Silicon carbide based devices to protect aircraft electrical systems

Flying during an electrical storm can be a terrifying business, with lightning paths travelling from cloud-to-ground or cloud-to-cloud – and with an aircraft in flight sometimes forming part of this route.

Despite all appearances to the contrary, such an event doesn’t spell danger as the outer skin of the aircraft, which is traditionally aluminium, does much to accommodate the lightning’s path. Meanwhile, voltage surge suppression devices protect aircraft electronics from overload by the current involved.

However, the next generation of aircraft, with their increased use of composite materials for constructing their airframes – and resulting reduced electrical screening – will require a new approach to this. Although lighter and more fuel-efficient aircraft are certainly more attractive, it is highly important that their lightning protection functions are not reduced.  

As a result, researchers are exploring the possibility of using a silicon carbide based device to protect aircraft electrical systems, in the form of Innovate UK-funded Current Limiting Diodes (CLDs), which will absorb excess energy surges induced in the electrical wiring by a lightning strike while reducing the size and therefore the weight of traditional suppressor devices.

The project is being led by Controls and Data Services, part of the Rolls-Royce Group, alongside Raytheon UK, which is lending its expertise in high-temperature silicon carbide (HiTSiC).

It also includes Newcastle University, who are taking the role of design authority, and TT Electronics Semelab. Presently, Newcastle University is conducting electrical characterisation tests while TT Electronics Semelab is developing the CLD’s packaging.

‘We are working with Newcastle University, who conceptualised the idea,’ said Greg Wells, chief of research and technology at Rolls Royce Controls and Data Services. ‘The devices are currently being produced by Raytheon and then need to be packaged and tested further.’

The equal partner project is expected to be completed by late 2015, and the resulting technology could also have applications elsewhere.

‘The devices are applicable anywhere where the high integrity of the control system and high temperature are concerns, and where excessive current limits this,’ said Robin Hill, engineering fellow for high integrity electronics at Rolls-Royce. ‘It also has possibilities for use in the oil and gas industry.’