EMC-optimised design of a converter power stage by reduction of surface currents

In modern motor vehicles the increasing demand on electric power offers novel applications for power electronic components and systems. Apart from the functional behavior the electromagnetic compatibility (EMC) for these components has to be ensured. A common way is to investigate, if the devices comply with the limits of the applicable standards, when the first specimen is available. Dependent on the frequency range electromagnetic interferences can be reduced or even suppressed on the one hand by using suitable filters, on the other hand with special design features within the packaging- and interconnecting technology. An investigation of the electromagnetic behavior should ideally take place in the preliminary stages of the development or during the design phase. For this purpose investigations using field simulation tools are useful, because they allow an estimation of the EMC behavior while varying diverse parameters. In this paper the EMC performance of a power converter design for an integrated-starter-generator (ISG) for the 42 V powernet is investigated by simulation. This converter is set up using a three-dimensional packaging- and interconnecting technology, which eludes the common investigation practices for printed circuit boards (PCB). The model for the field simulation consists of surface structures. The convenience of this surface model is the calculability of surface currents, which are vitally important for the electromagnetic emission.