Search NASA⌕ Search

SEARCH · Search NASA

Results for “INDUCTION LOOP TECHNIQUE”

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.

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Estimation, Minimization, and Validation of Commutation Loop Inductance for a 135-kW SiC EV Traction Inverter

With growing interests in low inductance SiC based power module packaging, it is vital to focus on system level design aspects to facilitate easy integration of the modules and reap system level benefits. To effectively utilize the low inductance modules, busbar and interconnects should also be designed with low stray inductances. A wholistic investigation of the flux path and flux cancellations in the module-busbar assembly which as differentially coupled series inductors is thus mandatory for a system level design. This work presents a busbar design which can be adopted to effectively integrate the CREE’s low inductance 1.2 kV/1.7 kV SiC power modules. The paper also proposes a novel measurement technique to measure the inductance of the modulebusbar assembly as a whole rather than deducing it from individual components. The inductance of the overall commutation loop of the inverter which encompasses the SiC power module, interconnects and PCB busbar have been estimated using finite element analysis (FEA). Furthermore, insights gained from FEA provided the guidelines to decide on the placement of the decoupling capacitors in the busbar to minimize the overall commutation loop inductance from 12.8 nH to 7.4 nH which resulted in significant reduction in the device voltage overshoot. The simulation results have been validated through measurements using an impedance analyzer with less than 5% difference between extracted loop inductance from FEA and measurements. The bus bar design study and the measurement technique discussed in this paper, can be easily extended to other power module packages. Finally, the 135 kW inverter has been compared to a similar highpower inverter utilizing a laminated busbar to highlight the performance of the former.

42 ENGINEERING↗
DOE OSTI2025

Rapid Prototyping Techniques for Organic Direct-Bonded-Copper Power Modules

Organic Direct-Bonded-Copper (ODBC) is a novel packaging technology for power modules which allows higher flexibility in layout design. In this work, a set of rapid prototyping techniques are developed for ODBC modules based on a polyimide dielectric material. These techniques enable fast and low-cost fabrication of modules with 3-Dimensional (3D) layout features. An example half-bridge (HB) silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) module is designed and prototyped using the proposed techniques aiming at ultra-low power loop inductance. Finite element analysis (FEA)-circuit co-simulations results and experimental results validate an approximately 0.71nH power loop inductance for the example module design.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A PCB-Embedded 1.2 kV SiC MOSFET Half-Bridge Package for a 22 kW AC–DC Converter

This article presents the design and analysis of a double-side-cooled printed circuit board (PCB) embedded silicon carbide (SiC) MOSFET half-bridge package with low loop inductances and an integrated gate driver. The 1.2 kV SiC MOSFET dies used in the half-bridge package are embedded in the PCB using AT&S's patented technique. The dies are cooled and electrically connected to traces in the PCB through copper-filled microvias. The design methodology accounts for both electrical and thermal performance, limiting the power-loop inductance to 2.3 nH and the maximum package temperature to less than the 175 °C limit. The integration of the gate drive circuitry allows for a high power density and 2.2 nH gate-loop inductances. At 0.12 K/W, the measured junction-to-case thermal resistance with double-sided cooling is 57% lower than that of a TO-247 package. Under similar operating conditions, the PCB-embedded half-bridge package also achieves a 5.6 times lower voltage overshoot and a 0.5% higher peak efficiency than a TO-247-based half-bridge. This article reports the first demonstration of PCB-embedded 1.2 kV SiC MOSFET packages in buck, boost, and ac–dc converters. Furthermore, the prototype three-phase ac–dc converter for an electric vehicle on-board charger is composed of six PCB-embedded half-bridge packages and achieves an efficiency of 98.2% and a power density of 182 W/in 3 .

42 ENGINEERING↗
DOE OSTI2023

Start-up Operation Experience with a Liquid Fluoride Salt Forced Convection Loop

A liquid fluoride salt forced convection test loop was constructed at Oak Ridge National Laboratory. Its unique features include a pebble bed test section, high-temperature instrumentation, a noncontact rotating gas seal for the pump, a silicon carbide flow tube, and a unique inductive heating technique. Initial startup and shake-down testing has been completed. This paper describes how several of the systems performed, highlights those that worked well, and discusses issues that arose during the start-up process. This discussion should be of interest to those who intend to develop molten salt technologies and who are interested in some of the specific techniques used in this experiment.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Stabilization and control of persistent current magnets using variable inductance

Ultra-stable, tunable magnetic fields are desirable for a wide range of applications in medical imaging, electron microscopy, quantum science, and atomic physics. Superconducting magnets operated in persistent current mode, with device current flowing in a closed superconducting loop disconnected from a power source, are a common approach for applications with the most stringent requirements on temporal field stability. In this work, we present a method for active control of this persistent current by means of dynamic inductance change within the superconducting circuit. For a first realization of this general technique, we consider a variable superconducting inductor placed in series with the main magnet. The inductor acts as a dynamic flux storage device capable of transferring flux to or from the main magnet through inductance change. This allows for fine and fast adjustments of the persistent current without the use of thermal switches that limit the speed and accuracy of many present-day methods. With first experiments employing this technique, we demonstrate stabilization of a 1.95 T Nb–Ti round lens for electron microscopy against decay resulting from residual losses in the superconducting circuit, and more generally show flexibility for precise control over the magnitude and waveform of the persistent current.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Reconfigurable Real-Time Power Grid Emulator for Systems With High Penetration of Renewables

Novel power system control and new utility devices need to be tested before their actual deployment to the power grid. To assist with such a testing need, real-time digital emulators such as RTDS and Opal-RT can be used to connect to the physical world and form a hardware in the loop (HIL) emulation. However, due to the limitations of today's computational resources, the accuracy and fidelity suffer from different levels of model reductions in purely digital simulations. CURENT has developed a reconfigurable electric grid hardware testbed (HTB) to overcome the limitations of digital emulators. The HTB has been used to develop measurement, control, modeling, and actuation techniques for a national grid with a high penetration of renewables. The power electronic-based system includes emulators for synchronous generators; photovoltaics with grid-interfacing inverter; wind turbines; induction motor loads, ZIP loads, power electronic loads; batteries; ac and dc transmission lines; short circuit faults and grid relay protection; and a multiterminal HVDC overlay including power electronics interfaces. The system contains real elements of power flow, measurement, communication, protection, and control that mimic what would be seen in an actual electric grid. This paper presents an overview of the HTB and several scenarios that have been run to determine control and actions needed for the future power grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

2D Simulations of Diamagnetic Loop Calibrations

Diamagnetic loops can be used as a non-invasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. A comprehensive theory for interpreting data from a diamagnetic loop relates the rms beam radius to the excluded flux measured by the loop and the beam current. Thus, primary calibration of the loop must relate the loop signal directly to the exclude d flux. We have simulated these calibrations with a 2D field solver in order to identify possible sources of uncertainty in our calibration technique.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Theoretical analysis of key factors achieving reversed magnetic shear q-profiles sustained with lower hybrid waves on EAST

The phase space analysis technique is applied to provide new insights into the fully non-inductive lower hybrid current driven (LHCD) discharges on EAST (Garofalo et al 2017 Nucl. Fusion 57 076037). The analysis shows that there are bounded and unbounded topologies of lower hybrid (LH) waves in phase space. For typical parameters on EAST, the propagation domain for 4.6 GHz LH waves is bounded, while unbounded for 2.45 GHz LH waves and one of the conditions is recognized to be good for achieving an off-axis current profile driven by 4.6 GHz LH waves on EAST. The parametric analysis on the potential power deposition (PPD) region for those experiments demonstrates that the reversed magnetic shear dominates the wave behavior, and confines the LH power absorption to the far off-axis region as long as it occurs in the 4.6 GHz dominated LHCD discharge. GENRAY/CQL3D simulations also confirm this effect of reversed shear on the power absorption of 4.6 GHz waves. A bounded propagation domain and a positive feedback loop between magnetic shear reversal and off-axis LHCD profile could explain the LH-only-sustained strong reversed magnetic shear observed in experiments on multiple machines. In contrast, there is no such effect for 2.45 GHz waves on EAST since the PPD region is less sensitive to the change of reversed shear due to the unbounded propagation domain.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

The CMS Magnetic Field Measuring and Monitoring Systems

This review article describes the performance of the magnetic field measuring and monitoring systems for the Compact Muon Solenoid (CMS) detector. To cross-check the magnetic flux distribution obtained with the CMS magnet model, four systems for measuring the magnetic flux density in the detector volume were used. The magnetic induction inside the 6 m diameter superconducting solenoid was measured and is currently monitored by four nuclear magnetic resonance (NMR) probes installed using special tubes outside the barrel hadron calorimeter. Two more NRM probes were installed at the faces of the tracking system. The field inside the superconducting solenoid was precisely measured in 2006 in a cylindrical volume of 3.448 m in diameter and 7 m in length using 10 three-dimensional (3D) B-sensors based on the Hall effect. These B-sensors were installed on each of the two propeller arms of an automated field-mapping machine. In addition to these measurement systems, a system for monitoring the magnetic field during the CMS detector operation has been developed. Inside the solenoid in the horizontal plane, 4 3D B-sensors were installed at the faces of the tracking detector. Twelve 3D B-sensors were installed on the surfaces of the flux-return yoke nose disks. Seventy 3D B-sensors were installed in the air gaps of the CMS magnet yoke. A specially developed flux loop technique was used for the most complex measurements of the magnetic flux density inside the steel blocks of the CMS magnet yoke. The flux loops are installed in 22 sections of the flux-return yoke blocks. The areas enclosed by these coils varied from 0.3 to 1.59 m$^{2}$ in the blocks of the barrel wheels and from 0.5 to 1.12 m$^{2}$ in the blocks of the yoke endcap disks. The development of these systems and the results of the magnetic flux density measurements across the CMS magnet are presented and discussed in this review article.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Radiation-Induced Effects on the Extraction Properties of Hexa-n-octylnitrilo-triacetamide (HONTA) Complexes of Americium and Europium

The candidate An(III)/Ln(III) separation ligand hexa-n-octylnitrilo-triacetamide (HONTA) was irradiated under envisioned SELECT (Solvent Extraction from Liquid waste using Extractants of CHON-type for Transmutation) process conditions (n-dodecane/0.1 M HNO 3 ) using a solvent test loop in conjunction with cobalt-60 gamma irradiation. The extent of HONTA radiolysis and complimentary degradation product formation was quantified by HPLC-ESI-MS/MS. Further, the impact of HONTA radiolysis on process performance was evaluated by measuring the change in 243 Am and 154 Eu distribution ratios as a function of absorbed gamma dose. HONTA was found to decay exponentially with increasing dose, affording a dose coefficient of d = (4.48 ± 0.19) × 10 –3 kGy –1 . Multiple degradation products were detected by HPLC-ESI-MS/MS with dioctylamine being the dominant quantifiable species. Both 243 Am and 154 Eu distribution ratios exhibited an induction period of ~70 kGy for extraction (0.1 M HNO 3 ) and back-extraction (4.0 M HNO 3 ) conditions, after which both values decreased with absorbed dose. The decrease in distribution ratios was attributed to a combination of the destruction of HONTA and ingrowth of dioctylamine, which is capable of interfering in metal ion complexation. Furthermore, the loss of HONTA with absorbed gamma dose was predominantly attributed to its reaction with the n-dodecane radical cation (R˙ + ). These R˙ + reaction kinetics were measured for HONTA and its 241 Am and 154 Eu complexes using picosecond pulsed electron radiolysis techniques. All three second-order rate coefficients (k) were essentially diffusion limited in n-dodecane indicating a significant reaction pathway: k(HONTA + R˙ + ) = (7.6 ± 0.8) × 10 9 M –1 s –1 , k(Am(HONTA) 2 + R˙ + ) = (7.1 ± 0.7) × 10 10 M –1 s –1 , and k(Eu(HONTA) 2 + R˙ + ) = (9.5 ± 0.5) × 10 10 M –1 s –1 . HONTA-metal ion complexation afforded an order-of-magnitude increase in rate coefficient. Additional nanosecond time-resolved measurements showed that both direct and indirect HONTA radiolysis yielded the short-lived (< 100 ns) HONTA radical cation and a second long-lived (µs) species identified as the HONTA triplet excited state. The latter was confirmed by a series of oxygen quenching picosecond pulsed electron measurements, affording a quenching rate coefficient of k( 3 [HONTA]* + O 2 ) = 2.2 × 10 8 M –1 s –1 . Overall, both the HONTA radical cation and triplet excited state are important precursors to the suite of measured HONTA degradation products.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

The advanced tokamak path to a compact net electric fusion pilot plant

Abstract Physics-based simulations project a compact net electric fusion pilot plant with a nuclear testing mission is possible at modest scale based on the advanced tokamak concept, and identify key parameters for its optimization. These utilize a new integrated 1.5D core-edge approach for whole device modeling to predict performance by self-consistently applying transport, pedestal and current drive models to converge fully non-inductive stationary solutions, predicting profiles and energy confinement for a given density. This physics-based approach leads to new insights and understanding of reactor optimization. In particular, the levering role of high plasma density is identified, which raises fusion performance and self-driven ‘bootstrap currents’, to reduce current drive demands and enable high pressure with net electricity at a compact scale. Solutions at 6–7 T, ∼4 m radius and 200 MW net electricity are identified with margins and trade-offs possible between parameters. Current drive comes from neutral beam and ultra-high harmonic (helicon) fast wave, though other advanced approaches are not ruled out. The resulting low recirculating power in a double null configuration leads to a divertor heat flux challenge that is comparable to ITER, though reactor solutions may require more dissipation. Strong H-mode access (x2 margin over L–H transition scalings) and ITER-like heat fluxes are maintained with ∼20%–60% core radiation, though effects on confinement need further analysis. Neutron wall loadings appear tolerable. The approach would benefit from high temperature superconductors, as higher fields would increase performance margins while potential for demountability may facilitate nuclear testing. However, solutions are possible with conventional superconductors. An advanced load sharing and reactive bucking approach in the device centerpost region provides improved mechanical stress handling. The prospect of an affordable test device which could close the loop on net-electric production and conduct essential nuclear materials and breeding research is compelling, motivating research to validate the techniques and models employed here.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗