Programmable Power Supply Research Articles

Automation Of An I-V Characterization System

In this paper, an accurate I-V virtual instrument (VI) that has been developed to characterize electronic devices for research and teaching purposes is demonstrated. The virtual instrument can be used to highlight principles of measurement, instrumentation, fundamental principles of electronics, VI programming, device testing and characterization in wafer or discrete device level. It consists of a Keithley electrometer, model 6514, a programmable power supply BK Precision, model 1770, a Keithley source meter, model 2400-LV, an Agilent digital multimeter, model 34401, a PC computer and LabVIEW software. The instruments are interconnected using an IEEE 488 protocol. The characteristic VI devices graphs are generated from measured data previous computational processing. The instrument is used in basic courses of physical electronics as well as in advance curses of VLSI design and in research work for characterization of semiconductor materials and devices. This paper describes the VI instrument design, implementation and characterization experiments.

中国散裂中子源大功率可编程脉冲电源设计

中国散裂中子源大功率可编程脉冲电源设计

Autonomous Thermal Control System for Highly Variable Environments

An autonomous thermal control system has been developed for instruments with steady temperature requirements that are exposed to widely varying environmental conditions. The active thermal control system uses thermo-electric (Peltier) coolers with a programmable power supply, digital temperature sensors, and on-board proportional differential logic to track and predict temperature variations. This system is designed for instruments with large thermal mass and thermally sensitive electronic components that would be effected by variabilities in the local outdoor environment including weather, sunrise, and sunset. Presented are the test results of the design showing the temperature stayed within ±0.125°C during smooth ambient temperature changes (27°C ambient change over 80 min), remained within +0.375/−0.6875°C under a sharp ambient temperature drop (27°C sudden drop), and remained within +0.25/−0.875°C when random variabilities in the ambient were introduced (2–10°C degree variabilities over the time frame of minutes). For the thermal control system and test results presented, it is shown that several calibration and design points must be considered for a large thermal mass system in order to achieve steady thermal control. The system presented is capable of maintaining steady thermal control within the given constraints.

Testing of a small-scale stand-alone power system based on solar energy and hydrogen

Abstract An experimental small-scale stand-alone power system based on hydrogen and solar energy has been tested. The system performance and operational experience are reported. Future expansion of the test-facility is taken into consideration using solutions with wide working ranges. The test-facility is designed for testing of individual components, for subsystems, and for complete power system operation. The complete power system in this study consists of a 4.8 kW programmable power supply, 1.5 kW electrolyser, a hydrogen purification unit (99.999% H2 quality), a 14 Nm3 H2 metal hydride storage, a 0.5 kW fuel cell, a 300 Ah lead-acid battery, and a 0.6 kW programmable load. Possible applications for such small-scale power systems are mountain cabins, remote islands, and telecommunication stations, among others. The basic idea in this particular power system configuration was to make it as simple as possible; the fuel cell and the metal hydride unit were air-cooled, and the components were connected in parallel without DC/DC converters. The only control action possible in the power system (presented in this study) was to switch the components either ON or OFF. However, connecting the components electrically in parallel without DC/DC converters gives no degrees of freedom regarding the ability to regulate power and voltage levels of the different components. Air-cooled metal hydrides might fail to deliver hydrogen due to poor heat transfer.

Performance of Planar High-Temperature Electrolysis Stacks for Hydrogen Production from Nuclear Energy

An experimental program is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production in a temperature range from 800 to 900°C. This temperature range is consistent with the planned coolant outlet temperature range of advanced nuclear reactors. Results were obtained from two multiple-cell planar electrolysis stacks with an active area of 64 cm2 per cell. The electrolysis cells are electrolyte-supported, with scandia-stabilized zirconia electrolytes (~140 μm thick), nickel-cermet steam/hydrogen electrodes, and manganite oxygen-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed in a range of steam inlet mole fractions (0.1 to 0.6), gas flow rates (1000 to 4000 standard cubic centimeters per minute), and current densities (0 to 0.38 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Initial stack-average area-specific resistance values <1.5 Ω·cm2 were observed. Hydrogen production rates in excess of 200 normal liters per hour (NL/h) were demonstrated. Internal stack temperature measurements revealed a net cooling effect for operating voltages between the open-cell potential and the thermal neutral voltage. These temperature measurements agreed very favorably with computational fluid dynamics predictions. A continuous long-duration test was run for 1000 h with a mean hydrogen production rate of 177 NL/h. Some performance degradation was noted during the long test. Stack performance is shown to be dependent on inlet steam flow rate.

The upgraded Pegasus Toroidal Experiment

The Pegasus Toroidal Experiment was developed to explore the physics limits of plasma operation as the aspect ratio (A) approaches unity. Initial experiments on the device found that access to high normalized current and toroidal beta was limited by the presence of large-scale tearing modes. Major upgrades have been conducted of the facility to provide the control tools necessary to mitigate these resistive modes. The upgrades include new programmable power supplies, new poloidal field coils and increased, time-variable toroidal field. First ohmic operations with the upgraded system demonstrated position and current ramp-rate control, as well as improvement in ohmic flux consumption from 2.9 MA Wb−1 to 4.2 MA Wb−1. The upgraded experiment will be used to address three areas of physics interest. First, the kink and ballooning stability boundaries at low A and high normalized current will be investigated. Second, clean, high-current plasma sources will be studied as a helicity injection tool. Experiments with two such sources have produced toroidal currents three times greater than predicted by geometric field line following. Finally, the use of electron Bernstein waves to heat and drive current locally will be studied at the 1 MW level; initial modelling indicates that these experiments are feasible at a frequency of 2.45 GHz.

Three-phase adaptive frequency measurement based on Clarke's transformation

The utilization of Clarke's transformation in the estimation of power system frequency provides the classical single-phase methods with more robustness because the estimated frequency is computed using the information provided by the three-phase voltage. This approach is particularly important when asymmetric sags generate zero voltage in one of the three phases. In addition, the proposed algorithm exhibits good behavior during dynamic conditions. The Clarke components of the voltage signals are then used to compute the frequency of the system following an iterative approach based on a proportional-integral-derivative controller. The inverse component of the voltage is also used in order to detect unbalanced conditions. The proposed algorithm has been put to the test with distorted three-phase voltage supplied by an arbitrary waveform programmable power supply and with different signals generated with an Alternative Transients Program-Electromagnetic Transients Program model.

At-column heating and a resistively heated, liquid-cooled thermal modulator for a low-resource bench-top GC×GC

A transportable GC x GC instrument is under development for on-site applications that would benefit from the enhanced resolution and powers of detection, which can be achieved by this method. In the present study, a low-resource GC x GC instrument using an electrically heated and liquid-cooled single-stage thermal modulator that requires no cryogenic materials is evaluated. The instrument also uses at-column heating, thus eliminating the need for a convection oven to house the two columns. The stainless-steel modulator tube is coated with PDMS, which can be heated to 350 degrees C for sample injection into the second-dimension column. The modulator is cooled to -30 degrees C by a 100 mL/min flow of PEG by means of a commercial liquid chiller and a small recirculating pump. Resistive heating of the modulator tube is provided by a programmable power supply, which uses a voltage program that results in increasing modulator temperature during an analysis. This, together with more rapid cooling by the use of a liquid cooling medium, results in reduced solute breakthrough following each heating cycle as the modulator cools to a temperature where quantitative trapping resumes. As a result, modulated peak widths at half-height of less than 40 ms are observed. Design and performance details are presented along with chromatograms of gasoline and an essential oil sample.

Semiempirical Model for Determining PEM Electrolyzer Stack Characteristics

A semiempirical equation was used to represent the performance characteristics of a 20-cell proton exchange membrane electrolyzer stack. The coefficients of the equation are the exchange current densities and membrane conductivity. These coefficients were determined using experimental data and a nonlinear curve fitting method. The anode exchange current density was found to be 1.65×10−8Acm−2, the cathode exchange current density 0.09Acm−2, and the membrane conductivity 0.075Scm−1. External programmable power supplies were used to obtain the (I‐V) characteristic curve of a commercial proton exchange membrane electrolyzer. Stack current, voltage, and system temperature were monitored while 1A current steps were applied to the electrolyzer stack.

Power modeling and characteristics of field programmable gate arrays

This paper studies power modeling for field programmable gate arrays (FPGAs) and investigates FPGA power characteristics in nanometer technologies. Considering both dynamic and leakage power, a mixed-level power model that combines switch-level models for interconnects and macromodels for look-up tables (LUTs) is developed. Gate-level netlists back-annotated with postlayout capacitances and delays are generated and cycle-accurate power simulation is performed using the mixed-level power model. The resulting power analysis framework is named as fpgaEVA-LP2. Experiments show that fpgaEVA-LP2 achieves high fidelity compared to SPICE simulation, and the absolute error is merely 8% on average. fpgaEVA-LP2 can be used to examine the power impact of FPGA circuits, architectures, and CAD algorithms, and it is used to study the power characteristics of existing FPGA architectures in this paper. It is shown that interconnect power is dominant and leakage power is significant in nanometer technologies. In addition, tuning cluster and LUT sizes lead to 1.7/spl times/ energy difference and 0.8/spl times/ delay difference between the resulting min-energy and min-delay FPGA architectures, and FPGA area and power are reduced at the same time by tuning the cluster and LUT sizes. The existing commercial architectures are similar to the min-energy (and min-area at the same time) architecture according to this study. Therefore, innovative FPGA circuits, architectures, and CAD algorithms, for example, considering programmable power supply voltage, are needed to further reduce FPGA power.

Hydrogen Production Performance of a 10-Cell Planar Solid-Oxide Electrolysis Stack

An experimental study is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800-900°C. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of 64cm2 per cell. The electrolysis cells are electrolyte supported, with scandia-stabilized zirconia electrolytes (∼140μm thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1–0.6), gas flow rates (1000-4000sccm), and current densities (0-0.38A∕cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Hydrogen production rates up to 100Nl∕h were demonstrated. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Stack performance is shown to be dependent on inlet steam flow rate.

Performance Measurements of Solid-Oxide Electrolysis Cells for Hydrogen Production

An experimental study has been completed to assess the performance of single solid-oxide electrolysis cells operating over a temperature range of 800 to 900°C. The experiments were performed over a range of steam inlet partial pressures (2.3–12.2 kPa), carrier gas flow rates (50–200 sccm), and current densities (−0.75–0.25A∕cm2) using single electrolyte-supported button cells of scandia-stabilized zirconia. Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dew-point instrumentation. Cell operating potentials and cell current were varied using a programmable power supply and monitored continuously. Values of area-specific resistance and thermal efficiency are presented as a function of current density. Cell performance is shown to be continuous from the fuel-cell mode to the electrolysis mode of operation. The effects of steam starvation and thermal cycling on cell performance parameters are discussed.

B#: A Battery Emulator and Power-Profiling Instrument

B# (B sharp) is a programmable power supply that emulates battery behavior. It measures current load, calls a battery simulation program to compute voltage in real time, and controls a linear regulator to mimic a battery's voltage output. The instrument enables validation of battery-aware power optimization techniques with accurate controllable reproducible results.

Hand-Held Microanalytical Instrument for Chip-Based Electrophoretic Separations of Proteins

The design, fabrication, and demonstration of a hand-held microchip-based analytical instrument for detection and identification of proteins and other biomolecules are reported. The overall system, referred to as muChemLab, has a modular design that provides for reliability and flexibility and that facilitates rapid assembly, fluid and microchip replacement, troubleshooting, and sample analysis. Components include two independent separation modules that incorporate interchangeable fluid cartridges, a 2-cm-square fused-silica microfluidic chip, and a miniature laser-induced fluorescence detection module. A custom O-ring sealed manifold plate connects chip access ports to a fluids cartridge and a syringe injection port and provides sample introduction and world-to-chip interface. Other novel microfluidic connectors include capillary needle fittings for fluidic connection between septum-sealed fluid reservoirs and the manifold housing the chip, enabling rapid chip priming and fluids replacement. Programmable high-voltage power supplies provide bidirectional currents up to 100 microAlpha at 5000 V, enabling real-time current and voltage monitoring and facilitating troubleshooting and methods development. Laser-induced fluorescence detection allows picomolar (10(-11) M) detection sensitivity of fluorescent dyes and nanomolar sensitivity (10(-9) M) for fluorescamine-labeled proteins. Migration time reproducibility was significantly improved when separations were performed under constant current control (0.5-1%) as compared to constant voltage control (2-8%).

Nanograin deposition via an electroplating reaction in an emulsion of dense carbon dioxide in a nickel electroplating solution using nonionic fluorinated surfactant

We investigated an electroplating reaction in a series of emulsions between an electroplating solution and dense carbon dioxide (CO 2) using a novel fluorinated surfactant F(CF(CF 3)CF 2O) 3CF(CF 3)COO(CH 2CH 2O) 7CH 3. The electroplating reaction took place in the emulsions as a function of the CO 2 volume fraction, and electroplating was found to be possible in an emulsion composed of even 80 vol.% CO 2 and 20 vol.% electroplating solution. Films composed of a nanograin structure with a grain size of about 10 nm were obtained. We elucidated the plating reaction by measuring the current values in the emulsion using minute terminals connected to a programmable power supply, while simultaneously observing the dispersion state of the emulsion through a high-pressure view cell. The flow of current values in the emulsion system fluctuated, and the current value decreased together with the amplitude of the fluctuant current when the pressure was increased. The fluctuant current flow in the emulsion was concluded to play an important role in the fabrication of the nanograin nickel structure in the plated film.

Processing and On-Wafer Measurements of Ferroelectric Interdigitated Tunable Microwave Capacitors

ABSTRACTNa0.5K0.5NbO3 (NKN) and Pb(Zr0.53Ti0.47)O3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, rcut), YAlO3 + 1% Nd (Nd:YAlO3-001), and quartz (Y+36°-cut) single crystal substrates. Interdigital capacitor (IDC) of coplanar waveguide (CPW) structures were defined by a standard lift off technique in a Au(0.5μm)/Cr(10nm) electrode electron beam evaporated on ferroelectric film surface. IDCs consisted of five pairs of fingers separated by 2 and 4 μm gap. On-wafer microwave characterization was performed using a workbench equipped with a coplanar probe station (Cascade Microtech) with G-S-G (Ground-Signal-Ground) Picoprobe, a network analyzer (Agilent Technologies E8364A) operating in 45 MHz to 40 GHz range and programmable power supply for dc DUT (Device Under Test) biasing. Assumed equivalent circuit for the IDC/CPW structure contains planar capacitor under test C, the coplanar line with a complex impedance ς and a parasitic capacitance Cp between the signal and ground lines. The de-embedding technique has been employed to determine all six complex parameters C, ς and Cp from S-parameter measurements performed for three different device structures: device, open and thru. NKN film interdigital capacitors on sapphire show superior performance in this microwave range: the frequency dispersion was as low as 18%, voltage tunability = 1 – C(40V)/C(0) (40 V, 200 kV/cm) about 14%, loss tangent ∼ 0.11, K-factor = tunability/tanδ from 131% @ 10 GHz to 56% @ 40 GHz. The reliability of the de-embedding procedure is clearly proved by analysis of the frequency dependences of the parasitic capacitance and loss tangent as well as impedance of the coplanar line. Within the accuracy of experimental data and de-embedding calculations these values appear to be voltage independent: Cp ∼ 70 fF, tan δp changes from 0.07@10 GHz to 0.15@40 GHz; real and imaginary part of interconnect impedance increases with frequency from 0.16Ω@10 GHz to 0.36Ω@40 GHz and from 1.6Ω@10 GHz to 5.84Ω@40 GHz respectively.

Measurement of Specific Heat Capacity and Electrical Resistivity of Industrial Alloys Using Pulse Heating Techniques

The determination of the specific heat capacity and electrical resistivity of Inconel 718, Ti-6Al-4V, and CF8M stainless steel, from room temperature to near the melting temperatures of the alloys, is described. The method is based on rapid resistive self-heating of a solid cylindrical specimen by the passage of a short-duration electric current pulse through it while simultaneously measuring the pertinent experimental quantities (i.e., voltage drop, current, and specimen temperature). From room temperature to about 1300 K, the properties are measured using an intermediate-temperature pulse-heating system by supplying a constant current from a programmable power supply and measuring the temperature using a Pt-Pt:13% Rh thermocouple welded to the surface of the specimen. From 1350 K to near the melting temperatures of the alloys, the properties are measured using a millisecond-resolution high-temperature pulse-heating system by supplying the current from a set of batteries controlled by a fast-response switching system and measuring the temperature using a high-speed pyrometer in conjunction with an ellipsometer, which is used to measure the corresponding spectral emissivity. The present study extends the application of these techniques, previously applied only to pure metals, to industrial alloys.

A Gas Sample Pre‐concentration Device Based on Solid Phase Microextraction (SPME) and Temperature Programmed Desorption (TPD)

A sample pre‐concentration device, based on solid phase microextraction (SPME) fiber and temperature programmed desorption (TPD), was developed and tested in the analysis of volatile organic compounds. The pre‐concentrator device consists of a low dead volume quartz tube that houses the SPME fiber during the extraction/ desorption steps, a Ni:Cr heating element, and a programmable power supply. Compounds are extracted from air into the SPME fiber according to their affinity and solubility to the fiber material. Following this extraction step, samples are desorbed by a pre‐programmed temperature ramp for their subsequent detection. The SPME fiber was exposed and sample extracted for a pre‐determined amount of time (1 min, in this work). Because of the limited specificity of the stationary phase in SPME fibers towards the analyte, background interfering compounds are unavoidably co‐extracted during this process. A TPD step was then applied to sequentially desorb and detect analytes and interferences. The temperature ramp was designed so as to maximize temporal resolution between target analytes and background chemical interferences. The SPME/TPD pre‐concentrator was tested with a binary chemical system consisting of dimethyl‐methylphosphate (DMMP, a chemical warfare simulant) and toluene (a common commercial solvent). Analyte desorption was monitored on‐line with a quadrupole ion trap mass spectrometer. Five SPME fibers with different stationary phases were tested: polyacrylate (PA), polydimethylsiloxane (PDMS), carboxen–polydimethylsiloxane (CAR/PDMS), polydimethylsiloxane–divinylbenzene (PDMS/DVB), and carbowax/divinylbenzene (CW/DVB). Best results were obtained with the PDMS (100 µm) fiber. Two other SPME fibers, CW/DVB and CAR/PDMS, along with the TPD step, were also successful in the temporal resolution the of DMMP and toluene. The approach is rapid in that the extraction and desorption steps take less than 3 min. Implications and applications of the SPME/TPD system as a sample pre‐concentration step in handheld devices are discussed. The simplicity of the device makes it amenable to miniaturization by available microfabrication techniques.

Advances in Oil Exploration Electronics Soft-Switching Power Supplies:Smoothing Out the Rough Edges in Powering Data Acquisition and Drilling Equipment

Technology Brief Over the last two decades, the use of sophisticated electronic equipment to test and measure the size of prospective finds has increased rapidly throughout the global oil industry. Today, "downhole" cables often carry down electricity controlled by programmable DC power supplies to power drilling equipment located 30,000 feet beneath the surface, and then send sensitive telemetry data back up to computers. In these situations, electrical "noise" can diminish data transmission rates, slowing down acquisition data used by the geologists to map petroleum finds, or even lead to the complete loss of data through power surges that cause computers to reset. In addition, in order to develop 3D maps of a find, drilling companies are now using sensitive electronic data measurement equipment that can be disrupted by power surges. In any case, the cost of reacquiring this lost data can be expensive. Soft switching in power supplies is an advanced technological solution to the noise and power surge issue involved in the oil drilling industry. Although relatively new, soft switching power conversion has already found widespread acceptance among electronic manufacturers. Yet, as with all new technologies, questions still abound among end users. What are the advantages, and how can soft switching help oil exploration and drilling teams? First, the origins of soft switching. Soft switching is a superior switch-mode power supply topology (technology) developed by power supply manufacturers that dramatically reduces the electrical noise created by the main power transistors during the switching process, the micro-moment in time when the power supply is switched on and off. (see Figure 1) Its main function is to reduce or eliminate radio frequency interference (RFI) and other problems that have been associated with the switching process since the emergence of high-frequency "hard switching" switch mode power supplies in the 1980s. Around that time, there was a rapid increase in the use of electronic products in all manner of industrial applications. This, in combination with the phenomena of RFI and other electromagnetic effects, drew the attention of regulatory bodies around the world. In particular, it became apparent that the large amounts of electromagnetic interference conducted and radiated by this type of supply could interfere with radio communication, and have a negative impact on the operation of sensitive electronic and computer circuits in a variety of industries, including the oil industry. The main benefit derived by the oil exploration and drilling industries from soft switching power supplies is a marked reduction in electrical noise levels. This enables the telemetry coming from below the ground to be detected more easily. Received from deep-land or deep-sea drilling sites, the data usually has a small amplitude by the time it reaches the recording instruments on the surface. It's important the signal-to-noise ratio be sufficient to acquire the signals at these great distances. Since the signal is quite weak, generating less noise is the key. With the older, traditional "switch-mode" power supply technologies, the problem of noise and power surges is a result of power transistors incorporated to "hard switch" the unregulated input voltage.

Application of programmable discharge of capacitive energy store for current pulse forming in railgun and electrodischarge launcher

This paper describes the pulse formation of a programmable multi-stage pulsed power supply for electric railguns. This power supply allows optimal operation of the railgun by maintaining a near constant acceleration force over the launch period. This constant force is gained by matching the voltage of the power supply to the variable inductance and resistance of the launcher. A way to estimate the load inductance is presented in this paper.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>