Search NASA⌕ Search

SEARCH · Search NASA

Results for “Speed Control”

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.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

System and method for continuous solids slurry depressurization

A system includes a first pump having a first outlet and a first inlet, and a controller. The first pump is configured to continuously receive a flow of a slurry into the first outlet at a first pressure and to continuously discharge the flow of the slurry from the first inlet at a second pressure less than the first pressure. The controller is configured to control a first speed of the first pump against the flow of the slurry based at least in part on the first pressure, wherein the first speed of the first pump is configured to resist a backflow of the slurry from the first outlet to the first inlet.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Energy-Efficient Cruise Control Using Optimal Control for a Hybrid Electric Vehicle

Increasing connectivity in passenger vehicles provides for a large amount of look-ahead information about driving conditions. An intelligent control algorithm is presented that takes advantage of this information to obtain the operation strategy for the powertrain of a parallel hybrid electric vehicle, in an uncongested highway cruising situation. In order to guarantee sufficient computational efficiency to meet future online requirements, the algorithm is based on Pontryagin’s Minimum Principle. The whole driving/operation strategy is composed of a series of solutions to the optimal control sub-problem for each separate route segment. The control sequence computed offline is then evaluated in Autonomie. The simulation result shows 6% fuel savings compared to a baseline rule-based controller with no speed optimization.

Shen, Daliang↗
DOE OSTI2021

Irrigation system

A gravity irrigation system includes a distribution piping having apertures to distribute water to a field, and a valve located upstream of the distribution piping. The valve limits a pressure of the water being delivered to the distribution piping. The system also includes a sump to receive the water at a lowest elevation of the field, a depth sensor disposed within the sump, and a return pump disposed at least partially within the sump to move the water to an elevated portion of the field. The system also includes a motor to drive the return pump, and a power source coupled to a variable frequency drive that powers the motor and controls a motor speed proportionately to an indication of the depth sensor. The system also includes a transfer piping to bring the water from the return pump to a check valve and to the distribution piping.

Henry, Christopher G.↗
DOE OSTI2024

"Traffic Control via Connected and Automated Vehicles: An Open-Road Field Experiment with 100 CAVs"

The CIRCLES project aims to reduce instabilities in traffic flow, which are naturally occurring phenomena due to human driving behavior. These "phantom jams" or "stop-and-go waves,"are a significant source of wasted energy. Toward this goal, the CIRCLES project designed a control system referred to as the MegaController by the CIRCLES team, that could be deployed in real traffic. Our field experiment leveraged a heterogeneous fleet of 100 longitudinally-controlled vehicles as Lagrangian traffic actuators, each of which ran a controller with the architecture described in this paper. The MegaController is a hierarchical control architecture, which consists of two main layers. The upper layer is called Speed Planner, and is a centralized optimal control algorithm. It assigns speed targets to the vehicles, conveyed through the LTE cellular network. The lower layer is a control layer, running on each vehicle. It performs local actuation by overriding the stock adaptive cruise controller, using the stock on-board sensors. The Speed Planner ingests live data feeds provided by third parties, as well as data from our own control vehicles, and uses both to perform the speed assignment. The architecture of the speed planner allows for modular use of standard control techniques, such as optimal control, model predictive control, kernel methods and others, including Deep RL, model predictive control and explicit controllers. Depending on the vehicle architecture, all onboard sensing data can be accessed by the local controllers, or only some. Control inputs vary across different automakers, with inputs ranging from torque or acceleration requests for some cars, and electronic selection of ACC set points in others. The proposed architecture allows for the combination of all possible settings proposed above. Most configurations were tested throughout the ramp up to the MegaVandertest.

Lee, Jonathan↗
DOE OSTI2016

Top-seeded solution crystal growth of noncentrosymmetric and polar Zn{sub 2}TeMoO{sub 7} (ZTM)

A top-seeded solution growth (TSSG) method was used to grow large, centimeter size, crystals of Zn{sub 2}TeMoO{sub 7} (ZTM) – a noncentrosymmetric and polar material. A TeO{sub 2}–MoO{sub 3} mixture in combination with the parent compound was used as a flux. The morphologies of the crystals can be controlled by different rotation speeds. Optical spectra indicate that ZTM is transparent up to 5.25 µm with a UV absorption edge of 300 nm. In addition, the refractive index along the optical x, y, and z axes was measured at different wavelengths. - Highlights: • Zn{sub 2}TeMo{sub 2}O{sub 7} crystals were grown by top-seeded solution growth (TSSG) method. • The morphology of the single crystals is controllable by changing rotation speed. • Optical transmission spectra indicate Zn{sub 2}TeMo{sub 2}O{sub 7} has a broad transmission range. • Refractive index along optical axes was measured at different wavelengths.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Abrasive Waterjet Machining

The abrasive waterjet machining process was introduced in the 1980s as a new cutting tool; the process has the ability to cut almost any material. Currently, the AWJ process is used in many world-class factories, producing parts for use in daily life. A description of this process and its influencing parameters are first presented in this paper, along with process models for the AWJ tool itself and also for the jet–material interaction. The AWJ material removal process occurs through the high-velocity impact of abrasive particles, whose tips micromachine the material at the microscopic scale, with no thermal or mechanical adverse effects. The macro-characteristics of the cut surface, such as its taper, trailback, and waviness, are discussed, along with methods of improving the geometrical accuracy of the cut parts using these attributes. For example, dynamic angular compensation is used to correct for the taper and undercut in shape cutting. The surface finish is controlled by the cutting speed, hydraulic, and abrasive parameters using software and process models built into the controllers of CNC machines. In addition to shape cutting, edge trimming is presented, with a focus on the carbon fiber composites used in aircraft and automotive structures, where special AWJ tools and manipulators are used. Examples of the precision cutting of microelectronic and solar cell parts are discussed to describe the special techniques that are used, such as machine vision and vacuum-assist, which have been found to be essential to the integrity and accuracy of cut parts. The use of the AWJ machining process was extended to other applications, such as drilling, boring, milling, turning, and surface modification, which are presented in this paper as actual industrial applications. To demonstrate the versatility of the AWJ machining process, the data in this paper were selected to cover a wide range of materials, such as metal, glass, composites, and ceramics, and also a wide range of thicknesses, from 1 mm to 600 mm. The trends of Industry 4.0 and 5.0, AI, and IoT are also presented.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Chapter 6: Wind Turbine Control Design

In this chapter, the author introduced wind turbine control, discussing sensors and actuators, operating regions, and the operational controller loops. The author then described the different levels of models needed in the controller development process, emphasizing that the models needed for control design are a simplification of the detailed models used in control simulation testing. Scripts used in conjunction with MATLAB are used to synthesize the controller, and detailed models are used for controller simulations. We described the design of the basic operational controller based on simplified models, including the generator torque controller for optimizing energy capture, and the blade pitch controller for regulating turbine speed (or power). The author described how to account for the effects of turbine nonlinearities and actuator dynamics and saturation. We then gave an overview of modern state-space control design methods, which are useful when designing a controller to meet multiple control objectives. The author also described a variety of advanced multivariable control methods. The author gave an overview of the use of advanced sensors (such as lidar sensors for upwind wind-speed measurements) and actuators (outboard blade aerodynamic devices used in 'smart' blade technology). The use of individual blade pitch, although not considered an advanced actuator, was also described. The author concluded with some special control issues for offshore floating systems.

17 WIND ENERGY↗
DOE OSTI2019

Design of ECH launcher for KSTAR advanced Tokamak operation

For the advanced tokamak operation in Korea Superconducting Tokamak Advanced Research (KSTAR), up to 6 MW of electron cyclotron heating (ECH) is planned. The ECH launcher should be able to operate in steady state and serve as a central/off-axis heating and current drive, q-profile control, and control of the neoclassical tearing mode (NTM) and sawtooth. The water cooled launchers have been upgraded to include continuous operation with precise, high-speed real-time control of the beams by integration with the plasma control system (PCS) for supporting the experiments, in particular for suppressing NTM. Here, the launcher was successfully operated for 78 s with about 650 kW EC power, where the temperature of the coolant, with a flow rate of 9.6 lpm, is saturated and approximately 2 °C. The launcher control system had a maximum control cycle of 5 kHz and a motor latency of about 10 ms, and the poloidal scanning speed of the beam was 20 °/s. Additionally, for the higher localization of power deposition, the curvature and size of the mirrors in the launcher were optimized. This paper presents the ECH launcher design and its control system with the operation results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Sound Assisted Low Temperature Spalling: Upscaling and Throughput

In evaluating the state-of-the-art spalling techniques, the key factor that is missing is the control of crack propagation, which is responsible for low quality wafers due to high surface roughness and Total Thickness Variation, TTV. This project has shown that acoustic waves can alter the conditions at the crack tip during thermal spalling, modifying the propagation speed and the stress field around it (stress intensity factor, K). Both factors are directly related to the roughness of the spalled surface, so as we control speed and stress, we can fine-tune the surface roughness through the entire wafer as suggested by Arakawa.

42 ENGINEERING↗
DOE OSTI2017

Active Power and Flux Control of a Self-Excited Induction Generator for a Variable-Speed Wind Turbine Generation

A Self-Excited Induction Generation (SEIG) for a variable speed wind turbine generation(VS-WG) is normally considered to be a good candidate for implementation in stand-alone applications such as battery charging, hydrogenation, water pumping, water purification, water desalination, and etc. In this study, we have examined a study on active power and flux control strategies for a SEIG for a variable speed wind turbine generation. The control analysis for the proposed system is carried out by using PSCAD software. In the process, we can optimize the control design of the system, thereby enhancing and expediting the control design procedure for this application. With this study, this control design for a SEIG for VS-WG can become the industry standard for analysis and development in terms of SEIG.

17 WIND ENERGY↗
DOE OSTI2017

A generalized approach for determining electric machine drive switching schemes using evolutionary optimization algorithms

The number of inverter switching events in one fundamental cycle of an electric machine can be limited by many factors such as inverter switching frequency, rotational speed, and computational time required by control algorithms. Even at low and moderate speeds, switching harmonics cause distortion in the phase current, which can lead to increased torque ripple and core losses when compared to operation with ideal waveforms. Furthermore, as rotational speed increases and voltage limitations are encountered, overmodulation schemes must be implemented to overcome increasing reactance and back-EMF (or pseudo back-EMF). The goal of this paper is to establish a framework and demonstrate methods for determining optimal switching times for a set number of switching events in a fundamental cycle using particle swarm optimization and multivariable fitness functions.

Burress, Timothy↗
DOE OSTI2024

Analysis of Power-Maximizing Region 2 Controllers for Wind and Marine Turbines

Wind and marine energy are rapidly growing and complementary technologies that share some techniques for simplified modeling and control, particularly in below-rated flow speeds. A turbine operator has several choices of controller for maximizing power in Region 2. The simple and ubiquitous KΩ 2 control law is often effective but limited in its flexibility. Alternative controllers use reference tracking to split the control objectives into a low-bandwidth optimal tip-speed ratio tracking loop to maximize steady-state power and a higher-bandwidth proportional-integral control loop to reject inflow turbulence. Several options exist for identifying the slowly varying optimal set point during operation, based on estimating the inflow velocity or filtering the power or torque signals. This study compares the trade-offs between performance and other design priorities for a few choices of reference-tracking controller in the literature for reference wind and marine turbines. Analysis is performed in the frequency domain using the linearization of each controller, and the impact of turbulent disturbances on the closed-loop system is described. The controllers are simulated in OpenFAST to analyze their performance with higher-order nonlinear turbine dynamics.

17 WIND ENERGY↗
DOE OSTI2016

Retrofit device and method to improve humidity control of vapor compression cooling systems

A method and device for improving moisture removal capacity of a vapor compression system is disclosed. The vapor compression system is started up with the evaporator blower initially set to a high speed. A relative humidity in a return air stream is measured with the evaporator blower operating at the high speed. If the measured humidity is above the predetermined high relative humidity value, the evaporator blower speed is reduced from the initially set high speed to the lowest possible speed. The device is a control board connected with the blower and uses a predetermined change in measured relative humidity to control the blower motor speed.

42 ENGINEERING↗
DOE OSTI2022

Efficient Refrigerated Display Cases - Can They Flex Their Power? Preprint

Refrigerated display cases are widely-used, critical equipment in supermarkets for maintaining product safety and quality. Energy-efficient medium temperature liquid-cooled refrigerated display cases can save 25-70% of the total supermarket energy, according to manufacturers. Traditionally, cases operate by maintaining a temperature around a user-input setpoint that is dependent on the product in the case. Although cases are major electrical energy consumers, they are hardly ever considered for implementing load-flexibility strategies. With added load-flexibility capabilities, refrigerated display cases can shed (reduce), or shift (by adding and subsequently shedding) load. Supermarkets can reduce their energy costs and enhance electric grid integrity by implementing these smart load-flexibility control strategies. Advanced controls can also enable load-shifting to coincide with optimum periods of renewable energy generation. This will further improve operational costs and reduce greenhouse gas emissions without compromising food safety and quality. In this research, we have evaluated the energy savings of liquid-cooled medium temperature display cases and developed load flexibility strategies leveraging an advanced controls system, a variable speed compressor, and heat rejection via a water-cooled condenser. This study further assessed the impact of load flexibility strategies in a controlled environment chamber for a single refrigerated display case.

ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION↗
DOE OSTI2018

Load Mitigation on Floating Offshore Wind Turbines with Advanced Controls and Tuned Mass Dampers

General Electric, the National Renewable Energy Laboratory (NREL), the University of Massachusetts Amherst (UMass), and Glosten have recently completed a US Department of Energy (DOE)-funded research program to study technologies for mitigating loads on floating offshore wind turbines through the use of advanced turbine controls and tuned mass dampers (TMDs). The analysis was based upon the Glosten PelaStar tension leg platform (TLP) with GE Haliade 150 turbine, a system developed in a previous front end engineering design (FEED) study funded by the Energy Technology Institute (ETI) in the UK. The platform was designed for the WaveHub wave energy research site, with a mean water depth of 59-m. Loads were analyzed by running time-domain simulations in four 50-year return period (50-YRP) ultimate load state (ULS) conditions and 77 fatigue load state (FLS) environmental conditions. In 50-YRP conditions advanced controls are not active. The influence of TMDs on ULS loads have been reported previously (Park et al. [2]). In FLS conditions advanced controls and TMDs afford dramatic reductions in fatigue damage, offering the potential of significant savings in tower structural requirements. Simulations in turbine idling conditions were run in OrcaFlex, and simulations in operating conditions were run in FAST. Simulations were run with a baseline turbine controller, representative of the current state of the art, and an advanced controller developed by NREL to use collective and individual blade pitch control to maintain rotor speed and reduce tower loads. UMass developed a number of TMD types, with varying system configurations, including passive nonlinear dampers and semi-actively controlled dampers with an inverse velocity groundhook control algorithm. Loads and accelerations in FLS conditions were evaluated on the basis of damage equivalent loads (DELs), and fatigue damage was computed by Miner's summations of stress cycles at the tower base. To study sensitivity to water depth, loads were analyzed at both the 59-m WaveHub depth and a more commercially realistic depth of 100 m. TMDs reduce fatigue damage at the tower-column interface flange by up to 52% in 59-m water depth and up to 28% in 100 m water depth. Advanced controls reduce fatigue damage at the tower-column flange by up to 22% in 59-m water depth and up to 40% in 100 m water depth. The most effective load-mitigation strategy is combining advanced controls with TMDs. This strategy affords a 71% reduction in fatigue damage in both 59-m and 100-m water depths.

17 WIND ENERGY↗
DOE OSTI2017

Improving the Fuel Economy of Class 8 Military Vehicles using a Smart Cruise Control Algorithm

Connected and Automated Vehicles (CAVS) have the potential for improving fuel economy by changing the way vehicles are driven. Fuel economy can be improved through a wide range of technologies, many of which do not require Level 5 automation. One of the most promising technologies is a smart cruise control for which a speed-matching algorithm can be designed to account for fuel economy. Accounting for fuel economy in the algorithm leads to different driving behavior than simply matching the driver entered set speed. This paper describes the application of such a smart cruise control to a class 8 vehicle both in simulation and in the actual vehicle on a close test track. This paper evaluates the algorithm and describes the correlation procedure used to calibrate the model using test data from the vehicle.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2018

Characterization of temporal variations and feedback timescales of exhaust gas recirculation gas properties using high-speed diode laser absorption spectroscopy for next-cycle control of cyclic variability

Dilute combustion offers efficiency gains in boosted gasoline direct injection engines both through knock-limit extension and thermodynamic advantages (i.e. the effect of γ on cycle efficiency), but is limited by cyclic variability at high dilution levels. Past studies have shown that the cycle-to-cycle dynamics are a combination of deterministic and stochastic effects. The deterministic causes of cyclic variations, which arise from feedback due to exhaust gas recirculation, imply the possibility of using active control strategies for dilution limit extension. While internal exhaust gas recirculation will largely provide a next-cycle effect (short-timescale feedback), the feedback of external exhaust gas recirculation will have an effect after a delay of several cycles (long timescale). Therefore, control strategies aiming to improve engine stability at dilution limit may have to account for both short- and long-timescale feedback pathways. This study shows the results of a study examining the extent to which variations in exhaust gas recirculation composition are preserved along the exhaust gas recirculation flow path and thus the relative importance and information content of the long-timescale feedback pathway. To characterize the filtering or retention of cycle-resolved feedback information, high-speed (1–5 kHz) CO 2 concentration measurements were performed simultaneously at three different locations along the low-pressure external exhaust gas recirculation loop of a four-cylinder General Motors gasoline direct injection engine using a multiplexed two-color diode laser absorption spectroscopy sensor system during steady-state and transient engine operation at various exhaust gas recirculation levels. It was determined that cycle-resolved feedback propagates through internal residual gases but is filtered out by the low-pressure exhaust gas recirculation flow system and do not reach the intake manifold. Intermediate variations driven by flow rate and compositional changes are also distinguished and identified.

Dilute combustion↗
DOE OSTI2023

Controlled In Situ Foaming for Mechanical Responsiveness of Architected Foams

Addition of chemical blowing agents to polysiloxane resins produces foams with closed–cell morphology. Combining this chemistry with the 3D–printing technique direct ink writing (DIW) permits the creation of architected foams with controllable, hierarchical tiers of porosity. Here, using a two–component foaming ink, the extent of foaming can be controlled by incorporating an active mixing printhead as part of the fabrication process. Changes in the mixing speed allows for in situ control of the foaming reaction where the mixing speed is directly correlated with the resulting foaming that occurs upon extrusion. These architected foams display tunable mechanical responses, porosities, and open–to–closed cell ratios. While chemically blown polysiloxane foam is a well–established material, utilizing DIW as fabrication technique presents a novel approach for creating tailored, architected foams that require minimal post–processing.

36 MATERIALS SCIENCE↗