Electrical machines are estimated to contribute to more than 99% of global generation and more than 50% of all utilisation of electrical energy. Their role will be more pronounced as we move towards a more sustainable carbon neutral economy. Taking the UK automotive industry as an example, it is the fastest growing sector in the European economy, utilising more than 30% of our primary energy resources. UK automotive production is around 2 million vehicles in 2017. By renewing end of life products with more energy efficient ones, such as electric and hybrid electric vehicles (EV and HEV), this strong growth will increase the efficiency of energy use and help meet UK government targets in CO2 emission reduction - a 34% cut in 1990 CO2 emission levels by 2020 and 80% by 2050. This trend of electrification in transport will lead to a huge demand in powertrain (machines and drives) research. To remain competitive, electrical machine manufacturers endeavour to increase power density and efficiency of electrical machines. However, the machine industry is a relatively mature sector and the margin for further improvement in machine efficacy and power density is slim without novel materials or radical cooling technologies. This is particularly the case for machine end-windings, which often have the highest temperature and hence have the biggest impact on machine achievable efficiency, power density and also life span. Methods such as spray cooling, flooded or semi-flooded stator are proposed for end-winding cooling. Both methods are very effective because the cooling fluid is in direct contact with the end-windings. However, due to corrosion and erosion of spray nozzles, the spray cooling suffers from reliability and robustness issues. Moreover, both spray cooling and flooded stator often require a closed circuit liquid (oil or deionised water) supply equipped with mechanical pumps, filters, etc. which adds to capital and operating costs while also leading to a reduction in effective machine power density. In order to overcome the challenges facing the traditional cooling technologies, this project aims to develop a novel thermomagnetic liquid cooling for machine end-windings. The thermomagnetic cooling medium is based on ferro-fluid, which is an electrically nonconductive, temperature sensitive fluid mainly consisting of ferromagnetic nano-scale particles (such as iron, cobalt, nickel, etc.) in a liquid carrier (such as synthetic oils, hydrocarbons, etc.). When such liquid experiences a temperature variation under an external magnetic field, the fluid behaves as a smart fluid, i.e. it will have higher magnetisation in the lower temperature region (farther away from the heat source) than in the higher temperature region. As a result, a net magnetic driving force is produced to self-drive the fluid to flow towards the heated area (heat source with higher temperature). Due to this special feature, the thermomagnetic liquid cooling will be self-regulating, pumpless and maintenance free and hence very cost effective. In this project, by adopting a multiphysics optimisation approach that combines electromagnetic and thermomagnetic domains into a single framework for machines with ferrofluid cooling, this project aims to achieve a temperature reduction of >30oC compared to a forced air cooled machine with rotor mounted fans. This is significant because the reduction in machine temperature, particularly the winding temperature, not only increases machine's life span, e.g. a 10oC increase in winding temperature will halve the winding insulation life (similar effect for bearings' life span), but also increases the machine's efficiency due to reduced power losses.

Performance improvement of electrical machines in terms of power-density and efficiency is central to the success of hybrid- and electric- vehicles and more- or all- electric aircraft, as indicated by the UK Advanced Propulsion Centre and the Aerospace Technology Institute. Efficiency and packaging volume of conventional electrical machines are limited by the method used to manufacture electrical windings, i.e. using pre-insulated conductors of uniform cross-section wound around the teeth of the stator. Here, we propose the use of metal additive manufacturing (3d printing), in which feedstock or powdered material is selectively bonded in a succession of 2D layers to incrementally form a compact 3D winding. The geometric freedom offered by additive manufacturing allows the simultaneous minimisation of end-winding volume and individual shaping of conductor profiles to optimise efficiency all while acting as a substrate for high performance inorganic electrical insulation materials. The technology could address the increasing drive to low batch size, flexibility and customisation in design for high integrity and high value electrical machines for the aerospace, energy and high value automotive sectors while enabling CO2 reductions demanded by legislation and market sentiment. Specifically, I will lead this multidisciplinary project exploring the potential benefits of Additive Manufacturing of High Performance Shaped Profile Electrical Machine windings leveraging expertise from industrial and academic partners Renishaw, 3TAM, Motor Design Ltd and Teesside University. The partners represent leading electrical machine design (Motor Design Ltd, University of Bristol), electrical insulation materials (Teesside University), UK additive manufacturing supply chain (Renishaw) and end-use additive manufacturing part production (3TAM). This range of partners cover the necessary skills and capability to go from theoretical winding design to manufactured, insulated prototype windings. As such, the project will result in a significant growth in the UK's knowledge and skills base in this area and develop a technology demonstrator to illustrate the quantitative benefit of such windings to industry and academia. This will allow new cross-sector relationships and collaborations to be cultivated with a view to perpetuate the research beyond the project period, ultimately leading to industrial adoption and further poising the UK as a centre for excellence in high value electrical machine technologies.

Electrical machines are estimated to contribute to more than 99% of the global generation and 50% of all utilisation of electrical energy. Electric motors and generators will underpin the transition towards a more sustainable carbon neutral economy being at the heart of renewable energy generation in wind and marine power systems. They will also contribute to significant changes in our life as low emission transportation systems with "more electric" or "all electric" technologies in the automotive, marine, railway and aerospace industries are quickly growing in a market conservatively estimated to be worth over £50bn. Reliability is of paramount importance for the acceptance of electrical drives in safety critical applications such as those in aerospace industry. Increased reliability and availability can also generate significant commercial benefits to operators and users in sectors such as industrial, transport (e.g. electric/hybrid vehicles) and renewables (e.g. offshore wind generators) where the cost of maintenance, downtime and repair can markedly affect the business case for adopting new and innovative technologies. Electrical faults in machines, usually caused by progressive degradation of insulation materials, accounts for over 40% of the reported failures in industrial installations. To increase availability without increasing maintenance and associated downtime, it is necessary to monitor machines during operation, autonomously, with well-founded information on the current state of machine health available in real-time to the operator. Robustness of the methods for assessing degradation is critical, since false-positives, i.e. condition alerts which do not reflect the actual condition of elements of the machine, can be equally damaging in terms of availability and operational costs. Unfortunately, universally accepted and industrially validated methods for online condition monitoring remain elusive due to their lack of generality and robustness, the need for tuning specific algorithms for each individual application or the requirement for invasive and costly off-line testing. The research has two main aims that will contribute to a unified solution for online condition monitoring of inverter-driven electric machines. The first is the determination of a quantifiable model of lifetime of electrical motors under realistic operating conditions, including thermal, electrical and thermo-mechanical stresses, informing a methodology that can be used in real-time applications for continuous indication of the remaining useful life. The second is the demonstration of an innovative concept for condition monitoring of the state-of-health of the machine insulation without the need for additional expensive testing hardware, or modification to existing drives. The method, based on the real-time measurement of the common-mode impedance of the machine and its variations over the lifetime of the drive system, can provide a quantifiable indication of the progressive degradation of the insulation material. The research will allow a cost-effective solution to significantly improve reliability and operating costs in a large number of potential applications including transportation and renewable energy generation.

Step changes in electrical machine (e-machine) performance are central to the success of future More-Electric and All-Electric transport initiatives and play a vital role in meeting the UK's Net Zero Emission target by 2050. E-machine technology roadmaps from the Advanced Propulsion Centre (APC) and Aerospace Technology Institute (ATI) seek continuous power-density of between 9 and 25 kW/kg by 2035, in stark contrast to the 2-5 kW/kg available today. E-machine power-density is ultimately limited by the ability to dissipate internally generated losses, which manifest as heat, and the temperature rating of the electrical insulation system. The electrical conductors, referred to as windings, are often the dominant loss source and are conventionally formed from electrically insulated copper or aluminium conductors. Such conductors are manufactured using a drawing and insulation technique, which aside from improvements in materials, has seen little change in the past century. Exploring alternative manufacturing methods could allow reduction in losses, enhanced heat extraction and facilitate increased temperature ratings, ushering the necessary step changes in power-density and e-machine performance. Metal Additive Manufacturing (AM) is a process in which material is selectively bonded layer by layer to ultimately form a 3D part, enabling complex parts to be produced which may not be feasible using conventional methods. The design freedom offered by AM provides much sought-after opportunities to simultaneously reduce winding losses and packaging volume, improve thermal management and enable the use of high-temperature electrical insulation coatings. The design of such windings requires the development of new multi-physics design tools accounting for electromagnetic, thermo- and fluid- dynamics, mechanical and Design for AM (DfAM) aspects. It is important to have an understanding of the AM process, including the resulting material properties of parts and limitations on feature sizes and geometry in order to fully exploit the design freedoms whilst ensuring manufacturing feasibility. Establishing how to use build-supports and post-processes to improve component surface quality and facilitate application of electrical insulation coatings is another important aspect. To this end, I conducted initial studies in collaboration with academic and industrial partners focusing on shaped profile windings which have demonstrated the potential benefits of metal AM in e-machines and the drastic expansion of design possibilities to be explored. I intend to expand on this initial work through this fellowship which will provide me with flexible funding over a 4 + 3 year term to support The Electrical Machine Works, an ambitious and comprehensive research programme reminiscent of a Skunk Works project which draws together UK industry and academic expertise in AM, material science and multi-physics e-machine design to establish an internationally leading platform in this important emerging field. It is envisaged that the fellowship and associated platform, The Electrical Machine Works, will facilitate interdisciplinary collaboration with both industry and academia, catalysing high quality academic outputs disseminated through appropriate conference and journal publications, and the generation of Intellectual Property (IP), helping to keep the UK competitive in Power Electronics Machines and Drives (PEMD) and at the forefront of this area. If successful, in time The Electrical Machine Works will become a centre of excellence for AM in e-machines, contributing to a future skills and people pipeline and aiding in the raising of Technology Readiness Levels (TRL) in line with national priorities as expressed by the UK's Industrial Strategy, Advanced Propulsion Centre (APC), Aerospace Technology Institute (ATI) and Industrial Strategy Challenge Fund (ISCF) Driving the Electric Revolution (DER) and Future Flight (FF) initiatives.

Rapid and transformative advances in power electronic systems are currently taking place following technological breakthroughs in wide-bandgap (WBG) power semiconductor devices. The enhancements in switching speed and operating temperature, and reduction in losses offered by these devices will impact all sectors of low-carbon industry, leading to a new generation of robust, compact, highly efficient and intelligent power conversion solutions. WBG devices are becoming the device of choice in a growing number of power electronic converters used to interface with and control electrical machines in a range of applications including transportation systems (aerospace, automotive, railway and marine propulsion) and renewable energy (e.g. wind power generators). However, the use of WBG devices produces fast-fronted voltage transients with voltage rise-time (dv/dt) in excess of 10~30kV/us which are at least an order of magnitude greater than those seen in conventional Silicon based converters. These voltage transients are expected to significantly reduce the lifetime of the insulation of the connected machines, and hence their reliability or availability. This, in turn, will have serious economic and safety impacts on WBG converter-fed electrical drives in all applications, including safety critical transportation systems. The project aims to advance our scientific understanding of the impact of WBG devices on machine insulation systems and to make recommendations that will support the design and test of machines with an optimised power density and lifetime when used with a WBG converter. This will be achieved by quantifying the negative impact of fast voltage transients when applied to machine insulation systems, by identifying mitigating strategies that are assessed at the device and systems level and by demonstrating solutions that can support the insulation health monitoring of the WBG converter-fed machine, with support from a range of industrial partners in automotive, aerospace, renewable energy and industrial drives sectors.