Stator Design and Performance of Superconducting Motors for Aerospace Electric Propulsion Systems

Abstract

Hybrid electric propulsion has been identified as a potential solution to the ambitious environmental emissions and noise targets of the aerospace industry. Superconducting machines may be the key component of that topology enabling the high power densities and efficiencies needed in aerospace. Fully superconducting machines, however, are not a mature technology. This paper looks at the different machine design configurations focusing on the stator magnetic circuit of a fully superconducting motor. The motor has been designed for an aerospace distributed fan propulsion motor with an aerospace benchmark specification of 1 MW. The AC fully superconducting machine includes superconducting bulk magnets mounted on a conventional rotor core and an MgB2 superconducting wire wound stator. The AC losses in the stator winding are particularly sensitive to exposure to the main rotor field so different screening solutions were used to shield the superconducting windings from the rotor field. The effectiveness of the screening techniques for the stator coils and the impact on the machine performance and weight were evaluated for different stator designs, such as full stator core and air core with and without flux diverters. Various combinations of pole numbers, diverter geometries and magnetic materials have been checked. Results show that there is a tradeoff between stator iron losses and superconducting losses.

Barriers and Challenges Going from Conventional to Cryogenic Superconducting Propulsion for Hybrid and All-Electric Aircrafts

“…Another electric motor designed for aerospace propulsion is the one presented in [47]. The motor has been designed for an aerospace distributed fan propulsion system with an aerospace benchmark specification of 1 MW.…”

“…Ref. [47] presents a centralized system with large cryocoolers and liquid methane as a possible solution. This suggests that the new electric aircraft needs a total redesign to accommodate these new systems while guaranteeing their goals.…”

Feasibility Analysis on Cryogenic Properties of Supercritical Nitrogen to be used in the Cooling of Hg-Based High Temperature Superconductors for Electric Aircraft Propulsion

“…High temperature superconductors (HTS) are one of eligible contender which have been exploited in various applications such as energy storage [6]- [8], proficient power transmission (transformers or cables) [9]- [11], ship propulsion using motors [12]- [15], power generation (Generators) [16]- [18], and magnetic levitating trains [19] [20]. To maintain superconductivity, there is a need to dissipate the heat load generated due to AC losses imposed on the superconducting tape [21]- [23].…”

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

“…The development of High-Temperature Superconductors (HTSs) such as the cuprate family with the REBaCuO superconductors (Rare Earth elements (RE)), the Iron-Based Superconductors (IBS) with the Pnitide and Chalcogen families and the MgB 2 compound allow a quick evolution of superconducting devices for many 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].…”