Cooling of Power Electronics by Embedded Solids

Thermal issues have become a major consideration in the design and development of electronic components. In power electronics, thermal limitations have been identified as a barrier to future developments such as three-dimensional integration. This paper proposes internal embedded cooling of high-density integrated power electronic modules that consist of materials with low thermal conductivity and evaluates it in terms of dimensional, material property, and thermal interfacial resistance ranges. Enhanced component conductivity was identified as a possible economically viable internal cooling option. Thermal performance calculations were performed numerically for conductive cooling of internal component/module regions via parallel-running embedded solids. Thermal advantage per volume usage by the embedded solids was furthermore optimized in terms of a wide range of geometric, material, and thermal parameters. In the dimensional and material property range commonly found in passive power electronic modules, parallel-running cooling layers were identified as an efficient cooling configuration. Numerically based thermal performance models were subsequently developed for parallel-running cooling inserts. A multifunctional experimental setup was constructed to study the cooling of ferrite (operated as a magnetic core) by means of embedded aluminium nitride layers and to verify the thermal model. Results corresponded well with theoretically anticipated performance increases. However, interfacial thermal resistance constituted a major limitation to the cooling performance and future power density increases. With the thermal model developed, functional optimization in terms of magnetic flux density for parallel-running cooling layer configurations was performed for a wide range of material and geometric conditions.