Thermal modeling and characterization for designing reliable power converters for LHC power supplies

Power supplies for LHC experiments (ATLAS) require DC-DC power converters able to work in very hostile environments. The APOLLO collaboration, funded by the Italian Istituto Nazionale di Fisica Nucleare (INFN), aims to study dedicated topologies and to design, build and test demonstrators, developing the needed technology for the industrialization phase. Besides the presence of radiation and magnetic fields, thermal specifications are particularly stringent in the working environment. In order to have the wanted features in terms of reliability and availability during the experimental activity, these power electronics circuits must be cooled by specifically designed water heat sinks, and an accurate thermal design is mandatory in order to guarantee safe and reliable operation. Moreover, an optimized thermal design allows to have a maintenance strategy in compliance with the requirements of the experiments. In this paper thermal characterization is used for tuning a coupled thermo-fluid-dynamic 3D numerical model, for both the water heat sink and the whole system. Based on this model an optimized water heat sink was designed and fabricated. Thermal characterization of the power converter demonstrator in different operating conditions shows good agreement with simulation results.