The Influence of Network Impedance on Conducted Disturbances Within the High-Voltage Traction Harness of Electric Vehicles

Currently, automotive traction systems are increasingly being revised from combustion engine drives to electric propulsion. The high power cables of electric vehicles are routed close to various communication, sensor, or control units. This circumstance results in a tightened challenge for the developing engineers, who need to ensure the electromagnetic compatibility of these miscellaneous and adjacent systems. A trial-and-error approach in the development process of electromagnetic interference filters can only be avoided if the influence of the network impedances within the high voltage traction harness on conducted RF disturbances is known. This contribution presents the current methodology of determining the conducted emissions of power inverters for electric driven cars. It highlights the differences between the traditional low-voltage cable wiring and novel high-voltage traction harnesses, and their impact on the network impedances. An adaption of the line impedance stabilization networks used recently to the characteristic impedance of the high-voltage cables applied shows the influence of termination mismatch on conducted emissions within the traction harness. High-voltage components employed in a car are usually supplied by a traction accumulator battery, which acts as transmission line termination. The influence of a battery's input impedances on disturbances within a component level EMC test setup is shown.