit (MCU) of an EV for EMC pre-compliance testing. A step-by-step modeling approach of the cable input impedance is outlined for EMC testing, considering both a single cable and two cables in parallel. The parasitic values of the cables are investigated, and various cable models are evaluated compared to the measured input impedance of the cable. For the two parallel cables, the capacitive coupling and inductive coupling of the two parallel cables are also analyzed through simulation and experimental testing. The results verify that the modeling approach is accurate within an error of 2.1%, and the model can be used for further EMC analysis of the wiring harnesses within electric vehicles.