Experimental characterisation of radial oil spray cooling on a stator with hairpin windings

Thermal management is critical to increase the power density and the continuous operating limit of electric motors due to the drive for electrification of the automotive industry. A more advanced active cooling is required and direct oil spray cooling method is an attractive solution because it can give effective convective heat transfer. However, the technical literature providing practical guidelines of how oil spray cooling should be applied to stator with hairpin winding is limited. This paper presents the experimental characterisation of radial oil spray cooling by using different spray nozzles. The test data is analysed to investigate the impact of nozzle velocity on the temperature variation of the end windings.