Simulation of the Waveform Control Pulse Magnetization of a High-Temperature Superconducting Bulk with Negative Feedback.

Pulsed magnetization of superconducting bulks is attractive for promoting the use of superconducting technology in various commercial applications. Several researchers have been developing new magnetizing techniques to improve the trapped magnetic field obtained with pulsed magnetization. Waveform control pulsed magnetization (WCPM) is one of these new magnetizing techniques. The WCPM has been developed for a few years in our laboratory and has shown promising results so far. In this presentation, a numerical simulation of the magnetization technique has been performed with the aim of better understanding and improving the WCPM. The experimental set-up, consisting of one (RE)Ba2C3O7- (REBCO, RE = rare earth) bulk sandwiched in between two vortex type coils similar to the internal configuration of an axial-gap type superconducting rotating machine has been modelled in COMSOL Multiphysics. A coupled H-A field formulation has been implemented so that the regions containing the superconductor are solved using the magnetic field H and the surrounding regions, containing the vortex-type coils are solved using the magnetic vector potential A. A thermal model has been added to consider the rise of temperature in the bulk during the magnetization. The coils are connected through a circuit interface, in which the circuit of our pulsed magnetization system has been implemented. The trapped magnetic flux density obtained using a simple pulsed field magnetization is compared by the trapped magnetic flux density obtained with WCPM using negative feedback. The important parameters are discussed as well as the impact of this technique on the heat generation in the bulk during the magnetization.