The 'Equivalent Cable Bundle Method': an Efficient Multiconductor Reduction Technique to Model Industrial Cable Networks

Abstract

In automotive electromagnetic (EM) compatibility (EMC), the cable bundle network study is of great importance. Indeed, a cable network links all the electronic equipment interfaces included the critical ones and consequently can be assimilated both to a reception antenna and to an emission antenna at the same time. On the one end, as far as immunity problem is concerned, where an EM perturbation illuminates the car, the cable network acts as a receiving antenna able to induce and propagate interference currents until the electronic equipment interfaces and potentially induce dysfunction or in the worst case destruction of the equipment. At low frequency, the interference signal propagating on the cable network is generally considered as more significant than the direct coupling between the incident field and the equipment. On the other end, as far as emission problem is concerned, the EM field emitted by the cable network may disturb itself the electronic equipments by direct coupling. To avoid these problems, automotive manufacturers have to perform normative tests before selling vehicles. These tests are applied on electronic equipments outside and inside the car first to verify that the equipments are not disturbed by an EM perturbation of given magnitude and second to ensure that the EM emission of each equipment does not exceed a limit value at a given distance. Obviously, these tests are not exhaustive and fully representative of real conditions. For example, in immunity tests, two polarizations (vertical and horizontal polarizations) of the EM perturbation are generally tested in free space conditions. In reality, the EM perturbation due for example to a mobile phone outside the car could happen from any direction of space and be reflected by all the scattering objects located in the close environment of the vehicle (ground, other vehicles, buildings,...). Consequently, the contribution of EM modelling is a great tool for automotive manufacturers in order to proceed to numerical normative, additional and also parametric tests at early stages of the car development on numerical models and for a reasonable cost. Moreover, numerical modelling will reduce the number of prototypes built during the