PCIM I Preview
Growing
in the wind
At PCIM, power electronics companies will be putting their minds together to find ways of making renewable energy more efficient. Steve Rogerson reports
year’s PCIM Europe in Nuremberg (4- 6 May 2010), with the focus on increasing the efficiency to make power sources such as solar and wind more cost effective. But whereas once the concentration would have been on the different vendors promoting their methods over others, now there appears to be a more conciliatory approach allowing the speakers and delegates to discuss the pros and cons of the available technologies and work out which are best for which applications. “Rather than saying this is good or
T
bad, we will be looking at the different features of each device,” said one of the speakers, Björn Backlund of ABB in Switzerland. “It is not one against the other. It will be the application that will decide which is best.” For example, Backlund’s paper will
look at high power semiconductors for controlling the generation and connection to the network of renewable energy sources such as wind turbines and photo voltaic. In particular, he will be comparing IGBTs (insulated gate bipolar transistors) with RGCTs (resonant
he whole area of renewable energy looks set to be one of the major talking points at this
gate commutated thyristors). “IGBTs have the capability to
control the switching through the gate,” he said. “RGCTs don’t have that but have low losses. We want to show which applications are better for each.” Despite this, one of the big
debates that does split those working on power semiconductors is the argument between the proponents of silicon carbide (SiC) and gallium nitride (GaN) as the technology that will replace silicon. “Always when you talk about this,
people compare SiC and GaN,” he said. “These tend to be more expensive than silicon even though the components may be better. But if you wait for SiC or GaN you will be lost. I have read that GaN is the future, but the gains you get from it are quite small. The main gain is when you start to use power electronics. If you then switch to GaN that extra gain is small.” He advises people not to wait for
more modern technologies but to switch to the available power electronics now so they can start making gains straight away. He said that only 10 to 15 per cent of medium voltage motors had a drive. “If all these had a drive, then 220TWhr would be saved
Alberto Guerra: “Today there is a premium with GaN but people will pay the difference for some applications to get the extra efficiency.”
worldwide,” he said. “Use power electronics today rather than waiting for something better. It might be a few percent better in the future, but it makes sense to do it today.” However, this view is not shared
by all. Alberto Guerra, vice president of strategic marketing at International Rectifier, will also be presenting a paper in this session and he will be plugging GaN. The main thrust of his paper though will be looking at how to boost the efficiency of solar panels. A key plank of this strategy is following the general trend to use micro-inverters for each solar panel rather than an overall inverter for an array of panels, and to improve on this using GaN. This technology, he said, could reduce losses in each stage of the power conversion and thus improve the overall energy harvesting. “GaN will improve the efficiency
using micro-inverter technology,” he said. “We have a small inverter that will operate with a single panel and will take the DC power direct to AC that can be fed into the grid. The most important thing is that it boosts the efficiency in the inverter.” For silicon, which has about 80 to
95 per cent of this market, the classic efficiency was in the 16 to 22 per cent range. But he said a one per cent improvement in the inverter could raise the overall efficiency by 10 per cent. He said using individual inverters
worked better because with an array connected in series a problem with one panel could reduce the efficiency of the whole array. “If one panel is shaded by dirt or
cloud, then that impacts the whole system,” he said. “The classic centralised inverter across the whole array doesn’t allow for problems with individual panels. With this system, each panel is controlled individually and that improves the efficiency of the system.”
10 April 2010
Components in Electronics
www.cieonline.co.uk
Exhibition Centre, Nuremberg
4-6 May 2010
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