Silicon Carbide Power Conversion for Telecommunications Satellite Applications

Lead Research Organisation: University of Warwick
Department Name: Sch of Engineering

Abstract

State-of-the-art power electronics hardware on board satellites and other space vehicles have reached the limit of current radiation-hard silicon technology. Implementation of silicon carbide (SiC)-based power conversion in space is therefore an opportunity to bring about a step change in converter efficiency, size, and weight. Most importantly however, the higher temperature rating of SiC electronics would facilitate, for the first time, the co-location of the electronic power conditioners (EPCs) onto the same thermal baseplate as the travelling wave tubes (TWTs) they supply. In a telecommunications satellite, the space saved by this, and the removal of high voltage cabling, is expected to allow for 16 more RF channels to be added to the current maximum of 50.
Despite the adoption of wide bandgap technology in terrestrial applications, particularly in the electric vehicle drivetrain and in solar inverters, there is a lack of progress towards rad-hard SiC parts. Until now, researchers and companies have unsuccessfully attempted to retrofit radiation hardness, by repackaging terrestrial devices or by modifying traditional vertical device topologies. However, it is clear from decades of development in silicon that radiation hard devices require their own bespoke solutions (e.g. silicon-on-insulator or superjunction technology), requiring the materials and epitaxy, the device layout and the packaging all to be optimised. With considerable room for innovation in the SiC radiation-hard field, bespoke, patentable SiC devices will be developed, which take their inspiration from the rad-hard family of Si devices developed in the last 30 years.

The ambition of this project is to prove that SiC power devices can modernise radiation-hard power systems. Schottky diodes and MOSFETs will be developed, within a range of novel architectures, with immunity to high energy radiation their primary design feature. Through three development cycles, the radiation and electrical performance of the new SiC devices will be benchmarked to results from commercial terrestrial SiC devices and the Si state of the art. A set of 1200 V SiC diodes and 600 V MOSFETs will be evaluated by Thales Alenia Space for use in their telecommunications satellite EPCs. A UK-based route to commercialisation has been identified, supported by the project partners, involving higher TRL follow-on funding to bring the devices close to market. The project shall prove definitively, for the first time, whether SEE susceptibility in SiC is inherent or, as in Si, can be overcome through bespoke device design.

Warwick are uniquely positioned to make this leap, thanks to the expertise of its academic and research staff, and the investment in its epitaxy and fabrication facilities, that make it one of very few research groups in Europe, or even the world, that can innovate at every stage of development.

Planned Impact

Radiation-hardened power devices are proposed, which stand to revolutionise the satellite and spacecraft industries. To date, only terrestrial device topologies have been trialled in the pursuit of a space-rated SiC power device. This leaves considerable room for innovation in this field, with this project set to develop bespoke, patentable SiC devices, which take their inspiration from the rad-hard family of Si devices developed in the last 30 years. Warwick are uniquely positioned to make this leap, thanks to the expertise of its academic and research staff, and the investment in its epitaxy and fabrication facilities, that make it one of very few research groups in Europe, or even the world, that can innovate at every single stage of development. The ambition of this project is to demonstrate the potential of the novel SiC device layouts, in their immunity to SEE and TID, developing these to TRL4, just short of formal commissioning. The 42-month timetable allows the team sufficient time to realise the full potential of each of the structures proposed and to patent and publish the findings, before a final set of devices are developed and delivered to Thales Alenia Space for evaluation.
The specific impacts of the project, detailed in more detail in the Pathways to Impact, include the following:
- Economic. A rad-hard SiC product will boost the UK SiC supply chain. A commitment has been made from the research team and the project partners to use this research project to develop radiation hard SiC power devices in the UK, boosting the SiC supply chain. In collaboration with the project partners (Thales Alenia Space, Micross, Clas-SiC Wafer Fab Ltd, and the Compound Semiconductor Applications Catapult), opportunities will be sought (such as Innovate UK Smart Grants) beyond the end of this project, to advance the best devices produced to TRL5 and to a commercial product.
- Society. Satellite technology is central to tackling the issues facing society today, including energy security, population growth, environmental damage and the increased digitisation of daily life. By increasing the RF channel capacity in telecommunication satellites, we will be have added more capacity for the applications they serve: from GPS to weather, television to 5G and much more. Grander social tasks such as the exploration of space will also benefit from smaller, lighter, high temperature power supplies.
- Scientific advancement. This project aims to produce a definitive answer as to whether SiC is a viable material for space-based power electronics. To date, there have been no visible investigations into the bespoke design of radiation hard SiC device architecture, as the Si industry did in the 1990s. We will therefore move the field forwards by publishing the findings of our research in the leading journals and conferences in the field (see the Pathways to Impact).
- Intellectual Property. By the same argument above, the paucity of work into rad-hard SiC devices, leaves significant opportunity for patents, protecting the key scientific advancements made.
- Education. With the work taking place in a leading Engineering School, we have plenty of opportunity to inspire our undergraduates, and local school pupils students through our research. Interdisciplinary group projects, individual projects, and summer placements are planned linkin our project with the already established, and highly successful, Warwick Satellite (WUSAT) project. The School and the University are also involved in a number of local community days, including Enginering Days and Family Days, all of which this project can engage with. To this end the School of Engineering has committed to contribute match funding for educational projects related to this research.

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