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.

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.

The urgent need for EV technology is clear. Consequently, this project is concerned with two key issues, namely the cost and power density of the electrical drive system, both of which are key barriers to bringing EVs to the mass market. To address these issues a great deal of underpinning basic research needs to be carried out. Here, we have analysed and divided the problem into 6 key themes and propose to build a number of demonstrators to showcase the advances made in the underlying science and engineering. We envisage that over the coming decades EVs in one or more variant forms will achieve substantial penetration into European and global automotive markets, particularly for cars and vans. The most significant barrier impeding the commercialisation EVs is currently the cost. Not until cost parity with internal combustion engine (ICE) vehicles is achieved will it become a seriously viable choice for most consumers. The high cost of EVs is often attributed to the cost of the battery, when in fact the cost of the electrical power train is much higher than that of the ICE vehicle. It is reasonable to assume that that battery technology will improve enormously in response to this massive market opportunity and as a result will cease to be the bottleneck to development as is currently perceived in some quarters. We believe that integration of the electrical systems on an EV will deliver substantial cost reductions to the fledgling EV market Our focus will therefore be on the two major areas of the electrical drive train that is generic to all types of EVs, the electrical motor and the power electronics. Our drivers will be to reduce cost and increase power density, whilst never losing sight of issues concerning manufacturability for a mass market.

Power electronics and electrical machines are key components in a low-carbon future, enabling energy-efficient conversion and control solutions for a wide variety of energy and transportation applications. The strength of the UK manufacturing base and its strategic importance to the UK was highlighted in the UK government strategy document "Power Electronics: A Strategy for Success" (UK government Department for Business Innovation and Skills, October 2011). This calls for concerted action across the industrial and academic communities to ensure that the full potential of this growing global market can be realised for the UK economy. Specific recommendations relevant to the UK academic community include: 1) the development of a co-ordinated strategy for postgraduate training; 2) support for research focussing on underpinning the core technology areas whilst ensuring that the national capability in Power Electronics remains internationally leading; 3) establishment of a Virtual Centre linking world-class UK universities with each other and with industry. A core team including the universities of Bristol, Cambridge, Greenwich, Imperial College, Manchester, Newcastle, Nottingham, Sheffield, Strathclyde and Warwick, has been formed to develop this proposal for a UK Virtual Centre. Our vision is that the Centre will be the UK's internationally recognised provider of world-leading, underpinning power electronics research, combining the UK's best academic talent. It will focus on sustaining and growing power electronics in the UK by delivering transformative and exploitable new technologies, highly skilled people and by providing long-term strategic value to the UK power electronics industry. Centre activities will be divided into three main strands: research, community and pathways to impact. Our research activities will bring together the leading academic research groups from across the UK to address key research challenges, build critical mass and develop a widely recognised internationally leading research capability. We will develop a UK research strategy for power electronics which will build on foresight activities to inform our research direction. Our community support activities will build capacity through the training of researchers at doctoral and postdoctoral level. We will extend our research funding to the broader community through themed calls for pump priming, strategic support and feasibility projects. In addition we will support and coordinate responses to major initiatives from national and international funding bodies. Pathways to impact will include: 1) the establishment and development of the Centre brand and communication mechanisms, 2) the development and implementation of an exploitation plan which benefits UK industry, 3) support for government policy development and 4) the development of collaborative links with key power electronic research teams around the world. The Centre programme focuses on fundamental power electronics research at low technology readiness level (TRL) and hence supports a wide range of application areas with a medium to long-term time horizon. Key challenges to be addressed are: increased efficiency, increased power density, increased robustness, lower electromagnetic interference (EMI), higher levels of integration and lower through life cost. The work programme is split into four high-level themes of Devices, Components, Converters and Drives, each of which will address the key challenges, supported by a coordinating Hub. The themes will deliver the majority of the technical output of the Centre.

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.