THERMAL ANALYSIS AND VALIDATION OF SPACE GRADE DC-DC CONVERTER UNDER THERMO VACUUM CONDITION
Medium power DC-DC Converter used for space application will dissipate more heat due to less efficiency. The efficiency of these converters will depend on the choice of components, processes used and higher derating of components. The Thermal design of these DC-DC Converters is very challenging in order to withstand stringent operating conditions to meet high reliability requirements. The thermal design need to be in such a way that there is no second iteration to avoid redesign, long manufacturing and testing time. The time and cost involved in design, manufacturing and testing of these high reliability converters is very high and any change in design will affects the time and also will incur huge cost due to high components and testing cost. For Spacecraft environment the thermal design need to be done by considering only conduction and radiation modes of heat transfer since there in no convection available in space due to vacuum condition. Subsequently the testing also needs to be carried out in the thermo-vacuum condition which is one of the critical environmental tests for space hardware to see the thermal performance of the converter under vacuum conditions.
This paper explains the thermal analysis done using computational fluid dynamics and thermal testing of 57W Converter. Thermal analysis carried out by considering the heat dissipation of 21.5W. Thermal modeling has been done using Ansys Icepak, and only conduction and radiation mode of heat transfer is considered for the analysis. Similarly Thermal testing has been carried out at ambient air temperature of 25 Deg C for identifying the hotspot in the convertor using thermal camera before it is tested at high temperature. The DC-DC converter then tested in Thermo vacuum chamber for the extreme hot temperature of 75 Deg C and hot spot temperatures are measured. The results of the analysis have been compared and discussed with actual testing of the DVM (Design Verification Model) converter which is equivalent to Qualification/Flight Model (QM/FM) under thermal vacuum testing systems.