Computation of Superconducting Stacks Magnetization in an Electrical Machine

Abstract

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.

Magnetization and Losses for an Improved Architecture of Trapped-Flux Superconducting Rotor

“…When these currents are slowly ramped down (Stage 3 ofFig. 3), currents are induced in the superconducting layers inside the stacks, which effectively traps the flux level and reproduces the applied value[21]. current profile fed to the stator (a) and rotor temperature (b) during the field cooling magnetization process.…”

Testing of Surface Mounted Superconducting Stacks as Trapped-Flux Magnets in a Synchronous Machine

“…Vicente Climente-Alarcon, Member, IEEE, Anis Smara, Lukasz Tomkow, Bartek A. Glowacki, Thomas Reis A field cooling magnetization procedures [6,12], although an experimental evaluation of its accuracy was pending. In addition to this design-related question, several others related to their operation inside the machine arise.…”

“…This work addresses by performing an experiment both of the above mentioned questions: the evaluation of the accuracy of novel numerical methods devised to designing rotating electrical machines with superconducting regions [6,12] and the assessment of the demagnetization rate under actual operational conditions of these machines. In this experiment the machine used in [21] has been configured as a 4-pole pair generator setting 8 stacks around the surface of its rotor and its stator winding has been connected to a load through a circuit breaker.…”

“…2) To provide an insight into the accuracy of the numerical methodology proposed in [11] and used in [6,12] to assess different rotor configurations of a fully superconducting motor.…”

Field Cooling Magnetization and Losses of an Improved Architecture of Trapped-Field Superconducting Rotor for Aircraft Applications

“…When these currents are slowly ramped down (Stage 3 in Fig. 3), currents are induced in the superconductor forming the stacks, effectively trapping a flux level that reproduces the one applied [21].…”