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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Static DC to DC Power Conditioning-Active Ripple Filter, 1 MHZ DC to DC Conversion, and Nonlinear Analysis

Dc to dc static power conditioning systems on unmanned spacecraft have as their inputs highly fluctuating dc voltages which they condition to regulated dc voltages. These input voltages may be less than or greater than the desired regulated voltages. The design of two circuits which address specific problems in the design of these power conditioning systems and a nonlinear analysis of one of the circuits are discussed. The first circuit design is for a nondissipative active ripple filter which uses an operational amplifier to amplify and cancel the sensed ripple voltage. A dc to dc converter operating at a switching frequency of 1 MHz is the second circuit discussed. A nonlinear analysis of the type of dc to dc converter utilized in designing the 1 MHz converter is included.

Sander, W. A., III↗
DOE OSTI2025

A study on dc fault handling of dc-dc converter based on series and parallel connected DABs in MVdc applications

With the increase of direct current (dc) based power generating stations and loads, multi-terminal medium voltage dc (MT-MVdc) systems are gaining popularity. The dc sources and loads are interfaced with the MT-MVdc systems using series and parallel connected dual-active-bridge (SP-DAB). In this paper, the dc fault ride through procedure of SP-DAB meant for MT-MVdc application is analyzed. The need for dc breaker (DCB) under the requirements of MT-MVdc is established through EMT simulation studies. It is shown that an additional dc filter capacitor is essential at the output terminals of the SP-DAB to ride through the dc faults.

Jaldanki, Sreenivasa [ORNL] (ORCID:000000028122322↗
DOE OSTI2020

DC Link Voltage Balancing of the Active Front-End for the Extreme Fast Charging Stations

One of the most important challenges of the extreme fast charging (XFC) stations is to balance the DC link voltages of the active front-end (AFE). The multilevel cascaded H-bridge (CHB) converter is a great topology for the AFE applications due to the high power density, low total harmonic distortion (THD), and a low number of active and passive components. In this paper, a technique is proposed for balancing DC-link capacitor voltages of a three-phase CHB converter, when a phase shiftPWM modulation technique is used on all cells of the converter. To reach this goal, the redundant states of the CHB converters are used for generating different AC voltage levels by sorting the voltages of the converters. The proposed voltage balancing technique uses the principles that are employed for the DC link voltage balancing of the low-frequency modulation techniques to balance the DC link voltages of the CHB converter. As shown in this paper, the DC link voltages of the CHB converter can accurately be balanced very fast without using PI controllers, which are used in the conventional DC link voltage balancing techniques. A controller also is proposed which will be used to control the dq currents of the CHB converter. To verify the advantages of the proposed technique, the simulation results of the proposed technique will be carried out in a three-phase 7-cell CHB AFE.

Grid-tied converters, cascaded H-bridge, DC link v↗
DOE OSTI2024

PV-BESS DC-Series Integration for Regulated DC Systems

DC-series integration introduces a novel approach to seamlessly integrate a solar photovoltaic (PV) array and a battery energy storage (BES) in series. This system, referred to as the PV-integrated battery energy storage system—dc series (PVBESS-DCS), simplifies integration and enhances power density by leveraging the inherent voltage-source characteristics of batteries and adopting the concept of partial power processing. However, addressing voltage variations of a PV array and a BES under different operational conditions remains a challenge to apply the PVBESS-DCS to a regulated dc system, where the dc-bus voltage is fixed. This article proposes a PVBESS-DCS solution tailored for regulated dc systems. Within this framework, we present a controllable series voltage source compensating for the voltage differences between the PV and BES sources and the dc bus. Thus, the system can perform PV maximum power point tracking and curtailment control while charging and discharging BES and connected to a regulated dc bus. Additionally, we present a single-stage multiport partial power processing dc–dc converter designed for the proposed PVBESS-DCS. It utilizes a triple active bridge dc–dc converter topology. Finally, this article presents operating principles, control strategies, simulation results, and experimental findings of the proposed PVBESS-DCS for regulated dc systems.

25 ENERGY STORAGE↗
DOE OSTI2021

Magnetic triggering — time-resolved characterisation of silicon strip modules in the presence of switching DC-DC converters

Modules for the ATLAS Inner Tracker (ITk) strip tracker include a DC-DC converter circuit glued directly to the silicon sensor which converts the 11 V supplied to the module to the 1.5 V required for the operation of the readout chips. The DC-DC converter unit, consisting of a copper solenoid and custom ASIC, is located directly above the silicon strip sensor and therefore needs to be shielded to protect the sensor from EMI noise created during the operation of the circuit. Despite dedicated shielding, consisting of an aluminium shield box with continuous solder seams encompassing the surface components and a copper layer in the PCB beneath it, module channels connected to sensor strips located beneath the converter circuit were found to show a noise increase. While the DC-DC converter unit causing the underlying EMI noise operates at a frequency of 2 MHz, module characterisation measurements for ITk strip tracker modules are typically performed asynchronously to the DC-DC switching and are therefore averaged over the full range of time bins with respect to the converter frequency. In order to investigate the time dependence of the noise injection relative to the DC-DC switching frequency, a dedicated setup to understand the time-resolved performance change in modules was developed. By using a magnetic field probe to measure the field leaking through the shield box and triggering on its rising edge, data taking could be synchronised with the DC-DC switching. This paper illustrates the concept and setup of such time-resolved performance measurements using magnetic triggering and presents results for the observed effects on signal and noise for ATLAS ITk strip modules from both laboratory and beam tests.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Interleaved multi-channel, multi-level, multi-quadrant DC-DC converters

Direct-current-to-direct-current (DC-DC) power converters that include two or more multi-quadrant, multi-level, DC-DC, switching converter subcircuits, connected in parallel at respective input and output sides, so as to provide a multi-channel, multi-quadrant, multi-level configuration, are disclosed. The DC-DC power converters further include a control circuit configured to control the switching converter subcircuits so that corresponding switching semiconductors in each of the switching converter subcircuits are switched in an interleaved manner. In some embodiments, each of the switching converter subcircuits is a three-level, neutral-point-clamped, four-quadrant DC-DC converter circuit. In other embodiments, each of the switching converter subcircuits is a three-level, neutral-point-clamped, two-quadrant DC-DC converter circuit. In any of these embodiments, a filter capacitor may be connected between across a pair of output terminals at the output sides of the switching converter subcircuits.

Du, Yu↗
DOE OSTI2022

DC compensation for power transformer through neutral DC injection

A power transmission system can include a transformer and compensator circuit(s), each coupled between a node of the transformer and a ground connection. The compensator circuit(s) can each be configured to counteract a DC signal component of an AC signal at the transformer. The compensator circuit(s) can include a converter circuit having an AC side and a DC side and configured to convert a DC voltage on the DC side to an AC signal at the AC side. The compensator circuit(s) can include a DC link coupled to the DC side of the converter circuit. The compensator circuit(s) can include a controller configured to measure a DC signal component between the load and the ground; to determine, based at least in part on the DC signal component, a compensating signal configured to counteract the DC signal component; and to inject, by the converter circuit, the compensating signal to counteract the DC signal component.

Burkes, Klaehn W.↗
NASA NTRS2001

Radiation Effects on DC-DC Converters

In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25.97 MeV-square cm/mg. This might be due to fact that the device is radiation hardened.

Zhang, De-Xin↗
NASA NTRS2002

Efficient Design in a DC to DC Converter Unit

Space Flight hardware requires high power conversion efficiencies due to limited power availability and weight penalties of cooling systems. The International Space Station (ISS) Electric Power System (EPS) DC-DC Converter Unit (DDCU) power converter is no exception. This paper explores the design methods and tradeoffs that were utilized to accomplish high efficiency in the DDCU. An isolating DC to DC converter was selected for the ISS power system because of requirements for separate primary and secondary grounds and for a well-regulated secondary output voltage derived from a widely varying input voltage. A flyback-current-fed push-pull topology or improved Weinberg circuit was chosen for this converter because of its potential for high efficiency and reliability. To enhance efficiency, a non-dissipative snubber circuit for the very-low-Rds-on Field Effect Transistors (FETs) was utilized, redistributing the energy that could be wasted during the switching cycle of the power FETs. A unique, low-impedance connection system was utilized to improve contact resistance over a bolted connection. For improved consistency in performance and to lower internal wiring inductance and losses a planar bus system is employed. All of these choices contributed to the design of a 6.25 KW regulated dc to dc converter that is 95 percent efficient. The methodology used in the design of this DC to DC Converter Unit may be directly applicable to other systems that require a conservative approach to efficient power conversion and distribution.

Bruemmer, Joel E.↗
DOE OSTI2021

A Multiport DC Transformer to Enable Flexible Scalable DC as a Service

The rapid adoption of new DC loads and sources, including photovoltaic arrays, DC fast charging of electric vehicle, battery energy storage and data centers, requires a large amount of DC power conversion. A majority of new deployments also necessitate the integration of multiple DC loads and sources at one site. The traditional approach to serve these new applications relies on multiple standard power converters, each dedicated to a source or load, and results in highly customized systems, with challenging control coordination, complex protection strategies, and poor scalability. Instead, this paper proposes the concept of a multiport DC transformer (MDCT) as a modular building block for realizing a flexible, scalable DC as a Service system and address this rapidly growing need. The MDCT uses the S4T to achieve very tight control of cycle-by-cycle energy exchange between multiple ports, with high efficiency. A single multiport converter replaces 4-6 distinct converters, integrates all energy flows and manages protection. As a result, a new layered control architecture is introduced to ensure stability and scalability of the MDCT, with multiple S4T power converter building blocks connected in parallel to realize a fully modular system and reach the target power levels.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

A 20-kW DC Oak Ridge Converter with Integrated AC & DC Sources for Grid Services and Energy Storage Systems

This paper proposes a wireless power transfer (WPT) platform with integrated energy conversion that has the capability for 1) recharging the energy storage systems (ESSs) from the grid systems, including renewable energy sources such as wind, solar, etc., 2) off grid systems recharging the ESSs from dc grid systems, 3) grid recharging of electric vehicles (EVs), and 4) off grid recharging of EVs from ESSs. The unique aspect of the method is the use of multi-interface power electronic converter for the grid and ESSs and EVs that can support a range of applications with ac / dc and dc / dc energy conversion ability in a single converter system. The key enabling technology to achieve these functionalities is Oak Ridge Converter (ORC) with polyphase coupler coil system both developed at ORNL. This new technology enables higher power density WPT systems while allowing the coils to interface from ac grid at 60 Hz frequency or dc source directly merging with 85 kHz operating frequency of switching component. The experimental results of the proposed system are presented for 20 kW output power with the system overall efficiency around 95.4% from dc source and 93% overall efficiency from ac grid achieving 9-10% current total harmonic distortion (THD) and 0.98-0.99 power factor (PF).

Asa, Erdem↗
DOE OSTI2021

Inverted Geometry Ceramic Insulators in High Voltage DC Electron Guns for Accelerators

A direct current (dc) high voltage photo-emission electron gun operating at 130 kV is utilized at the Jefferson Lab (JLab) Continuous Electron Beam Accelerator Facility to generate spin-polarized electrons for nuclear physics experiments. Over the past decade, JLab has tested and implemented inverted-geometry ceramic insulators in photoguns, connecting the cathode electrode in vacuum to the high voltage power supply using commercial high voltage cables. This contribution reports on tests performed up to 375 kV dc, implementation of inverted insulators in a 300 kV dc photogun generating magnetized electron beams, and describes plans to develop a reliable insulator-cable connector for applying 500 kV dc to a future polarized beam photogun operating reliably and without field emission at 350 kV.

Hernandez-Garcia, C.↗
DOE OSTI2020

Applying Machine Learning to the Classification of DC-DC Converters. NA-22 Final Report

Tools are now available that enable measurement electromagnetic radiation (EMR) from active electronics in an item. This radiation may be intended WIFI or cellular network links, for example or unintended such as the switching noise generated by DC-to-DC converters. It would be extremely valuable to have the capability to discriminate between the low-voltage DC-to-DC converters or other digital noise prevalent in most modern electronics, versus the high-voltage DC-to-DC converters used in utility firesets. Previous work performed under a Sandia Laboratory Directed Research and Development (LDRD) project on Charge State Detection using a deep neural network has been continued in this effort. A state-of-the-art supervised machine learning algorithm has not only been extended to discriminate between low and high voltage converters but has been validated in determining a converters make and model.

42 ENGINEERING↗
NASA NTRS1977

A Theory of Control for a Class of Electronic Power Processing Systems: Energy-Storage DC-To-DC Converters

An analytically derived approach to the control of energy-storage dc-to-dc converters, which enables improved system performance and an extensive understanding of the manner in which this improved performance is accomplished, is presented. The control approach is derived from a state-plane analysis of dc-to-dc converter power stages which enables a graphical visualization of the movement of the system state during both steady state and transient operation. This graphical representation of the behavior of dc-to-dc converter systems yields considerable qualitative insight into the cause and effect relationships which exist between various commonly used converter control functions and the system performance which results from them.

Burns, W. W., III↗
NASA NTRS1977

A new optimum topology switching dc-to-dc converter

A novel switching dc-to-dc converter is presented, which has the same general conversion property (increase or decrease of the input dc voltage) as does the conventional buck-boost converter, and which offers through its new optimum topology higher efficiency, lower output voltage ripple, reduced EMI, smaller size and weight, and excellent dynamic response. One of its most significant advantages is that both input and output current are not pulsating but are continuous (essentially dc with small superimposed switching current ripple), thus resulting in a close approximation to the ideal physically nonrealizable dc-to-dc transformer. The converter retains the simplest possible structure with the minimum number of components which, when interconnected in its optimum topology, yield the maximum performance.

Cuk, S.↗
NASA NTRS1980

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

Lee, F. C.↗
NASA NTRS1997

Materials Testing on the DC-X and DC-XA

Flight testing of thermal protection materials has been carried out over a two year period on the base heat shield of the Delta Clipper (DC-X and DC-XA), as well on a body flap. The purpose was to use the vehicle as a test bed for materials and more efficient repair or maintenance processes which would be potentially useful for application on new entry vehicles (i.e., X-33, RLV, planetary probes), as well as on the existing space shuttle orbiters. Panels containing Thermal Protection Systems (TPS) and/or structural materials were constructed either at NASA Ames Research Center or at McDonnell Douglas Aerospace (MDA) and attached between two of the four thrusters in the base heat shield of the DC-X or DC-XA. Three different panels were flown on DC-X flights 6, 7, and 8. A total of 7 panels were flown on DC-XA flights 1, 2, and 3. The panels constructed at Ames contained a variety of ceramic TPS including flexible blankets, tiles with high emissivity coatings, lightweight ceramic ablators and other ceramic composites. The MDS test panels consisted primarily of a variety of metallic composites. This report focuses on the ceramic TPS test results.

Smith, Dane↗
NASA NTRS2002

Digital Control Technologies for Modular DC-DC Converters

Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

Button, Robert M.↗