Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New solid-state power switch safeguards electric service

15.08.2003


Electricity moves across miles in seconds to power manufacturing and utilities nationwide. But, for all its speed, the loss of just fractions of seconds of electric power is costing the U.S. economy $100 billion a year.



"The nation’s electric grid is operating so close to capacity that many of today’s electric load demands for fast and dynamic voltage support cannot be provided fast enough," says Alex Huang, professor of electrical and computer engineering at Virginia Tech.

To solve the problem, Virginia Tech researchers have developed a high-power semiconductor switch. The invention has earned a 2003 R&D 100 Award from R&D Magazine.


Huang, a researcher with the Center for Power Engineering Systems (www.cpes.vt.edu) is the principal developer of the switch, called an Emitter Turn-off (ETO) Thyristor.

"The ETO is a solid-state switch that is suitable for use in high-frequency power converters that can provide fast and dynamic voltage support to our nation’s congested power grid," says Huang. It offers fast switching speed, rugged turn-off capacity, and voltage control.

The ETO is a three terminal integrated power switch. An optical pulse is applied to turn on current flow with very little resistance. When it is closed, it can conduct 10,000 amps of current. "This is not your typical switch," says Huang.

For continuous operation, the range is 1,500 amps to keep the temperature below 125 degrees C. When the optical pulse is removed, and the ETO switch opens, it can block voltage as high as 6,000 V. The ETO changes from on to off and off to on in less than 5 microseconds. During switching, the ETO withstands high voltage and high current simultaneously. It is a voltage turnoff device with real time current sensing capability that can be used for control and protection.

"This switch allows us to advance very high power converters from a line speed of 60 Hz to 1 to 3 kHz (kilo hertz) switching at the same power level. This speed allows you to chop the voltage into whatever shape you need," says Huang.

Present technology is the Gate Turn-Off (GTO) Thyristor, the main power switch in use. The GTO is reliable and inexpensive, but requires a "snubber" capacitor to protect it in the turnoff process. The snubber uses significant power itself, increases the size of the switch and the complexity of energy recovery circuits. In addition to being a complicated gate design, it slows the on-off process.

"The significance is the ETO allows you to reduce energy storage elements and size (conductors, capacitors), which reduces the size, the weight, and the cost of the power converter," says Huang.

An insulated gate bipolar transistor (IGBT), which doesn’t require a snubber, was developed in the early 1990s. It offered improved control and reliability, but it is LESS useful in high power applications. The ETO is a hybrid of the GTO and the IGBT - "so is proven reliable," says Huang.

The U.S. Department of Energy’s Energy Storage Systems Program, managed by Sandia National Laboratory, first funded Huang’s research on what are known as "flexible AC transmission systems (FACTS). Because the ETO has the highest power handling capacity among all solid-state switches, it was deemed useful for such high-power application as FACTS devices and the U.S. Navy’s new electromagnetic aircraft launch system. The Tennessee Valley Authority is currently funding research by Virginia Tech to use the ETO in a high-power converter for dynamic voltage support in transmission and distribution grids.

Material limitations and the high cost of power electronic devices have restricted the wide spread use of power electronics in utility transmission and distribution grids. The ETO is a key enabling technology for lower cost power electronic systems. The timing is excellent. "Deregulation has created new demands on the transmission infrastructure, straining reserves. Power electronic systems, such as the ETO, can improve quality and capacity of the transmission grid by 25 to 60 percent," says Jing Leng of Solitronics, a spin-off company started in Blacksburg, Va., to commercialize the ETO.

The increasing frequency of electricity outages and outage duration are due primarily to lack of quick voltage support, leading to voltage collapse in many regions of the country and poor quality of power (flicker, for instance), she wrote in the R&D entry. One result has been lost opportunities in manufacturing and other businesses dependent on steady or high capacity power systems.

"We are losing hundreds of millions of dollars due to the loss of electrical power," says Huang.

"Our ability to get electrical power to where it is needed, when it is needed, is impeded by technology that is too slow," Leng wrote.

But with the ETO, you can respond to demand faster, says Huang. "When to stop and when to conduct electricity can be determined by a computer. Several ETO switches will be in systems connected to an electric grid. When you can switch faster, the equipment can respond faster.

"So, it’s low cost, high performance, high frequency, high power," says Huang. "It will withstand 16 megawatts of instantaneous power. Like turning on 100 stoves instantly through a unit about the size of a graham cracker. And you can stop them all at once too."


Solitronics licensed the product from Virginia Tech Intellectual Properties, Inc. Several patents are pending.

R&D Magazine will announce the "100 most technologically significant products introduced into the marketplace over the past year" in its September issue. Awards will be presented at a banquet in Chicago on Oct. 16.

Contact for more information:

Alex Q. Huang, 540-231-8057 or huang@vt.edu
PR contact: Susan Trulove 540-231-5646, strulove@vt.edu
Jing Leng, Solitronics, 540-961-6805

Alex Huang | EurekAlert!
Further information:
http://www.technews.vt.edu/
http://www.vtip.org
http://www.research.vt.edu/resmag/2002winter/power.html

More articles from Power and Electrical Engineering:

nachricht Molecular switch will facilitate the development of pioneering electro-optical devices
24.05.2018 | Technische Universität München

nachricht Supersonic waves may help electronics beat the heat
18.05.2018 | DOE/Oak Ridge National Laboratory

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Research reveals how order first appears in liquid crystals

23.05.2018 | Life Sciences

Space-like gravity weakens biochemical signals in muscle formation

23.05.2018 | Life Sciences

NIST puts the optical microscope under the microscope to achieve atomic accuracy

23.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>