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 Producing electricity during flight
20.09.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Solar-to-fuel system recycles CO2 to make ethanol and ethylene
19.09.2017 | DOE/Lawrence Berkeley 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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>