Power for change

6 min read

A national power electronics strategy is being developed in order to take advantage of the opportunities available in the emerging low carbon economy. By Graham Pitcher.

The production of greenhouse gases through electricity generation is generally accepted to be the major contributor to global warming. Recognising this, governments from around the world have committed themselves to reducing the amount of CO2 which their countries generate. In the UK's case, the target is to cut CO2 emissions by 34% of their 1990 levels by 2020. Achieving that goal will require some rapid changes to the way we generate, distribute and consume power. But it will also require major changes in the way in which electronic products are designed. In particular, power electronics is believed to have an opportunity to play a leading role in the so called Low Carbon economy – and the UK is poised to make a major contribution. Recognising the potential, the Department for Business, Innovation and Skills (BIS) is looking to develop a national strategy for power electronics. In doing so, the work will identify where the UK's strengths lie, as well as determining the capabilities of the power electronics supply chain. The initiative has been driven by the National Microelectronics Institute (NMI). Derek Boyd, NMI chief executive, explained. "The work was started in 2009 by the NMI's electronics enabled low carbon economy network. The objective is to make the role of electronics in the low carbon economy much clearer than it is today." The NMI network has identified a number of points, including: * low carbon use and sustainable energy are major societal challenges; * many UK based companies have as a core competency semiconductor enabling processes that are crucial to achieving low carbon targets; * an entire electronics supply chain and ecosystem exists in the UK, with a strong and relevant research base and design and systems house presence; * there is a need for increased collaboration and accelerated change towards global targets. Although a range of activities is currently underway in the UK, they are all likely to develop point solutions. Because of this, there is no coherent strategy that will create a framework to enable the sector to grow in the UK. BIS believes the industry would benefit from taking the time to develop such a strategy in order to maximise the benefits. And the first steps in developing that strategy took place last week, when a two day meeting of interested parties started to put the pieces together. Boyd, commenting in advance of the event, said: "There will be discussions involving key people in the supply chain for the UK's power electronics industry. They will develop the strategy and identify what further investigations might be needed. I certainly don't see this as being the end of the process and I hope the strategy will be ready for publication in April 2011." That strategy, when developed, is likely to have a 10 year vision. "It will provide opportunities for the whole electronics supply chain," Boyd believed. In setting up the strategy development meeting, BIS envisaged the initiative's scope would include organisations that are engaged in manufacturing components or devices that perform energy conversion (harvesting or storage), as well as those producing high level power management systems, including signalling and control. As far as applications are concerned, the net spreads far and wide. Areas to be addressed include: electric motor control; lighting drivers and control; electric vehicle power management; smart grids, including integrating micro generation into the grid, dc in the home and maximising the use and efficiency of intermittent renewable generation; and digital controls for the nuclear industry. An important element of the work to date has been to define what power electronics actually is. According to a report commissioned by NMI, along with the Carbon Trust and Sagentia, 'conventional definitions are accurate, but not very useful'. This accurate definition is 'electronics which is concerned with the transformation or management of power'. Instead, the partners have decided to adopt what they call a 'layered' definition. And that is 'semiconductor devices which perform an energy switching/conditioning function, together with associated circuitry, including passives and energy storage, and higher level power management, including signalling and control systems'. The report noted that, while there are many different applications of power electronics, a relatively small number of functional 'building blocks' accounts for most of the uses of power electronics. These are: solid state relays; drives; converters, inverters and rectifiers; switched mode power supplies; and regulators. The study also found there was no single power electronics community. The reason; the wide difference of power ratings involved. 'Different voltage and power levels demarcate very different worlds in power electronics', the report noted. Four particular bands were identified: kV and MW, for use in power generation, trains, ships, large industrial applications and the electricity grid; three phase at tens of kW, for general industrial applications; 240V at up to hundreds of Watts, for domestic mains powered equipment; and 0 to 12V at milliWatt levels for battery powered devices. The presence of the Carbon Trust in the project is of significance. Boyd said: "We have a relationship with Carbon Trust and have undertaken a lot of work with it on energy efficiency. Through this relationship, we started to talk more about some of the ways in which the electronics would be critical to the long term future of the UK's economy." Where does Boyd see the opportunities? "The smart grid, for a start, will require more and more electronics content," he claimed, "while electric vehicles will have to use more and more electronics, not only in the car, but also within the necessary infrastructure. There will also be opportunities in applications as different as high efficiency lighting and machine drives and controls." This latter sector is likely to see even more attention in the coming months and years. "Currently," said Boyd, "electric motors consume more than 50% of total electrical energy consumption, according to the e4u project." Using that energy more efficiently will be something in which governments and consumers alike will be interested. "All in all," Boyd continued, "it's a massive market and one which is forecast to grow at more than 10% per year. And UK companies should be well positioned to take advantage of the opportunities." Boyd noted there are still a lot of companies in the UK who are involved in the power electronics sector. "They range from those producing materials and devices through equipment manufacturers to the large power systems companies. And almost all UK based semiconductor manufacturers are producing power products; companies such as NXP, International Rectifier, Plessey and Diodes. Meanwhile, downstream in the supply chains are companies like Siemens." He also pointed to a large academic community, with universities such as Strathclyde, Nottingham and Warwick all interested in power electronics. Bearing in mind Boyd's contention that the UK has a well established power electronics community – even though the study says it can be seen as the 'Cinderella' of the electronics industry – why is there the need for a national strategy? According to the joint study, one of the reasons is that the sector lacks 'a common roadmap and trajectory'. Amongst the issues that need to be addressed are developing devices with: higher voltage and higher power handling capability; robustness and packaging; and reliability. Another reason for a national strategy will be to focus research into what are seen as key areas. One of these areas is research into 'wide band gap' materials, such as silicon carbide, gallium nitride and diamond. These materials are seen, potentially, to be the answer to many problems. The power electronics strategy kick off meeting is likely to have discussed a number of key issues, including: * What is the current capability and status of UK power electronics within different application areas? * What is the potential for improvement? Can more, or different, power electronics devices be developed such that greater carbon savings could be achieved. And what sorts of improvements should be expected? * To what extent will the existing market structure and innovation ecosystem active be capable of delivering these improvements? * What is the potential for making things happen differently or faster through further public intervention? Illustrating the second point, the example of a wind turbine is offered. Assuming a nominal output of 3MW, a turbine will generate more than 7500MWh of electricity per year. With thermal power generation emitting 430g of CO2/kWh, the turbine saves more than 3300tonne of CO2 per year per turbine. Even a slight improvement in the efficiency of the power electronics brings additional savings. A 1% additional improvement would boost power production by 77MWh a year, saving 33tonne of CO2 per year per turbine. Such improvements may well be made by moving away from silicon as the basis for power electronics devices to those based on wide band gap materials. According to the report, 'silicon devices are unlikely to improve much more in terms of their efficiency, so any step changes to reduce losses will involve new semiconductor materials – such as those with wider band gaps than silicon'. In a survey commissioned by NMI and Carbon Trust, companies were asked what they thought a power electronics network might be able to achieve. The biggest response was 'identifying and communicating with the UK power electronics supply chain to promote precompetitive collaboration'. The second most important area was to find ways of 'influencing the UK Government to encourage it to support its indigenous Power electronics community e and enable it to provide input to the European Commission for EU funding in areas of interest'. And a further area of concern addressed funding for training at engineers at undergraduate and post graduate levels, as well as maintaining 'blue sky' research efforts. "What we want to achieve," Boyd asserted, "is for power electronics to be recognised as an industrial sector in its own right." But he doesn't believe this will necessarily need an approach similar to that taken with the plastic electronics sector, where a national technology centre has been established in the north of England. "There are existing centres of excellence," he said, "and we want to see better relationships with industry. We want power electronics to be part of the UK's innovation system and we think we will work more effectively together," he concluded.