Time domain modeling of constant power loads for electromagnetic transient simulations
Not Available
Alboaouh, Kamel↗
SEARCH · Engineering Papers
Results for “capacitive loads”
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.
A self diagnostic system for piezoelectric sensors
A technique for determining the mounting conditions of a piezoelectric accelerometer is presented. This technique electrically stimulates the piezoelectric element in the 'diagnostic' frequency band measuring the electrical frequency response characteristics across a capacitive load impedance. The diagnostic frequency band is tipically much higher than the operating bandwidth of the accelerometer. The resonant frequencies of the accelerometer are included in the diagnostic band. By monitoring the shift in these resonant frequencies, via electrical stimulation techniques, certain diagnostic conditions including mounting conditions can be determined. Experimental data from a compression mode accelerometer is used to demonstrate this technique.
Atherton, William J.↗
Exploration of operator method digital optical computers for application to NASA
Digital optical computer design has been focused primarily towards parallel (single point-to-point interconnection) implementation. This architecture is compared to currently developing VHSIC systems. Using demonstrated multichannel acousto-optic devices, a figure of merit can be formulated. The focus is on a figure of merit termed Gate Interconnect Bandwidth Product (GIBP). Conventional parallel optical digital computer architecture demonstrates only marginal competitiveness at best when compared to projected semiconductor implements. Global, analog global, quasi-digital, and full digital interconnects are briefly examined as alternative to parallel digital computer architecture. Digital optical computing is becoming a very tough competitor to semiconductor technology since it can support a very high degree of three dimensional interconnect density and high degrees of Fan-In without capacitive loading effects at very low power consumption levels.
Source record↗
A kind of small hydrogen maser for time-keeping
A kind of small hydrogen maser standard for timekeeping is being developed at Shanghai Observatory. The maser employs a cylindrical capacitively loaded cavity construction, resulting in significant size and weight reduction compared to a traditional hydrogen maser. The Q of the compact cavity is electronically enhanced by a suitable positive feedback into the cavity to enable sustained maser oscillation. The long-term stability of the maser is improved by a cavity frequency stabilization servo-system. The design and development of the maser, as well as photographs of the new maser system during the construction phase.
Z. C. Zhai↗
High-precision buffer circuit for suppression of regenerative oscillation
Precision analog signal conditioning electronics have been developed for wind tunnel model attitude inertial sensors. This application requires low-noise, stable, microvolt-level DC performance and a high-precision buffered output. Capacitive loading of the operational amplifier output stages due to the wind tunnel analog signal distribution facilities caused regenerative oscillation and consequent rectification bias errors. Oscillation suppression techniques commonly used in audio applications were inadequate to maintain the performance requirements for the measurement of attitude for wind tunnel models. Feedback control theory is applied to develop a suppression technique based on a known compensation (snubber) circuit, which provides superior oscillation suppression with high output isolation and preserves the low-noise low-offset performance of the signal conditioning electronics. A practical design technique is developed to select the parameters for the compensation circuit to suppress regenerative oscillation occurring when typical shielded cable loads are driven.
Tripp, John S.↗
Experimental Analysis of Reduced-Sized Coplanar Waveguide Transmission Lines
An experimental investigation of the use of capacitive loading of coplanar waveguides to reduce their line length and, thus the size, of monolithic microwave integrated circuits is presented. The reduced sized coplanar waveguides are compared to unloaded transmission lines and to lumped element transmission line segments. The phase bandwidth, defined by 2 percent error in S(sub 21), and the return loss bandwidth, defined by a return loss greater than 15 dB, of coplanar waveguides reduced from 0 to 90 percent are compared, and the insertion loss as a function of the size reduction is presented.
Ponchak, George E.↗
Single Event Upset Behavior of CMOS Static RAM Cells
An improved state-space analysis of the CMOS static RAM cell is presented. Introducing theconcept of the dividing line, the critical charge for heavy-ion-induced upset of memory cells can becalculated considering symmetrical as well as asymmetrical capacitive loads. From the criticalcharge, the upset-rate per bit-day for static RAMs can be estimated.
Lieneweg, Udo↗
Single-Event Transients in Voltage Regulators
Single-event transients are investigated for two voltage regulator circuits that are widely used in space. A circuit-level model is developed that can be used to determine how transients are affected by different circuit application conditions. Internal protection circuits-which are affected by load as well as internal thermal effects-can also be triggered from heavy ions, causing dropouts or shutdown ranging from milliseconds to seconds. Although conventional output transients can be reduced by adding load capacitance, that approach is ineffective for dropouts from protection circuitry.
circuit testing↗
Wide Range SET Pulse Measurement
A method for measuring a wide range of SET pulses is demonstrated. Use of dynamic logic, faster than ordinary CMOS, allows capture of short pulses. A weighted binning of SET lengths allows measurement of a wide range of pulse lengths with compact circuitry. A pulse-length-conservative pulse combiner tree routes SETs from combinational logic to the measurement circuit, allowing SET measurements in circuits that cannot easily be arranged in long chains. The method is applied to add-multiplex combinational logic, and to an array of NFET routing switches, at .35 micron. Pulses are captured in a chain of Domino Logic AND gates. Propagation through the chain is frozen on the trailing edge by dropping low the second "enable" input to the AND gates. Capacitive loading is increased in the latter stages to create an approximately logarithmic weighted binning, so that a broad range of pulse lengths can be captured with a 10 stage capture chain. Simulations show pulses can be captured which are 1/5th the length of those typically captured with leading edge triggered latch methods, and less than the length of those captured with a trailing edge latch method. After capture, the pulse pattern is transferred to an SEU protected shift register for readout. 64 instances of each of two types of logic are used as targets. One is a full adder with a 4 to 1 mux on its inputs. The other is a 4 x 4 NFET routing matrix. The outputs are passed through buffered XNOR comparators to identify pulses, which are merged in a buffered not-nand (OR) tree designed to avoid pulse absorption as much as possible. The output from each of the two test circuits are input into separate pulse measurement circuits. Test inputs were provided so that the circuit could be bench tested and calibrated. A third SET measurement circuit with no inputs was used to judge the contribution from direct hits on the measurement circuit. Heavy ions were used with an LET range from 12 to 176. At LET of 21 and below, the very small number of SETs were not significantly higher in the test over the control circuits. At higher LET the test circuit SETs are one or two orders of magnitude greater than for the control circuit. The NFET circuit produces more and slightly longer SETs as expected. But the differences do not appear to be significant enough to modify strategies now used to avoid capture of SETs in chips such as FPGAs. Complete data and graphs will be in the full paper / presentation. In the summary figure below left, NOCL is the reference circuit without any input, and number of stages triggered is plotted. Simulation at right shows the smallest pulse captured (stage 2) at about 300 ps. Our conclusion is that the method is promising, but that improvements in the merge network are desirable before applying in a deep submicron process
Shuler, Robert L.↗
Wide-Bandgap Semiconductor Amplifiers for Fusion Plasma Heating and Control
This paper discusses power electronics developed under the ARPA-E GAMOW program to support nuclear fusion power production. The goal of this project was to develop and assess the potential for wide-bandgap (WBG) semiconductor devices in power electronics to enable high-efficiency and high-voltage solid-state systems for fusion plasma generation, heating, and control. The power electronics use an architecture in which multiple high-power boards can be combined to produce megawatt-level power, where using multiple boards provides high reliability. Two main areas of power electronics boards are developed in this project for fusion plasma heating and control applications: (1) pulse generation and control and (2) radiofrequency generation. The first area is for boards capable of driving high-voltage millisecond pulses at high duty cycles. The envisioned application of these pulses is in plasma control of magnetohydrodynamic instabilities, plasma position, and edge-localized modes. Pulse-width modulation allows for the implementation of a wide variety of linear and nonlinear control systems. The boards developed for this project could actuate control coils based on digital input signals and can be parallelized to provide megawatts of output power. The design of the pulse generator is a low-side load switch. A load switch was designed and constructed that utilized 2-kV-rated field-effect transistor (FET)-based cascodes developed by Qorvo under this project to perform initial testing of these cascodes. The second area is being implemented using class E amplifiers with WBG devices and a reactance steering network to handle inductive or capacitive plasma loads. Applications include ion cyclotron resonance heating (ICRH) and high-harmonic fast-wave (HHFW) heating. A class E reactance steering network is demonstrated in modeling and experiment with a resistive-inductive load that models an inductively-coupled plasma. Power combining of boards with class E reactance steering networks is also simulated and demonstrated experimentally, to enable scaling up to high power. Modeling of high-power-density cooling and remaining useful life is conducted to enable reliable, effectively cooled high-power electronics for fusion applications.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Capability of Impedance Measurement Using Spread Spectrum Time-Domain Reflectometry
Spread spectrum time-domain reflectometry (SSTDR) has been proposed for measuring electrical impedance on live, energized systems, in electrically noisy environments, or for measuring multiple channels simultaneously. Here we evaluate the capability of SSTDR for impedance measurement from near dc to 96 MHz and find that they agree very well with measurements from a vector network analyzer (VNA). Time gating is used to remove (calibrate out) transmission line effects. We evaluate the frequency ranges over which SSTDR at different modulation frequencies is accurate for the measurement of series resistive–capacitive ( RC ) loads and observe that fusing measurements from multiple modulation frequencies can broaden the effective measurement bandwidth.
14 SOLAR ENERGY↗
Evaluation of a high power inverter for potential space applications
The ADM-006 inverter discussed utilizes a unique method of using power switching circuits to produce three-phase low harmonic content voltages without any significant filtering. This method is referred to as the power center approach to inverter design and is explained briefly. The results are presented of tests performed by MSFC to evaluate inverter performance, especially when required to provide power to nonlinear loads such as half or full wave rectified loads with capacitive filtering. Test preocedures and results are described. These tests show that the power center inverter essentially met or exceeded all of claims excluding voltage regulation (3.9 percent versus specified 3.3 percent) and would be a good candidate for high power inverter applications such as may be found on Space Station, Spacelab, etc.
Guynes, B. V.↗
Airplane Ice Detector Based on a Microwave Transmission Line
An electronic instrument that could detect the potentially dangerous buildup of ice on an airplane wing is undergoing development. The instrument is based on a microwave transmission line configured as a capacitance probe: at selected spots, the transmission-line conductors are partly exposed to allow any ice and/or liquid water present at those spots to act as predominantly capacitive electrical loads on the transmission line. These loads change the input impedance of the transmission line, as measured at a suitable excitation frequency. Thus, it should be possible to infer the presence of ice and/or liquid water from measurements of the input impedance and/or electrical parameters related to the input impedance. The sensory transmission line is of the microstrip type and thus thin enough to be placed on an airplane wing without unduly disturbing airflow in flight. The sensory spots are small areas from which the upper layer of the microstrip has been removed to allow any liquid water or ice on the surface to reach the transmission line. The sensory spots are spaced at nominal open-circuit points, which are at intervals of a half wavelength (in the transmission line, not in air) at the excitation frequency. The excitation frequency used in the experiments has been 1 GHz, for which a half wavelength in the transmission line is .4 in. (.10 cm). The figure depicts a laboratory prototype of the instrument. The impedance-related quantities chosen for use in this version of the instrument are the magnitude and phase of the scattering parameter S11 as manifested in the in-phase (I ) and quadrature (Q) outputs of the phase detector. By careful layout of the transmission line (including the half-wavelength sensor spacing), one can ensure that the amplitude and phase of the input to the phase detector keep shifting in the same direction as ice forms on one or more of the sensor areas. Although only one transmission-line sensor strip is used in the laboratory version, in a practical application, it could be desirable to install multiple strips on different areas to detect localized icing. In that case, a multiplexer should be used to connect the various strips to the phase detector for sequential measurements. Experiments have been performed with freezing and thawing of water and of water/glycol mixtures. The experiments have shown that, whether or not glycol is present, it is possible to distinguish between liquid water and ice via the I and Q outputs; in particular, the equipment can be adjusted so that when water freezes, I decreases and Q increases. With respect to the operation of this instrument, the main effect of glycol is to increase the freezing or thawing time.
Ngo, Phong↗
Topic Refresher: The Power Triangle
This fact sheet provides an overview on active, reactive, and apparent power.
41 EE - Solar Energy Technologies Office (EE-4S)↗
Medium-Voltage Isolated Auxiliary Power Supply Design for High Insulation Capability, Ultra-Low Coupling Capacitance, and Small Size
To fully utilize the benefits of medium-voltage (MV) silicon carbide (SiC)-based converter and achieve high power density, the isolated auxiliary power supply (IAPS) needs to be as small as possible. However, the high insulation and low coupling capacitance requirements, considering the high voltage and high dv / dt , are constraints of size reduction. This article proposes an MV IAPS design for high insulation capability, ultra-low coupling capacitance, and small size. The topology selection, efficiency, load regulation, coupling capacitance, and size reduction considerations are discussed. A 2.5 W MV IAPS is designed and built for a 10 kV SiC mosfet -based 13.8 kV/100 kW three-phase converter, achieving a partial discharge (PD) inception voltage of higher than 15 kV rms, ultra-low coupling capacitance of 1.03 pF, and smaller size than that of the commercial products as well as the state-of-art research prototypes. Experimental results of PD test, 10 kV SiC mosfet -based half-bridge test, and 13.8 kV/100 kVA three-phase converter full rating test are conducted for design validation.
42 ENGINEERING↗
Scaling of energy delivered through an electrostatic discharge to a small series load
We study the energy delivered through a small-resistance series “victim” load during electrostatic discharge events in air. For gap lengths over 1 mm, the fraction of the stored energy delivered is mostly gap-length independent, with a slight decrease at larger gaps due to electrode geometry. The energy to the victim scales linearly with circuit capacitance and victim load resistance but is not strongly dependent on circuit inductance. This scaling leads to a simple approach to predicting the maximum energy that will be delivered to a series resistance for the case where the victim load resistance is lower than the spark resistance.
42 ENGINEERING↗
The design of hydraulic pressure regulators that are stable without the use of sensing line restrictors or frictional dampers
A direct-acting hydraulic pressure regulator design which incorporates stability margin, response and droop margin is developed. The pressure regulator system does not involve a nonlinear sensing line restrictor (which may degrade transient response) or linear damping (which is sensitive to clearance and viscosity). The direct-acting hydraulic pressure regulator makes use of the technique of lead network stabilization (i.e., the tuned stabilizer concept). An analytically derived circuit pressure regulator is tested to study the stability limit under a parallel capacitive plus resistive load and the stabilizing effect of the tuned stabilizer.
Gold, H.↗
Extended Characterization of the Common-Source and Common-Gate Amplifiers using a Metal-Ferroelectric-Semiconductor Field Effect Transistor
Collected data for both common-source and common-gate amplifiers is presented in this paper. Characterizations of the two amplifier circuits using metal-ferroelectric-semiconductor field effect transistors (MFSFETs) are developed with wider input frequency ranges and varying device sizes compared to earlier characterizations. The effects of the ferroelectric layer's capacitance and variation load, quiescent point, or input signal on each circuit are discussed. Comparisons between the MFSFET and MOSFET circuit operation and performance are discussed at length as well as applications and advantages for the MFSFETs.
Hunt, Mitchell↗