MASTERMIND2

In the framework of climate change, the European Union has set key targets to reduce CO2 emissions, in particular by increasing energy efficiency. As electric motors consume about 45 % of the electrical energy produced in the European Union and considering that, this percentage will inevitably increase in a very near future with the electrification of the mobility, any increase of the efficiency of these motors can potentially lead to major energy savings. Among consumed energy, about 90 % is converted into mechanical work and the remaining part, so called losses, are dissipated through heat. Reduction of losses, in particular iron losses, in electrical machines constitutes a major issue in energy-saving requirements. In this context, the Mastermind2 project aims to reduce the iron losses due to magnetic ageing, i.e. degradation of in-service efficiency of soft magnetic steels due to materials ageing during operation at moderate temperatures. This effect is far from negligible as it may lead to an increase in losses up to 15%. However, in the literature no models are available to describe the phenomenon of magnetic ageing, i.e. models linking the microstructure changes to the magnetic behaviour. The originality of the project relies on the improvement of the knowledge of intrinsic mechanisms associated to thermal ageing of electrical steels in order to develop models able to predict accurately the iron loss evolution while accounting for the operating conditions of modern electrical machines. During operation, electrical steels experience thermal excursions in the 150-200°C temperature range during which carbides are prone to precipitate. These carbides will interact with walls of the magnetic domains and thus modify their mobility involving an increase in iron losses. The Mastermind project will develop multi-physics modelling relying on the multi-scale characterization of samples subjected to typical constraints due to manufacturing and/or operating conditions. The model robustness will be demonstrated on electrical steel grades used for industrial motors as well as for electric mobility. Complementarity in skills of the three laboratory partners of the consortium is a key in the project success. IM2NP is recognized for his expertise in nano-scale characterization by using high-tech methods like transmission electron microscopy or tomographic atom probe. MSMP has developed competencies in solving industrial problems linking process, microstructure and properties. L2EP is well-known in electrical engineering, in particular for his skills in the macroscopic characterization and modelling of the magnetic behaviour of steels used in electrical machines. Besides scientific outcomes of the project in fields of materials science and electrical engineering, this project will offer the opportunity to create a bridge between these two scientific communities and to develop new synergies. Main results of the project will also be disseminated towards industrials, in particular manufacturers of soft magnetic steels or of electrical machines.