Global production of electric vehicles is recording a 40% growth in past recent years with increasing trends for the future. Major progress in the field of battery packs and consequentially electric motors led to their increased power and compact design. This in turn, caused a rise in power density of electric motors as well as a rise in heat loss generation which became more difficult to extract. Therefore, providing thermal stability and efficient cooling to an electric drive system turned into one of the most important tasks when designing such a system. Based on a detailed three-dimensional model of a synchronous AC motor with permanent magnets we created a simplified version with major details preserved. We described boundary conditions and local heat sources of individual components in the system at nominal electric motor power of 40 kW. We then created 25 different models of cooling channel geometry to cover main heat loss spots and then evaluated them in the process of CFD simulation. We gathered numerical results about pressure drops, velocity fields and temperature fields at the given load conditions and inlet coolant flow of 6 l/min with its temperature of 60°C. The versions that performed best included smoother transitions, flow disturbers and textured inner surfaces of the channels. We used decision matrix method to extract the best performing versions.
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