High Current Power Supply Research Articles

Current sharing design of ITER poloidal field converter bridges

Due to high rated current and special Fault Suppression Capacity (FSC) criterion, 12 thyristors connected in parallel are applied in one bridge arm of ITER Poloidal Field (PF) converter. A large amount of parallel thyristors will give rise to significant difficulties in the current sharing design due to the electromagnetic coupling between different parts of the bridge arm. This paper presents a new method to analyze the influence of the electromagnetic coupling on current sharing performance and guide the bridge arm structure design. At first, the bridge arm is decomposed to many segments and the stray inductances are extracted. Then, an equivalent circuit of the decomposed model is built and a mathematical model is established to analyze the circuit. It will result in the current waveforms of parallel thyristors and thus provide the current sharing information. Based on the mathematical model, the optimization design of PF converter is conducted along with conventional methods. Experimental tests are also performed, and the results fit well with the analyzed ones. The current sharing coefficient of the 12-parallel thyristors is over 0.8, which is far beyond the value required by ITER Organization. In a word, the method presented in this paper provides an effective tool for the current sharing structure design for high-current fusion power supplies.

Rapid Electrophoretic Staining and Destaining of Polyacrylamide Gels.

Coomassie brilliant blue (CBB) dyes have been commonly used for the staining of protein bands in polyacrylamide gel electrophoresis (PAGE) gels. However, the staining and destaining of CBB dyes are time-consuming, and the use of methanol is hazardous to one’s health. I introduce a rapid electrophoretic destaining method using a semi-dry transfer unit and a high current power supply. In this method, ethanol was used instead of the hazardous methanol. Most of the protein bands became visible in 30 min. After a secondary destaining step, residual CBB was completely destained. The detection limit for a tested protein (5 ng) was higher than that of the conventional method. Therefore, this method is superior in its speed, safety, low cost, and sensitivity.

Design and development of a low cost, high current density power supply for streamer free atmospheric pressure DBD plasma generation in air.

This paper presents a new power supply architecture for generating a uniform dielectric barrier discharge (DBD) plasma in air medium at atmospheric pressure. It is quite a challenge to generate atmospheric pressure uniform glow discharge plasma, especially in air. This is because air plasma needs very high voltage for initiation of discharge. If the high voltage is used along with high current density, it leads to the formation of streamers, which is undesirable for most applications like textile treatment, etc. Researchers have tried to generate high-density plasma using a RF source, nanosecond pulsed DC source, and medium frequency AC source. However, these solutions suffer from low current discharge and low efficiency due to the addition of an external resistor to control the discharge current. Moreover, they are relatively costly and bulky. This paper presents a new power supply configuration which is very compact and generates high average density (∼0.28 W/cm2) uniform glow DBD plasma in air at atmospheric pressure. The efficiency is also higher as no external resistor is required to control the discharge current. An inherent feature of this topology is that it can drive higher current oscillations (∼50 A peak and 2-3 MHz frequency) into the plasma that damp out due to the plasma dissipation only. A newly proposed model has been used with experimental validation in this paper. Simulations and experimental validation of the proposed topology are included. Also, the application of the generated plasma for polymer film treatment is demonstrated.

6.4 High Current DC power Supply—Power Supply System for Super Conducting Tokamak Device—

6.4 High Current DC power Supply—Power Supply System for Super Conducting Tokamak Device—

Long-pulse power-supply system for EAST neutral-beam injectors

The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences): one for the neutral-beam test stand and two for the EAST neutral-beam injectors (NBI-1 and NBI-2, respectively). Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 keV was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.

Improvements and Performance of the Fermilab Solenoid Test Facility

The Solenoid Test Facility at Fermilab was built using a large vacuum vessel for testing of conduction-cooled superconducting solenoid magnets, and was first used to determine the performance of the MICE Coupling Coil [1, 2]. The facility was modified recently to enable testing of solenoid magnets for the Mu2e experiment, which operate at much higher current than the Coupling Coil. One pair of low current conduction-cooled copper and NbTi leads was replaced with two pairs of 10 kA HTS leads cooled by heat exchange with liquid nitrogen and liquid helium. The new design, with additional control and monitoring capability, also provides helium cooling of the superconducting magnet leads by conduction. A high current power supply with energy extraction was added, and several improvements to the quench protection and characterization system were made. Here we present details of these changes and report on performance results from a test of the Mu2e prototype Transport Solenoid (TS) module. Progress on additional improvements in preparation for production TS module testing will be presented.

Management of a Proton Exchange Membrane Fuel Cell System to Feed a Superconducting Coil

Proton Exchange Membrane Fuel Cells (PEMFC) and Superconducting Coils (SC) are electrical devices which give us a large number of possibilities in the applied research domains. We know that PEMFCs are used as alternative power supplies that convert hydrogen and oxygen redox reaction into electrical energy. This is a clean power source that produces only water and heat as waste. While the PEMFC can produce an important current density (0.5 A/cm² to 1 A/cm²) in a dedicated working zone, its voltage is too small and needs to be conditioned by power electronics to make it suitable for use in electrical systems. In addition, the superconducting coils are used to produce strong magnetic fields, with less energy, at cryogenic temperature, e.g. the temperature of liquid Helium. Their main applications are in Magnetic Resonance Imaging (MRI) devices or in embedded systems. In order to create these magnetic fields, the SC require special kinds of power supplies capable of providing high current at low voltage. Usually, these power supplies generate non negligible harmonics. In this paper, we propose a solution for overcoming these problems. Indeed, we are working on a system that uses a PEMFC as an autonomous power supply for SC. The PEMFC will replace a high current power supply and it fits perfectly as an alternative energy supply for such systems, with the benefit of zero harmonic pollution. A model dedicated to a set of a superconducting coil fed by a PEMFC is reported. The inherent problems in connecting these two devices and some solutions to ensure the proper energy management are also given.

Design and fabrication of a catheter magnetic navigation system for cardiac arrhythmias

In the past decade, remotely controlled catheter ablation has emerged as a novel approach to reduce fluoroscopy exposure and provide stable and reproducible catheter movement during cardiac surgeries for arrhythmias, and many groups have obtained very promising achievements in this research field. Meanwhile, the catheter magnetic navigation system (MNS) is very competitive among these catheter navigation systems since there are no moving parts in the magnet system. A catheter MNS that provides real-time navigation of the catheter in the beating heat is under development in the Institute of Electrical Engineering, Chinese Academy of Sciences. The catheter navigation system consists of eight spherically aligned electromagnets that generate the dynamically shaped magnetic field around the torso of the subject, eight four-phase high-current power supplies that excite the eight electromagnets to generate the needed magnetic field in time, and programmed magnetic navigation software that transfers the control signal to the electromagnets on the basis of the designated directions given by the joystick. The real-time shaping of the magnetic field functions for the 3-D direction change of a magnetized electrophysiology ablation catheter in the beating heart. EnSite-NavX™ 3-D electroanatomic mapping system is employed to integrate with the MNS. Detailed design, fabrication, and test of the remotely controlled MNS (RCMNS) are mainly introduced herein, and preliminary study on animals using RCMNS is on the way.

Optimal Design of DCM <italic>LCC</italic> Resonant Converter With Inductive Filter Based on Mode Boundary Map

LCC resonant converter with inductive filter operating in discontinuous current mode (DCM) can achieve zero-current switching (ZCS) for both the power switches and rectifier diodes. Therefore, it is suitable for high-power, low-voltage, high-current power supplies. The DCM LCC resonant converter with inductive filter might operate in different operating modes when input voltage or load changes, which challenges the design. This paper derives a mode boundary map, from which the operating mode of the converter can be easily determined. Based on the mode boundary map, a generalized optimal design procedure is proposed and a set of optimal and normalized converter parameters is determined, which can be easily converted into real parameters according to the converter specification. Three 5 kW prototypes with different converter parameters are fabricated and tested in the lab, and the experimental results show that with the set of optimal parameters, the converter can achieve the highest efficiency over the entire input voltage and load range.

Water Purification by a Lamp Discharge-Electronic Ballast System Using a Full Bridge Inverter

The presence of pathogenic microorganisms in the water poses a risk to the health of consumers of all ages. Water conventional chemical treatments are not always a good solution. Difficult to implement, they have the double disadvantage of denaturing the organoleptic qualities of water: by acting on its physico-chemical composition and rejection of polluted water. Chlorination treatment is generally used to solve the bacteriological quality problems of both unconventional drinking water and treated wastewater. The use of chlorination is increasingly avoided due to the production of chlorinated products of carcinogenic and to the little action on the virus. The search for alternative solutions has summarized in several studies. The use of “ultraviolet irradiation” is still interesting alternative solution. Sterilization system using UV radiation is recommended in health services, hospitals, pharmacies, agriculture, aquariums, water extraction fromwells orrainwater, etc. UV radiationhas a fast acting, efficient, safe and constitutes an economic process that respects the environment. In recent years, high-frequency electronic ballasts for discharge lamps have been presented as a substitute for the magnetic ballast. because of their superior qualities such as high system performance (improved power factor), weight light, the light produced per watt, long service life, the function of lighting control, non-flashing, non-presence of audible noise and more technical aspects and requirements, special attention must be given to costs of an electronic ballast. This paper presents the design of a high frequency current power supply (electronic ballast based PWM inverter) to power a low-pressure UV lamp Mercury-Argon which has a germicidal effect for water treatment. So, the main purpose is to generate maximum UV at 253.7nm (germicidal effect) and this is achieved by having at the ballast output a sinusoidal current with a frequency of 50 KHz and rms value of 0.65 A.

Power supply system for KSTAR neutral beam injector

The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120kV/70A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600V and the high voltage rectified transformers to supply DC voltage of 20kV, 30kV, and 50kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5kV/5A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to accelerator grid. This paper presents configuration and features of power supply system, main controller, and interlock system of KSTAR NBI.

High‐current variable‐voltage rectifiers: state of the art topologies

Applications such as electrolysis, electrowinning, DC arc furnaces and plasma torches require high-current (several kA) power supplies at low-voltage levels (few hundreds of volts). In this study, conventional rectifier topologies (diode- and thyristor-based multi-pulse rectifiers with on-load tap changing transformer and chopper-rectifier) used for high-current, variable-voltage applications are reviewed along with recent advancements in the field. The main applications themselves are also discussed. Issues with conventional topologies are highlighted. Power quality techniques like passive and active filters are discussed for power factor and current harmonics compensation. Advanced medium- to high-frequency transformer-based topologies (with current and voltage source rectifiers) are discussed along with simulation results.

Design and Development of a Test Rig for HTS Generator Components

High temperature superconducting (HTS) rotating machines show several significant advantages compared to machines built in conventional technique. Former experiments on rotating electric synchronous machines like motors and generators in the power range up to several MW confirmed the well-known benefits of HTS machines like smaller size, less weight and last but not least, a significantly increased efficiency. Especially the increased efficiency of large HTS-Generators up to several hundreds of MW-as operated by utilities-promises an efficient use of fuel and energy sources. This will allow reduced carbon dioxide emissions and becomes more and more important. The development of HTS rotor technology for generators in the range of hundreds of MW bears new challenges. HTS generator windings capable to withstand large centrifugal forces and carrying large currents are required. Also a special cooling system for the rotating winding and further components with novel design will be necessary and have to be developed. In a future HTS generator based on such components, these will have to operate very reliably, so a facility is needed to be able to perform tests. Therefore it is essential to design and build a specific test rig for investigation and test of the required new components. The present paper deals with design and development of such a test rig that allows component tests under realistic conditions, using radii in the range of 0.45 m as in a generator application at rotational speed of up to 3000 rpm, and at low operating temperatures of about 30 K. Additionally a 3 kA high current power supply for HTS test objects like coils or contacts is projected. Aspects of rotor dynamics and fatigue strength analysis had to be considered.

The Development of High-Current Power Supply System for Electrolytic Copper Foil

A 6.5 V/50 kA high-frequency switching power supply (HSPS) system composed of 10 power modules is developed to meet the requirements of copper-foil electrolysis. The power module is composed of a two-leg pulse width modulation (PWM) rectifier and a DC/DC converter. The DC/DC converter adopts two full-wave rectifiers in parallel to enhance the output. For the two-leg PWM rectifier, the ripple of the DC-link voltage is derived. A composite control method with a ripple filter is then proposed to effectively improve the performance of the rectifier. To meet the process demand of copper-foil electrolysis, the virtual impedance-based current-sharing control method with load current full feedforward is proposed for n-parallel DC/DC converters. The roles of load current feedforward and virtual impedance are analyzed, and the current-sharing control model of the HSPS system is derived. Virtual impedance is used to adjust the current-sharing impedance without changing the equivalent output impedance, which can effectively reduce current-sharing errors. Finally, simulation and experimental results verify the structure and control method.

Dry reforming of methane in a tip–tip arc discharge reactor at very high pressure

Over the last two decades there has been growing research interest in the oxidative reforming of methane using carbon dioxide (CO2), with the aim of producing syngas (mixture of H2 and CO) which can be converted to synthetic fuels via the Fischer–Trospch process. Among the different options investigated, non-thermal plasma technology is considered to have a high potential for natural gas to syngas (and higher hydrocarbons) conversion at relatively lower energy consumption and cost. While many studies on plasma dry reforming of methane have been carried out over the years using different non-thermal plasma technologies, almost all these studies have been undertaken at near-atmospheric pressure. The aim of this paper is to study the influence of the pressure on the plasma dry reforming of methane. For this purpose, a tip–tip plasma batch-reactor connected to a high voltage direct current power supply has been used. This reactor has a maximum pressure limit of 20 MPa. All experiments were carried out with a CH4/CO2 reactant gas ratio of 1.8, a current of 350 mA, an interelectrode gap of 0.4 mm, and discharge duration of 60 s. The results presented in this paper show the variation of the concentration of the different obtained products: CO, H2, C2 and C3 hydrocarbons versus the operating pressure. From these results, the selectivity, chemical yield, H2/CO ratios and energy balances have been determined. The results from this study are compared to other plasma dry reforming studies in the literature. The high pressure reactor shows a high potential in terms of energy efficiency despite the low conversion due to the specific energy consumed by the reactant and the small discharge volume. The conversion could possibly be improved by increasing the interelectrode gap, and thus create a larger arc discharge reaction zone.

Improvements of a Beam Current Monitor by using a High Tc Current Sensor and SQUID at the RIBF

To measure a beam current non-destructively, a conventional DC current transformer (DCCT) has been used at accelerator facilities. However, the current resolution of the DCCT is worse than 1μA. This current resolution is sufficient for electron and proton accelerators in which the beam intensity is high, but it is not sufficient for lower intensity heavy-ion beams. Thus, superconducting technology has been applied to the precise measurement of the beam current. In particular, to measure the DC current of high-energy heavy-ion beams non-destructively at high resolution, a high critical temperature (HTc) superconducting quantum interference device (SQUID) beam current monitor (HTc SQUID monitor) has been developed for use in the radioactive isotope beam factory (RIBF) at RIKEN in Japan. Beginning this year, the magnetic shielding system has been greatly reinforced. The measurement resolution is determined by the signal to noise ratio, that is improved by attenuating the external magnetic noise and is mainly produced by the distribution and transmission lines from the high current power supplies. The new strong magnetic shielding system can attenuate the external magnetic noise to 10−10.

The Direct Cooling of the Preoptic-Hypothalamic Area Elicits the Release of Thyroid Stimulating Hormone during Wakefulness but Not during REM Sleep

Thermoregulatory responses to temperature changes are not operant during REM sleep (REMS), but fully operant in non-REM sleep and wakefulness. The specificity of the relationship between REMS and the impairment of thermoregulation was tested by eliciting the reflex release of Thyrotropin Releasing Hormone (TRH), which is integrated at hypothalamic level. By inducing the sequential secretion of Thyroid Stimulating Hormone (TSH) and Thyroid Hormone, TRH intervenes in the regulation of obligatory and non-shivering thermogenesis. Experiments were performed on male albino rats implanted with epidural electrodes for EEG recording and 2 silver-copper wire thermodes, bilaterally placed in the preoptic-hypothalamic area (POA) and connected to small thermoelectric heat pumps driven by a low-voltage high current DC power supply. In preliminary experiments, a thermistor was added in order to measure hypothalamic temperature. The activation of TRH hypophysiotropic neurons by the thermode cooling of POA was indirectly assessed, in conditions in which thermoregulation was either fully operant (wakefulness) or not operant (REMS), by a radioimmunoassay determination of plasmatic levels of TSH. Different POA cooling were performed for 120 s or 40 s at current intensities of 80 mA and 125 mA, respectively. At both current intensities, POA cooling elicited, with respect to control values (no cooling current), a significant increase in plasmatic TSH levels in wakefulness, but not during REMS. These results confirm the inactivation of POA thermal sensitivity during REMS and show, for the first time, that this inactivation concerns also the fundamental endocrine control of non-shivering thermogenesis.

MATHEMATICAL MODELING OF THE THERMOPHYSICAL PROCESSES IN SEMICONDUCTOR THERMOELECTRIC CONVERTERS

This paper presents a mathematical model of layered thermoelectric energy Converter, designed for high current power supply. The obtained thermal fields and fields of thermo-mechanical stresses in it. Advantages of high-current layered design elements before the classic U-shaped.

Optimized method for rapid protein electroblotting

Protein electroblotting is a common method for transferring proteins out of a polyacrylamide gel onto a membrane for subsequent western blotting. With a high-current power supply, such as that found in the Thermo Scientific™ Pierce™ G2 Fast Blotter, and a high–ionic strength transfer buffer, protein transfer from nitrocellulose or polyvinylidene difluoride (PVDF) membranes can be achieved in 5–10 m, even with proteins as large as 300 kDa.

Advanced Low-Voltage Power MOSFET Technology for Power Supply in Package Applications

In this paper, a high-current dc-dc power supply in package is reported with an emphasis on the design aspects of the low- and high-side power MOSFETs embedded in the power module. A new NexFET structure with its source electrode on the bottom side of the die (source down) is designed to enable an innovative stacked-die PSiP technology with significantly reduced parasitic inductance and package footprint. A gate voltage pulldown circuitry monolithically integrated in the low-side NexFET is introduced to effectively prevent shoot-through faults even when a very low gate threshold voltage is used to reduce conduction and body diode reverse-recovery-related power losses. In addition, an asymmetric gate resistor circuitry is monolithically integrated in the high-side NexFET to minimize voltage ringing at the switch node. With all these novel device technology improvements, the new power supply in package module delivers a significant improvement in efficiency and offers an excellent solution for future high-frequency, high-current-density dc-dc converters.