Engineering
The semiconductor silicon carbide could potentially be used to create faster, cheaper transistors that can operate at higher voltages, which could prove useful for handling megawatts of power such as in wind turbines. Researchers from the Intelligent Efficient Power Electronics (IEPE) platform are looking to demonstrate the advantages of this new technology
A new generation of medium voltage transistors
Modern wind turbines use low voltage power electronics, which are cheap to produce
due to modern assembly line
techniques and high volume demand. Unfortunately, as new technology increases the power that turbines can generate, low voltage transistors will eventually become a limiting factor due to the higher currents needed. Medium voltage transistors could potentially be used to circumvent this challenge, but silicon (which most low voltage transistors are made of) has a voltage limitation of around 6kV. Silicon carbide is a new semiconductor
in the market that can significantly improve the behaviour of transistors compared to those that use silicon. Silicon carbide can operate at higher voltages than silicon — potentially up to 15kV — and make much faster transistors. It is these properties that have made Professor Stig Munk-Nielsen believe that transistors for the next generation of wind turbines should be made of silicon carbide. “When transistors are low voltage, a number of clever tricks are needed to increase the voltage to a useable level,” he says. “If you have transistors that can handle higher
10kV 10A power modules
“If you have transistors that can handle higher voltages, it introduces simplicity and will eventually lower costs”
voltages, it introduces simplicity and will eventually lower costs.” One of the issues facing silicon carbide
power electronic devices is packaging. The tiny block of semiconducting material used in a transistor must always be encapsulated in a supporting case that prevents physical damage and corrosion and provides sufficient heat removal. The methods for encapsulating silicon are well known, but with semiconductors such as silicon carbide that operate at higher voltages and temperatures, the
knowledge does not exist yet. This is one of the problems that Munk-Nielsen and his colleagues have been looking to solve as part of IEPE (Intelligent Efficient Power Electronics),
a platform involving
industry and academia with the goal of producing cheaper, more reliable electronic devices that can accelerate the transition to sustainable energy solutions. The team have obtained silicon carbide
dies — small blocks of the semiconductor on which circuits are fabricated — and put them together in a small packaging facility that has been established at Aalborg University to create prototype power modules. The power modules have solid and rugged terminals that enable a simple mechanical connection to other power converter components. There are widely accepted power module dimensions that enable engineers to design power converters using well- defined building blocks. “It is these power modules that are the basic building blocks for people who build power converters for wind turbines,” explains Munk-Nielsen. “We have done some basic tests on these power modules and have
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Insight Publishers | Projects
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