Power electronic modules (PEMs) and higher-level systems play an increasingly important role in adjustable-speed drives, unified power quality correction, utility interfaces with renewable energy resources, energy storage systems, electric or hybrid electric vehicles and more electric ship/aircraft. The power electronic technologies provide compact and high-efficient solutions to power conversion but deployment of power electronic modules in such applications comes with challenges for their reliable and safe operation. This project aims to address four key challenges which the power electronics manufactures, and PEM end-users continue to face: Challenge 1: No in-line and non-destructive inspection methods for PEM package quality and internal integrity assessment (wire bonds, die attachment and encapsulant) embedded within the production line. Challenge 2: No comprehensive PEM data on design-quality-reliability characteristics, no processes for chartreisation and test data integration and management, and for data modelling and analysis. Challenge 3: No advanced capabilities for accurate assessment of PEM deployment risks and for lifetime management. Challenge 4: No or limited data is fed back from end-users to PEM designers/manufacturers, no application-informed design and manufacturing quality. The project seeks to develop a digitalised Data Analytics and Analysis Platform (DAAP) for PEMs. The following novel and beyond current state-of-art developments in the project address the above stated challenges: 1) Non-Destructive Testing (NDT) with real-time data acquisition capability. A novel technique for NDT using LF-OCT imaging will be enhanced and optimised to provide quality data for individual PEMs. The proposed NDT method can quantitatively measure the mechanical deformation of gel-encapsulated bonding wires down to nanometer level. It can capture an entire cross-sectional image without any mechanical scanning, providing novel capability of running in-line with the packaging process. 2) Quality Predictions using AI and Machine Learning (ML): Research on integration and use of multiple data formats and sources, including standard datasets of electrical parameter test measurements, image data from in-line LF-OCT, and off-line X-ray and other imaging techniques, will be undertaken. The integrated data will underpin the accurate and automated quality evaluation of each individual PEM by enabling the development of ML and Deep Learning models. The modelling capability will enable packaging quality evaluations based on comprehensive sets of design and packaging process attributes. 3) Reliability Predictions. Current state-of-art in design-reliability and in-service degradation modelling for PEMs will be advanced through the proposed inclusion of manufacturing quality characteristics and design attributes in the reliability predictions. This will result in enhanced knowledge and more accurate, quality-informed reliability modelling and insights into the relations between design, quality and reliability by analytics of manufacturing and end-user data. 4) Data-Modelling-Optimisation Capabilities' Integration. The proposed integration (DAAP) of data, information exchange, and different modelling capabilities with multi-objective optimisation methods will be a novel development. The proposed optimisation routines will provide new capabilities for power semiconductor packaging design (e.g. module architecture, materials, interconnect solutions, application-specific reliability performance, etc.) and optimal process control on the manufacturing line.

Many industrial applications make use of high voltage power electronic devices. Examples include traction, marine power and power system based power electronics. Further developments are currently taking place within the aerospace sector that will mean the market for such devices will continue to grow. Most of the applications that power electronic devices are used in demand reliable operation. In turn this means that care must be taken in the design of the insulation system. Modules that operate at voltages over 5kV are currently available and there will always be a drive to improve the power density of the module by raising voltages or by miniaturisation. To do this, weak points in the dielectric system must be progressively improved. A power electronic module is typically composed of a metallized substrate soldered onto a baseplate. Different techniques are used to achieve this such as directly bonded copper or active metal brazing. The high voltage silicon IGBTs / diodes are typically soldered this substrate that is itself made from aluminum nitride (AlN), a ceramic with a good insulation strength. Wire bonds are then used to make connections between the individual IGBT / diode terminals and external connections for gate drives / busbars. The whole assembly is immersed in a soft dielectric, typically silicone gel, in order to provide the dielectric strength along the surfaces of the substrate, between the busbars and any other parts of the module subject to high electric fields. An epoxy layer may then be placed over the top of the entire dielectric system. The critical area in which the insulation system of a power module is extremely weak is at the edge of the metallisation of the substrate. The performance of the silicon gel is particularly critical in this location not just in terms of preventing discharge within the gel itself but also in terms of preventing discharge at the gel-substrate interface in close proximity to the metallisation.The invention being developed by the University of Manchester relates to the modification of the dielectric system of a module thus reducing the probability of electric discharge at this interface. The use of the technology being developedwould help to reduce the high levels of failure rates that can currently occur on low volume production runs of high value power electronic modules. It would also significantly improve the reliability of power electronic modules as insulation defects that did not show up in initial testing but which exist and have the ability to cause cumulative damage would be reduced in severity by the technology.The funding of this project through the follow on fund mechanism will allow the technical case for the technology to be enhances through a more thorough understanding of the ability of technology to enhance the dielectric system and through the understanding of the relationship between the manufacturing process and the electrical performance. In parallel, the commercial activities that are discussed will allow the commercial case for the technology to be strengthened through the completion of a cost benefit analysis, the appraisal of the technology to be used in the next generation of power electronic modules and the identification of prospective partners.The close association with the University of Manchester Intellectual Property team will also allow the mechanism for long term promotion and development of this technology to be identified as well as understanding the ways in which the technology can be used in other technical areas.

Modern society's reliance on electrical energy is almost as critical as its reliance on food and water. In the UK, majority of the electrical energy is generated by electrical machines powered by fossil fuels. The principles of sustainability require that the energy consumption pattern changes since fuel reserves are finite. Furthermore, shifting away from fossil fuels is integral to the de-carbonisation of the economy which is critical for tackling global warming. To this end, substantial progress has been made on harnessing wind, solar and other renewable energy sources. However, change is also required in the manner in which electricity is transmitted and distributed through the grid. Renewable energy is usually intermittent and unpredictable, characteristics which make it unsuitable for direct connection with the electric grid. Renewable sources like wind and solar energy can only interface with the electrical grid through power electronics. Power electronics is required for the processing and conditioning of electrical energy so as to make it complaint with the grid. At the heart of power electronics, we have power semiconductor devices which have traditionally been fabricated out of silicon bipolar technology. However, silicon is reaching its fundamental limits in terms of energy density, hence, moving to advanced power materials like silicon carbide can give added impetus to the field of power electronics. Silicon carbide is a wide bandgap semiconductor with a higher critical electric field and higher thermal conductivity. In this project, the reliability of power converters implemented in Silicon-Carbide MOS-Transistor technology is investigated. These power converters will typically be used in off-shore wind-farms for power conversion in high voltage DC transmission (HVDC) systems. The converters can also be used in flexible AC transmission systems like STATCOMS (Static Compensators). The overall objective is to characterize the reliability of power converters implemented in silicon-carbide MOS transistors.

Silicon carbide (SiC) N-channel IGBTs have the potential to enable new and highly efficient ultrahigh voltage (10 kV+) applications such as the Smart Grid and HVDC, enabling a low carbon society. However, to date, only four research groups have reported on their successful development, due to the considerable challenge associated with their fabrication. Exploiting a consortium made up of experts from the fields of SiC materials, simulation and fabrication, and building on a recent history of SiC MOSFET, Si IGBT and SiC materials research, the aim of the Switch Optimisation theme of Underpinning Power Electronics is to be amongst the first groups in Europe and the world to develop these devices, and to push the boundaries of what has been achieved in this fledgling field to date. Once a quality benchmarked ~15 kV SiC IGBT process is developed as the first milestone in this project, the process will be modified to explore areas not to-date explored, including the development of lower voltage (5-10 kV) SiC IGBTs benchmarked to SiC MOSFETs, trench SiC IGBTs, and novel topologies such as hybrid SiC MOSFET-IGBTs. The consortium will all work together towards these ambitious goals, with the work packages split by expertise (materials development, simulation, fabrication and testing) to cut across each of the objectives.

There are two very particular places in energy networks where existing network technology and infrastructure needs radical change to move us to a low carbon economy. At the Top of network, i.e. the very highest transmission voltages, the expected emergence of transcontinental energy exchange in Europe (and elsewhere) that is driven by exploitation of diversity in renewable sources and diversity in load requires radical innovation in technologies. Many of these proposed interconnectors will be submarine or underground cable and High Voltage Direct Current (HVDC) must be used. Power ratings for the voltage source AC/DC converters for HVDC use are presently around 500 MW while the need is for links of up to 20 GW. A change of this magnitude requires radical innovation in technology. To focus our research in HVDC cable technology and power converters we have defined target ratings of 1 MV and 5 kA. The Tail of the network is the so-called last mile and behind the meter wiring into customer premises. More than half the capital cost of an electricity system is sunk in the last mile and cost and disruption barriers have made it resistant to change. Not only have recent changes in consumer electronics yet to impact network design, there are radical changes in future heat and transport services that need to be met. The challenge is to reengineer the way in which the last mile assets are used without changing the most expensive part: the cables and pipes in the ground. To get this right means starting with a fresh look at the energy services required and seeing what flexibility there is to meet the service expectation differently. A consortium of universities has been brought together to address this transformation of our energy networks. Several of the bid partners have had leading roles in Supergen consortia in the networks area but this consortium includes new partners whose expertise, especially in the power electronics field, is strongly indicated as game-changing. For the first time, the power electronics researchers in Warwick, Nottingham, Imperial and Strathclyde and the insulation materials groups in Manchester and Southampton are proposing to work together bringing developments of underpinning technologies to bear on network issues. These technology developments are folded into the energy network planning and operations work of Strathclyde, Manchester, Cardiff and Imperial. Birmingham brings energy economics expertise and Imperial expertise in energy policy and the social science of consumer acceptance. Several important industrial companies are engaged with this programme to form our scientific advisory board and to pick up and use results that emerge. These in clued network operators such as National Grid and Central Networks, equipment manufacturers such as Alstom Grid and Converteam and component manufacturers such as Dynnex and Dow Chemicals.Although the proposed project will address major challenges of technology, we recognise that transforming our energy networks is not merely a technical question. Members of the consortium already have links with civil servants and advisors in a number of administrations in the UK including DECC, the Scottish Government, WAG and NIE. These links allow us to understand the context in which energy policy is made. Consortium members have given advice to Ofgem on the Low Carbon Networks Fund, Parliamentary Select Committees and have been active in projects commissioned through the Energy Technologies Institute. Thus although the focus of your project is on a timescale of 20-40 years the results of our research will impact network development much earlier. Discussions to date with our partners in these organisations suggest a great deal of excitement about what work on the Energy Networks Grand Challenge can contribute.