4-MW Class High-Power-Density Generator for Future Hybrid-Electric Aircraft

Abstract

This paper describes the underpinning research, development, construction and testing of a 4MW multi-three phase generator designed for a hybrid-electric aircraft propulsion system demonstrator. The aim of the work is to demonstrate gravimetric power densities around 20 kW/kg, as required for multi-MW aircraft propulsion systems. The key design choices, development procedures and trade-offs, together with the experimental testing of this electrical machine connected to an active rectifier are presented. A time-efficient analytical approach to the down-selection of various machine configurations, geometrical variables, different active and passive materials and different thermal management options is first presented. A detailed design approach based on 3D Finite Element Analysis (FEA) is then presented for the final design. Reduced power tests are carried out on a full scale 4 MW machine prototype, validating the proposed design. The experimental results are in good agreement with simulation and show significant progress in the field of high power density electrical machines at the targeted power rating.

High-Speed Synchronous Reluctance Machines: Materials Selection and Performance Boundaries

“…On the contrary, CoFe alloys are relegated to niche applications (e.g. aerospace and motor sport) where the higher power density benefit, allowed by the higher saturation levels, outweighs the higher cost [3]. Analysing Fig.…”

“…The material selection is particularly important when designing high power density electrical machines where the constituent materials are pushed to the working limits in order to maximize their exploitation [2]. Indeed, transportation applications in the aerospace sector require impressively high power density levels in order to compete with the mechanical counterparts [3]. Similar challenges are faced by the automotive industry [4], although the electrical machine requirements are different.…”

Overview of Degrees of Freedom in the Design of PM Synchronous Machines

“…In this section, a review of PMSM structures where the additional degrees of freedom are exploited will be presented. The aim is to explore how these techniques can be combined in order to cope with highly constrained design problems such as electrical traction, where both high torque and high speed operations are required, or aeronautical applications where the needs are expected to reach power densities as high as 20 kW/Kg [9], or renewable energy conversion where high torque density generators are needed [10].…”

“…Mechanical integration is also important, because in electrical machines designed for applications requiring high power density and high torque density, the so-called "nonactive" parts mass can exceed the active parts mass [9,80]. It is then pertinent to integrate different parts insuring different functions together [77].…”

Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications

“…Among them, lead by ecological, economical, and practical needs, the electrical machines associated with superconducting materials such as electromagnet [1], permanent magnets [2][3][4][5], or windings [6,7] look increasingly more attractive for future transports such as electrical ships [8], aircraft [9][10][11], and levitation trains [12] for the high specific power potential of HTS machines. Indeed, for the aviation sector in particular, the growing need for electrical power on board requires the development of electrical machines with a target power-to-weight ratio of 20 kW/kg for MW class machines [4,13,14].…”