Abstract
The main aim of this thesis was to study and experimentally assess the additional iron losses in the stator (electrical lamination steel) of high performance permanent magnet synchronous machines (PMSM) designed for aircraft applications, in relation with the "more-electric-aircraft"project.The extra iron losses are caused by manufacturing processes (cutting, sticking, insulation, stacking, pressing, shrink-fitting, thermal treatment,...) and the real conditions of use of electrical motor (namely: rotational flux, saturation, high frequency,...). Indeed, the mechanical and thermal stresses during the manufacturing steps can deteriorate the magnetic properties of the material and significantly increase the iron losses. These aspects are difficult to accurately evaluate by analytical models or standard measurements (Epstein frame,...) and require experimental assessment to precisely calculate the motor efficiency.First of all, we started by developing a test bench equipped with drive motor: PMSM 8000 RPM ; 42 kW. For accurate assessment, the losses in this machine are separated on the test bench. In the winding, we used bar-wound conductors, which is an original technology developed in our laboratory, and whose advantage among others is the unusual copper fill factor that reaches almost 90 %.Subsequently, we explored the high frequency machines (>1 kHz) in order to increase the power-to-weight ratio (cross the threshold of 2.5 kW/kg). We proposed, the following to the analytical and finite element study, a first conventional prototype with a power-to-weight ratio equal to 4.5 kW/kg and 94 % efficiency at full load, operated at 1666 Hz and 5000 RPM. A second motor had been also proposed with both rotor and winding in aluminum, in this case the power-to-weight ratio reaches around 6 kW with, however, less efficiency (93 %).Finally, this HF motor was tested at no load on the aforementioned test bench. The experiments were carried out on a multitude of FeCo and FeSi stator core samples coming from different manufacturing processes (insulation: bonding varnish and C-5 varnish; cutting: laser and EDM "Electrical Discharge Machining" and thermal treatment) in real operating conditions of a high frequency PM machine in order to experimentally obtain the famous "additional coefficient" of iron losses (K add ).