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Kansai Electric and Cree Demonstrate a 100 kVA Silicon Carbide Three Phase Inverter
An inverter is used in a variety of applications to convert power from DC to AC or for changing the operating frequency in variable-speed motor drives. Applications include heat pumps, industrial motors, and electric vehicles. Inverters are also used to transfer power onto the grid from battery, wind and solar sources. “In the future, a tremendous amount of energy savings could be realized in industry by switching from Si inverters to SiC inverters because the power loss of the inverters is estimated to be reduced by more than 50 percent,” comments Dr. Yoshitaka Sugawara, executive researcher and manager of the SiC program at KEPCO. “Kansai Electric plans on further increasing the power capability of these inverters in order to apply them to a variety of power systems.” “We are advancing SiC power device technology through a variety of improvements ranging from lower defect density crystal growth to improved epitaxial processes, device design and processing,” states Dr. John Palmour, Cree’s executive vice president of advanced devices. “While more development is required, these improvements are moving the technology closer to the point where a significant reduction in the need for new power plants and reduction in greenhouse gas emissions are possible.” The SiC switching device developed for this inverter is a 4.5 kV, 100 A design called the SiC Commutated Gate Turn-off Thyristor (SiCGT), jointly developed by Cree and KEPCO. The chip size is 8mm x 8mm, enabled by a significant reduction in crystalline defect densities. This switch, which can turn off or on in less than 2 microseconds, has a 10 times higher switching speed than that of an equivalently rated silicon Gate Turn-off Thyristor (GTO). This device does not require a snubber circuit, a commonly used protective circuit for GTOs, thus reducing the part count and heat dissipation. A SiCGT module was then developed that utilizes one SiCGT and one 6mm x 6mm SiC PiN diode in a metal can package. The module can operate at higher temperatures (300°C) than conventional silicon modules (125°C), by utilizing a new high-temperature resin, “Nanotec-resin KA100,” for dielectric insulation. Using six of these modules, the three-phase Pulse Width Modulation (PWM) inverter demonstrated an output power of about 110 kVA. The PWM frequency was 2 kHz. About Kansai Electric Power Company About Cree, Inc. Cree drives its increased performance technology into multiple applications including exciting alternatives in brighter and more tunable light for general illumination, backlighting for more vivid displays, optimized power management for high-current switch-mode power supplies and variable speed motors, and more effective wireless infrastructure for data and voice communications. Cree customers range from innovative lighting fixtures makers to defense related federal agencies. Cree’s product families include blue and green LED chips, lighting LEDs, LED backlighting solutions, power switching devices and radio frequency/wireless devices. For additional product specifications please refer to www.cree.com. This press release contains forward-looking statements involving risks and uncertainties, both known and unknown, that may cause actual results to differ materially from those indicated. Actual results may differ materially due to a number of factors, such as the risk we may be unable to develop and release commercial products with acceptable performance and reliability for the applications; the risk we will be unable to manufacture the products with sufficiently low cost to offer them at competitive prices or with acceptable margins; the rapid development of new technology and competing products that may impair demand or render our products obsolete; the potential lack of customer acceptance for the products; and other factors discussed in Cree’s filings with the Securities and Exchange Commission, including its report on Form 10-K for the year ended June 26, 2005, and subsequent reports filed with the Commission. Cree and the Cree logo are registered trademarks of Cree, Inc.
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