Developing Highly efficient HTS AC windings for fully superconducting machines

Superconductors have zero resistivity below their critical temperatures, enabling them to carry large amounts of current. Therefore, superconductors can be used to construct powerful electrical machines with light and compact designs. However, one key difficulty when designing superconducting machines is that superconductors dissipate heat when they carry AC current or in AC magnetic fields. This heat dissipation (AC loss) in a low temperature environment adds to the cost and difficulties of keeping the superconductors at low operational temperature. The AC loss reduces system efficiency because up to a hundred times the cooling power in room temperature is required to remove it. In order to increase the machine efficiency it is therefore vital to be able to accurately estimate how much AC loss is dissipated in a superconducting machine and to identify strategies to reduce this loss.

Significant progress has been made towards understanding the AC loss of superconductors in research laboratories worldwide. However, estimating the AC loss of superconductors in electrical machines is an intrinsically difficult task. There is a complicated interaction between the current and the magnetic field inside an electrical machine and the influence of this interaction on the machine AC loss is unknown at this moment. Actions, both experimentally and numerically, are required to understand the AC loss of superconducting machines.

The aim of this project is to develop new experimental and numerical tools to estimate the AC loss of superconducting machines. We will design an experiment to measure the AC loss of superconductors in a simulated electrical machine environment. We will also develop a new FEM model, which will be validated by experimental data, to efficiently estimate the AC loss of fully superconducting machines. Furthermore, we will use the model to identify new strategies to reduce the AC loss and improve the efficiency of fully superconducting machines, based on the latest HTS technologies.

The impact of this project on the aviation industry will be significant. The European Commission's "Flightpath 2050" road map has set the target for the aviation industry to achieve a 70% cut in CO2, a 90% cut in NOx, and 75% reduction in external noise based on the 2000 standards by 2050. The aviation industry is keen to identify advanced enabling technologies that can facilitate these dramatic changes. The UK has the second largest aviation industry in the world, so it is well-placed to lead this effort. However, to do this, the UK must invest in fundamental research in order to support the development of these enabling technologies. Fully HTS machine is one such enabling technologies. Improvements in the understanding of fully superconducting machines and improvements in their efficiency provided by the project will make an important contribution in paving the way towards superconducting electric aircraft. Therefore, the outcomes of the project will influence the future directions of aviation industry.

High temperature superconductivity technologies can potentially lead to a new industrial sector with significant economic impact. It is estimated by International Superconductivity Industry Summit that the emerging energy markets for HTS conductors will be £8-15 billion by 2030. Due to the strict space and weight limits on-board an aircraft or a ship, HTS devices with high power densities, such as HTS machines and cables, will play an indispensable role in the electrification of the future transportation industry. The project will create substantial impact on the high temperature superconductor industry by creating new market opportunities in the transportation sector, thereby attracting new industry stakeholders. It will also give specific recommendations to superconductor manufacturers for further developing their materials to be more suitable for electrical power applications. Further improvement of the technology will accelerate the penetration of HTS conductors into the power and transportation industries.

A significant impact of the project on the social and environmental sectors is also envisaged. Electrical aircraft enabled by fully HTS propellers can not only cut emissions but also reduce aviation noise pollution to minimize the environmental impact of aviation. High power density HTS machines will help lower the cost of offshore wind generation, because this technology can increase the generator capacity without significant increased infrastructure investment. In addition to these wide-ranging technological impacts, superconductors can be used to generate general public interest therefore arising public awareness of CO2 reduction and low carbon technologies. This project will maximise its impact on the public as detailed in the Pathways to Impact document.