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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.

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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

EMI Mitigation of a Ćuk-Based Power-Electronic System Using Switching-Sequence-Based Control

Switching-sequence-based control (SBC) laws when designed based on topological switching behavior can have positive effects on slow- and fast-scale dynamics of a power-electronic system (PES). The slow-scale control can encompass fast PES state regulation and tracking, based on predefined objective, while fastscale control can address differential-mode (DM) and commonmode (CM) spectral-peak energy associated with PES switching operation. Such control laws may offer enhanced programmability to conventional PES design where bulky electromagnetic interference (EMI) filters have been traditionally used to reduce EMI of switching power converters to meet EMI regulatory standards. An EMI filter is always a less programmable solution since it is usually designed for the worst-case EMI mitigation and usually overkill for a PES operating under reduced load condition. The control scheme outlined in this article offers EMI mitigation across wide operating regions without compromising PES regulation. Moreover, it does so by use of switching sequences that guarantee the reachability of the PES dynamics using an advanced Lyapunov-function-based approach. SBC is a powerful tool to generate control actions for a PES based on multivariate PES state constraints. Hence, contemporary EMI regulatory standards are used as constraints in the SBC formulation to operate the PES under wide operating regime while autonomously mitigating the EMI levels. The work may be of paramount importance for operating the ultra-fast-transition recent wide-bandgap semiconductor devices like GaN–FET and SiC MOSFET under higher power with increasing switching frequencies, which is usually desirable for increased power density and reduced switching losses. Here, a hardware Cuk–PES operated ´ with GaN–FETs is fabricated and is used for case illustration. It is shown by experimental results how SBC mitigate DM and CM EMI noise of the PES while maintaining regulation even for the higher order nonminimum phase PES, while reducing sensor requirements using state observer derived from the switching model of the PES.

42 ENGINEERING↗
DOE OSTI2022

A 1MHz Oak Ridge AC / DC Converter for UAV Contactless Charger Implementation

In this paper, a 1 MHz single-phase Oak Ridge Converter (ORC) AC/DC wireless power transfer (WPT) system is introduced for unmanned air vehicle (UAV) charging applications. The proposed advanced solution eliminates the design, weight, volume, and the cost of the power factor correcting (PFC) front-end rectifier compared to the conventional practices. Additionally, grid power quality requirements can be achieved with the presented innovative idea. With this method, single stage WPT primary side uses the hybrid grid frequency and high frequency (60 Hz and 1 MHZ) from ac source through the coupler coils and to UAV battery with GaN FETs. Experimental results of the single-phase system is presented to confirm the mathematical analyses with the source voltage of 110 VAC, RMS and output voltage of 40 VDC at 1 kW power with 6 inches air gap between couplers. The primary coupler consists of a ferrite-backed single-turn coil with a radius of 1.5 ft, and the secondary coupler is made with an air-core single-turn coil with radius of 1.2 ft. The system overall ac to dc efficiency is measured 77 % acquiring 0.99 power factor (PF) and 3.3 % current total harmonic distortion (THD) at 1 kW power.

Asa, Erdem↗
DOE OSTI2024

Tunnel junction-enabled monolithically integrated GaN micro-light emitting transistor

GaN/InGaN microLEDs are a very promising technology for next-generation displays. Switching control transistors and their integration are key components in achieving high-performance, efficient displays. Monolithic integration of microLEDs with GaN switching devices provides an opportunity to control microLED output power with capacitive (voltage)-controlled rather than current-controlled schemes. This approach can greatly reduce system complexity for the driver circuit arrays while maintaining device opto-electronic performance. In this work, we demonstrate a 3-terminal GaN micro-light emitting transistor that combines a GaN/InGaN blue tunneling-based microLED with a GaN n-channel FET. Further, the integrated device exhibits excellent gate control, drain current control, and optical emission control. This work provides a promising pathway for future monolithic integration of GaN FETs with microLED to enable fast switching, high-efficiency microLED display and communication systems.

42 ENGINEERING↗
DOE OSTI2023

PV Inverter Systems Enabled by Monolithically Integrated SiC based Four Quadrant Power Switch (4-QPS) [BiDFET]

The purpose of this project was to develop a new breed of Power Conversion Systems (PCS) for PV integration that is enabled by the newly developed 4-Quadrant Single Die SiC Power Semiconductor Switches (4-QPS) or also referred to as “Bidirectional FET (BIDFET)”. This work includes semiconductor die development, advanced packaging, converter design, development, and testing of 4-QPS enabled hardware prototypes at 1 kW (for single phase residential application) and 10 kW (for three phase commercial application). The BiDirectional Field-Effect Transistor (BiDFET) can enable circuit topologies requiring four-quadrant switches, that were earlier designed using discrete combinations of MOSFETs, IGBTs, GaN HEMTs, and PiN diodes. The monolithic nature of the BiDFET allows lower device count, smaller switch volume, lower inductance, and simpler packaging, and hence more reliable and commercially viable implementation in power electronics converters. The matrix converter topologies, now feasible using BiDFETs, can eliminate the bulky and unreliable dc link capacitors or inductors required for conventional voltage-source or current-source converters in ac–ac and ac–dc applications. The 1.2 kV BiDFET has the potential to disrupt all the applications utilizing 1.2 kV switches, including electric vehicle (EV) drivetrain, bidirectional EV chargers, industrial motor drives, solid-state transformers, datacenter power supplies, elevator drives, dc microgrids, energy storage grid integration, solid-state breakers, etc.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Trap Passivation for Reducing On-Resistance and Saturation Voltage in Wafer-Bonded InGaAs-Channel/GaN-Drain Vertical FETs

High frequency and high power are the driving forces behind semiconductor transistor technology. However, conventional devices have the tradeoff of either being high speed or high breakdown—but not both. Wafer-bonded current aperture vertical electron transistors (BAVETs) help eliminate the tradeoff by combining a high-speed III-As channel to a high-breakdown III-N drift region. The device presented herein comprises of an InAlAs gate-barrier/InGaAs channel, wafer-bonded to an InGaN/GaN drift region, with the InGaAs/InGaN interface referred to as the wafer-bonded interface (WBI). The electronic behavior of WBIs is yet less known but necessary in realizing the potential of a BAVET. Herein, strong trap activity at the WBI is shown to be the cause of abnormally high saturation voltage ( V DS_SAT ) in BAVETs. The traps cause unintentional space charge (SC) region in the drain region of the device. This causes a drain resistance, a higher ON-resistance ( R ON ), and a higher V DS_SAT . Here, the challenge is overcome by hydrogen passivation of traps at WBI by using a p-doping for the InAlAs layer, which reduces the trap-charge concentration at the WBI. Consequently, the width of the SC region is reduced and a reduction in V DS_SAT is demonstrated, wherein it reduces from >12 to 5 V.

36 MATERIALS SCIENCE↗