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At least 487 records · Page 27

All sources NASA NTRS DOE OSTI

DOE OSTI2022

Power supply circuit with multiple stages for converting high voltage to low voltage and power train having the same

A power supply circuit for converting a first voltage to a second voltage where the first voltage is greater than the second voltage, and a power train having the same, are provided. The power supply circuit may have multiple stages and each stage of the power supply circuit may include a first circuit block configured to provide a start-up power to a second circuit block; a second circuit block configured to generate a Pulse-Width-Modulation (PWM) signal that controls a pulse duration of a transistor; a third circuit block configured to activate or deactivate the transistor based on the PWM signal; a fourth circuit block configured to reset a magnetic flux in a transformer to a zero state when the transistor is deactivated; and a fifth circuit block configured to maintain an output of a stage below a predetermined value by adjusting a voltage across the transformer.

Singh, Brij N.↗

DOE OSTI2022

Three-phase differential mode converter

A system for charging a battery includes three sub-modules, each receiving a respective phase of a three-phase alternating current (AC) signal. The three sub-modules cooperate to transform the respective phases of the three-phase AC signal to a direct current (DC) signal by passing the respective phases of the three-phase AC signal through a respective semiconductor device configured to discontinuously modulate the respective phase of the three-phase AC signal to convert it to a DC signal provided to the battery to charge the battery.

Mazumder, Sudip K.↗

DOE OSTI2022

Wave energy converter buoy with variable geometry

A nonlinear control design technique capitalizes on a wave energy converter comprising a shaped buoy having a variable geometry wave energy. For example, the shaped buoy can have an hourglass (HG) geometry having a variable cone or steepness angle. The HG buoy is assumed to operate in the heave motion of the wave. The unique interaction between the HG buoy and the wave creates a nonlinear cubic storage effect that produces actual energy storage or reactive power during operation. A multi-frequency Bretschneider spectrum wave excitation input was simulated for the HG design both with constant and varying steepness angle profiles which demonstrated further increased power generation with changing sea states for the variable design.

Wilson, David G.↗

DOE OSTI2023

Alkane dehydrogenation catalyst and methods of converting alkanes to alkenes

Provided herein is an alkane dehydrogenation catalyst, a method of manufacturing an alkane dehydrogenation catalyst, and a method of converting alkanes to alkenes.

Marshall, Christopher L.↗

DOE OSTI2023

Low-cost connectors for inverters and converters and methods of manufacturing and using the same

In some embodiments, systems and methods for connector assembly for use with an AC or DC power interface of a power conversion device, such as a converter and an inverter, are provided. The connector assembly can include a circuit board, a power connector, and a pin. The power connector can have a base configured to be secured relative to the circuit board and define a first channel extending through the power connector along a first channel axis. The first pin can have a first pin body that extends along a first pin axis and a first connection element that extends along the first pin axis from the first pin body to a first terminal end that is skewed relative to the first pin axis.

Khaligh, Alireza↗

DOE OSTI2023

Power packet networks for wave energy converter arrays

One of the biggest challenges for all renewable energy sources (RES) is that they are variable power generators which will require reactive power or energy storage systems (ESS) to provide reliable power quality (ideally power factor of one) at the power grid generation side. The present invention is directed to a power packet network (PPN) for integrating wave energy converter (WEC) arrays into microgrids. Specifically, an array of WECs can be physically positioned such that the incoming regular waves will produce an output emulating an N-phase AC system such that the PPN output power is constant. ESS requirements are thereby minimized whilst maintaining grid stability with high power quality. This will enable RES integration onto a future smart grid for large-scale adoption and cost reduction while preserving high efficiency, reliability, and resiliency.

Wilson, David G.↗

DOE OSTI2023

Control of matrix converters using machine learning

A method of controlling a matrix converter system is provided. The method includes receiving an operating condition and consulting a trained Q-data structure for reward values associated with respective switching states of the switching matrix for an operating state that corresponds to the operating condition. The Q-data structure is trained using Q-learning to map a reward value predicted for respective switching states to respective discrete operating states. The method further includes sorting the reward values predicted for the respective switching states mapped to the operating state that corresponds to the operating condition, selecting a subset of the set of the mappings as a function of a result of sorting the reward values associated with the switching states of the operating state, evaluating each switching state included in the subset, and selecting an optimal switching state for the operating condition based on a result of evaluating the switching states of the subset.

Chamie, Mahmoud El↗

DOE OSTI2023

Mooring structure for ocean wave energy converters

A mooring system for an Ocean Wave Energy Converters (OWEC) includes multiple structural members such as legs and braces that are linearly extendible and connected using mobile joints, each joint providing two degrees of freedom for rotations about the joint. Mobile joints also attach bottom ends of the legs to mooring points. A jacking system can change lengths of the extensible structural members to adjust depth of the OWEC for operation or for storm safety, to lift the OWEC out of the water for maintenance, or to align the OWEC to an incoming wave direction.

Siegel, Stefan G.↗

DOE OSTI2023

Method and system embodiments for converting ethanol to para-xylene and ortho-xylene

Disclosed herein are embodiments of a method and system for converting ethanol to para-xylene. The method also provides a pathway to produce terephthalic acid from biomass-based feedstocks. In some embodiments, the disclosed method produces p-xylene with high selectivity over other aromatics typically produced in the conversion of ethanol to xylenes, such as m-xylene, ethyl benzene, benzene, toluene, and the like. And, in some embodiments, the method facilitates the ability to use ortho/para mixtures of methylbenzyaldehyde for preparing ortho/para xylene product mixtures that are amendable to fractionation to separate the para- and ortho-xylene products thereby providing a pure feedstock of para-xylene that can be used to form terephthalic anhydride and a pure feedstock of ortho-xylene that can be used for other purposes, such as phthalic anhydride.

Ramasamy, Karthikeyan Kallupalayam↗

DOE OSTI2024

Parameter-Varying Hydrodynamic Model of a Single Vane in a Variable-Geometry Oscillating Surge Wave Energy Converter: Preprint

This paper presents a study on the time-varying hydrodynamic modeling of an individual flap of a variable geometry oscillating surge wave energy converter (VGOSWEC). The WEC design incorporates controlled surfaces that can modify their orientation relative to the wave motion, reducing hydrodynamic pressure and related loads. This research focuses on characterizing the behavior of the oscillating WEC using a simplified model and three methods for achieving a continuous time-variant model: discrete hydrodynamic parameters, interpolation of hydrodynamic parameters, and a fitting function. The results of this study contribute to the understanding of time-varying hydrodynamic effects in variable geometry oscillating WECs. The findings provide insights into the potential for reducing structural loads and improving the overall performance of such devices. Further research and development in this area could lead to advancements in WEC technologies, enabling their integration into the competitive energy market.

HYDRO ENERGY,TIDAL AND WAVE POWER↗

DOE OSTI2024

WEC-Sim Modeling of Laminar Scientific's Patented Seesaw Wave Energy Converter: Preprint

Laminar Scientific's patented seesaw wave energy converter was modeled in WEC-Sim to predict performance. The device operates by utilizing ocean surface waves to rotate a truss in pitch about a pivot. The pivot is located at the top of two pylons, which are embedded in the seafloor. The seesaw has a float on either end, and the buoyancy forces from each float cause the system to rise or fall with passing waves. Device performance relies upon seesaw length and ocean wavelength creating an antiphase effect. The seesaw truss has an adjustable length intended to achieve this effect. The operation method enforces a narrow band of wavelengths which induce the largest rotational motion from the device. The hydrodynamic analysis of the device was performed using Capytaine, and the results confirmed that the device operates best in a narrow frequency band. Four float-to-float spacing cases and three pylon radii were examined. The hydrodynamic results indicate a match between the model and the physical expectations for the device, and that varying the pylon radii by 0.1-m increments for three instances creates minimal changes in hydrodynamic properties. Power matrices for three float spacing cases of the device were simulated with Joint North Sea Wave Project spectra waves and optimal power take-off damping in WEC-Sim. The maximum average power production for the 15-m spacing case was 14.1 kW with a 5.0-s peak wave period and 4-m significant wave heights. Plots of capture-width ratios indicated that the device performance was linear and confirmed that the device is optimal in a narrow frequency band. The maximum percentage of the available wave power produced by the 15-m device was approximately 16%. Simulations of the device in regular waves were used to produce plots of average power compared to a ratio of float spacing to wavelength. These plots indicate that the power production is maximized at a ratio of 0.5, and further confirm that the device has a narrow frequency response. The device was simulated at an example field location, where the device produced an annual average power rating of 1.6 kW given an average omnidirectional wave climate of 10.3 kW m-1 and an optimal, linearized power take-off model. While the maximum predicted device performance is reliant upon a narrow band of wave frequencies, the conducted analysis provides an opportunity to improve device design prior to prototyping and testing. Modifying the design to respond to a broader frequency range would improve device performance.

numerical modeling↗

DOE OSTI2024

Adaptive Narrowband Damping for Improving Harmonic Stability of Modular Multilevel Converter: Preprint

Harmonic instability events between modular multilevel converter (MMC) and ac systems have been widely reported in recent years. To resolve it, this paper proposes an adaptive narrowband damping control that automatically programs, adds and adjusts damping around the oscillation frequency when detect the oscillation. The paper first presents a low-pass filter design for MMC control loops, which pushes all negative damping of MMC impedance down to the medium frequency range (< approximately 1000 Hz). This makes narrowband damping can be more targeted and easier to design because multiple harmonic oscillations are avoided. An adaptive damping control that uses online oscillation detection is then proposed, which can automatically configure the narrowband damper to provide damping to the MMC at the detected oscillation frequency. In contrast to existing narrowband damping methods, the proposed adaptive narrowband damper adjusts the damping gain (e.g., to zero when system resonance disappears) and the width of the damping range automatically based on continuous monitoring of system resonance conditions. Electromagnetic transient (EMT) simulation results validate the efficacy of the proposed method in two typical MMC-based power systems.

active damping↗

DOE OSTI2024

System and method for power converter interfacing with multiple series-stacked voltage domains

According to various embodiments, a power conversion circuit is disclosed. The power conversion circuit includes at least one DC bus. The power conversion circuit further includes a plurality of DC-AC conversion units coupled to the DC bus and configured to convert a DC voltage into an AC voltage. The power conversion circuit also includes a multi-winding transformer comprising a magnetic core and a plurality of windings, where each DC-AC conversion unit is coupled to a corresponding winding of the multi-winding transformer.

Chen, Minjie↗

DOE OSTI2024

Low inductance bus assembly and power converter apparatus including the same

An apparatus, such as a power converter, includes first, second and third core bus plates arranged in parallel. The apparatus also includes a first bus extension plate joined to the first core bus plate and extending therefrom at a first angle and a second bus extension plate joined to the second core bus plate and extending therefrom at a second angle. The apparatus further includes a third bus extension plated joined with the third core bus plate and disposed parallel to the first bus extension plate and a fourth bus extension plate joined with the third core bus plate and disposed parallel to the second bus extension plate.

Nojima, Geraldo↗

DOE OSTI2024

Adaptive control of wave energy converters

A wave energy capture system deployed in water converts mechanical motion induced by waves in the water to electrical energy. A controller of the wave energy capture system receives input regarding real-time wave conditions in a vicinity of the wave energy capture system. The controller applies a control model to the received input to select a value of a control parameter for the wave energy capture system, where the control model includes a model that has been trained using machine learning to take wave condition data as input and to output control parameter values selected based on the wave condition data in order to increase an amount of energy captured by the wave energy capture system. The controller implements the selected value of the control parameter on the wave energy capture system.

Orona, Alexander J.↗

DOE OSTI2024

Three-phase differential mode converter

Mazumder, Sudip K.↗

DOE OSTI2024

Window-integrated charge-mode digital-to-analog converter for arbitrary waveform generator

A digital-to-analog converter circuit that creates an analog waveform from an input digital waveform. Operating the circuit comprises using the input digital waveform to 1) operate a charge control switch to set a charge time period, 2) operate a discharge control switch to set a discharge time period, 3) set a charge current magnitude using a charge gain, and 4) set a discharge current magnitude using a discharge gain. A charge source electrically charges a load capacitor during the charge time period (i.e., the charge mode). A discharge source electrically discharges the load capacitor during the discharge time period (i.e., the discharge mode). A circuit output transmits the analog waveform defined by the charge mode and the discharge mode. A charge current magnitude greater than the discharge current magnitude produces an upward-sloping analog waveform. A charge current magnitude less than the discharge current magnitude produces a downward-sloping analog waveform.

Li, Shaorui↗

DOE OSTI2024

A Fully Decentralized Modulation Scheme for Modular Multilevel Converters

As the number of submodules rapidly increase, control architecture of Modular Multilevel Converters (MMCs) is transforming from centralized to distributed in order to address the challenges of tremendous computational burden and massive wiring. In this digest, we propose a modulation scheme for the MMCs with distributed controls, where each submodule is able to handle both controls and modulation in a decentralized manner. It enables the distributed controllers to synchronize in terms of fast-switching pulse width modulation (PWM). Aiming at this key technical challenge, this research develops a physics-informed PWM control strategy of mirroring the spontaneous synchronization feature of coupled oscillator’s behavior at switching frequency. Thanks to less reliance on wirings and communications, the proposed approach has the potential of i) improving reliability of MMC systems, and ii) reducing cost and space requirements for MMCs. The proposed approach has been preliminarily verified through a simulation tool for power electronics systems.

Lu, Minghui [BATTELLE (PACIFIC NW LAB)]↗