Reliability is a critical attribute of power networks due to their importance to modern civilisation. The increasing use of renewable generation in our power system means that power electronic converters, which are needed to connect them to the power grid, are becoming widespread. Unlike traditional power systems devices, power converters are more prone to failures. However, they offer much more precise control and performance than conventional power system devices and are an indispensable part of modern power systems. Hence, the reliability of power converters is of paramount importance. Offshore wind systems have been acknowledged as one of the leading solutions to decarbonise energy systems in the UK, with deployment anticipated to reach 84 gigawatts installed capacity by 2050. Due to their wind profile reliability, offshore wind farms offer longer-term solutions than onshore ones. The availability of many suitable sites, the excellent wind resources and the existing capabilities of the offshore petroleum industry make the UK ideally placed to be a world-leading player in floating wind systems. Typically, floating offshore wind farms with power ranging from five to fifty megawatts are expected to be connected to medium voltage power networks, therefore, requiring step-up transformers. Although such transformers have proven robustness, they are expensive and bulky. The project aims to develop a novel power electronics converter to connect floating offshore wind turbines to power networks, ensuring resilience, high efficiency, superior reliability and the least impact on the environment. This will be achieved by undertaking advanced modelling and computer simulation to identify the optimal converter design, followed by the development of intelligent control software to maximise the efficiency and fault-tolerant operation of the converter. The performance of the final design will be validated through prototype hardware implementation and testing in consultation with the industrial partner.

Electrification of aviation will be central to achieve ambitious environmental targets for the reduction of carbon emission, fuel burn and noise. The UK Aviation Strategy 2050 sets out objectives to ensure a safe and secure way to travel, support growth while tackling environmental impacts. A current game-changing concept is hydrogen-powered electric aircraft. Airbus ZEROe concept aircraft enables investigation of hydrogen technologies that will shape the future zero-emission aircraft. Large-scale hydrogen-powered electric aircraft of multi-megawatt level have very high requirements on power density and efficiency of the on-board electric network. Liquid hydrogen offers a cryogenic environment for the electric network, which opens new opportunities for the use of superconductivity. A cryogenic and superconducting direct current (DC) distribution network is a key step for the development of large-scale hydrogen-powered electric aircraft due to its high efficiency, high-power density, and reduced impact on the overall weight of the aircraft. The Fellowship aims to make an important contribution towards the development of large-scale hydrogen-powered electric aircraft by developing the first reliable high-power density and high efficiency cryogenic and superconducting DC distribution network. A cryogenic and superconducting direct current (DC) distribution network is attractive due to its high-power density, high efficiency, and reduced impact on the overall weight of the aircraft. This Fellowship will address the highly demanding safety and reliability requirements of the superconducting DC distribution network, necessary to ensure the supply to flight critical loads and to enable the safe recovery of the supply from any fault conditions. It will do so through a novel, powerful combination of numerical and experimental methods to deliver the first cryogenic hybrid DC circuit breaker combined with a superconducting fault current limiter (SFCL). By collaborating with Airbus, ATI FlyZero, IXYS UK Westcode Ltd., and University of Manchester, a pioneering method for the control and protection of the superconducting DC distribution network for large-scale hydrogen-powered electric aircraft will be demonstrated as a vital pathway to make the technology viable for future commercial zero emissions and low noise electric aircraft.

Power Electronics plays a very important role in the electrical power conversion and is widely used in transportation, renewable energy and utility applications. By 2020, 80% of electrical power will go through power electronics converters somewhere between generation, transmission, distribution and consumption. So high-efficiency, high-power-density and high-reliability are very important for power electronics converters. The conventional power electronics devices are based on silicon materials and have reached the limit of their potential. The emergence of wide-bandgap (WBG) material such as silicon-carbide (SiC) and Gallium-Nitride (GaN) based devices has brought in clear opportunities enabling compact, more efficient power converters, operating at higher voltages, frequencies and powers to meet the increasing demand by a range of existing and emerging applications. For example, more/full electric aircrafts with hybrid propulsion requires 10s of MW efficient power conversion with high frequency drives, higher voltage levels as well as higher power density. Wireless power charging is pushing the frequency from 100s of kHz to MHz at kW power level to minimise passive elements such as inductors and capacitors. Transformerless, compact, high-efficiency medium-voltage (1kV~10kV) power conversion enabled by high voltage SiC devices is critical for the realisation of power electronics based distribution networks (including energy storage interfacing) for smart grid as well as future transportation systems. Whilst WBG devices offer the possibility to operate at higher voltages with lower on-state losses, and faster switching speeds than Si devices, maximising the performance benefits at a converter level creates a range of interrelated challenges. For example, high voltage and current changing rates of WBG devices will generate significant electro-magnetic-interference (EMI) and affect the running of other equipment. Identifying the most effective circuit topologies, passive component technologies and control methods, and managing the very high switching rates to extend the frequency/voltage/power envelope present great challenges to power electronic engineers, but are vital if the true potential of WBG circuits is to be achieved. They therefore form the main motivation for this project. This Converter Architecture (CA) project brings together the UK's best academic and industrial expertise to investigate optimal converter architectures, advanced passive components design methods, fast speed control techniques and holistic optimisation to realise the full potential of WBG devices in achieving higher efficiency, high power density with extended voltage, frequency and power handling capability.

Over the next twenty years, the automotive and aerospace sector will undergo a fundamental revolution in propulsion technology. The automotive sector will rapidly move away from petrol and diesel engine powered cars towards fully electric propelled vehicles whilst planes will move away from pure kerosene powered jet engines to hybrid-electric propulsion. The automotive and aerospace industry has worked for the last two decades on developing electric propulsion research but development investment from industry and governments was low until recently, due to lag of legislation to significantly reduce greenhouse gases. Since the ratification of the 2016 Paris Agreement, which aims to keep global temperature rise this century well below 2 degrees Celsius, governments of industrial developed nations have now legislated to ban new combustion powered vehicles (by 2040 in the UK and France, by 2030 in Germany and similar legislation is expected soon in China). The implementation of this ban will see a sharp rise of the global electric vehicle market to 7.5 million by 2020 with exponential growth. In the aerospace sector, Airbus, Siemens and Rolls-Royce have announced a 100-seater hybrid-electric aircraft to be launched by 2030 following successful tests of 2 seater electric powered planes. Other American and European aerospace industries such as Boeing and General Electric must also prepare for this fundamental shift in propulsion technology. Every electric car and every hybrid-electric plane needs an electric drive (propulsion) system, which typically comprises a motor and the electronics that controls the flow of energy to the motor. In order to make this a cost-effective reality, the cost of electric drives must be halved and their size and weight must be reduced by up to 500% compared to today's drive systems. These targets can only be achieved by radical integration of these two sub-systems that form an electric drive: the electric motor and the power electronics (capacitors, inductors and semiconductor switches). These are currently built as two independent systems and the fusion of both creates new interactions and physical phenomena between power electronics components and the electric motor. For example, all power electronics components would experience lots of mechanical vibrations and heat from the electric motor. Other challenges are in the assembly of connecting millimetre thin power electronics semiconductors onto a large hundred times bigger aluminium block that houses the electric motor for mechanical strength. To achieve this type of integration, industry recognises that future professional engineers need skills beyond the classical multi-disciplinary approach where individual experts work together in a team. Future propulsion engineers must adopt cross-disciplinary and creative thinking in order to understand the requirements of other disciplines. In addition, they will need an understanding of non-traditional engineering subjects such as business thinking, use of big data, environmental issues and ethical impact. Future propulsion engineers will need to experience a training environment that emphasises both deep subject knowledge and cross-disciplinary thinking. This EPSRC CDT in Power Electronics for Sustainable Electric Propulsion is formed by two of UK's largest and most forward thinking research groups in this field (at Newcastle and Nottingham Universities) and includes 16 leading industrial partners (Cummins, Dyson, CRRC, Protean, to name a few). All of them sharing one vision: To create a new generation of UK power electronics specialists, needed to meet the societal and industrial demand for clean, electric propulsion systems in future automotive and aerospace transport infrastructures.