Current distribution in shielded cable-connector systems for power transmission in electric vehicles

With the electrification of vehicle propulsion systems, shielded cables were introduced for delivering the power from HV-battery to inverter and/or from inverter to three-phase motor. On the one hand the shield should improve EMC behaviour, on the other hand the shield should protect passengers and service staff from the high voltage. While in typical communication application of shielded cables the shield carries the return current from the inner conductor and the current sum is zero, the automotive power cable employs a second shielded, and, for three phase applications, a third shielded cable, for the return currents. There is no current injection into the shield. Shield currents are mainly induced by inductive coupling. Knowing the shield currents is essential for evaluating the common mode current and thus the relevant fields caused by a cable configuration. In this paper an analytic approach for estimating the current distribution in and the fields from a shielded cable system for EV for low frequencies is presented. With this method typical systems are calculated and discussed regarding the common mode currents and the magnetic fields.