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Analytical Sizing Models to Assess the Performances of High Specific Power Electric Motors for Hybrid Aircraft

by Laurence Laffont - published on , updated on

Sarah TOUHAMI conducted her thesis intitled "Analytical Sizing Models to Assess the Performances of High Specific Power Electric Motors for Hybrid Aircraft" on September 15th, 2020, at 2 p.m. in IMFT’s Amphithéâtre Nougaro.

Her work has been supervized by Mr Yvan Lefèvre and Mr Jean-François Llibre.

Mr Noureddine TAKORABET, University of Lorraine, Member
Mr Abdelmounaïm TOUNZI, University of Lille 1, Rapporteur
Mr Jean-Frédéric CHARPENTIER, École Navale, Rapporteur
Mr Yvan LEFÈVRE, INP de Toulouse, Thesis Supervisor
Mr Jean-François LLIBRE, INP de Toulouse, Thesis co-Supervisor
Mrs Nathalie RAVEU, INP de Toulouse, Member
Mr Matthieu FENOT, ISAE-ENSMA, Guest
Mr Xavier ROBOAM, INP de Toulouse, Guest
Me Jean François ALLIAS, AIRBUS FRANCE, Guest

After the industrial and the environmental successes of hybridization railwaystransport,the hybridization of aviation transport is acquiring more and more consideration. In this context, the European Union in partnership with the aerospace manufacturers, has launched in 2014 a largest research program Clean Sky 2 aiming to reduce aircraft fuel consumptions and noise levels. Clean Sky 2 research program includes several projects among of them: Academic reSearch on Thermal & Electric Components & Systems "HASTECS project" which aims to identify and to develop the most promising technologies for decreasing the weight and increasing efficiency of hybrid propulsion chain. "HASTECSproject"is organized around six Work Packages(WPs)dedicated to thecomponents ofhybrid propulsion chain, for instance, the WP1is dedicated to electric motors and theWP3is dedicated to their cooling systems.Indeed, the estimated reduction fuel consumptions for a short range flight would be 3.5% if the specific power of electric machines and power converters with their cooling systems is respectively increased to 5kW/kg and 15kW/kg for 2025, and also increased to 10kW/kg and 25kW/kg for 2035. The targets are significantly higher than those of today. Specific power planned of the industrial electric machines and power converters is higher than the currently one. However, these specific powers present some limitations which depend on the involved material properties and by environment conditions such as: thermal limitations and partial discharges risk.For reaching targeted specific powers for instance in electric machines, the mechanical, electrical and the magnetic loads linked to the materials and cooling technologies must be increased. However, considering the limitations and the environment constraints, choice of loads should be adequate. Therefore, it is important to develop models and tools allowing assessing the actual and the future technologies which allow achieving the HASTECS targets. The present thesis focuses to the development of models and tools for satisfying the HASTECS targets about the electric machines and their cooling systems. There are several different electric machine topologies, namely: radial flux machines, axial flux machines, permanent magnet synchronous machines, wound rotor synchronous machines, asynchronous machines, etc. Performing for each electric machine topology a model for identifying the most promising technologies is a very complex and laborious task. Nevertheless, an analytical model of non-salient sine wave electric machines associated to load ability concepts characterizes a quite lot of electric machine topologies. Based on it, a Target Setting Tool is developed for assessing electric motor technologies considering limits and constraints while without specifying the electric motor topology. Therefore, very few input data are required to make quick trade-offs on electric motor performances as specific power and efficiency whereas Target Setting is based on huge assumptions. For assessing cooling system weight, sizing specified structure of electric motor is unavoidable. Moreover, studies of others work packages are strongly linked to the electric motor structure. Surface Mounted Permanent Magnet Synchronous Motor topology is one of electric motor topology which satisfies the analytical model of Target Setting Tool. A sizing tool called "SM-PMSM" has been carried out based on Surface Mounted Permanent Magnet topologyhelpful for others packagesfor providing more details and for checking the Target Setting Tool validity. Two sizing of electric motors with their cooling systems were carried out using Target Setting Tool, SM-PMSM and others tools performed by WP3 to identify the required technologies for the term medium (2025) and long (2035) term HASTECS targets. The sizing using these tools was checked by finite element analysis.

Keywords: Hybrid Aircraft Propulsion, HASTECS Project, Clean sky 2 European Research Program, High Specific Power, Electric Motors, Cooling Systems, Technological Levels, Loadconcepts, High Speed, Thermal Constraints, Mechanical Constraints, Target Setting Tool, Sizing Tool, Analytical Model, Finite Element Analysis.