Due to increasing power demands and decreasing component size, thermal management has become the bottleneck for many power electronic applications. The aerospace industry has focused on reducing weight, operating temperature, and pumping power of power converters since these will limit an aircrafts' range and load carrying capacity. This paper outlines a tool created in MATLAB to automate the cold plate design process for DC-DC converters (or similar applications). The tool incorporates a genetic algorithm to fi nd the optimal aligned or staggered pin fi n confi guration that maintains the devices below their critical junction temperature while reducing the system's overall weight and pressure drop. Utilizing this MATLAB design tool, a cold plate was designed, manufactured, and tested. The convection coefficient calculated within MATLAB (via empirical correlations) was veri fed using simplifi ed CFD simulations within 5% of each other. The same CFD setup, boundary condition types, and methodology are then applied for the full-sized prototype cold plate simulations. These simulations were then validated using the experimental results. For all cases, the percentage error between the simulated convection coefficient values (CFD) and the experimental results was less than 12%. The experiments' measured surface temperature and pressure drop errors were less than 8% of the predicted CFD results. Therefore, the MATLAB tool and its correlations/calculations could be veri fied (via CFD) and validated (experimentally) based on good agreement between the CFD and the experimental results. This three-pronged approach (analytical calculations, CFD simulations, and experimental validation) is an effective and robust method to solve heat transfer problems. Overall, with the framework outlined in this thesis, a complete cold plate design can now be completed in weeks instead of months. This streamlined approach will save companies signifi cant time and money in the design and simulation phases, making this tool a valuable addition to the current literature available. / Thesis / Master of Applied Science (MASc)

In the current climate crisis situation, the development and wide operating range of electric mobility is of great importance, with electric rail traction being the main form of electric transport over medium-long distances. In this sense, electric traction converters are undergoing a deep modification, moving towards more powerful, more compact converters with a wider operating range. This project addresses the problem of overheating of the internal air of a railway electric traction converter when it operates in extreme environments with high temperatures, around 50o C or 60o C. In these cases, the existing cooling system, which uses external air at ambient temperature as the coolant fluid, is not enough to ensure safe operation of the converter. This limits the operating range of electric trains with high power density converters, which cannot operate in hot climates. Furthermore, it poses a risk for other operating ranges in the near future, where the development of converters with higher current levels and thus higher power losses will again challenge conventional cooling systems. This project uses the MITRAC/TC1500TM traction converter developed by Alstom as a basis for proposing different additional cooling systems that complement the conventional one, with the use of different cooling technologies, including forced air convection, heat pipes, liquid-cooled cold plates and Peltier cells, also called thermoelectric coolers. The implementation of the different technologies is evaluated based on mathematical models developed in MATLAB® and computational fluid dynamics simulations in StarCCM+® . The results obtained allow to conclude that the use of heat pipes and Peltier cells is the most recommendable for the development of thermal management systems for electric traction converters, provided that they are implemented with a good external heat dissipation medium, preferably ambient temperature air flows already that already exist in the converter. Furthermore, it is shown that the same cooling technology can provide very different results depending on its implementation. / I den rådande klimatkrisen är det mycket viktigt att utveckla elektrisk mobilitet och att ha ett brett användningsområde, där elektrisk järnvägsdrift är den viktigaste formen av elektrisk transport över medellånga avstånd. Omvandlarna för elektrisk traktion genomgår därför en genomgripande förändring, mot kraftfullare och mer kompakta omvandlare med ett bredare driftsområde. Detta projekt behandlar problemet med överhettning av den inre luften i en elektrisk traktionsomvandlare för tåg när den används i extrema miljöer med höga temperaturer, runt 50o C eller 60oC. I dessa fall är det befintliga kylsystemet, som använder extern luft vid omgivningstemperatur som kylmedel, inte tillräckligt för att garantera en säker drift av omvandlaren. Detta begränsar användningsområdet för elektriska tåg med omvandlare med hög effektdensitet, som inte kan användas i varma klimat. Dessutom utgör det en risk för andra driftområden inom den närmaste framtiden, där utvecklingen av omvandlare med högre strömnivåer och därmed högre effektförluster återigen kommer att utmana konventionella kylsystem. I projektet används MITRAC/TC1500TM , en traktionsomvandlare som utvecklats av Alstom, som grund för att föreslå olika ytterligare kylsystem som kompletterar det konventionella, med användning av olika kyltekniker, inklusive luftkonvektion, värmerör, vätskekylda kylplattor och Peltierceller, även kallade termoelektriska kylare. Implementeringen av de olika teknikerna utvärderas baserat på matematiska modeller som utvecklats i MATLAB® och beräkningsflödesdynamiska simuleringar i StarCCM+®. De erhållna resultaten gör det möjligt att dra slutsatsen att användningen av värmerör och Peltier-celler är det mest rekommenderade för utvecklingen av termiska styrsystem för elektriska traktionsomvandlare, förutsatt att de implementeras med ett bra externt värmeavledningsmedium, helst luftflöden vid omgivningstemperatur som redan finns i omvandlaren. Dessutom visas att samma kylteknik kan ge mycket olika resultat beroende på hur den implementeras.