Search NASA⌕ Search

SEARCH · Search NASA

Results for “overvoltage”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

99 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Extending the Life of NASA’s Tracking and Data Relay Satellite (TDRS)-8: TDRS-8 Power Challenges And Planning for End of Mission

The United States National Aeronautics and Space Administration (NASA) Near Space Network’s Space Relay (SR) System provides communication relay services to a number of scientific and manned space missions with its Tracking and Data Relay Satellite (TDRS) constellation. NASA’s eighth Tracking and Data Relay Satellite (TDRS) has been experiencing a decline in the health of its power subsystem, and recent reliability analyses indicate that the end of its mission serving the Space Relay is imminent. Launched in 2000, TDRS-8 is the oldest TDRS built upon a Boeing 601 platform, and as such it is the first TDRS to experience these age-related failures. The most prevalent elements of the power subsystem to decline are the solar array circuitry and the Bus Voltage Limiters (BVLs), which prevent too much power from the solar arrays being transferred to the bus by shunting excess current. This means that while the loss of solar array circuits introduces concerns that the solar arrays will continue providing the spacecraft with enough current to remain power positive, the loss of BVLs introduces a concern that the bus may not be adequately protected from overvoltage events. Spacecraft engineers at the TDRS primary ground terminal, the White Sands Complex (WSC) in Las Cruces, New Mexico, and at NASA's Goddard Space Flight Center (GSFC) have also been working in collaboration with Boeing to develop innovative techniques to extend the serviceable life of TDRS-8.

tdrs↗
DOE OSTI2022

Characterization of Hamamatsu VUV4 SiPM Performance for Liquid Argon Scintillation

Detection of light signals is crucial to a wide range of particle detectors. In particular, efficient detection of vacuum ultraviolet (VUV) light will provide new opportunities for some novel detectors currently being developed, but is technically challenging. In this article, we characterized the performance of Hamamatsu VUV4 silicon photomultipliers (SiPMs) for detecting VUV argon scintillation light without wavelength shifting. Here, using a customized cryogenic amplifier design, we operated two models of VUV4 SiPMs inside liquid argon and thoroughly examined their direct sensitivities to liquid argon scintillation. In addition to describing their cryogenic performance, we measured a photon detection efficiency of 14.7+1.1–2.4% and 17.2+1.6–3.0% at 128 nm for these two VUV4 models for operation at 4 V of overvoltage, with the main uncertainty arising from the SiPM reflectivity for VUV light.

Pershing, Teal↗
DOE OSTI2022

Qualification study of SiPMs on a large scale for the CMVD Experiment

A Cosmic Muon Veto (CMV) detector using extruded plastic scintillators is being designed around the mini-Iron Calorimeter (mini-ICAL) detector at the transit campus of the India based Neutrino Observatory, Madurai for the feasibility study of shallow depth underground experiments. The scintillation signals that are produced in the plastic due to muon trajectories are absorbed by wavelength shifting (WLS) fibres. The WLS fibres re-emit photons of longer wavelengths and propagate those to silicon photo-multipliers (SiPMs). The SiPMs detect these photons, producing electronic signals. The CMV detector will use more than 700 scintillators to cover the mini-ICAL detector and will require around 3000 SiPMs. The design goal for the cosmic muon veto efficiency of the CMV is >99.99%. Hence, every SiPM used in the detector needs to be tested and characterised to satisfy the design goal of CMV. A mass testing system was developed for the measurement of gain and choice of the overvoltage ($V_{ov}$) of each SiPMs using an LED driver. The $V_{ov}$ is obtained by studying the noise rate, the gain of the SiPM. This paper describes the experimental setup used to test the SiPMs characteristics along with detailed studies of those characteristics as a function of temperature.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Mass testing of SiPMs for the CMVD at IICHEP

A Cosmic Muon Veto Detector (CMVD) is being built around the mini-Iron Calorimeter (mini-ICAL) detector at the transit campus of the India based Neutrino Observatory, Madurai. The CMV detector will be made using extruded plastic scintillators with embedded wavelength shifting (WLS) fibres which propagate re-emitted photons of longer wavelengths to silicon photo-multipliers (SiPMs). The SiPMs detect these scintillation photons, producing electronic signals. The design goal for the cosmic muon veto efficiency of the CMV is $>$99.99% and fake veto rate less than 10$^{-5}$. A testing system was developed, using an LED driver, to measure the noise rate and gain of each SiPM, and thus determine its overvoltage ($V_{ov}$). This paper describes the test results and the analysed characteristics of about 3.5k SiPMs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

High voltage switch with cascaded transistor topology

A switching apparatus includes three or more series-connected transistors, and it further includes a balancing network. The balancing network includes a resistor network configured to divide a voltage from a voltage source across the series-connected transistors. The resistor network includes at least two resistive legs connected in parallel. In each resistive leg, two or more resistors are connected in series. The balancing network may further comprise at least one capacitive leg of series-connected capacitors connected across the series-connected transistors, and it may further comprise at least one leg of series-connected avalanche diodes connected across the series-connected transistors for overvoltage protection. In example embodiments, the series-connected transistors are JFETs. In other example embodiments, the series-connected transistors may be HEMTs or GaN transistors.

Gill, Lee↗
DOE OSTI2020

Methodology of Low Inductance Busbar Design for Three-Level Converters

Three-level (3L) converters are more susceptible to parasitics compared with two-level converters because of their complicated structure with multiple switching loops. In this article, the methodology of busbar layout design for 3L converters based on the magnetic cancellation effect is presented. The methodology can fit for 3L converters with symmetric and asymmetric configurations. A detailed design example is provided for a high-power 3L-active neutral point clamped (ANPC) converter, which includes the module selection, busbar layout, and dc-link capacitor placement. The loop inductance of the busbar is verified with simulation, impedance measurements, and converter experiments. Furthermore, the results match with each other, and the inductances of short and long loops are 6.5 and 17.5 nH, respectively, which are significantly lower than the busbars of NPC-type converters in other references.

42 ENGINEERING↗
DOE OSTI2022

PacWave Grid Integration Study: Transient and Dynamic Conditions (Final Report)

This report describes the results of PSCAD simulations that were performed in 2020 to assess the impacts of PacWave generation on CLPUD's 12.47-kV distribution and 69-kV subtransmission systems. PacWave South (PacWave) is a wave energy test facility planned by Oregon State University. PacWave shore facilities will be located south of Seal Rock on the Oregon coast. PacWave is expected to be operational in 2022 and will connect up to 10 MW of generation to CLPUD's Seal Rock distribution feeder.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2019

A Simple Control to Reduce the Voltage Stress of Non-Conducting Switches in Three-Level ANPC Converter

With the development of wide band-gap (WBG) technology, the switching speed of power semiconductor devices is increased, which makes circuits more sensitive to parasitics. For three-level active neutral point clamped (3L-ANPC) converters, the over-voltage of non-conducting switches can be an issue. This paper analyzes the multiple commutation loops in 3L-ANPC converter and summarizes the impact factors of the over-voltage for the non-conducting switch. It is found that the nonlinearity of the output capacitance of the device can significantly influence the over-voltage. A simple control without introducing any additional hardware circuit is proposed to attenuate the impact of the nonlinearity. With the proposed control, the peak over-voltage of the non-conducting switch can be reduced significantly. Multi-pulse test is conducted for a 3L- ANPC converter built with silicon carbide (SiC) MOSFETs. The testing results show that the peak over-voltage decreases from 892 V to 624 V with the proposed control. More detailed analysis and experimental results will be provided in the final paper.

SiC MOSFET↗
NASA NTRS2019

Design of Low Inductance Busbar for 500 kVA Three-Level ANPC Converter

The adoption of SiC devices in high power applications enables higher switching speed, which requires lower circuit parasitic inductance to reduce the voltage overshoot. This paper presents the design of a busbar for a 500 kVA three-level active natural clamped converter. The layout of the busbar is discussed in detail based on the analysis of the multiple commutation loops, magnetic cancelling effect, and DC-link capacitor placement. The loop inductance of the designed busbar is verified with simulation, impedance measurements and converter experiment. The results can match with each other and the inductances of small and large loop are 6.5 nH and 17.5 nH respectively, which is significantly lower than the busbars of NPC type converters in other references.

SiC MOSFET↗