Low-voltage Part Research Articles

A realization of super-fast scanning power supply for proton therapy

This paper introduces a method to achieve fast scanning power supply for Proton Therapy. To meet the specific needs of this power supply, a new structure consists of dynamic module (high voltage part) and static module (low voltage part) has been designed and tested. The simulation results and actual waveform were listed in this paper. The results showed that the current rising slope can reach 90kA/s.

Assessing the EV Hosting Capacity of Australian Urban and Rural MV-LV Networks

With the expected uptake of electric vehicles (EVs), it is vital for distribution companies to investigate the EV hosting capacity of their networks given the increase in demand. Asset congestion and voltage issues need to be quantified considering both the medium voltage (MV) and low voltage (LV) parts as well as the unbalanced nature of the problem. Since LV models are not available, this paper adopts an approach to expand existing MV-only models by incorporating pseudo-LV feeders. The EV hosting capacity is assessed by exploring multiple EV penetrations and considering their time-varying behaviour during the peak demand day (worst-case scenario). Two realistically modelled Australian MV-LV networks (urban and rural) are used as case study considering EV profiles derived from the Electric Nation project in the UK. The results show the importance of detailed network and EV modelling to adequately inform distribution companies and their EV planning strategies.

Probing the current-phase relation in Josephson point-contact junctions between hbox {Pb}_{0.6}In_{0.4} and hbox {Ba}_{0.6}K_{0.4}(FeAs)_2 superconductors

The Josephson effect in point contacts between an “ordinary” superconductor hbox {Pb}_{0.6}In_{0.4} (T_c approx 6.6 , {mathrm {K}}) and single crystals of the Fe-based superconductor Ba_{0.6}K_{0.4}(FeAs)_2 (T_c approx 38.5 , {mathrm {K}}), was investigated. In order to shed light on the order parameter symmetry of Ba_{0.6}K_{0.4}(FeAs)_2, the dependence of the Josephson supercurrent I_s on the temperature and on sin (dvarphi ) with d = 1, 2 was studied. The dependencies of the critical current on temperature I_c (T) and of the amplitudes of the first current steps of the current–voltage characteristic i_n^{exp} (sqrt{P})(n = 0, 1, 2) on the power of microwave radiation with frequency f = (1.5 div 8), {mathrm {GHz}} were measured. It is shown that the dependencies I_c (T) are close to the well-known Ambegaokar–Baratoff (AB) dependence for tunnel contacts between “ordinary” superconductors and to the dependence calculated by Burmistrova et al. (Phys Rev B 91, 214501 (2015)) for microshorts between an “ordinary” superconductor and a two-band superconductor with s pm order parameter symmetry at certain values of the transparency of boundaries and thickness of the transition layer. It is found that the dependencies i_n^{exp} (sqrt{P}) cannot be approximated within the resistively shunted model using the normalized microwave frequencies Omega = 2 pi f / (2eV_c / hbar ) with characteristic voltages V_c = I_c R_N, (R_N—normal resistance of the contact) found from the low-voltage parts of the current–voltage characteristics. The reasons for this failure are discussed and a method is proposed for accurately determining the value of Omega, which takes into account all the features of the point contact affecting the period of the dependence i_n^{exp} (sqrt{P}). An analysis of the I_c (T) and i_n^{exp} (sqrt{P}) dependencies shows that the superconducting current of the Josephson contacts under investigation is proportional to the sin of the phase difference varphi, I_s = I_c sin(varphi ). The implications of these results on the symmetry of the order parameter are also discussed.

18.5: Size‐dependence Characterization of GaN‐based Green Micro‐LED

GaN‐based light‐emitting diode (LED) arrays are a promising technology in a wide range of applications. Research on size dependence performance is important in GaN‐based LED. In this paper, we study the electrical properties of 100µm, 150µm, and 200µm devices. The ideal factor is calculated by measuring the current density‐voltage characteristics to study the carrier transport mechanism. It is found that the forward low bias voltage part is mainly composed of recombination current and diffusion current. The current density in the high bias voltage part depends on the current crowding effect. The temperature variation study proves that the ideal factor has no size dependence. Besides, the electroluminescence (EL) spectrum is studied to understand size dependence in GaN internal structure. As the size decreases, the quantum confinement Stark effect (QCSE) will be suppressed, which is proved by the relationship between optical power and turn‐on voltage. These studies indicate that the application of Micro‐LED and even smaller‐sized Micro‐LEDs has unlimited possibilities and broad prospects.

P‐61: Size‐Dependence Characterization of GaN‐Based Green MicroLED

GaN‐based light‐emitting diode (LED) arrays are a promising technology in a wide range of applications. Research on size dependence performance is important in GaN‐based LED. In this paper, we study the electrical properties of 100µm, 150µm, and 200µm devices. The ideal factor is calculated by measuring the current density‐voltage characteristics to study the carrier transport mechanism. It is found that the forward low bias voltage part is mainly composed of recombination current and diffusion current. The current density in the high bias voltage part depends on the current crowding effect. The temperature variation study proves that the ideal factor has no size dependence. Besides, the electroluminescence (EL) spectrum is studied to understand size dependence in GaN internal structure. As the size decreases, the quantum confinement Stark effect (QCSE) will be suppressed, which is proved by the relationship between optical power and turn‐on voltage. These studies indicate that the application of Micro‐LED and even smaller‐sized Micro‐LEDs has unlimited possibilities and broad prospects.

Optimization of Non-Uniform Deformation on Piezoelectric Circular Diaphragm Energy Harvester with a Ring-Shaped Ceramic Disk.

Piezoelectric energy harvesting technology using the piezoelectric circular diaphragm (PCD) has drawn much attention because it has great application potential in replacing chemical batteries to power microelectronic devices. In this article, we have found a non-uniform strain distribution inside the PCD energy harvester. From the edge to the center of the ceramic disk, its output voltage first increases and then decreases. This uneven output voltage reduces the output power of the PCD energy harvester. Based on this phenomenon, we reduce the ceramic disk diameter and dig a hole in the center, analyzing the effect of removing the ceramic disk’s low output voltage part on the PCD energy harvester. The experimental results show that removing the ceramic disk’s low output voltage part can improve the output power, reduce the resonance frequency, and increase the optimal impedance of the PCD energy harvester. Under the conditions of 10 g proof mass, 9.8 m/s2 acceleration, the PCD energy harvester with a 19-mm diameter and a 6-mm hole can reach a maximum output power of 8.34 mW.

A Technique for Detecting Electric Line Sections with Wire Breakage

This article considers the effects of wire breakage in networks with an insulated neutral, as well as issues related to detecting the location of such damage. The need to use means and techniques for rapidly localizing line sections with wire breakage is revealed and justified. The analysis conducted allows proposing a technique for detecting line sections with phase wire breakage in branched networks with an insulated neutral. This technique is based on analyzing voltage readings from the meters installed in the low-voltage part of transformer substations connected to the damaged network. The implementation of this technique requires using software that is integrable with available electronic supervisory control resources without installing additional equipment because it is possible to use electric counters with data transmitters installed everywhere at transformer substations as voltage meters.

THE MICRO- AND NANOSECOND DISCHARGES IN GAS BUBBLES FOR WATER DISINFECTION AND PURIFICATION

Purpose. Comparison of electrical circuits of experimental plants for obtaining micro- and nanosecond discharges in gas bubbles in water and comparing the experimental results obtained for disinfecting water using such discharges. Methodology. To obtain high-voltage pulses on the load in the form of a gas bubbles and a layer of water with a frequency of more than 2000 pulses per second, a method of generating micro- and nanosecond pulses using high-voltage pulse generators based on a pulse transformer (PT) according to Tesla, with a transistor opening switch IGBT in the low-voltage part of the circui . A current-limiting resistor with a resistance Rcl = 24 kW is used to protect the transistor switch at microsecond discharges. At nanosecond discharges, a multi-gap spark gap is used to sharpen the front of high-voltage pulses. We used a capacitive voltage divider with a division factor of Kd = 7653 to measure voltage pulses, a shunt with a resistance of Rs = 2.5 W for measuring current pulses. RIGOL DS1102E digital oscilloscope with a 100 MHz bandwidth was used as a recording device. Results. The effect of micro- and nanosecond discharges in gas bubbles on microorganisms was experimentally investigated. It was possible to reduce the biochemical oxygen consumption of water during microsecond discharges, reduce the turbidity of water, and improve its organoleptic qualities. The energy released in a single pulse with microsecond discharges Wµ ≈ 17 mJ, with nanosecond discharges Wn ≈ 7.95 mJ. At nanosecond discharges, complete inactivation of E.coli bacteria was achieved. The disinfecting and purifying action of nanosecond pulses is better compared to microsecond pulses due to an increase in the amplitude of the pulsed voltage up to 30 kV, and a pulsed current of up to 35 A. Originality. The possibility of effective microbiological disinfection of water using nanosecond discharges in gas bubbles at low specific energy consumption has been experimentally shown. Practical value. The obtained experimental results on water disinfection using micro- and nanosecond discharges offer the prospect of industrial application of installations using such discharges for disinfecting and purification wastewater, swimming pools, and post-treatment of tap water.

Highly Defective Hard Carbon Anode for Na-Ion Batteries By Microwave Heating

Hard carbon has been considered as one of the most promising anode materials for Na-ion batteries (NIBs). As low cost is one of the major advantages of NIBs over Li-ion batteries (LIBs), the relative high cost of hard carbon has been the bottleneck for the commercialization of NIBs. In addition, a large portion of the capacity for conventional hard carbon is contributed from the low-voltage plateau part, which increases the risk of dendrite formation, thus causing a safety concern. Guided by the mechanism of Na-ion storage in hard carbon we proposed, where the sloping capacity is correlated to the structural defects, we design a new hard carbon by a microwave treatment on a low-temperature annealed hard carbon. The microwave treatment enhances its conductivity by forming a heterogeneous carbon structure, where there are highly ordered large nanodomains formed under microwave as conducting conduits and importantly during the short microwave treatment, i.e., 6 seconds, the carbon structure still retains its high extent of structural defects, as demonstrated by neutron scattering and pair distribution function results. Such a structure exhibits short plateau Na-ion storage but high sloping capacity, where surprisingly the Na-ion diffusivity in the microwave-treated carbon is higher than conventional hard carbon formed by high temperature annealing. Notably, the microwave treatment is much energy efficient in preparation of hard carbon than conventional annealing. This work supports our prior proposed mechanism and points out a new direction for hard carbon preparation as NIB anodes.

Secure Automated Home Energy Management in Multi-Agent Smart Grid Architecture

This paper describes an approach to decentralised and automated demand response and home energy management that takes into consideration privacy and security of home users implemented using a multi-agent system. The novel approach allows the management of flexibility within the low-voltage part of the electricity distribution networks where decentralised decision making will result in better value for prosumers, efficiency and market competitiveness. The hierarchical agent architecture allows agents that represent different stakeholders to make decisions as a result of changes in energy consumption and generation using mechanisms such as optimisation and access control. The multi-agent system connects to home devices through a uniform software layer that abstracts the heterogeneity of home devices.

The Performance of an Integrated Transformer in a DC/DC Converter

The separation between the low-voltage part and high-voltage part of the converter is formed by a transformer that transfers power while jamming the DC ring. The resonant mode power oscillator is utilized to allow elevated competence power transfer. The on-chip transformer is probable to have elevated value inductance, elevated quality factors and elevated coupling coefficient to decrease the loss in the oscillation. The performance of a transformer is extremely dependent on the structure, topology and other essential structures that create it compatible with the integrated circuits IC process such as patterned ground shield (PGS). Different types of transformers are modeled and simulated in MATLAB; the performances are compared to select the optimum design. The on-chip transformer model is simulated and the Results of MATLAB simulation are exposed, showing an excellent agreement in radio frequency RF.

MIMO-OFDM narrowband-PLC in distribution systems: Impact of power transformers on achievable data rates

Power-line communication (PLC) is gaining a renewed interest, due to the smart grid (SG) emerging communication requirements. Among other communication technologies, PLC is a very efficient and feasible solution, especially for the extended SG distribution networks. However, it is very challenging to consider both the medium- and low-voltage parts of the distribution network as a whole communication medium, due to the attenuating effects of distribution transformers, limiting PLC applicability. In this paper, data transmission through distribution transformers is investigated by means of multiple-input multiple-output (MIMO) narrowband power-line communication (NB-PLC) system, utilizing orthogonal frequency-division multiplexing (OFDM) technology. Multi-conductor distribution line and measurement-based transformer models are developed to characterize the MV–LV PLC channel. In addition, OFDM signal processing techniques are applied to enhance the achievable data rates. The transmit power budget and bit allocation across the OFDM sub-channels of the spatial beams are optimized to maximize the data rate through the distribution transformer. The achievable data rates are calculated and systematically analysed for different scenarios to investigate the effects of the distribution lines, connected loads, noise models, etc. Results reveal the superiority of the proposed MIMO design against the traditional SISO systems. In addition, the possibility for an extensive and reliable application of MV–LV PLC communications through distribution transformers is shown.

Analysis of capacitive currents in the winding of a high voltage measuring autotransformer

The paper analyzed the distribution of capacitive currents in the winding of measuring high-voltage autotransformer at its operating frequency 50 (60) Hz. It is revealed that idling high-voltage autotransformer at significant nominal dividing coefficient these currents can acquire essential values against the current idling, which can affect the accuracy of large-scale conversion of high-voltage measuring autotransformers. The paper presents an approach to account values of interlayer capacitive currents in the windings of high-voltage autotransformers to clarify the distribution of voltage on their low-voltage (output) winding parts. It is shown that the distribution of capacitive currents significantly different to the first, last and middle layers of windings that must be considered when designing the windings of high-voltage autotransformers and calculate the number of turns in the respective high-voltage and low-voltage parts of windings. This analysis is particularly important for the development of standard measurement tools using high-voltage autotransformer scale transformation.

ELABORATION OF HIGH-VOLTAGE PULSE INSTALLATIONS AND PROVIDING THEIR OPERATION PROTECTIVE MEASURES

The article presents design engineering methods for the high-voltage pulse installations of technological purpose for disinfection of drinking water, sewage, and edible liquids by highfield microand nanosecond pulsing exposure. Designing potentialities are considered of the principal elements of the high-voltage part and the discharge circuit of the installations towards assuring the best efficient on-load utilization of the source energy and safe operation of the high-voltage equipment. The study shows that for disinfection of drinking water and sewage it is expedient to apply microsecond pulse actions causing the electrohydraulic effect in aqueous media with associated complex of physical processes (ultraviolet emission, generation of ozone and atomic oxygen, mechanical compression waves, etc.) having detrimental effect on life activity of the microorganisms. In case of disinfecting edible liquids it is recommended to use the nanosecond pulses capable of straight permeating the biological cell nucleus, inactivating it. Meanwhile, the nutritive and biological values of the foodstuffs are saved and their organoleptic properties are improved. It is noted that in elaboration process of high-frequency pulse installations special consideration should be given to issues of the operating personnel safety discipline and securing conditions for the entire installation uninterrupted performance. With this objective in view the necessary requirements should be fulfilled on shielding the highand low-voltage installation parts against high-frequency electromagnetic emissions registered by special differential sensors. Simultaneously, the abatement measures should be applied on the high-voltage equipment operational noise level. The authors offer a technique for noise abatement to admissible levels (lower than 80 dB⋅A) by means of coating the inside surface with shielded enclosure of densely-packed abutting sheets of porous electro-acoustic insulating material.

지상변압기 중성선 접지 탈락에 의한 화재위험성 고찰

한국전력공사 지상변압기 중 일부 제조사의 변압기는 고압측 중성점 접지와 저압측 중성점 접지가 공통으로 구성되어 있다. 이러한 변압기로부터 저압수전을 받고 있는 밀집된 주택 및 소형상가는 지상변압기의 중성점 접지가 탈락 시 변압기의 전류불평형률에 따라 저압측에 수천V까지 유입될 수 있다. 따라서 저압수용가의 분전반 및 전기사용 설비 등이 절연파괴로 소손되면서 화재로 이어질 수 있어 화재예방을 위한 지상변압기의 설계 및 관리적 대책과 저압측 수용가의 안전대책을 제시하였다. Some of the PAD-mounted transformers managed by KEPCO share the common neutral ground for both low and high voltages. When the common neutral ground of PAD-mounted transformer is disconnected, high voltage current is supplied to the low voltage circuits due to the current imbalance in the transformers, exposing the residential areas to unexpected high voltage currents supply. As a result, there is increased risk of fire due to damages in low voltage distribution boards and electrical equipments. This work presents recommendations in the design and the maintenance of the PAD-mounted transformers and additional safety measures for low voltage parts to mitigate the risks of fire.

Current-voltage characteristics of voltage-biased Tl2Ba2CaCu2O8 intrinsic Josephson junctions

The voltage-biased current-voltage (I–V) characteristics of intrinsic Josephson junctions (IJJs), which are fabricated with misaligned high temperature superconducting Tl2Ba2CaCu2O8 (Tl-2212) thin film, are investigated experimentally. Three characteristic regions in the I–V curve are observed at 47 K. In the low voltage part, the current firstly increases and then decreases slowly with increasing the biased voltage, which is shown as a bump. In the next region, the current slightly increases with increasing the biased voltage until a sudden decrease of the current appears. Thereafter, branch structure forms with increasing the voltage on the I–V characteristic. The influence of the self-heating on the I–V characteristics is investigated and the temperature dependence of the I–V characteristics is measured to explore these characteristics in detail.

A Preliminary Study on CSAMT Anti-Jamming Transmitter System

On the basis of the relevant identification theory of pseudo-random code signal, the signals of CSAMT are divided into three parts according to the frequency of the signal. The signals which are susceptible to 50Hz interference signal and its harmonic components should be set by pseudo-random code way. Others are set by single square waveform way. The Control and signal generation software of the transmitter system is built on the advanced virtual instrument platform, LabVIEW. The hardware of the transmitter system is mainly composed of host computer, data acquisition card, high-speed optocoupler, IGBT driver module and four IGBT switches. The data acquisition card generate PWM signals, the high-speed optocoupler isolates low-voltage part and high-voltage part. IGBT drive module and four IGBT switches constitute high-voltage part. Entire transmitter system is suitable for different environments and research tasks, the transmit frequency are adjustable, and the pseudo-random code signal has strong capability to suppress the interference signals. The control software on host computer is simple and clear. There is good prospect for the use.

Millimeter-wave induced sloping step in Tl2Ba2CaCu2O8 misaligned thin film

The millimeter-wave responses of the intrinsic Josephson junctions (IJJs) in misaligned Tl2Ba2CaCu2O8 thin film have been experimentally studied. In the low voltage part on the current–voltage (I–V) characteristics, sloping steps are induced under different frequencies. By presenting the dV/dI–I curves, it shows that corresponding to the sloping steps on the I–V characteristics, resistive bumps appear. The dV/dI–I and dV/dI–V plots from 72GHz to 80GHz and at different power show the variation of the step voltage.

A Physics-Based Analytical Compact Model for the Drift Region of the HV-MOSFET

This paper presents a novel physics-based analytical compact model for the drift region of a high-voltage metal–oxide–semiconductor field-effect transistor (HV-MOSFET). According to this model, the drift region is considered as a simple 1-D problem, just as that of a low-voltage inner MOS transistor. It exploits the charge-sheet approximation and performs linearization between the charge in the drift region and the surface potential. The drift region model combined with the standard charge-sheet MOS model for the low-voltage part adds up to a complete HV-MOSFET model, which is verified against technology computer-aided design simulations and measurements of HV-MOS transistors. The comparisons demonstrate its accurate physics foundations and underline that this novel approach to the modeling of the drift region of the HV-MOSFET is promising.

Peculiarities of the photon-assisted field emissions from GaN nanorods

The peculiarities of electron field and photon-assisted field emission from GaN nanorods are presented here. Well-aligned GaN field-emitter rods with nanometer-scale diameter were processed on a wafer with n+-GaN top active layer on n+-Si substrate by plasma and photoelectrochemical etching. The current-voltage characteristics of emission current in Fowler–Nordheim (FN) plots show different slopes for the initial device and with different wavelengths illuminated devices. At electron-field emission from GaN, as a rule, the curves with two slopes (lower at a low voltage and higher at a high voltage) in Fowler–Nordheim coordinates were observed. The influence of light illumination on the field emission was discovered only on the low-voltage part of the curve. At higher voltages, the experimental curves without and with illumination practically coincided. The slope of the low-voltage part of FN plots decreased as a result of illumination. This fact points at the lowering of the energy barrier at field emission due to the electron excitation caused by light. The energy-barrier heights at field and photofield emission were estimated. For the explanation of experimental results, a model based on electron excitation by light, subbandgap and band-to-band transitions, and electron emission from different valleys with their specific electron affinities has been proposed.