Speaker
Description
Only a handful of high-temperature superconducting (HTS) electric machines using HTS bulks as magnetic poles have been developed. This is mostly due to the need for the bulks to be magnetized before use, which is a challenge for practical application. It is important to develop a magnetization method for the bulk arrays because recently we have used them as an armature for high power superconducting rotating machines. To magnetize easily the bulks, a pulsed-field magnetization (PFM) method is preferable over a slower field cooling method. However, the time and practicality gained are often at the expense of the intensity of the trapped magnetic field. Several methods have been developed to improve the PFM of a single or two bulks, but the magnetization of multiple bulks arranged in an array has not as often been addressed in the past. In this presentation, a rectangular array of HTS bulks has been modeled to reproduce the magnetic pole of a superconducting motor. An H-formulation has been used to model the bulks, surrounded by A-formulation to solve the regions without superconductors using the potential vector A. The thermals of the bulks during the magnetization will be taken into account. The magnetization process of the bulks using different types of coils has been considered as well as the impact of the modification of the shape and size of the coil on the trapped magnetic field. The order in which the bulks are magnetized is also important as magnetizing bulks close to already magnetized bulk could reduce the overall trapped magnetic flux density. The thermal behavior and trapped magnetic field quality depending on various parameters are discussed.
