Design and assessment of a 2 MW high-temperature superconducting electric motor for regional aircraft propulsion

Resumen

The objective of this Thesis is to investigate towards the increase of power density and reliability of electric motors for aeronautic electric propulsion. To achieve that, this work aims, firstly, to evaluate the current state of the art in aeronautical propulsion technology using electric machines. On this research, the emerging challenges concerning MW-class electric propulsion motors are discussed, identifying several technologies available to overcome those challenges. Moreover, some conclusions about the contribution of motor technology to the feasibility of short-term electrification of single aisle regional aircraft are pointed out. Finally, the proceedings relative to the modelling of the insulation of high voltage electric machines and the arcing effects that may occur on the system are presented. Insulation assessment of electrical machines for aircraft propulsion is evaluated and several tests are proposed. The tests to be performed can be separated into two completely different blocks: dielectric strength tests of different materials and partial discharge tests of the complete winding of an electrical machine. A self-developed partial discharge inception voltage prediction model is also presented and validated with the results obtained from the partial discharge tests. The analysis carried out on the state of the art will provide information on the design guidelines that have been taken in recent years, as well as the different projects and studies that are planned for the medium-term future. Thanks to this framework, geometric and performance requirements of the motor are defined together with the objectives to be met. To achieve this goal, the design of a 2 MW partially superconducting salient-pole electric motor for the electric propulsion of a regional single-aisle aircraft, as an alternative of conventional turbines is presented. An innovative design with a vacuum chamber comprising both the resistive stator and the superconducting rotor is exposed, along with the assessment of a skewed winding. In order to validate the technological achievements of the presented motor, a lab-scale validator is proposed in terms of electromagnetic and thermal calculations, explaining the construction of the validator components, considering, as well its assembly and test procedures. Moreover, the oil- flooded cooling system is presented and validated with a CFD Model. Finally, the conclusions drawn from the different chapters are summarised, which will serve as a guideline for the further steps of the Thesis.