Determining crucial sources of conducted interference in power electronics from heat sink capacitive coupling

In power electronics, wide band gap materials enable faster transients and higher switching frequencies. Therefore, more efficient power electronic systems can be realized, but also greater EMC problems in magnitude and frequency arise. Heat sinks, which are often necessary for cooling power semiconductors, are a well known source of EMC issues. In this paper, crucial sources of conducted interference from capacitive coupling via the heat sink are determined and approaches to reduce this conducted interference are discussed. For the investigations, a combined approach using simulation as well as circuit diagram analysis was used. Three different topologies were investigated to obtain general recommendations to reduce interference caused by heat sink capacitive coupling.