Trapped-flux magnets characterization for application in synchronous machines

Abstract

Abstract: Trapped-flux magnets comprising stacked superconducting tape constitute a promising development to increase the power density of electrical machines, whilst at the same time keeping the complexity required in their construction in manageable levels that allow their use in applications such as aircraft propulsion. However, the conditions in which superconducting stacks operate inside an electrical motor differ quite significantly from the materials characterization experiments commonly developed to model their behaviour. This work presents the results of studying the applicability of these devices as magnetic flux source in the rotor of synchronous machines considering the influence of whole magnetic circuit. Several aspects are assessed, such as flux harmonics, magnetization, losses and demagnetization. Analytical expressions, which provide limited accuracy but allow fast calculations, are used for this purpose. The results illustrate the different trade-offs that arise during the design of a synchronous electric motor using trapped-flux magnets.