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Generally, for pulsed power applications with low jitter and high repetition rates, the use of semiconductor switches have replaced the traditional gap switches and thyratron circuits due to the limited lifetime of the thyratron and gap switches under such operating conditions. However, the limited ratings of these semiconductor switches require series and/or parallel stacking in order to handle high voltages and current levels associated with the discharge energy. Described in this paper is the design of a high voltage switch that uses a simple and reliable gate driver circuit for pulsed power application. In this design, the switch module is made up of insulated-gate bipolar transistor (IGBTs) and their gate driver circuits compactly fitted onto a single module. The ease by which the switch modules can be configured (series stacking and/or parallel stacking) to meet future load variations allows for flexible operation of this design. In addition, the detailed implementation of the gate driver circuit for reliable and easier synchronization of the switches, the simultaneous transfer of both signal and power for current boost are also described in this paper. A 120 nF capacitor bank energy was discharged using a configuration of the developed high voltage switch and a developed 15 kV, 1.5 kJ/s peak power capacitor charger, and by experimental results, the operation of the proposed circuit was verified to be effectively used as a switch for pulse discharging. [ABSTRACT FROM AUTHOR]

In this paper, we propose and design a novel generator for the high voltage square pulses with the changeable polarities in order to reach the requirements and the needs for the intended experiments on sterilization of microorganism. The major component of our circuits is a non-trivial combination between a half bridge Marx generator and an H bridge in series, combining with the DSP control unit, which can adjust the voltages, frequencies, pulse widths and polarities, and also tolerate various loads. More precisely, we illustrate the design and operation principles for each module in the constructed circuit and analyze the system performance with various loads. The effectiveness and correctness of our proposed circuit and methodologies have been verified and demonstrated by both PSIM simulation results and our own prototype. In this paper, we also show the stability and reliability of the pulse generator we proposed in terms of various load conditions and operation safety respectively. Furthermore, we also observe that the key parameters based on our constructed pulse generator can be easily adjusted which include voltages, frequencies, pulse widths and polarities. We hope that our work will stimulate the further investigations on design and analysis of pulse generators with a focus on modularization and miniaturization. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to investigate the effect of a high-frequency high-voltage impulse conditioning technique on the inrush current interruption phenomena. In this paper, the inrush current interruption phenomena referred to the actual interruption and the currentless period following interruption. First, Six 7.2 kV vacuum interrupters (VIs) were conditioned by 400 batches of voltage impulses. The duration of each batch were set to 0.1 s. The peak value of each impulse could reach up to 100 kV. The repetition frequency of the impulse was set to 1000 Hz. The contact gap was 0.8 mm. The VIs were tested for the inrush current interruption performance with inrush current set to 2 kA and 5 kA, with a frequency of about 3800 Hz. The experimental results showed that there were two different types of inrush current interruption depending on high-frequency high-voltage impulse conditioning. The inrush current interruption type I referred to the inrush current interruption during the prestrike process before the contacts touched. This type inrush current interruption could be caused by the erosion of prestrike arc. Moreover, the high frequency voltage impulse conditioning influenced the occurrence frequency, the number of interruptions and the duration of the inrush current interruption type I. The inrush current interruption type II referred to the inrush current interruption during the contact bouncing process after the contacts touched. The inrush current interruption type II occurred only in the case of the VIs after conditioning. Furthermore, the occurrence frequency of the inrush current type II decreased with increasing inrush current. [ABSTRACT FROM AUTHOR]

Nowadays the phase controlled switching is a preferred method for capacitive switching. Thus the prestrike characteristic is an important issue for the control strategy. The objective of this paper is to understand the prestrike characteristics of vacuum interrupters (VIs) in the capacitive making operations of 40.5 kV vacuum circuit breakers (VCBs). In the experiment, three VIs with CuCr50 (50 wt% of Cr) contact material and three VIs with CuCr40 (40 wt% of Cr) contact material with contact diameter of 50 millimeters were prepared. The CuCr50 and CuCr40 contact materials are made by using infiltration and arc-melted technology, respectively. An L-C oscillating circuit generated an inrush current with a frequency of 207 Hz and with a peak of 6.48 kA, while the applied voltage was 46.3 kV which is equivalent to the peak voltage for a 35 kV three-phase network whose capacitive voltage factor is 1.4. The experimental results show that the complementary cumulative distribution function (CCDF) of the prestrike gaps dpre follows a 3-parameter Weibull distribution. The prestrike gap below which prestrike would always occur is similar for all six test VIs which is 2.4–3.1 mm. However, the average values of d\0, ¿50 and ¿90 for infiltration CuCr50 contact material are 57.5%, 45.3% and 28.9% higher than the ones in arc-melted CuCr40 contact material, respectively. During the inrush current flowing, at each zero-crossing of the inrush current the prestrike arc tries to extinguish with the occurrence of three types of contact gap breakdowns. Furthermore, if the contact gap breakdowns are withstood at the inrush current zero-crossing, inrush current interruption phenomenon happens, which proves a common phenomenon in capacitive making operation. The inrush current interruption phenomenon is mainly determined by the prestrike distance and not by the material quality. The experimental results imply that the field emission dominated breakdown and the micro-particle induced breakdown both take effect in the prestriking and contact gap breakdown process. [ABSTRACT FROM AUTHOR]

Recently, the pulsed power systems have found wide applications. For this reason, using the pulsed power generators that in addition to responding to the needs of the user, are providing the advantages of compactness, high flexibility, high repetition rate and cost efficiency is inevitable. This paper proposes a converter which is a combination of Marx topologies and solid state voltage multipliers. It is capable of producing high voltage pulses with varying amplitudes at different frequencies where is modular and flexible. The resonant circuit used in this structure can reduce the stress on switching element and increase the output voltage while providing a zero current switching for the full bridge converter. Its analytical design is described and its verification is proved by the simulation results in MATLAB\SIMULINK. As a proof of concept, the measurement results taken from the experimental prototype, are presented as well. [ABSTRACT FROM AUTHOR]

According to the IEC standards, test objects in back-to-back capacitor bank switching tests are subjected to inrush currents of 20 kA peak and 4250 Hz frequency during making operations. For vacuum interrupters (VIs), the contact surfaces may be seriously damaged by the high-energy arc of the inrush current. The field emission current characteristics reflect the surface microscopic conditions after undergoing the inrush current. The objective of this paper is to investigate the impact of the inrush current during back-to-back capacitor bank making operations on the field emission current characteristics of vacuum interrupters under AC power frequency voltage. The amplitudes of the inrush current were set as 10 and 20 kA, respectively. The sample VIs underwent the inrush current at each amplitude twice. After each inrush current, the field emission current of the VI was measured by applying a power frequency voltage upon the contacts with a fixed gap of 1 mm. By applying an AC power frequency voltage, an unsymmetrical field emission current was measured. In addition, according to the Fowler-Nordheim (F-N) theory, the field enhancement factor β and the effective emission area Ae were calculated. The experimental results show that there is a significant unsymmetrical field emission current at each polarity of the power frequency voltage. Moreover, during the voltage rising phase, the field enhancement factor β is higher and the effective emission area Ae is smaller than that during the voltage falling phase for both positive and negative voltage polarities. A heating-cooling hysteresis effect of the emission sites could explain the phenomena. [ABSTRACT FROM PUBLISHER]

Pulsed electric field (PEF) can be used effectively in water treatment applications by passing infected water through two electrodes excited from a high voltage pulsed power supply which guarantees killing the harmful germs. In this paper, a new high-voltage pulse-generator with closed loop control of its output voltage is presented for treating water via underwater pulsed streamer corona discharge. The proposed generator is fed from a low AC voltage source (utility mains 220 V, 50 Hz) which makes it suitable for domestic applications. The proposed topology provides transformer-less operation which reduces the system size and enhances the overall efficiency. The proposed topology is based on capacitor-diode voltage multiplier (CDVM) circuits in conjunction with DC-DC converters (Boost and Buck-Boost converters). The simulation and experimental results elucidate the proposed configuration. [ABSTRACT FROM AUTHOR]

This paper presents the design of IGBT-based switching modules for a nitrogen gas laser. First, the CC-topology, which drives the laser, is discussed and simulated. Simple models of the laser tube and the switch are presented. The comparison of the simulation with experimental data shows good accuracy. The results are used to discuss the influence of the parasitic inductance and the capacitances on the laser tube behavior. Cascades with an 11-cell series connection based on different IGBT-chips (1700 V and 1200 V) have been built up and measured. The focus of the design is the high speed synchronous switching of all switching cells. Therefore, the design of a pulse transformer-based gate drive and a symmetrization network is presented. The module equipped with the four parallel 1200 V/35 A-IGBTs per cell produces the highest switching power. Among the variants, the switch peak current is up to 700 A at blocking voltages of up to 13.2 kV in the real environment of the nitrogen laser. The switch current slope reaches up to 30 A/ns and the laser tube current up to 1.8 kA. The variant with 1200 V/35 A-IGBTs produces an output energy which is about 15 % higher compared to the former MCT-based switch. Furthermore, a modified CCtopology for lower blocking voltage is investigated. The IGBT-based switches are able to replace the MCT-switches in this application. Between the different switches a tradeoff has to be done between high output energy and the effort for the assembly. [ABSTRACT FROM PUBLISHER]

Many research fields need special high-voltage pulses in pulsed power applications, which are different from typical rectangular pulses. In this paper, a high-voltage waveform modulator of two methods using a solid-state Marx generator has been developed and tested. Instead of manufacturing a generator with a specialized structure, the modulator can control a general Marx generator by low-voltage programmable logic devices to produce an irregular but controllable high-voltage triangular pulse with pulse length of ~4.5 μs and peak voltage of ~123 kV. [ABSTRACT FROM PUBLISHER]

This paper presents a capacitor charging power supply (CCPS) using high-voltage dc/dc converter for pulsed power applications. For the main converter, it used full-bridge phase-shifted (FBPS) pulse-width modulation (PWM) converter. The proposed CCPS has modularity concept, and the output voltage was boosted by a high-voltage high-frequency (HVHF) transformer included in FBPS PWM converter. The control method is used a phase-shifted PWM to reduce the losses caused by switching. To solve the voltage unbalancing problem of the output capacitors, synchronization algorithm is selected. Also Thermal characteristics are analyzed by theoretical calculation and simulation. Experimental results of the single module and CCPS are provided to validate the effectiveness of the proposed system and it was carried out the 20-kV 160-kW prototype. [ABSTRACT FROM PUBLISHER]

The electromagnetic radiation effect of high-voltage, subnanosecond pulsed electric fields attracts strong interest from researchers because of its significant development potential in biological treatments, particularly in noninvasive diagnosis and treatment. But up to now, high-voltage subnanosecond pulse generators are widely used for national defense and military, and they are difficult to implement successfully in the civil medical field. A compact, self-contained, repetitive frequency, high-voltage subnanosecond pulsed power source is proposed in this paper. It was designed, built, and tested successfully. Based on a four-stage, low-inductance Marx generator, the pulsed source produces subnanosecond rise-time pulses. A chopping switch was designed to cut off unformed signals and generate subnanosecond pulses. A measurement device, based on the principle of a capacitive voltage divider, was also constructed to determine both the amplitude and the rise-time of the pulse delivered by the source. Preliminary tests show that the source can produce repetitive frequency pulses with a peak value that exceeds 30 kV, as well as rise-time and pulse width (full wave at half maximum) within 1 ns under atmospheric pressure conditions. The pulse amplitude may be extended to hundreds of kilovolts by filling the switch system with an inert gas. The rise-time would be shortened as well. The pulsed power source shows optimistic prospects in the biological fields. [ABSTRACT FROM PUBLISHER]

With the fast development of multi-terminal high-voltage direct-current (HVDC) transmission technology, there is an urgent demand for the HVDC interruption technique. In this paper, an interruption scheme for HVDC based on artificial current zero is proposed with its main circuit breaker consisting of modularized vacuum switch in series. A triggered sphere gap is adopted as the commutation switch to achieve bidirectional DC interruption. The interruption process, particularly, the most important two commutation processes, is simulated based on a circuit model. The residual current and its influence after current commutation, which might exist due to the weak arc extinguishing capacity of the sphere gap, are analyzed. It is proposed to use back-up circuit breakers to interrupt the residual current. Furthermore, the influence of the frequency of the countercurrent on the interruption process, particularly, on the integral of i2t in the triggered sphere gap due to the residual current, is discussed. [ABSTRACT FROM AUTHOR]

Along with rapid advancement of power semiconductors, voltage multipliers have introduced new series of pulsed power generators. In this paper, based on conventional voltage multiplier and by using power electronics switches a new topology in high voltage pulsed power application is proposed. This topology is a modular circuit that can generate a high output voltage from a relatively low input voltage with fast rise time and adjustable frequency, pulse width, and voltage levels using a series connection of switched capacitor cells. A comparative analysis is carried out to show the advantages of proposed topology. Experimental and simulation results are presented to confirm the analysis. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate an impact of the inrush current on the prestrike and restrike characteristics of vacuum interrupters (VIs) during capacitive current switching duty. Eleven 7.2 kV VIs are used. Their contact parameters are contact gap 4 mm and contact material CuCr25 (25%weight of Cr). A series of 80 CO operations are executed for each test VI. The amplitude of inrush current Iinrush (3800 Hz) is set to 0 kA, 2 kA, 5 kA and 10 kA, respectively. The switching current is less than 1 A rms. The (1-cosωt) shape of the recovery voltage with a peak of 15 kV is applied to the test VI. The experimental results show that the prestrike and restrike phenomena are significantly influenced by the contact surface conditions damaged by the inrush current. The cumulative probability of the prestrike gap dpre follows a 3- parameter Weibull distribution. When Iinrush increases from 2 kA to 5 kA, the prestrike gap increases accordingly. The 10% dpre increases from 0.5 mm to 0.7 mm. The 50% dpre increases from 0.7 mm to 1.0 mm. The 90% dpre increases from 1.0 mm to 1.5 mm. The scale in the Weibull distribution, which can describe the scattering of dpre, is 0.2 mm and 0.6 mm in the case of Iinrush = 2 kA and Iinrush = 5 kA, respectively. It is found that the occurrence frequency of the inrush current interruption increases from 37.9% to 68.3% with the increase of Iinrush from 2 kA to 5 kA. Moreover, the inrush current also has an impact on the restrike types, which are classified into three types according to the waveform features. The average restrike probability increases from 4.6% to 17.9% and further to 30.4% with the increase of the inrush current from 0 kA to 2 kA and 5 kA, respectively. In addition, the higher the inrush current, the restrike tends to occur earlier during the recovery voltage period. [ABSTRACT FROM AUTHOR]

Capacitor charging power supply (CCPS) is one of the most important components of a pulsed power system. The CCPS studied in this paper is used in power conditioning systems for Laser Nuclear Fusion. With a view to enabling multiple CCPSs to work concurrently in an environment of high voltage, high power and strong electromagnetism, this paper carries out a profound and systematic research into the characteristics of a capacitor charging power supply, including charging rate, harmonic features, efficiency and voltage precision, etc. Furthermore, some measures to improve the characteristics of CCPS are put forward. The advantages of high charging rate, low harmonic, high efficiency and accurate charging voltage are proved by the results of experiments and the performance in practical operation on a 23.5 kV, 50 kW, 4400 μF CCPS. [ABSTRACT FROM AUTHOR]

When driving capacitive loads, pulses with steep falling edges are difficult to obtain using conventional pulsed power modulators, which also makes them unsuitable for operating at higher frequencies. In this paper, a repetitive high voltage pulse adder is described, which can generate nearly rectangular pulses even with capacitive loads. This pulse adder is based on solid-state switches, and each power stage contains two Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs): one set which outputs high voltage pulses and the other set which is used to dissipate charges stored in the load and distributed capacitors. Testing the proposed pulse adder with dielectric barrier discharge (DBD) loads, nearly rectangular pulses are obtained. In our present work, a 40-stage modulator has been built and successfully operates at an output voltage of 30 kV and a repetitive frequency of 20 kHz. The rise and fall times are less than 200 ns, and a minimum pulse width of 6 μs was obtained. This prototype has been applied in DBD experiment research. [ABSTRACT FROM AUTHOR]

This paper describes the design of a 48 kJ/s high-voltage capacitor charging power supply (CCPS), focusing on its efficiency, power density, and reliability. On the basis of a series-parallel resonant converter (SPRC) that provides high efficiency and high power density owing to its soft-switching, the design of the CCPS is explained in detail, including its input filter, resonant tank parameters, high-voltage transformer and rectifier, as well as its protection circuit. By using two resonances per switching cycle, which provides a trapezoidal instead of a sinusoidal waveform of the resonant current, the proposed CCPS can take advantage of the lower conduction loss and reduced switching loss by improving the crest factor and allowing a higher value of the snubber capacitor, respectively. In addition, the compact design of an input filter without bulky components such as a DC reactor and an electrolytic capacitor allows for high power density, a high power factor, and low cost. In addition, the control loops for the voltage and current were optimized with a fast response time in order to compensate for the low frequency ripple of the input voltage, which results from the reduced filter component. Experiments on the developed charger were carried out with both resistor and capacitor loads in order to measure not only its efficiency and power factor with respect to the output power but also its charging time, in order to estimate the average charging current. The experimental results obtained with a resistor load showed a maximum efficiency of 96% and a power factor of 0.96 for a full-load condition. For the measured charging time of a 4 mF capacitor, with 9.68 s for 10 kV charging, the average charging current was estimated as 4.13 A. Moreover, to verify the reliability of the developed CCPS, a variety of tests, including opening and shorting of the output terminal as well as misfiring of the discharge switch during the charging operation, were performed with a 200 kJ pulsed power system. Finally, it was experimentally confirmed that the developed CCPS shows high performance in terms of efficiency (96 %), power factor (0.96), and reliability with a high power density (820 W/L). [ABSTRACT FROM AUTHOR]

This paper describes a novel MOSFET gate driver circuit design for pulsed power application. It is shown that MOSFET switching speed can be enhanced by using an energised inductor as a high current source in series with the gate terminal of a power MOSFET. This topology demonstrates switching speeds of less than 10ns for MOSFETs with high input gate capacitance. It is also shown that by increasing the current in the gate drive and with an optimised layout, a single gate driver can be used to drive multiple parallel connected MOSFETs synchronously without compromising their performance. The circuit design is analysed and experimental results presented when operating at an instantaneous power of 25 kW. [ABSTRACT FROM AUTHOR]

Capacitor charging power supply (CCPS) is a developed technology that utilizes resonant converters topology for high power applications. This paper proposes new a capacitor charging power supply using leg-rotation control method within a phase-shifted PWM full-bridge dc/dc converter. The capacitor charging power supply was connected in series to increase output voltage. Also, the proposed system is designed with soft switching techniques in order to achieve high efficiency, and a leg-rotation control method was used to reduce the heat generated from the IGBTs. The operation of the converter and design methodology will be described. A simplified model of a high-voltage high-frequency transformer is given and the structure is designed to decrease high-voltage stress. The validity of the proposed system is then verified by experimental results. The performance test of the capacitor charging power supply was carried out with a 2 μF capacitive load with a 20 kV output voltage. [ABSTRACT FROM AUTHOR]

This paper describes the design of a compact and highly repetitive pulsed power modulator based on semiconductor switches. Output specifications of the proposed modulator are as follows: variable output pulse voltage, 1-10 kV; width, 1-10 μs; pulse repetition rate (PRR), 1-50,000 pps; and average output power, 10 kW. The proposed solid-state pulsed power modulator has two main parts: an IGBT stack that hasa gate drive circuit for the pulse output with a variable pulse width and repetition rate, and a capacitor charger that has a controllable output voltage. To connect all the storage capacitors in a series for high voltage pulses, a simple and reliable IGBT stack structure was proposed based on the Marx generator. In addition, the gate driver circuit, which supplies power and signals to all the IGBTs simultaneously, was introduced. This providesa superior protection function against the arc and the short. To charge the storage capacitors, a novel 10 kW (10 kV, 1 A) high voltage capacitor charger with the combined advantageof a series-loaded resonant converter and a ZVS (zero-voltage-switching) full-bridge pulse width modulation (PWM) converter was proposed and designed especially for the solid-state pulsed power modulator. Theexperiment results verified that the proposed scheme and structure can be used effectively for a high voltage pulsed power modulator that requires variable voltage, repetition rate, and pulse width, depending on the process of the applications. [ABSTRACT FROM AUTHOR]

In this paper athree-stage pulse generator architecture capable of generating high voltage, high current pulses is reported and system issues are presented. Design choices and system dynamics are explained both qualitatively and quantitatively with discussion sections followed by the presentation of closed-form expressions and numerical analysis that provide insight into the system?s operation. Analysis targeted at optimizing performance focuses on diode opening switch pumping, energy efficiency, and compensation of parasitic reactances. A compact system based on these design guidelines has been built to output 8 kV, 5 ns pulses into 50 ?. Output risetimes below 1 ns have been achieved using two different compression techniques. At only 1.5 kg, this light and compact system shows promise for a variety of pulsed power applications requiring the long lifetime, low jitter performance of a solid state pulse generator that can produce fast, high voltage pulses at high repetition rates. [ABSTRACT FROM AUTHOR]

This paper presents a novel topology for the generation of high voltage pulses that uses both slow and fast solid-state power switches. This topology includes diode-capacitor units in parallel with commutation circuits connected to a positive buck-boost converter. This enables the generation of a range of high output voltages with a given number of capacitors. The advantages of this topology are the use of slow switches and a reduced number of diodes in comparison with conventional Marx generator. Simulations performed for single and repetitive pulse generation and experimental tests of a prototype hardware verify the proposed topology. [ABSTRACT FROM AUTHOR]

This paper presents operational data and parameters of the newest generation of polyphase resonant high voltage converter modulator (HVCM) as developed and delivered to the KAERI 100 MeV "PEFP" accelerator. The KAERI design realizes improvements from the SNS and SLAC designs. The present KAERI system operates two parallel THALES TH2089F 350 MHz klystrons with total power draw of 50 amperes at 105 kV. An additional 3 klystron system operating at 105 kV and 75 A is also being considered for the high energy sections of this accelerator. In these systems, to improve the IGBT switching performance, the HVCMs will be fitted with artificial zero-voltage-switching (ZVS) networks at turn-off. This new method of artificial ZVS should result in a 6 fold reduction of IGBT switching losses. This will improve the HCVM conversion efficiency to better than 95% at full average power, which is 500 kW for the 2 klystron system and 750 kW for the 3 klystron system. The artificial ZVS is accomplished by placing a soft switching capacitor network across the resonant boost transformer primary winding. This low loss snubber circuit reduces the dv/dt across the IGBTs at turn-off. As the transformer input busswork is extremely low inductance (<10 nH), the single network acts like it is across each IGBT collector-emitter terminal of the 4 transistor H-bridge switching network. We will review these topological improvements and the overall system as delivered to the KAERI accelerator with details of the installed operational results. [ABSTRACT FROM AUTHOR]

This paper describes the operation of a solid-state series stacked topology used as a serial and parallel switch in pulsed power applications. The proposed circuit, developed from the Marx generator concept, balances the voltage stress on each series stacked semiconductor, distributing the total voltage evenly. Experimental results from a 10 kV laboratory series stacked switch, using 1200 V semiconductors in a ten stages solid-state series stacked circuit, are reported and discussed, considering resistive, capacitive and inductive type loads for high and low duty factor voltage pulse operation. [ABSTRACT FROM AUTHOR]

Improving efficiency and flexibility in pulsed power supply technologies is the most substantial concern of pulsed power systems specifically with regard to plasma generation. Recently, the improvement of pulsed power supply has become of greater concern due to the extension of pulsed power applications to environmental and industrial areas. With this respect, a current source based topology is proposed in this paper as a pulsed power supply which gives the possibility of power flow control during load supplying mode. The main contribution in this configuration is utilization of lowmedium voltage semiconductor switches for high voltage generation. A number of switch-diode-capacitor units are designated at the output of topology to exchange the current source energy into voltage form and generate a pulsed power with sufficient voltage magnitude and stress. Simulations carried out in Matlab/SIMULINK platform as well as experimental tests on a prototype setup have verified the capability of this topology in performing desired duties. Being efficient and flexible are the main advantages of this topology. [ABSTRACT FROM AUTHOR]