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 A big nano boost for solar cells
18.01.2017 | Kyoto University and Osaka Gas effort doubles current efficiencies

nachricht Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>