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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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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Design of a Robust Memristive Spiking Neuromorphic System with Unsupervised Learning in Hardware

Spiking neural networks (SNN) offer a power efficient, biologically plausible learning paradigm by encoding information into spikes. The discovery of the memristor has accelerated the progress of spiking neuromorphic systems, as the intrinsic plasticity of the device makes it an ideal candidate to mimic a biological synapse. Despite providing a nanoscale form factor, non-volatility, and low-power operation, memristors suffer from device-level non-idealities, which impact system-level performance. To address these issues, this article presents a memristive crossbar-based neuromorphic system using unsupervised learning with twin-memristor synapses, fully digital pulse width modulated spike-timing-dependent plasticity, and homeostasis neurons. Additionally, the implemented single-layer SNN was applied to a pattern-recognition task of classifying handwritten-digits. The performance of the system was analyzed by varying design parameters such as number of training epochs, neurons, and capacitors. Furthermore, the impact of memristor device non-idealities, such as device-switching mismatch, aging, failure, and process variations, were investigated and the resilience of the proposed system was demonstrated.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Power Solitons in Inverter-based Electric Energy Systems: Observation, Analysis and Implications

The discovery of an unfamiliar class of nonlinear energy waves in electric energy systems with dominating coupled inverter-based energy resources has been reported in a recent research project. Whenever there are slight but persistent differences among the reference signals used by inverters in pulse-width modulation, i.e., a weak group modulation instability condition, the unfamiliar energy waves appear, which contain not only the familiar frequency components present in electric power systems but also self-organized components in the ultra-high frequency region of the energy spectrum. These components are found to be exploding solitary waves with concentrated energy masses, hence we call them power solitons. This paper explains the work of the discovery reported, and the implications of the presence of power solitons for grid integration of inverter-based resources and power system protection.

14 SOLAR ENERGY↗
DOE OSTI2024

A New Approach to Robot Motor Control

This poster details the motor control improvements to Fermilab's Remote Viewing Robot (RVR). It is a robot tasked with remotely investigating issues within the accelerator tunnels at Fermilab. Initially controlled by a single Raspberry Pi that housed all the robot s operations, the RVR will now use a Raspberry Pi Pico W for its motor control. This was achieved using Pulse Width Modulation (PWM) to allow for precise speed and torque control for the robot. This enhances the robot s reliability. By addressing the challenge of navigating high radiation environments, the upgrade helps assist the RVR s goal of decreasing the need for human intervention in accelerator tunnels.

Lopez, Jacob↗
DOE OSTI2024

Lightweight Embedded Controller in Advanced FPGA SoC for Radar Signal Processing [Poster]

The objective of the project is to demonstrate that critical control functions can be implemented using little resources in modern microelectronics. A finite state machine (Figure 1) is implemented onto a field programmable gate array (FPGA). The functionality of the system is demonstrated by sending binary instructions to the controller. The controller transmits patterns through an LED, controls an electromechanical device, and uses pulse-width modulation (PWM) for radar functions.

42 ENGINEERING↗
DOE OSTI2020

Matrix converter operating in current control mode using feed forward signals

A matrix converter system having a current control mode operation is provided. The system includes a matrix converter having a switching matrix. The matrix converter is coupled at its low-voltage side to a generator and at its output load side to a load. A controller having a pulse width modulation (PWM) control circuit is configured to control the matrix converter via its switching matrix to increase energy within the internal inductances of the generator when the switching matrix causes a short circuit. A feed forward calculator is configured to calculate a feed forward output phase angle. The feed forward output phase angle is an estimation of an angle between an output current vector and an output voltage vector that represent feedback signals of current and voltage output by the matrix converter. The angular position of the voltage output vector is adjusted as a function of the feed forward output phase angle to align angular position or phase angle of the voltage output vector that represents the voltage output with a selected angular position or phase angle.

42 ENGINEERING↗
DOE OSTI2022

Analysis of Inter Converter Interactions using Harmonic State Space Modeling

Power converters have become a key participant within the modern grid, facilitating the grid's interaction with renewable energy sources and various loads, among others. These converters can also interact with each other, creating harmonics that were previously absent in the grid. While some previous research studies have focused on inter-converter interactions, not much focus has been on the role of pulse width modulators in these inter-converter interactions. This paper focuses on the issue and builds upon harmonic state-space modeling (HSS) to observe inter-converter harmonic interactions. A new modulator model is developed, and its implementation within HSS modeling to observe harmonic coupling between multiple inverters is highlighted. A simulation testbench is developed, and to verify the advantages and limitations of the proposed modeling approach, it is compared with two other traditional modeling methods: namely, average and switching models. The proposed method is shown to be significantly more accurate and informative than conventional average modeling methods and has considerably lower computation costs and simulation time than detailed switching models. The results are verified using extensive simulations on MATLAB.

Xue, Yaosuo↗
DOE OSTI2021

Smart controller with phantom inductor current sensing for switched mode power supplies

Voltage on the output terminal of an inductor is obtained as a first input signal to a control block (CB); the inductor has an input terminal connected to a power switch and driver block at a switching node. A sense input voltage is obtained on an output terminal of a sensing circuit that is not directly connected to the switching node, as a second input signal to the CB. A voltage is generated on a first output terminal of the CB and is selected such that the CB can use its first and second input signals to infer the current through the inductor. A pulse width modulation (PWM) signal is generated on a second output terminal of the CB, based on the inferred current through the inductor; the second output signal from the CB is provided to a PWM input terminal of the power switch and driver block.

Zhang, Xin↗
DOE OSTI2023

Startup process for a dual active bridge converter to prevent over-voltage failure and thermal run-away

A system and method for controlling a dual active bridge based DC/DC converter. A controller implements a startup control scheme and DC bus pre-charge routine to prevent damage to the converter upon startup. During startup of the converter, the startup control process can be used to prevent excessive phase-shift and the DC bus pre-charge routine adjusts the pulse width modulated duty cycle by increasing the dead time between signals, resulting in a decreased DC bus capacitor.

Singh, Braj K.↗
DOE OSTI2023

Unfolder-based single-stage AC-AC conversion system

A power converter includes an unfolder connected to a three-phase source and has an output connection with three output terminals. A three-input converter connected to the unfolder produces a quasi-sinusoidal output voltage across converter output terminals. Switches of the converter selectively connect each of the three output terminals across the converter output terminals. A pulse-width modulation controller controls a first duty ratio and a second duty ratio for the converter based on a phase angle of the source and a modulation index generated from an error signal related to a control variable. The duty ratios are time varying at a rate related to a fundamental frequency of the source. The modulation index relates to output voltage of the converter, peak voltage or current of the source and/or peak current at the output terminals.

Teeneti, Chakridhar Reddy↗
DOE OSTI2023

Broadside coupled coplanar inductors

A broadside coupled coplanar inductor device includes first and second coplanar inductors in which the conductors of the first and second coplanar inductors are broadside coupled. The conductors are located one above the other at a first distance and the return paths are located to the side of the respective first and second conductor signal paths at a second distance. One or both of the dimensions of the first and second first distances is defined so as to maximize a mutual inductance between the conductors. First and second driver circuit apply voltages across each conductor. The input pulse width modulation signals applied to the first and second driver circuits are 180 degrees out of phase.

Takken, Todd E.↗
DOE OSTI2024

A New Approach to Robot Motor Control

This essay details the motor control improvements to Fermilab's Remote Viewing Robot (RVR). It is a robot tasked with remotely investigating issues within the accelerator tunnels at Fermilab. Initially controlled by a single Raspberry Pi that housed all the robot s operations, the RVR will now use a Raspberry Pi Pico W for its motor control. This was achieved using Pulse Width Modulation (PWM) to allow for precise speed and torque control for the robot. This enhances the robot s reliability. By addressing the challenge of navigating high radiation environments, the upgrade helps assist the RVR s goal of decreasing the need for human intervention in accelerator tunnels.

Lopez, Jacob↗
DOE OSTI2024

A Comparison of Battery Charge Controller Technologies for Wave Energy Converters: Preprint

Wave energy is a uniquely challenging field for electrical system designers. High peak and low average power potential with a constantly varying energy input is difficult to harness and control through conventional means. To power the blue economy, low-powered wave energy converters (WECs) need batteries for energy storage. Safely and effectively charging batteries from waves requires a charge controller to properly monitor and control voltage and current going to the battery. Currently, off-the-shelf charge controllers exist for other renewable generation such as wind, hydro, and solar. Two topologies were validated: a buck converter and a pulse width modulation (PWM) charge controller. Using an in-lab dry testbed, wave energy power inputs were simulated to properly validate the effectiveness of existing charge controller technologies, identifying the shortcomings and improvements needed to effectively harness wave energy.

battery storage↗
DOE OSTI2023

Dual Triggered Beam Extraction Kicker (Rev. 1)

A Blumlein modulator is a relatively inexpensive pulsed power device that can deliver highly repeatable pulses that can be used to change the path of beam pulses. The modulator is primarily built with transmission line cable which is relatively inexpensive. Due to the highly repeatable nature of a Blumlein modulator it is a great tool for kicking beam pulses while producing very little spill or losses in beam current. One of the challenges with a Blumlein kicker is that the length of the kicking pulse output by the modulator is determined by the length of the cables. Cable lengths are set prior to implementation for the desired kicking pulse width. The Blumlein modulator at LANSCE uses a single thyratron which can deliver two 50-kilovolt 1,000-amp pulses of opposite polarity to kicking plates at the same time. This method makes for a very strong kick that is highly repeatable. A method that has been discussed, to deliver a different pulse width, is to add a second trigger that would be fired, once the desired pulse width has been delivered, cutting out the remaining pulse. The second trigger would offer a lot of variability with the pulse width of the kicker. This method has only ever been attempted using low current and relatively low voltages compared to the scale needed to properly kick a beam pulse. This in turn allows for the use of power supplies with a higher repetition rate. The advancement of this standard kicker technology in the accelerator facilities would attract attention within the scientific and engineering communities. The project detailed within will investigate the capabilities of different triggering topologies and design a prototype dual triggered Blumlein kicker modulator capable of variable kicking pulse width.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

PWM for Simultaneous Minimization of Switching Losses and CM Voltage in Current Source Inverters

This article proposes a new pulsewidth modulation (PWM) scheme that reduces common-mode (CM) voltage and switching losses simultaneously in CSI. The proposed PWM [i.e., reduced voltages PWM (RVM)] reduces CM voltages and switching losses by selecting the optimal zero current vector and PWM sequence based on the CSI output voltage conditions. This article also proves the proposed RVM achieves both objectives (i.e., reduced CM voltage and switching losses) simultaneously for all CSI operating conditions without compromising the other objective. The proposed RVM inherently achieves zero-voltage switching (ZVS) conditions during the zero current vector transitions, further reducing the switching losses. Experimental results demonstrate significant reductions in CM voltage, reaching up to approximately 95%, accompanied by an increase of up to about 5.5% in CSI efficiency across a wide operating range compared to alternative PWM methods, confirming the predicted advantages of the proposed RVM.

42 ENGINEERING↗
DOE OSTI2020

A Novel Voltage Balancing Control With dv/dt Reduction for 10-kV SiC MOSFET-Based Medium Voltage Modular Multilevel Converter

Using high voltage (HV) silicon carbide (SiC) power semiconductors in a modular multilevel converter (MMC) is promising because it results in fewer submodules and lower switching loss compared to conventional Si based solutions. The nearest level pulsewidth modulation (NL-PWM) is commonly used in the MMC for medium voltage applications. However, with the NL-PWM and existing voltage balancing control, there are many submodules that switch their modes in a control cycle, resulting in a high dv/dt during the deadtime of the power semiconductor, which could be multiple times of the dv/dt of the single device. This poses great challenges on the noise immunity and insulation design in the MMC using HV SiC devices, which have very fast switching speed. A novel voltage balancing control, which ensures only two submodules switch their modes in a control cycle, is proposed in this article, limiting the maximum dv/dt to the dv/dt of a single power semiconductor and also maintaining the voltage balance performance. Furthermore, the proposed voltage balancing control is experimentally validated in a 10-kV SiC mosfet based MMC with four submodules per arm.

42 ENGINEERING↗
DOE OSTI2025

Interleaved Cuk Converter Wave Energy System With Advanced Control and Grid Support Functions for Seamless Integration

This paper presents an innovative wave energy conversion system that integrates an interleaved Cuk converter with advanced nonlinear control for seamless grid integration. The system efficiently extracts power on the DC side using the interleaved Cuk converter, while an inverter manages power transfer to the grid or load on the AC side. A nonlinear control architecture, based on the Lyapunov energy function, ensures stable and optimal operation under varying wave conditions, effectively addressing the challenges of variability and unpredictability inherent in wave energy. The proposed system also incorporates features to enhance power quality and minimize losses, making it a robust solution for renewable energy integration. The system's effectiveness in harnessing wave energy and achieving smooth grid integration is validated through comprehensive computer simulations in MATLAB/Simulink, with case study results demonstrating its capabilities.

HYDRO ENERGY,TIDAL AND WAVE POWER↗