Welcoming in a New Generation of Power SystemsApril 02, 2015 by Girvan Patterson
As Spring arrives in the Northern Hemisphere, nature’s power of renewal and reinvention can be seen all around us and we humans look forward to the stimulus
As Spring arrives in the Northern Hemisphere, nature’s power of renewal and reinvention can be seen all around us and we humans look forward to the stimulus of the year’s new challenges. In our industry, 2015 promises to be an exciting one as we welcome in a new generation of power systems driven by advances in power semiconductors.
Over the past eight years or so, there has been much talk of the need to replace silicon devices as they reach their performance limits and of possible technologies which might achieve the necessary leap forward. GaN and SiC emerged as contenders and both have been the subject of large amounts of investment, much inspired thinking and a great deal of developmental work by companies large and small around the world.
Silicon carbide (SiC) has better physical properties for power than silicon but is very costly and its properties are inferior to that of gallium nitride. GaN offers orders of magnitude improvement in switching and conduction performance – its unique material and electronic characteristics include high dielectric strength, high operating temperature, high current density, very high speed switching and low on-resistance. The excitement about GaN is its ability to achieve devices with power losses cut between 50% and 90%, system size and weight reductions of up to 75% and decreased BoM costs while dramatically increasing performance. GaN switches operate 100’s of times faster than silicon switches; have lower resistance per area and forty times better overall performance.
For energy-hungry applications such as data centers, this step change in performance is long overdue. In order to keep up with the pace of processor innovation and the explosion of cloud computing demands, data center designers now need to put 1.5 times the power conversion into the same space and have run out of options to accomplish this. Similarly, major automotive manufacturers are challenging their designers to halve the size of their onboard vehicle chargers and dramatically increase power electronics efficiency to meet cost, range and performance roadmaps. The same size and efficiency demand is consistent across industries and GaN is seen as the only cost-effective solution capable of meeting these rising performance demands.
Of course, there have been challenges to overcome in terms of device design and packaging and achieving a commercial price point.
2014 was the year several major milestones were attained. Firstly, recognition that a step change was imminent and the broad acceptance of GaN wide bandgap semiconductors as the enabling technology to usher in the new age of power electronics. No less an entity than Google joined the IEEE Power Electronics Society and has put up a USD1M prize to the team that can shrink a power inverter from the size of a large picnic cooler to less than that of a laptop and achieve an output of at least 50kW per cubic inch. Wide bandgap semiconductors are suggested as a promising technology to help achieve this and suppliers were invited to add a linked page for participants to contact to obtain parts.
The second milestone was commercial launch of devices onto the market. As one of the suppliers invited to supply a linked page for the Google/IEEE challenge, GaN Systems launched 650V and 100V parts in the first half of the year and had made sample parts available through global distributors by the end of the year.
So, what can be expected during 2015? Clearly, adopting new technologies is a learning curve and it is up to device manufacturers to ease the path of design engineers looking to build GaN high power switching devices into their latest designs. GaN Systems for example, has developed near chipscale, proprietary packaging, GaNPX™, which has no wire bonds, limiting inductance and eliminating a common reliability issue with semiconductor devices. The company’s Drive Assist™ on chip drivers simplify circuit design and solve device driving issues at the same time as improving the switching speed and noise immunity.
Which products will be among the first to incorporate GaN transistors? Until recently, the perception has been that early adopters would include automotive manufacturers, (EV and hybrid vehicle power train drive electronics, EV and hybrid vehicle car chargers), manufacturers of solar and wind energy products, switching power supplies, and other large transportation and industrial products. However, one surprise, at least for GaN Systems, has been the interest from the consumer sector. On reflection this should not have been unexpected – NPD cycles are generally shorter in consumer electronics as companies strive to be first with the latest “must have” tech gadget and gain market advantage. Towards the end of 2015 we are very likely to be admiring a new generation of super-thin TVs and be able to order one in time for Christmas. The generational change from silicon to gallium nitride has arrived – as design engineers it is up to us to embrace it.