Pulsed Voltage Method Research Articles

Detection of Interturn Short-Circuit Faults in Dry-Type Voltage Transformers Using the Pulse Voltage Method

This article investigates the application of the pulse voltage method for detecting interturn short-circuit faults in the high-voltage windings of dry-type voltage transformers. We determined the characterization parameters of the high-voltage windings of dry-type voltage transformers and trends in the variation of the characterization parameters with frequency in the presence and absence of faults. The viability of using the pulse voltage method for the detection of interturn short-circuit faults in dry-type voltage transformers was analyzed. A pulse voltage test platform was designed to analyze the response voltage waveforms using pulse-oscillating voltage experiments on transformers with various short-circuit faults. The results demonstrate that during a turn-to-turn short circuit, the equivalent resistance and inductance of a high-voltage winding are significantly lowered. When employing the pulse voltage method to investigate interturn short-circuit faults, tiny inductors are connected in parallel to produce an oscillating voltage waveform that is more uniform. Upon incurring a short circuit between turns, the pulse’s oscillating voltage frequency increases. The greater the number of turns in the short-circuit fault is, the more significant the effect of the test.

Research on Turn-to-Turn Insulation Test of Dry-Type Air-Core Reactor

The dry-type air-core reactor insulation detection is the key component of reactive power compensation and filter device, which needs to be tested. At present, there are few researches on detection method of dry-type air-core reactor insulation. Based on the principle of pulsed voltage method and reducing test cost, the mathematical model of dry-type air-core reactor is established, the actual parameters are entered for simulation analysis. The simulation results verify the feasibility of using the pulse voltage method to detect the turn insulation between the dry-type air-core reactors, which can guide the actual dry-type air-core reactor insulation detection method.

Suppression of ion migration in perovskite materials by pulse-voltage method* *Project supported by the National Natural Science Foundation of China (Grant No. 61805263) and Shanghai Sailing Program, China (Grant No. 18YF1426400).

Hybrid halide perovskites have great potential for applications in optoelectronic devices. However, the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement, instability of material, and degradation of device performance. The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic, which is still poorly understood in these semiconductors. Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration. Herein, we explore the pulse-voltage (PV) method on methylammonium lead tribromide single crystals to protect the device from the ion migration. A guideline is summarized through the analysis of measurement history and condition parameters. The influence of the ion migration on current–voltage measurement, such as repeatability and hysteresis loop, is under controlled. An application of the PV method is demonstrated on the activation energy of conductivity. The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method, introducing new physical insight on the current–voltage behavior of perovskite materials. The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.

Two designs for DC–DC stage of electric vehicle charging stations

Pulse-voltage and pulse-current methods are widely used in advanced battery charging systems, because they enhance the overall charging process and prolong the battery lifetime. This paper proposes two battery charging systems for an electric vehicle charging station based on these methods. The first design is a developed version of a studied non-dissipative pulse-current DC–DC stage in which the negative pulse current is generated by a current recirculating block. It employs a precisely designed control system to charge and discharge electric vehicles in a wide range of voltage level. The second design is a pulse-voltage DC–DC stage suggested for high-power applications for the first time based on power electronics circuits. It also attenuates the sudden battery power changes caused by pulse-voltage method. The two designs have been accurately formulated. The practical results with the frequency responses confirm that the two designs work well and have less output power changes compared to the recent relevant works.

Multichannel Online Lifetime Accelerating and Testing System for Power Light-Emitting Diodes

The accelerated life testing is a common tool to achieve lifetime prediction and reliability analysis for light-emitting diodes (LEDs). Currently, all popular accelerated methods, either offline or online, employ a large volume, energy-consuming temperature chamber, which will cause the instruments inside worse, and the methods are usually incapable of controlling the junction temperature online. In this paper, we propose a multifunctional online system that controls the temperature of heat sink directly by a heating plate integrated to electrical-current-stress fixture. The combinations of spectrometer with optical multiplexer and current source with electrical matrix switch are adopted to fulfill the comprehensive real-time testing of LEDs, including optical, electrical, colorimetric, and thermal properties. In particular, junction temperature is monitored and controlled online by pulse-voltage method, which raises the accuracy and reliability of lifetime analysis and prediction. A new file format-HDF5 is applied to process huge quantities of experimental data, which are helpful to analyze the failure mechanism.

Brush-like polyaniline nanoarray modified anode for improvement of power output in microbial fuel cell

Carbon cloth with brush-like polyaniline (BL-PANI) nanowire arrays generated on the surface was utilized as anode material in this study to improve the power output of MFCs. A novel pulsed voltage method was applied to fabricate BL-PANI with PANI nanowires of ∼230nm of length. By using BL-PANI modified carbon cloth as anode, the power output was improved by 58.1% and 36.1% compared to that of plain carbon cloth and PANI modified carbon cloth with ordinary structure, respectively. Electrochemical tests revealed that both electron transfer resistance and charge transfer resistance were decreased owing to high specific area for microbes’ growth and diffusion of charged species.

Characteristics of plasma in culture medium generated by positive pulse voltage and effects of organic compounds on its characteristics

We describe a positive pulse voltage method for generating plasma in culture medium with a composition similar to biological fluids. We also describe the plasma’s characteristics, liquid quality, and the effect of organic compounds in the culture medium on the plasma characteristics through comparisons to a solution containing inorganic salts at the same concentrations as in the culture medium. Light emission with Na and OH spectra was observed within a vapor bubble produced by Joule heating at the tip of the electrode. A downward thermal flow and shock wave were caused by the behavior of the vapor bubble. The culture medium pH gradually increased from 7.9 to 8.3 over the discharge time of 300 s. H2O2 was generated 1.1 mg l−1 in the culture medium after discharge for 300 s, and this value was 0.5 mg l−1 lower than the inorganic salts solution which does not contain organic compounds. This study provides important data that will help facilitate more widespread application of plasma medicine.

Fabrication of one-dimensional alumina photonic crystals by anodization using a modified pulse-voltage method

The alumina nanolayer structure with alternating high and low porosities is conveniently fabricated by applying a modified pulse voltage waveform with constant high and low voltage. This structure shows the well-defined layer in a long-range structural periodicity leads to a strong photonic band gap (PBG) from visible to near infrared and brilliant film colors. Compared with the previous reported tuning method, this method is more simple and flexible in tuning the PBG of photonic crystals (PCs). The effect of duration time of high, low and 0V voltages on PBG is discussed. The first PBG could be modulated easily from the visible to near infrared region by varying the duration time of constant high or low voltages. It is also found that the 0V lasting for appropriate time is helpful to improve the quality of the PCs. The formation mechanism of multilayer is also discussed.

Mechanism of localized electrical conduction at the onset of electroforming in TiO2 based resistive switching devices

The onset of localized current conduction during electroforming of TiO2-based resistive switching devices is investigated using a pulsed voltage method. The temperature rise at electroforming onset is found to vary from 25 to 300 °C as the pulse amplitude and the width are varied between 3–8 V and 10 ns–100 ms, respectively. The effective activation energy of the forming event is strongly electric field dependent and decreases from 0.7 eV at 3 V to almost zero at 8 V. The functional form of this dependence points toward charge trapping as the mechanism rather than oxygen vacancy motion.

Transient characterization of the electroforming process in TiO2 based resistive switching devices

The transient electroforming process of TiO2-based resistive switching devices is investigated using a pulsed voltage method, and the electroforming time is found to vary from 10−8 s to 10−1 s as function of pulse magnitude (3–8 V) and ambient temperature (25–100 °C). Pulsed experiments and thermal simulations reveal that Joule self-heating has a significant effect on the electroforming dynamics, specially for electroforming voltages above 5.5 V where there is little dependence on ambient temperature and the electroforming time (10–100 ns) is much shorter than the device thermal time constant (≈2 μs).

Quantitative Attachment and Detachment of Bacterial Spores from Fine Wires through Continuous and Pulsed DC Electrophoretic Deposition

We demonstrate the uniform attachment of bacterial spores electrophoretically onto fine wires in liquids and subsequently quantitatively detached back into suspension. It was found that the use of a pulsed voltage method resulted in a uniform coverage of spores and prevented visible bubble formation resulting from water electrolysis which tended to dislodge the spores from the wires. By monitoring the electrophoretically derived current, this method could also be used to quantitatively measure the surface charges on spores and the deposition rate. The method is generic and should be applicable to the deposition of any charged biological material (e.g., spores, bacteria, viruses) onto metal surfaces.

Novel sensorless driving method of SRM with external rotor using impressed voltage pulse

The paper presents an improved impressed diagnostic pulse-voltage method to estimate the rotor position of a switched-reluctance motor (SRM) with an external rotor. The fundamental method of impressed diagnostic pulse voltage is to impress pulse voltage at the inactive phases of a SRM that has an external rotor. Because the variations of inductance are dependent on the rotor position, and because the characteristic current values produced from the pulse voltage are dependent on the inductance, the rotor position can be inferred by observing the characteristic-current value. If the inductance of the SRM does not vary obviously, noise in the characteristic-current signal may cause failure of the sensorless-position-estimation method. Therefore, an improved impressed diagnostic pulse-voltage method is presented to increase the variations of characteristic current and estimate rotor position. First, the structure, characteristics, operational principles and mathematical model of the SRM with an external rotor are introduced. Then the improved impressed diagnostic pulse-voltage method is utilised to implement the sensorless position estimation for commutation control.

Controllable zeolite films on electrodes—comparing dc voltage electrophoretic deposition and a novel pulsed voltage method

We report here a novel application of pulsed voltage electrophoretic deposition (EPD) of zeolite 13X particles on glassy carbon surfaces. Our initial studies employing dc voltage EPD indicated that while adjustments of solution parameters (pH, supporting electrolyte concentration) and other experimental parameters (dc voltage, deposition time) allowed control of the amount of zeolite coated (from sub-monolayer to multilayer), difficulties of surface deactivation, controllability, uniformity, and reproducibility occurred under conditions suitable for the various films. These difficulties can be alleviated by utilizing a pulsed voltage program for EPD, an approach which has not been previously used for the fabrication of zeolite modified electrodes.

A study of photocurrent measurement and optical illumination effects on Schottky barriers

Abstract Effects of chopped illumination on the electrical noise of Schottky diodes are studied theoretically and experimentally. It is shown that the noise spectra of a bare diode illuminated by a He‐Ne laser show certain structures at specific frequencies. A theoretical model is presented for the observed noise spectra. Our theoretical results agree well with the experimental data. A periodic pulse voltage method is used to measure the equivalent voltage due to light illumination. This method can be used to find the equivalent photocurrent and quantum efficiency of Schottky diodes.

Investigation of conduction mechanism in thick film resistors trimmed by the pulse voltage method : Toshio Tobitaet al. IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 15(4), 583 (1992)

Investigation of conduction mechanism in thick film resistors trimmed by the pulse voltage method : Toshio Tobitaet al. IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 15(4), 583 (1992)

New trimming technology of a thick film resistor by the pulse voltage method : Toshio Tobita and Hayato Takasago. IEEE Trans. Compon. Hybrids mfg Technol.14(3), 613 (1991)

New trimming technology of a thick film resistor by the pulse voltage method : Toshio Tobita and Hayato Takasago. IEEE Trans. Compon. Hybrids mfg Technol.14(3), 613 (1991)

Investigation of conduction mechanism in thick film resistors trimmed by the pulse voltage method

The conduction mechanism of RuO/sub 2/-based thick-film resistor (TFR) trimmed by the pulse voltage trimming (PVT) method is discussed. The surface temperature distribution barely changed when power was applied to the TFR, moreover, no current crowding was found by results of scanning electron microscopy-voltage contrast (SEM-VC). The existence of electron traps in the TFR could not be detected from the results of temperature stimulus current (TSC) characteristics. The resistance value of the TFR increased at 600 degrees C and then decreased abruptly at 800 degrees C. It was supposed, therefore, that the heat stress accumulated in the TFR during the refiring process of the TFRs was relaxed by the thermal annealing due to the PVT. Consequently, the decrease in the resistivity of the TFR, after the PVT, was quite logical, if an increase in the number of conductive paths resulted when the conductive structure was modified in the TFR. In addition, frequency resistance characteristics of the TFRs qualitatively best fit the values predicted by the metal-insulator-metal model. >

New trimming technology of a thick film resistor by the pulse voltage method

To realize a noncut trimming method without any damage to the resistor surface of thick-film resistors for electronic devices, a pulse voltage trimming method (PVTM) has been developed for resistors of less than 0.5 mm/sup 2/. This trimming method combines coarse and fine adjustments which are, respectively, due to pulse peak voltage and the number of pulse groups. The PVTM ensures resistance accuracy with an error of less than 1%. High-frequency characteristics and current noise of the trimmed resistors are considerably improved by this trimming technique, and there is no loss in the power handling capability for the trimmed resistors. These advantageous features are obtained by the increased number of conductive paths in the trimmed resistors. >