An EMI modelling of heat sinks for SMPS applications

An EMI modelling of heat sinks employed in Switching Mode Power Supplies (SMPSs) is presented in this paper. In fact, the capacitive coupling between electronic power devices and their heat sinks generally lead to impulsive current circulation in the latter, making them able to generate conducted electromagnetic noise and/or to emit as antennas. Such electromagnetic noise may give rise to the incorrect electronic circuits and control system operations. Hence, the proposed heat sinks model is developed in order to evaluate these effects, aiming to be an useful tool in order to avoid system faults and to guarantee the compliance to EMC standards. In particular, the proposed model allows the achievement of the resonance frequency of a heat sink in a closed analytical form. The results obtained by employing the proposed modelling procedure is properly compared with those achieved by means of finite element investigations, highlighting the effectiveness of the proposed method. This is also corroborated by the experimental studies carried out in an EMC laboratory.