Abstract
Abstract. Power semiconductors are used in a growing number of applications. Furthermore, faster switching transients and therefore higher switching frequencies can be realised. This leads to higher radiated interferences at higher frequencies. In power electronic applications, often a cooling concept for the semiconductors is required to comply with the allowed temperature range. Typically, heat sinks are made of aluminium and their conductive behaviour can cause EMC problems. Via capacitive coupling, voltage transients are transferred from the power semiconductor to the heat sink, so that the heat sink behaves as an antenna and radiated interferences occur. Furthermore, a common mode current will appear if the heat sink is grounded. In this paper, a promising approach to reduce radiated interferences from the heat sink and solve the common mode issue by using an electrically isolating ceramic heat sink is presented. The influence of an aluminium nitride ceramic heat sink on cooling performance and EMC behaviour has been investigated. For this purpose, two geometrical identically heat sinks made from aluminium and aluminium nitride have been compared regarding thermal performance and radiated interferences characterised by S-parameters.
Highlights
The development of modern power semiconductors, especially based on wide band gap materials like gallium nitride and silicon carbide, allows for steeper switching edges and higher switching frequencies, which can be used to design more compact power electronic systems and systems with higher efficiency
That the aluminium nitride heat sink exhibit at least the same thermal performance as the heat sink made from aluminium
For compact power converters based on gallium nitride, a lower leakage current to earth could be a major advantage
Summary
The development of modern power semiconductors, especially based on wide band gap materials like gallium nitride and silicon carbide, allows for steeper switching edges and higher switching frequencies, which can be used to design more compact power electronic systems and systems with higher efficiency. These developments lead to rising radiated interferences at higher frequencies (Dolente et al, 2005; Kostov et al, 2013; Rong and Lin-Chang, 2002; Ryan et al, 2002). The antenna effect of a heat sink made from aluminium nitride is reduced because of its very high specific resistance of more than 5 × 1010 m
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