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  • 1
    Electronic Resource
    Electronic Resource
    Design, Fabrication and Application of 4H-SiC Trenched-and-Implanted Vertical JFETs (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 527-529 (Oct. 2006), p. 1191-1194 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper reports recent progress in the development of a vertical JFET, the purely verticalJFET based on trenched-and-implanted vertical JFET (TI-VJFET) approach that eliminates the needof epitaxial regrowth at middle of device fabrication and the need of a merged lateral JFET to controlthe vertical JFET. Different structures have been designed to target breakdown voltages ranging from600V to 1.2kV. Vertical channel width uniformity has been studied, showing the feasibility ofachieving below 0.1um variation for reasonably flat wafers of good thickness uniformity. Pitch size ofthe designs has been reduced compared to early report. Gate trench width has been reduced from3.8um to 2.3um, aimed at increasing the device current capability. Fabricated device cells have beentested and packaged into multi-cell 30A TI-VJFETs which have been characterized of DC andswitching characteristics at room and elevated temperatures. Very fast current rise/fall times of 〈10nswere observed from RT to 200°C. PSpice model for TI-VJFET has been developed and applied to theperformance prediction of 3-phase SiC power inverter, suggesting a high efficiency 97.7% at 200°Cjunction temperature without using soft-switching scheme. Preliminary experimental demonstrationof a PWM-controlled three-phase inverter based on SiC TI-VJFET power board is reported
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.527-529.1191.pdf
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    Fulltext
  • 2
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    Magnetic Bearing Amplifier Output Power Filters for Flywheel Systems (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Five power filters and two types of power amplifiers were tested for use with active magnetic bearings for flywheel applications. Filter topologies included low pass filters and low pass filters combined with trap filters at the PWM switching frequency. Two state and three state PWM amplifiers were compared. Each system was evaluated based on current magnitude at the switching frequency, voltage magnitude at 500 kHz, and power consumption. The base line system was a two state amplifier without a power filter. The recommended system is a three state power amplifier with a 50 kHz low pass filter and a 27 kHz trap filter. This system uses 5.57 W. It reduces the switching current by an order of magnitude and the 500 kHz voltage by two orders of magnitude. The relative power consumption varied depending on the test condition between 60 to 130 percent of the baseline.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2003-212510 , E-14070 , NAS 1.15:212510 , First International Energy Conversion Engineering Conference; Aug 17, 2003 - Aug 21, 2003; Portsmouth, VA; United States
    Format: application/pdf
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  • 3
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    Silicon Carbide Diodes Performance Characterization and Comparison With Silicon Devices (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers were electrically tested and characterized at room temperature. Performed electrical tests include steady state forward and reverse I-V curves, as well as switching transient tests performed with the diodes operating in a hard switch dc-to-dc buck converter. The same tests were performed in current state of the art silicon (Si) and gallium arsenide (GaAs) Schottky and pn junction devices for evaluation and comparison purposes. The SiC devices tested have a voltage rating of 200, 300, and 600 V. The comparison parameters are forward voltage drop at rated current, reverse current at rated voltage and peak reverse recovery currents in the dc to dc converter. Test results show that steady state characteristics of the tested SiC devices are not superior to the best available Si Schottky and ultra fast pn junction devices. Transient tests reveal that the tested SiC Schottky devices exhibit superior transient behavior. This is more evident at the 300 and 600 V rating where SiC Schottky devices showed drastically lower reverse recovery currents than Si ultra fast pn diodes of similar rating.
    Keywords: Electronics and Electrical Engineering
    Type: NASA/TM-2003-212511 , E-14071 , NAS 1.15:212511 , First International Energy Conversion Engineering Conference; Aug 17, 2003 - Aug 21, 2003; Portsmouth, VA; United States
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  • 4
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    Silicon Carbide Diodes Characterization at High Temperature and Comparison With Silicon Devices (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers rated at 200, 300, 600, and 1200 V, were electrically tested and characterized as a function of temperature up to 300 C. Electrical tests included both steady state and dynamic tests. Steady state tests produced forward and reverse I-V characteristic curves. Transient tests evaluated the switching performance of the diodes in either a hard-switched DC to DC buck converter or a half-bridge boost converter. For evaluation and comparison purposes, the same tests were performed with current state-of-the-art ultra fast silicon (Si) pn-junction diodes of similar ratings and also a Si Schottky diode. The comparisons made were forward voltage drop at rated current, reverse current at rated voltage, and turn-off peak reverse recovery current and reverse recovery time. In addition, efficiency measurements were taken for the buck DC to DC converter using both the SiC Schottky diodes and the Si pn-junction diodes at different temperatures and frequencies. The test results showed that at high temperature, the forward voltage drop for SiC Schottky diodes is higher than the forward drop of the ultra fast Si pn-junction diodes. As the temperature increased, the forward voltage drop of the SiC Schottky increased while for the ultra fast Si pn-junction diodes, the forward voltage drop decreased as temperature increased. For the elevated temperature steady state reverse voltage tests, the SiC Schottky diodes showed low leakage current at their rated voltage. Likewise, for the transient tests, the SiC Schottky diodes displayed low reverse recovery currents over the range of temperatures tested. Conversely, the Si pn-junction diodes showed increasing peak reverse current values and reverse recovery times with increasing temperature. Efficiency measurements in the DC to DC buck converter showed the advantage of the SiC Schottky diodes over the ultra fast Si pn-junction diodes, especially at the higher temperatures and higher frequencies.
    Keywords: Electronics and Electrical Engineering
    Type: NASA/TM-2004-213336 , AIAA Paper 2004-5750 , E-14806 , Second International Energy Conversion Engineering Conference; Aug 16, 2004 - Aug 19, 2004; Providence, RI; United States
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  • 5
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    Silicon Carbide Diodes Performance Characterization at High Temperatures (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA Glenn Research center's Electrical Systems Development branch is working to demonstrate and test the advantages of Silicon Carbide (SiC) devices in actual power electronics applications. The first step in this pursuit is to obtain commercially available SiC Schottky diodes and to individually test them under both static and dynamic conditions, and then compare them with current state of the art silicon Schottky and ultra fast p-n diodes of similar voltage and current ratings. This presentation covers the results of electrical tests performed at NASA Glenn. Steady state forward and reverse current-volt (I-V) curves were generated for each device to compare performance and to measure their forward voltage drop at rated current, as well as the reverse leakage current at rated voltage. In addition, the devices were individually connected as freewheeling diodes in a Buck (step down) DC to DC converter to test their reverse recovery characteristics and compare their transient performance in a typical converter application. Both static and transient characterization tests were performed at temperatures ranging from 25 C to 300 C, in order to test and demonstrate the advantages of SiC over Silicon at high temperatures.
    Keywords: Electronics and Electrical Engineering
    Type: Space Power Workshop; Apr 21, 2004; Manhattan Beach, CA; United States
    Format: text
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  • 6
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    Digital Control Technologies for Modular DC-DC Converters (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2002-211369 , E-13191 , NAS 1.15:211369 , 2000 Aerospace Conference; Mar 19, 2000 - Mar 25, 2000; Big Sky, MT; United States
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  • 7
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    Silicon Carbide Schottky Barrier Diode (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.
    Keywords: Electronics and Electrical Engineering
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  • 8
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    Description of the Prometheus Program Alternator/Thruster Integration Laboratory (ATIL) (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Project Prometheus Alternator Electric Thruster Integration Laboratory's (ATIL) primary two objectives are to obtain test data to influence the power conversion and electric propulsion systems design, and to assist in developing the primary power quality specifications prior to system Preliminary Design Review (PDR). ATIL is being developed in stages or configurations of increasing fidelity and complexity in order to support the various phases of the Prometheus program. ATIL provides a timely insight of the electrical interactions between a representative Permanent Magnet Generator, its associated control schemes, realistic electric system loads, and an operating electric propulsion thruster. The ATIL main elements are an electrically driven 100 kWe Alternator Test Unit (ATU), an alternator controller using parasitic loads, and a thruster Power Processing Unit (PPU) breadboard. This paper describes the ATIL components, its development approach, preliminary integration test results, and current status.
    Keywords: Electronics and Electrical Engineering
    Type: NASA/TM-2005-213895 , E-15266 , AIAA Paper 2005-5714 , Third International AIAA International Energy Conversion Engineering Conference; Aug 15, 2005 - Aug 18, 2005; San Francisco, CA; United States
    Format: application/pdf
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