Superconductivity and its Application in the Field of Electrical Machines

This paper provides a review on the most recent applications of superconductors in rotating electrical machines. The main types of superconductors for the present-day electrical applications are shown to highlight their main features. The main characteristics of superconducting synchronous machines, DC machines and induction machines for marine and vehicle propulsion, future electric aircraft, wind energy and industrial applications are discussed by presenting data of prototypes and demonstrators. The paper aims to raise awareness among researchers and engineers on the importance of superconductivity to enhance the performance of conventional electrical machines

Construction and Test of a Flux Modulation Superconducting Machine for Aircraft

International audienceThe increasing of drives towards More Electric Aircraft (MEA) or the development of electric propulsion aircraft calls for MW-class electrical machines with more compact and power dense designs. One way is to explore the use of superconducting materials to create a high magnetic field in order to reduce the mass of ferromagnetic components. This paper presents the construction and the test of a brushless axial flux superconducting machine. The brushless topology satisfies the aeronautics industry requirements in terms of maintenance, while the axial configuration ensures an optimal use of the anisotropic HTS tapes. The machine is classed as partially superconducting, only the inductor is made with superconducting materials. A special design concerning the use of a stationary cryostat is presented. This improvement reduces significantly the electromagnetic air-gap length. A 50kW prototype is manufactured with a minimal mass objective. The prototype constitutes a first step to a scale-up MW-class machine design

Computation of Superconducting Stacks Magnetization in an Electrical Machine

Superconducting technology offers the prospect of sharply increase the power density of rotating electrical machines, especially in the low speed, high torque range, with impact in applications such as wind energy and aircraft propulsion. Among the enabling technologies, stacks consisting of piling up layers of high temperature superconductor may provide a source of magnetic flux density for torque production, without the complexity of superconducting wound rotor poles. For this to happen, careful designs, optimizing electromagnetic, mechanical and thermal aspects at the same time, must be developed. In that sense, this work applies a recently developed combined electromagnetic formulation to compute the magnetization level of high temperature superconductor stacks installed in the airgap of an electrical motor after field cooling magnetization. The results are congruent with the applied field, show a strong interaction between teeth and stacks and provide a way of initializing the state of the machine prior to operation.Horizon 2020 research innovation programme under grant agreement No 7231119 (ASuMED consortium) and EPSRC grant EP/P000738/

Flux pump for HTS rotating machinery applications

High Temperature Superconducting (HTS) machines offer several benefits over the conventional machines. With the advent of YBCO materials, research and development in HTS applications has gained significant impetus. The application of flux pump has its own advantages over the conventional mechanism for magnetic field generation in superconductors. This paper reviews few relevant works and presents preliminary results from experiments carried out to provide justification on the application of flux pump for generating magnetic flux in a rotating machine

Field cooling magnetization and losses of an improved architecture of trapped-field superconducting rotor for aircraft applications

A hybrid electric configuration for aircraft propulsion can yield several advantages, reducing fuel consumption and take-off distance, improving control and decreasing emissions. For such a benign scenario to occur, advances destined to increase the power-to-weight ratio of actual electric motors must be developed. Superconducting technology offers the prospect of achieving such performance, but at the cost of increasing design and constructive complexity. In that sense, stacks consisting of piling up layers of high temperature superconductor have proven to trap high value current vortexes and thus can provide a source of magnetic flux density for torque production, without the need of current leads or other equipment in the rotor. However, these macroscopic currents must be induced prior to operation and then maintained undisturbed by any variation of the magnetic flux density in the airgap, which cause heating and demagnetization. This work presents the result of novel numerical computations on a new rotor architecture developed within the ASuMED project with the aim of facilitating the magnetization of the stacks from a superconducting stator and prevent their demagnetization during torque production. The performance of the machine is assessed, and the expected survivability of the stacks compared with laboratory measurements.EPSRC grant EP/P000738/

Design of a high-speed superconducting bearingless machine for flywheel energy storage systems

published_or_final_versio