The problem with power

As power demands surge, electricity networks are under strain. Can SiC power electronics save the grid, asks Compound Semiconductor.

Solar panels, a proliferation of electric vehicles and more are stretching today's electricity networks to the limit; silicon carbide-on-silicon devices can help.

As operators of residential electricity networks across Europe strive to meet escalating demands for power, SiC-on-silicon power devices from Anvil Semiconductors are set to make a real difference.

The UK-based SiC device developer is taking part in a £500,000 UK government-funded initiative to develop cutting-edge technology to boost the efficiency of power distribution across UK networks.

Working alongside a host of key power players - Schneider Electric, Western Power Distribution, Turbo Power Systems, Exception EMS and Aston University, UK - Anvil will develop SiC-on-silicon Schottky diodes and MOSFETs for power electronic converters.

As Jill Shaw, chief executive of Anvil highlights: "We will be supplying our devices to our partners, but these will be new, so we are well and truly involved with working to get the best out of these devices."

New power, old infrastructure

The project follows a government-funded feasibility study to find a cost-effective way to integrate the rising levels of distributed power generation and storage to existing electricity infrastructure.

Recent figures from Imperial College London, UK, estimate that come 2020, a hefty 10 million homes in the UK could have solar panels, up from around half a million today. Meanwhile, Navigant Research predicts sales of light-duty electric vehicles will more than double from today's 2.7 million to 6.4 million by 2023.

However, integrating such distributed power generation and storage to today's electricity networks brings myriad issues. An influx of photovoltaics, for example, can lead to unacceptable local voltage rises on the network while more electric vehicles means more demand for power. Factor in the uncertainties of predicting the loads and demands in a future two-way power, and clearly it's time for the network to adapt.

However, the feasibility study brings hope. Research indicates that increasing the local network phase voltage on existing electricity infrastructure to 400V would be a cost-effective way to handle the rising power demands and local voltages. And this is where Anvil's SiC-on-silicon devices are set to play a key role.

To step down the network voltage at each house to 230V, low cost power electronics converters (PECs) will need to be installed in a meter box outside each home. So with this in mind, project partners are now developing a prototype that Western Power Distribution will deploy in a small-scale demonstration network of around 100 homes. And of course, developing new, low-cost 3C SiC devices for the PEC is a must.

"The converter needs to be small and 99% efficient due to [space and] heat restraints within the meter box," highlights Shaw. "This drives the need for silicon carbide, but conventional devices just can't do this cheaply."

"Only by using our devices can you make this solution cost competitive, or cheaper than digging up electricity cables and replacing them," she adds.

Making MOSFETs

But a lot of work must take place first. As Shaw says: "We've developed the Schottky diodes but haven't yet got the MOSFETs so our partners [Turbo Power and Schneider] are developing prototype PECs around more expensive bulk SiC devices."

Right now Anvil is working with The Tyndall Institute, Ireland, on 'its first stage' MOSFETs. According to Shaw, device production started a few months ago, following process development to convince her and colleagues that they could get the performance they wanted out of their MOSFETs. And a finished device is expected in around six months.

"In about a year's time we will provide our MOSFETs," adds Shaw. "These will replace the [bulk SiC devices], and a converter will then be produced for the trial networks," she adds.

At this point, Western Power Distribution will test the converter on its trial site, and if successful, will be a long-term customer for the project partners. But this is just the beginning.

After the three-year project, Shaw expects a period of further development for commercialisation. The potential market is huge, and the impact on Anvil could be profound.

"Assuming we meet Western Power's requirements, the operator will then start integrating the converter [at peoples' home] across its distributed network," she says. "But clearly Schneider has recognised that there is a lot more of a market than Western Power."

"So if successful, Schneider will commercialise the converter and [it could reach] all the distributed network operators in the UK and the rest of Europe," she adds. "This is a worldwide issue that's got to be coped with. And this is a relatively cheap and easy way of doing it."

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