Power electronics high performance air-cooled heat sinks integrating graphite based materials

Abstract

The thermal management of the power electronics cooling in the aircraft is getting more attention in the recent years due to the progressive implementation of electrical systems, especially in the framework of the more electrical aircraft, one of Clean Sky framework research activitiesto allow Europe to lead the transition to more environmental friendly aircraft in the future. The reference innovative trend in the cooling of power electronics and other semiconductor devices has been to migrate from air cooled solutionsto liquid cooled or two-phase flow solutions, asthese being able to reach higher levels of heat transfer density and keep electronics temperatures within the required limits. However, in the context of new wide-bandgap semiconductor materials (GaN, SiC) that withstand higher operating temperatures with reduced losses, the use of air cooling is attracting again interest, as a potential candidate to reduce the complexity of thermal management systems, and indirectly their weight and cost. In this regard, the consortium of the Clean Sky 2 project ICOPE has been working in the development of new concepts of air cooled heatsinksthat incorporate advanced thermal materials such as Annealed Pyrolytic Graphite (APG) and Metal Matrix Composites (MMC) (Aluminium Graphite (ALG)).The project has evolved from pre-design steps to identify potential design candidates towards a final design with the support of CFD simulations and engineering assessment. Different versions of heatsink incorporating different combinations of the referred materials have been manufactured and successfully tested. A first loop of prototypes, called Stage A, implement APG, while a second loop of prototypes (Stage B) integrate APG and MMC in different interactions. This paper is conceived as a summary of the project developments and results at heatsink level, presenting the overall concept, the materials involved, and the experimental and numerical results obtained, which achieve the expected performances in terms of heat transfer, pressure drop and weight. The outcome of these results can suggest to reconsider the power electronics cooling design in other applications outside the aircraft sector, for example within Power Conversion applications or automotive field.