Thesis

Study AC loss of 2G HTS for future electric aircraft propulsion

Creator
Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2022
Thesis identifier
  • T16463
Person Identifier (Local)
  • 201879188
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • Superconductor technologies have attracted increasing appealing over the past decades, owing to advancements made in the material manufacturing technology and the reduction of cost. As a result, superconducting materials have received large interest and hence been widely investigated in many applications including power industries and aerospace, of which one of the most promising and popular applications is the electric machine, which plays an essential role in power generation and consumption. The second-generation (2G) high temperature superconducting (HTS) materials show great potential in situations of high magnetic field and high current density, benefiting from high energy efficiencies. Therefore, they have become a focus of superconducting research and are believed to usher in a period of development opportunities. However, there still exist many challenges related to the efficiency, cost-effectiveness, reliability, and safety of HTS machines, and the alternating current (AC) loss of HTS remains one of the most critical issues. Over the years, superconducting technology applications in electric machine have been developed and put into practice due to their significant advantages of higher efficiency and power density compared to conventional technology, which meet the requirements for future electrical aircraft propulsion. However, as the technology currently stands, the AC loss of HTS armature windings is hindering the improvement of overall machine efficiency. It has been an established understanding that the AC loss of 2G HTS windings must be accurately identified and minimized for fully HTS machine applications, in order to lower the constraint on the cryogenic coolingdemand and ensure long term operation. Aiming to push the HTS machine towards commercial use in power applications, this thesis studies the interpretation and understanding of AC loss of 2G HTS using bothexperimental and numerical methods, especially proposing several methodologies for AC loss reduction in 2G HTS cable. It provides a thorough study on exploring effective ways to minimize the AC loss of 2G HTS for future electric aircraft propulsion. This thesis is divided into three parts. The first part is Chapter 1, which provides a foundation for this thesis through a review of the theory of superconductivity and AC loss, and AC loss reduction challenges for a fully HTS machine. The second part consists of Chapters 2, 3 and 4, which form the core of this thesis, and include the experimental and numerical study of the AC loss of 2G HTS coils based on several proposed AC loss reduction strategies. The third part is Chapter 5, which illustrates the AC loss measurement mechanism at temperatures lower than 77 K, including a detailed cryostat design of the HTS machine demonstrator and helium cooling system working protocol. To sum up, this thesis discusses very interesting and useful aspects of 2G HTS AC loss reduction strategies. It is expected that this thesis will contribute to the loss quantification and minimization of 2G HTS in electric machines, providing a valuable reference for the design optimization of fully HTS machines.
Advisor / supervisor
  • Zhang, Min, 1986-
  • Yuan, Weijia
Resource Type
DOI

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