High Voltage DC Source Research Articles

A Modular Push–Pull–Flyback High-Voltage Pulse Generator for Electric Field Emulation During a Lightning Strike

To meet the requirements of simulating the electric field during a lightning strike, there is an urgent need for a voltage pulse generator that generates voltage pulses that are equivalent to the electric field during the lightning strike. A new pulse generator structure based on a push–pull DC–DC converter and a flyback converter is proposed. The pulses produced by the proposed generator have a variable voltage rise rate, and a modular design is used for the generator. Each module works independently and is powered by an exclusive lithium battery, which avoids the problems of the need for a high-voltage DC source, current sharing, and a complex control strategy in existing generators. The electrical behavior of the proposed generator during the switching transient is analyzed considering the effects of both the semiconductor switching device (insulated-gate bipolar transistor) and transformer. The method of selecting the specifications of each component and the method of designing the core component are presented in this study. The accuracy of the transient model and the feasibility of the proposed generator are verified in experiments, and a 60-stage prototype that produces pulses with amplitudes in excess of 1 MV, widths of 1–3 ms, and a variable voltage rise rate is developed.

A Multi-Source DC/AC Converter for Integrated Hybrid Energy Storage Systems

Hybrid energy storage systems are developed in various applications to integrate high-energy battery packs and high-power ultracapacitor banks. Multi-source inverters are used for the active control of energy sources in hybrid energy storage systems. Due to the magnetic-less topology of the multi-source inverters, the weight, volume, and power losses of the hybrid energy storage systems are reduced, while keeping similar performance. In this paper, a multi-source inverter is developed for the integration and active control of a high voltage DC source and a low voltage DC source, such as battery packs and ultracapacitor banks in energy storage system applications. The topology of the proposed multi-source inverter has a lower number of switching devices compared with the previously presented counterparts. Moreover, the number of conducting switches is reduced, which results in reduced power losses and improved efficiency. A closed-loop current controller is utilized to validate the proper operation of the proposed multi-source inverter topology. A proper space vector modulation technique is implemented to generate appropriate switching pulses during all operating modes. The performance of the proposed multi-source inverter is verified through simulations on PSIM software and experiments on a laboratory prototype.

Capacitor Voltage Regulation Strategy for 7-Level Single DC Source Hybrid Cascaded Inverter

Hybrid cascaded multilevel inverters have been proved to be an important alternative in the medium-voltage applications for their high-quality output. To reduce the use of dc sources, the single dc source cascaded H-bridge (SDS-CHB) inverter with the low-voltage dc source replaced by a capacitor is employed and investigated in this article. To address the challenge of the input capacitor voltage regulation, the charge/discharge modes with carrier-based pulsewidth modulation at different operation conditions are analyzed in detail and generally for all the combinations of load current magnitude and power factor from −1 to 1. The stability conditions for capacitor voltage control are analytically derived. Based on the analysis, a simple but effective capacitor voltage regulation strategy and an operation parameter optimization method are proposed. Within the identified stable operation regions, the proposed control strategy can keep the input capacitor voltage at the desired voltage level, i.e., half of the high-voltage cell dc source meanwhile can ensure the inverter high-quality output. The proposed operation parameter optimization method can minimize the output filter capacitor with good output. The capacitor voltage regulation strategy and operation parameter optimization method have been successfully substantiated by the simulation and experimental results of a seven-level hybrid cascaded inverter.

Fabrication of electrospinner for producing tube-shaped artificial blood vessels toward treatment applications in cardiovascular diseases

One of the most common causes of high mortality in Vietnam, as well as in the world, is related to cardiovascular disease. Therefore, the development of artificial blood vessels to replace damaged blood vessels in cardiovascular patients has become increasingly necessary. Realizing a growing need for these techniques, our team manufactured a specialized electrospinner machine to produce artificial blood vessel models. The electrospinner has the following components: high power supply source, collectors with tubular-type structures, and a syringe pump system. This study was conducted to (i) fabricate electrospinner machine and (ii) operate and evaluate the electrospinner. We found that the conditions of vascular formation can be optimized and these influencing parameters include DC high voltage source, distance between needle tip and collector, needle tip diameter, speed of syringe pump, and ambient temperature and humidity. The results show that this equipment is stable and safe for users.

Efficiency Improved Multi-Source Inverter for Hybrid Energy Storage Systems in Electric Vehicle Application

Multisource inverters (MSIs) as a new approach for the integration of the energy and the power sources in electric vehicle applications have gained considerable attraction. Such structures offer the active control of the dc sources without using any dc/dc converters or magnetic elements, which reduces the weight, and the volume of the power electronics interface between the sources and the load. Moreover, high power density and improved efficiency due to the elimination of the magnetics are the other significant features of an MSI. This article proposes a novel three-phase MSI for integration and active control of a high-voltage dc source and a low-voltage dc source. The proposed MSI structure employs a smaller number of semiconductor devices at the current path in various operating modes in comparison to the previously published counterparts, which results in an improved efficiency operation. Performance of the proposed MSI using a modified space vector modulation technique for all possible operating modes is verified through simulations and experiments on a laboratory prototype

Increasing environmental comfort using insect trap windows connected to DC high voltage source

A healthy and comfortable habitation in coastal areas is one of the requirements for establishing a modern society in the increasing number of water and air pollutions. On the one hand, high humidity and temperature levels reduce the convenience of settlements in coastal areas. This condition is even worsened in many houses, which are built with poor air circulation. On the other hand, when the house’s windows are opened to allow airflow, many insects such as mosquitoes will enter the room. Mosquitoes are carriers of many diseases in Indonesia, such as dengue fever, malaria, chikungunya and many more. For solving this problem, this paper proposes a solution by designing insect trap of windows connected to a DC high voltage source to exterminate mosquitoes. The source of electricity is obtained from PLN 220 Volt. The voltage from PLN is boosted to reach 3240 Volts. Our prototype has been demonstrated to exterminate a swarm of mosquitoes. When mosquitoes pass through the window trap, they will experience a short circuit, as their body is connected between negative and positive for a short period. The experiment results showed that the applied voltage of 14.6 kV was able to sting mosquitos to death. To prevent its high voltage impact and guarantee the safety of utilization, we provide a safety layer to prevent direct human contact. When it is not in use, the power source can be turned off by using wireless control.

A Novel DAC Generator for PD Testing of MV Cable Insulation

In this letter, a novel damped AC (DAC) generator is proposed and implemented, whose working principle is based on the seamless combination of the high voltage (HV) DC source and the HV solid switch by replacing the diodes in the DC voltage multiplier (VM) with controllable insulated gate bipolar translators (IGBTs). Both laboratory tests on a lumped capacitor and field tests on a 10 kV MV cable were performed to prove the feasibility of the proposed techniques.

Independent high voltage DC source development for renewable-grid integration interface

<span>Recent advancement in renewable-grid integration research, due to the concern on the environmental impact, leads to extensive study in isolated power converter as their interface. As part of isolation capability in power converter interface, extensive study of magnetic component has been carried out, especially on the design, construction and optimisation to achieve optimal operation. One of the main issue in verifying the analytical power loss model is to have independent HVDC link power source for an experimental validation work. This paper focus on the design and construction of DC link source, to be use in the experimental rig setup. Several DC link source option has been evaluated, and TDK-lambda PF500-360A power supply was selected due to the availability and excellent energy efficiency offered, at better price. External circuit is designed and implemented to achieve desired voltage and current supply characteristic. At the end, the voltage and current of the DC link supply for Dual H-bridges is obtained and shown promising result for experimental rig measurement and data collection work.</span>

High voltage designed and pulsed electric field circuit using standard sphere-gap method

The circuits designed of the high voltage pulsed source using the sphere-gap as switching and will be used as generating of the high voltage pulsed electric field (PEF). Based on the experiment testing that the high voltage source can produce 80 kV with the efficiency of high voltage DC source is 81.70% and the operating voltage of sphere-gap is 18.5 kV. Therefore, the intensity of the pulsed electric field of the design can be reached at 80 kV/cm. Based on this ranges that design can be used for electroporation process. Furthermore, this tool was tested into a sample, Nematode. For Nematode sample testing, the electric fields strength is E = 37.33 kV/cm on the voltage of between the electrode is 6.7 kV. Thus, the design of the pulsed electric field source using a sphere-gap has functioned.

Evaluation of Strength Measure for Static Voltage Stability Analysis of Hybrid Multi-Infeed DC Systems

This paper presents an evaluation method of strength measure for the static voltage stability analysis of the hybrid multi-infeed dc (HMIdc) system, which comprises both the line-commutated converter-based high voltage dc (LCC-HVdc) and voltage source converter-based HVdc (VSC-HVdc) links. For this purpose, the coupled single-port model proposed originally to assess the static voltage stability of ac power systems is first extended in the HMIdc system. In particular, how the LCC-HVdc and VSC-HVdc links should be modeled in the extended coupled single-port model is further investigated. Then, a generalized effective short-circuit ratio (GESCR) index is proposed as a strength measure for the static voltage stability analysis of the HMIdc system using the extended coupled single-port model. The GESCR can resolve the ambiguity encountered by earlier indices arising from empirical reasoning; thus, it is able to indicate the static voltage stability of the HMIdc system more accurately. Finally, the simulated results based on a classical simplified HMIdc system and a modified IEEE 118-bus system, both including two LCC-HVdc links and a VSC-HVdc link, validate the proposed GESCR.

Two-stage electrostatic precipitator with co- and counter-flow particle prechargers

Lab-scale, two-stage electrostatic precipitation system comprising of precharging stage, in which PM2.5 particles are electrically charged, and collection stage, in which the charged particles are removed from the flowing gas by electric field, was investigated in this paper. Two types of electrostatic particle prechargers were compared with respect to the collection efficiency of the system: (1) co-flow precharger, in which ionic current was generated co-currently with the gas conveying the particles, and (2) counter-flow precharger, in which ionic current was generated oppositely to the flowing gas. In each case, the electrodes of precharger were supplied with DC or AC high-voltage in order to compare the effect of discharge mode on the collection efficiency of two-stage electrostatic precipitator. The collection stage was formed by two parallel-plate electrodes connected to DC high voltage source. Plate electrodes without discharge points (spikes) are corona-free electrodes, which prevent the collection stage from electrical discharges, and reduce the probability of back discharge ignition. The back discharge decreases collection efficiency of conventional electrostatic precipitators.It was concluded that the co-flow electrode configuration of the precharger, supplied with DC high voltage, has the highest total number collection efficiency for PM2.5 particles, higher than 95% and the mass collection efficiency larger than 99%. The counter-flow precharger provided only about 90% number collection efficiency of two-stage electrostatic precipitator. It was also shown that by AC electrode excitation, the collection efficiency of the system is lower than for DC supply. The two-stage electrostatic precipitators allowed obtaining higher fractional collection efficiency for PM2.5 particles than other conventional systems and can be recommended as highly effective devices for gas cleaning in power plants or cement industry.

Experimental study of electrode erosion and aging process of a specially designed gas switch under repetitive arc discharge

In this paper, a study concerning self-breakdown voltage characteristics, electrode erosion, and degradation of the insulator, of a two-electrode spark-gap switch has been presented based on experiments. A 6 μF pulse capacitor and a DC high voltage source (set at −40 kV) were utilized to achieve ∼0.1 pulses per second repetitive arc discharge between two fixed Cu-W (Cu30/W70) alloy electrodes in the 1.2 L airtight chamber of the switch. With average transfer charge of 2.2 C per shot, this switch was tested for 5800 shots altogether. The results demonstrated the electrode erosion rate of the cathode was 6.3434×10−6 cm3/C whereas that of anode was 5.4691×10−6 cm3/C. Besides, by analyzing electrode surfaces' morphology and PTFE insulator surfaces' compositions after 5800 shots with the help of a scanning electron microscope, a dynamic 3D aspheric metrology instrument, an X-ray photoelectron spectrometer, a metallographic microscope, and a Mettler-Toledo analytical balance, some evidence of physical processes and chemical reactions between plasma channel, electrode materials, and insulation materials could be observed. Moreover, the chamber was opened and inspected for 10 times during the whole procedure, thus providing an overall description of the variation of the switch. It should also be pointed out that owing to complex mechanisms during the aging process, the self-breakdown voltage followed a mixed Normal distribution other than any other simple distributions.

A Simple and Cost-effective Precharge Method for Modular Multilevel Converters by Using a Low-Voltage DC Source

A simple and cost-effective precharge method for modular multilevel converter (MMC) by using a low-voltage direct current (dc) source is proposed in this paper. The submodule (SM) capacitors in MMC are required to be precharged to their nominal voltage values at start-up to ensure MMC work normally. Conventional methods perform the precharging either through grid side or dc side by using costly high-voltage bypass breakers, charging resistors or a high-voltage dc source. Voltage of the high-voltage dc source must be equal to SM capacitor voltage and could be as high as thousands of volts. By contrast, the proposed method employs a very low voltage dc source on dc bus through a series-connected blocking diode, and requires no charging resistor and bypass breakers. It takes advantages of the existing power devices, arm inductors, and SM capacitors in MMC, and configures them into boost circuit for the precharging. The proposed method is simple and cost-effective. Moreover, the characteristics of the boost circuit render the proposed method flexible. For instance, the voltage selection of the dc source is flexible and not restricted to a fixed value. The SM capacitors can be charged in different groups. In addition, the method is applicable to different MMC SMs, including SM with different capacitor voltages. The effectiveness of the proposed method is verified through simulation and experiment.

Study of the transient regime of the corona discharge generated by a triode electrode arrangement

Extensive research has been carried out on the electrostatic charging of the non-woven media for air filters. Nevertheless, the transient regime of corona charging of these media is a topic that still needs to be explored. The primarily aim of this paper is to study this phenomenon in the particular case of the corona discharge generated by a triode-type electrode arrangement. In the first set of measurements, the polypropylene non-woven media was subjected to positive or negative corona discharge generated by such an electrode arrangement, energized from a DC high-voltage source. The measured physical quantities were the electric current I m at the plate surface (with and without the sample in contact with the grounded plate) during the corona discharge process, for a duration of 30 s through a resistor R m = 10 MΩ connected between the metallic plate and the ground connection. The electrometer was interfaced with a computer to perform data acquisition using a virtual instrument developed in the LabView environment. The current I m stabilize after 5 s and was higher for an electrode without sample in contact with the grounded. The second set of experiments were similar to the first set of measurements except for the fact that the current in different areas of the grounded electrode was measured using a special designed printed circuit board (PCB) plate with seven strip current probes. The electrometer was connected as previously explained, in order to visualize the transient regime of corona current at different probes. The experimental results pointed out that the charging process is affected by the capacitance introduced by the media in the equivalent electric circuit of the triode electrode system.

Design and fabrication of compact fluorescent lamp igniter using TRIAC‐assisted high‐voltage DC source

A potential approach for designing and fabricating igniter for compact fluorescent lamp is introduced using high-voltage DC (HVDC) source which is controlled by gate pulse obtained from TRIAC-based firing circuit. The Cockroft-Walton voltage multiplier circuit is used to design HVDC (2 kV) sourc e where i ni ti al ly opti ma l rati ng of c apac it anc e f or each stage was considered based on experimental analysis. This design was further simulated by Multisim 11 and characterised experimentally. The response obtained by this method reveals that the HVDC source is able to ignite the fluorescence lamp potentially than the conventional available ignition processes. The major advantages of using HVDC are lower power to ignite fluore sc enc e l amp, longer li fe and cost ef fe ct ive.

A Novel Sinusoidal Damped Oscillating Voltage Generator for the Detection of Partial Discharge in MV Distribution Power Cables

This paper presents a damped oscillating voltage generator with a novel topology. In the proposed system, a sinusoidal voltage shape, rather than a cosinoidal shape, is used to detect the partial discharge (PD) of medium-voltage distribution power cables. Since this scheme uses a lithium battery instead of a high-voltage dc source, a mains power supply is unnecessary. The energy-storage device is used as an inductor rather than a capacitive test object, thus ensuring that the energizing process is successful even during the test of a deeply deteriorated specimen. This paper describes the working principle and the assembly and implementation of a laboratory prototype for the PD detection of a 200-m cable circuit. The experimental results prove the feasibility of the scheme.

Bifurcate modular multilevel converter for low‐modulation‐ratio applications

In this study, a novel modular multilevel converter (MMC) topology for low-modulation applications is proposed. The proposed topology has two three-phase AC ports and is characterised by its bifurcate arms and phase-shifted connection on the AC side. Conventional MMCs have been widely used in high-voltage direct current (HVDC) applications and are able to connect a low-voltage AC source to a high-voltage DC source, which makes them useful in applications such as DC/AC distribution systems and DC collection of renewable energy. However, high arm currents and high energy fluctuation caused by low-modulation ratio will increase converter losses and submodule capacitance. In the proposed bifurcate MMC, each arm has three branches and the branch current is lower than the arm current of the conventional MMC, so the difficulty of designing an MMC with low-modulation ratio is relieved to some extent. Theoretical analysis proves the stability of bifurcate MMCs and provides reference voltage solutions for each branch. A control scheme for a bifurcate MMC is also proposed, and further analysis shows that the circulating current is naturally suppressed under certain conditions. Detailed simulation is performed based on the RT-LAB platform and confirms the analysis results.

Mode Transition of Trichel pulses

The trichel pulse is a typical kind of negative corona current observed in electronegative gases. In this work, stochastic behavior of the trichel pulse has been investigated. The experiment is performed in a negative corona reactor consisting of a stainless steel pin and a stainless steel powered by a dc high voltage source. The characteristic parameters distributions of corona current pulses, including the amplitude, rise time, half-wave time, and repetition frequency, are analyzed statistically. The results show there is a mode transition during the period of voltage increasing. This transition process happens in a certain voltage region, and change of pulse amplitude is the main difference between the two modes.

A corona-discharge dipole engine

The construction and operation of a small-sized electrostatic engine are described. It consists of a rotor in the form of a thin-walled cylinder made from a dielectric material. There are two strips of metal foil along the two diametrically opposite generatrices of the cylinder. The gap between the longitudinal edges of the strips can be varied. Similarly, two electrodes, in the form of thin rigid plates with sharp edges facing the cylinder surface, are diametrically opposed to each other and parallel to the generatrices of the cylinder. Distances from the sharp edges to the surface of the cylinder have been varied. The device is powered by a highvoltage DC source providing a symmetrical bipolar corona discharge. Experimental dependences of the engine speed on the voltage between the electrodes for different geometrical parameters are given. Regression equations are derived and presented in a graphical form. An analytic substantiation of the engine operation principle is presented, and experimental and theoretical results are discussed.

Neutral gas temperature maps of the pin-to-plate argon micro discharge into the ambient air

This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device. The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.