This project proposes a paradigm shift in the operational management and use of power converters that entails active reliability management. This involves predicting failure and managing the remaining useable life of the power converter. Power electronic converters are indispensable to modern civilisation. They are responsible for electrical power conversion for a range of applications that span the few watts for portable hand-held electronics to several gigawatts for entire electrical power networks. Over the past few decades, the need for industrial decarbonisation has intensified the research into more efficient and reliable power electronic devices, components and converters. This is because power electronic converters are required for integrating renewable energy sources (solar, wind, tidal etc.) into the electrical system. Furthermore, electric transportation, which is seen as critical for reducing green-house emissions, relies very heavily on power electronics. Hybrid and full electric vehicles require power converters to control the traction machine, likewise, electric trains require power converters. Marine propulsion has also adopted the electric paradigm with the gas driven turbine replaced by a converter driven electrical motor. However, as power converters are driven at increasingly higher power densities, several reliability concerns have been recognised. The power converters are comprised of power modules, which in turn are comprised of switching power semiconductor devices in an electrically isolating but thermally conducting package. The reliability of the power semiconductor device and its mechanical interconnects has been intensely investigated by industrial and academic researchers over the last decade. Silicon devices have been the principal technology in power electronics for the last few decades however, silicon carbide and gallium nitride devices have emerged as viable alternatives. These new devices are referred to as wide bandgap devices because they have energy bandgaps larger than that of silicon. The simply means that they can withstand more energy thereby increasing the efficiency of power conversion. The reliability of these WBG semiconductors is increasingly becoming a very important topic since these new devices are gaining increasing market penetration. In applications with high failure costs, for example, automotive traction, aerospace and grid connected converters, the uptake of new technology is slow. By developing technologies that can improve the reliability of these new devices and monitor their health on-line, the uptake of new WBG power modules is very significantly de-risked. This project aims to do just this, by providing a condition monitoring and health management platform for WBG based power electronic modules.

Power electronics reduces our carbon footprint and contributes nearly £50bn per year to the UK economy and supports 82,000 skilled jobs in over 400 UK-based companies. Power electronic converters regulate the flow of power in most electrical devices, in electric vehicles etc. They do so by switching currents on and off, 10s of thousands of times per second, and the ratio of on-time to off-time determines the power flow. The efficiency, size, and weight of these converters are determined by the amount of waste heat generated. For example, the size of laptop power adapters has shrunk over the years, due to their increase in efficiency. In an electric car, waste heat causes power converters to be typically larger than the motors they are feeding. This heat is mostly produced in the instances when the transistors are switching. The power electronics industry is about to undergo significant change, as ultra-fast-transition transistors made from silicon carbide (SiC) or gallium nitride (GaN) have recently emerged. Their switching transitions are so short (below 10 nanoseconds) that, in principle, efficiency can be pushed to levels never achieved before. This could lead to a ten-fold miniaturisation, leading to converters that are much smaller than the motor being driven, or credit-card-sized laptop power adapters. The fast switching, however, comes with the downside of extreme electromagnetic noise, and industry is struggling to adopt these new technologies. Our project will provide answers to key uncertainties for adoption of these new technologies, namely how to drive the SiC and GaN power devices quickly, safely and quietly. The electromagnetic noise (EMI) is seen on an oscilloscope as sharp corners, rapid oscillations, and overshoot spikes, during the switching transitions. In this project, we are developing solutions to achieve clean switching, without these undesirable features, to quieten the EMI. These features are countered by feeding specially-shaped signals into the transistors' gates. The switching transition is too fast for any known signal generators and closed-loop control methods, or passive switching-aid (filtering) circuits to provide the required shaping of gate signals. Therefore, an alternative approach is adopted. We recently developed a chip that can adjust its current output every 100 picoseconds, i.e. the time it takes light to travel 3 cm. It is the only known driver chip that can interact frequently enough with a gate signal to shape these short sub-10 nanosecond switching transitions. We will create improved versions of this driver to drive gallium nitride and silicon carbide transistor gates with signals that are designed to soften the switching and cancel out unwanted high-frequency effects. The signals need to be changed automatically as the converter temperature changes, and when changes to its output power are requested. Also, each type of circuit requires slightly different signals. Therefore, automatic adaptation will be developed to simplify the use of this technology by industry. An interesting challenge is the safe generation of optimised gate signals, as the wrong signal can cause a power converter to fail. Another challenge is the regeneration of energy put into the gate, so that it can be used for the next switching event. The project develops microelectronics (high-speed, EMI-quietening gate drivers) and power electronics (converters and control systems). Industry advisors from 8 partner companies will steer the development for three years. In Year 4, the research is scaled down, and trials in UK-based industry set up to transfer knowhow, test the research, and provide new avenues for fundamental research. This research will help maintain the compatibility between emerging high-efficiency power electronics and modern ultra-low-power microelectronics that is increasingly susceptible to electromagnetic noise, and simplify and expedite industry adoption of SiC & GaN.

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.