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This paper has introduced two important indexes, turn-off surge voltage (TSV) on power switch and peak positive pole potential (PPPP) of storage batteries, which can be used to evaluate switching transient process of high-voltage energy storage system. Research on them is of great significance to power switch choice and high-voltage isolation design in engineering applications. Power switch response process at the turning off moment and transient process in freewheel stage have been analyzed by the established small-signal model of single power switch; then, a power switch test platform for hybrid energy storage system was built to verify it. Taking pulsed-power supply charging device with a novel inductor of low resistance and high inductance as a research object, this paper has analyzed dynamic process of the TSV and the PPPP at the turning off moment through establishing state space model of the whole system. Comparison shows that the numerical curves match the simulated curves well. Finally, the exactness of the employed model has been further verified in two pulse capacitor charging experiments. [ABSTRACT FROM AUTHOR]

This paper discusses a novel methodology to increase the voltage droop compensation range in generalized solid-state bipolar high-voltage Marx modulators with one resonant stage. To maintain the modularity characteristic of bipolar Marx modulators, the imbedding of additional resonant stages is not straightforward. Nevertheless, this paper proposes to add a second resonant stage to the already existing resonant-type voltage droop compensation stage. This second stage increases the voltage droop compensation percentage of a generalized solid-state bipolar Marx generator. The compensation of the bipolar pulse voltage droop is now achieved by adding two auxiliary synchronous compensation resonant voltages, to the output capacitive decaying voltage. Simulation and experimental results are presented for six Marx plus two resonant stages, 16% voltage droop, with 3-kV pulse amplitude, 100- $\mu \text{s}$ pulsewidth, 40-ms relaxation time, and 10-Hz pulse repetition rate. [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of a sample of Marx pulsed generator based on boost converter (BC) pulse-forming networks (BCPFNs). BCPFN is used instead of the conventional Marx floors for constructing this pulsed generator. BCPFN is carried out by connecting inductors and capacitors in series and parallel modes, respectively, by using solid-state switches, and during this procedure the pulsed generator converts to BC temporarily and increases the voltage of capacitors uniformly to a considerable value. This technique causes an increase in the discharging voltage level to the load that is many times more than its dc voltage source by charging the capacitors to a greater level. In order to take advantage of the benefits of Marx generator and PFN, this paper suggests a new circuit with the minimum number of switches. It means, to compose BCPFN and Marx, we have tried to design the circuit with fewer switches and instead of it we have achieved our desired performance with changing the operating mode in the states of BC, PFN, BCPFN, and BCPFN Marx. The results are simulated with MATLAB software. At the end, the experimental results of the construction of the above-mentioned system at low-power levels are presented, and the topology’s accuracy is proved by comparing them to the results of simulation. [ABSTRACT FROM AUTHOR]

High power pseudospark switches (PSSs) can control pulsed high voltage, high peak current discharges. In this paper, a PSS in series with a saturable inductor at the anode is investigated. The commutation process is analyzed with a time-resolved method. And the effects of the number of magnetic cores and anode voltages on discharge characteristics are studied experimentally. At the beginning of commutation process, when the anode voltage is 10.4 kV with four magnetic cores, the inductor is unsaturated, and there is a flat plateau of the forward voltage drop after the anode voltage drops rapidly to about 200 V, at the same time the current rise rate is 2.8 kA/ $\mu \text{s}$. When the inductor is saturated, there is a voltage spike that occurs at the end of the flat plateau, and the current simultaneously rises rapidly at the rate of 6.4 kA/ $\mu \text{s}$. The current sharp rise lags behind the voltage drop of the pseudospark gap, and the electrode erosion and energy dissipation reduce significantly. When the anode voltage is 15.6 kV, the commutation losses reduce by about 30% with seven cores in series at the anode. As a result, it is evident that the discharge process will speed up if the anode voltage is higher. And the trigger delay decreases by up to 8% when the anode voltage varies from 5.2 to 15.6 kV. Finally, in order to obtain a reproducible pseudospark discharge by the use of a saturable inductor, the number of magnetic cores has to be optimized for different anode voltages. [ABSTRACT FROM AUTHOR]

This paper describes a study on the high-voltage compact solid-state pulsed-power modulator for parallel reactor operation. The current capacity of the pulsed modulator has been improved to drive multiple reactors in parallel. The pulse discharge switch uses the IXYK120N120C3 (1200 V/120 A) insulated-gate bipolar transistor for a high current output. The gate driver has been improved according to the characteristics of the replaced switch. The output specifications of the modified pulsed-power modulator are a maximum output voltage of 40 kV, a maximum output current of 300 A, a pulsewidth ranging from 1.5 to $5~\mu \text{s}$ , a maximum repetition rate of 3 kHz, and an average power of 13 kW. The modulator has the dimensions of $450 \times 475 \times 600$ mm3, a maximum peak power of 12 MW, and a maximum power density of 93 kW/L. A resistive load experiment and a plasma reactor parallel drive test were performed. Four parallel reactors were driven using one modulator. In addition, a 50% reduction in the concentration of toluene was obtained through the experiment of the toluene gas treatment using only parallel plasma reactors. [ABSTRACT FROM AUTHOR]

Because it possesses higher current turn-off capability, the inverse current commutation with semiconductor devices (ICCOS) is a better option for the opening switch of an inductive pulsed power supply than the integrated gate commutated thyristor. This paper investigates the counter-current capacitor, which is the key component that determines the turn-off result and the volume of the counter-current branch. The major contributions of this paper include the following: 1) deriving an analytical expression for the minimum precharged capacitor voltage that can reliably turn off the main switch; 2) verifying this expression through a series of experiments within a current range of 0 to 4000 A and an energy range of 0 to 50 kJ; 3) giving an approximate expression for the optimal capacitance that minimizes the precharged energy; and 4) investigating the variation trends of the optimal capacitance and the corresponding optimal precharged energy with varying inductor current. [ABSTRACT FROM PUBLISHER]

Superconducting pulsed-power supply (SPPS) provides an efficient method for both high-density inductive energy storage and high current pulse generation. An SPPS consisting of eight high-temperature superconducting pulsed-power transformer (HTSPPT) modules with XRAM methodology was designed and simulated in preliminary studies. It recycled the leakage flux energy and reduced the voltage across the opening switch with a capacitor in primary. However, the SPPS with XRAM methodology has two problems. The first one is that it can provide high pulse amplitude, but cannot provide enough width. The other one is that the ratio of the maximum capacitive energy over the total inductive energy is relatively large, which cuts down the overall system energy density. This paper proposes a modified topology of SPPS with capacitor reuse methodology. Multiple HTSPPT modules are divided into several groups. Each group shares the same capacitor. The procedure of the modified SPPS is presented in detail. A 270-kJ SPPS with capacitor reuse methodology is designed and simulated to illustrate the modified topology. With the load parameters of a small railgun, the peak value of the load current is 207.15 kA and the pulse half-height width is 5.56 ms, the ratio of the maximum capacitive energy over the total inductive energy is 11%. The characteristics of the modified topology are also described in detail in this paper. [ABSTRACT FROM PUBLISHER]

In this paper, we discuss and demonstrate the potential of normally-on GaN high-electron-mobility transistors (HEMTs) as opening switches in miniaturized pulsed-power circuits. The high-breakdown electric field of GaN (~3 MV/cm) makes it possible to fabricate high-voltage devices in small dimensions, resulting in smaller parasitics and faster switching times. GaN HEMTs as opening switches are compatible with inductive topologies, which offer more than one order of magnitude higher energy density than capacitive topologies, allowing further miniaturization of pulsed-power systems. In this work, we demonstrate the application of fabricated 1.5-kV normally-on GaN HEMTs on an inductive switching topology, resulting in 300-fold voltage step-up, which makes it possible to generate high-voltage pulses with a low-voltage dc source in miniaturized circuits. [ABSTRACT FROM AUTHOR]

This paper proposed the use of a ringer, a self-switched inductive storage system, for applications involving reluctance accelerators, a kind of electromagnetic launcher, and compatible with applications where portability is a requirement. There will be shown three different useful approximations for the analysis of the ringer, employed as a power source for a reluctance accelerator. First, it described the equations governing the que behavior of an ideal unloaded ringer, and then the equations for the ringer with an uncoupled inductive load, and ultimately a Lagrangian model for the ringer as an inductive power source for a reluctance accelerator, capable to make predictions about the currents through the circuits and the exit speed of the projectile for a given firing. The accuracy of the predictions made with the third approximation, the Lagrangian model, was tested experimentally. [ABSTRACT FROM AUTHOR]

This paper is aimed at finding the effect of varying inductive energy storage systems’ (IESSs) inductance on resistance of an electrically exploded conductor-based opening switch and profile of current transferred into load, which has not yet been fully understood. Based on experimental results obtained, it is observed that when the inductance of IESS is varied, the magnitude of load current changes so as to conform to the magnetic flux conservation law but its rise time remains unchanged. Resistance of the opening switch and energy deposited in it has been estimated using recorded voltage and current waveforms. It has been found that with increasing inductance of IESS, the resistance of switch increases, whereas energy deposited in it decreases. Using these estimated values of energy, a possible explanation of observed behavior in resistance is presented. Effect of a mismatch between the inductance of IESS and load is seen to only affect the energy transfer efficiency or magnitude of load current but not its rise time emphasizing the novel finding that for a given load, the rise time of load current is independent of the inductance of IESS. [ABSTRACT FROM AUTHOR]

In this paper, a high-voltage unipolar pulse power generator is introduced for electroporation applications. Operating principle of the proposed structure is based on the buck–boost (BB) converter. The generator is comprised of parallel modules connected to the converter through an SCR and is supplied by a low-voltage dc source. Each module consists of an insulated gate bipolar transistor (IGBT), two diodes, and a capacitor. In fact, the proposed topology is a combination of the Marx generator and BB (MG-BB) converter. In comparison with other modular MG-BB structures, the proposed topology achieves interesting advantages including simpler structure, reduction of IGBTs voltage rating, and reducing number of components (inductors and switches). In order to clarify the features of the proposed structure, it has been compared with other unipolar MGs considering different aspects including the number of circuit components, number of required input supplies, amplitude of the output pulse, and the maximum voltage across switches and diodes. To validate the effectiveness of the structure, simulation and experimental results are presented. The results confirm that the proposed topology is capable of generating unipolar pulses with desirable amplitude and repetition frequency using a low-voltage dc supply. [ABSTRACT FROM AUTHOR]

Recently, inductive energy storage systems have attracted interests due to high energy densities. The high-temperature superconducting pulsed-power supply (HTSPPS) is one inductive PS topology for electromagnetic launching system. The topology can achieve a high amplitude load current and cut down the electrical losses due to the zero resistance characteristic of superconducting inductors. However, in this topology, the integrated gated commuted thyristor is used as a switch and cannot withstand high current, which limits the expansion of the system. Besides, it has significant current amplification ability as a single unit, but one module cannot provide sufficient amplitude and appropriate pulsewidth for the load current of the electromagnetic launching. In this paper, by applying the principle of inverse current commutation with semiconductor devices (ICCOS) in the HTSPPS, a novel circuit topology called HTSPPS with ICCOS is presented. This topology is analyzed and the multiple modules system is established. Simulation results show that the HTSPPS with ICCOS exceeds the current limitations of the original one and ensures the reliable cutting off of the main switch. It has potential applications in the future of high-energy systems while reducing the cost greatly. By asynchronous cooperative triggered discharge of the multiple HTSPPS with ICCOS modules in parallel, the appropriate amplitude and flat shape current of the load can be achieved through the careful design of the trigger time. [ABSTRACT FROM AUTHOR]

Paralleled pulse-forming units (PFUs) with different triggering delays might be a paramagnetic way for generating flat-topped current wave for electromagnetic launch. Many researchers have reported that multiple capacitive storage PFUs were implemented such current waves in laboratories. However, due to its low energy density, the applications of the capacitive pulsed-power supplies are limited. Since the inductor has advantages in energy density, the inductor pulsed-power supply becomes one of the hottest topics recently. The slow transfer of energy through capacitive hybrid meat grinder with inverse current commutation with semiconductor devices proposed by Tsinghua University has demonstrated its advantage and applicability recently. Using this kind of topology, this paper proposes the design of an inductive storage PFU with a stored energy of 100-kJ. The maximum load current reaches to 50 kA and its pulsewidth is at least 5 ms. The optimized inductive storage PFU shows superiority in contrast to the capacitive storage PFU with the same energy. This paper offers the theoretical analysis and the testing foundation for investigating the inductor pulsed-power supply with higher energy. [ABSTRACT FROM PUBLISHER]

The STRETCH meat grinder is one typical inductive pulsed-power supply topology for electromagnetic launch system. It has remarkable current amplification ability as a single unit, but one module cannot provide enough amplitude and width for the load current of the railgun launching. This paper discusses the effects of different triggering delays on the load current with two STRETCH meat grinder modules. To reduce the magnetic field coupling between the two modules, the two main switches are opened simultaneously. To make the load current waveform with no notch, the thyristor of the first module is triggered when its pulse-forming capacitor is fully reversely charged. For the thyristor of the second module, we consider several time points of triggering delay. Because of the practical constraint for the maximum rail current that ensures no rail erosion, the rectangular waveform is the most appropriate load current waveform. Therefore, the comparing criterion can be defined as the ratio of the load current waveform area and its maximum rectangle area at different current levels. Higher ratio means that the current is more like a rectangular wave and is better accordingly. Based on the above criterion and extensive simulation research, we found that the best delay time is the moment when the capacitor is reversely charging the inductor completely. This paper and the result are of great theoretical significance for the further study on the collaborative triggering of multiple STRETCH meat grinder modules. [ABSTRACT FROM PUBLISHER]

A novel circuit with the better performance for the inductive pulsed power supplies in the electromagnetic launch system is proposed in this paper, namely, the meat grinder with capacitive pulse forming unit (CPFU). Its working process is qualitatively analyzed stage by stage. Its practical feasibility is verified through a 7.5-kJ experiment. From the perspectives of circuit structure and working principle, this circuit can be regarded as the combination of a meat grinder and a CPFU. Compared with its preceding circuits, this circuit possesses following advantages: 1) the self-recovery of the capacitor precharged voltage can easily be achieved, which is conducive to continuous operations of the whole circuit and 2) the waveforms of the inductor currents contain no capacitive components, which can promote the energy storage density of the inductors. [ABSTRACT FROM PUBLISHER]

The opening switch is one of the critical technologies in the development of inductive pulsed-power supply. The power requirement is very high when the opening switch is desired to commutate a large current. This paper presents a zero-current opening circuit for inductive pulsed-power supply based on a high-temperature superconducting pulsed-power transformer. First, there are two types of current flowing through the opening switch, one comes from the secondary side of the pulse transformer, and the other one comes from superconducting energy storage inductance. The orientation of the two current is opposite. Then, when the current flowing through the opening switch closes to zero, the switch is opened and this restrains the over-voltage pulse of the opening switch. The simulation results indicate that this zero-current opening circuit is feasible and has potential applications for high-energy systems in the future electromagnetic launcher. [ABSTRACT FROM PUBLISHER]

A 200 kJ pulsed power system (PPS) has been built up to drive pulsed plasma devices. This PPS consists of two 100 kJ capacitor bank modules, each comprising of five capacitors of each 178~\mu \textF , a discharge switch, and a pulse-shaping unit. When both the banks are charged simultaneously to −15 kV using full charging technique, it delivers a peak current 100 kA at the load (damping resistor and pulse-shaping inductor). Later on, a plasma system will be attached at the load which will also have an inductive and resistive effect. A fiber-optic triggering unit controls both the modules and there exists a flexibility of sometimes operating a single module only, besides there are provisions for further up gradation of the PPS to a targeted 600 kJ. Prior to this development, PSpice simulation was carried out to estimate the parameters of the circuit components to achieve the required wave pulse with precision. Using these parameters, a design of the PPS was made keeping into account about the critical issues involved and the ratings of the components, some of which were fabricated in house. This paper basically includes the criticality surrounding the operation of a high-energy long-pulse PPS under negative operating voltage. [ABSTRACT FROM AUTHOR]

The meat grinder is a basic circuit for inductive pulsed-power supply (IPPS). Based on meat grinder, the Institute of Advanced Technology proposed a circuit called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder, in which an Integrated Gate Commutated Thyristors (IGCT) is selected as the main switch. Tsinghua University proposed the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS) in which the main switch is replaced by a thyristor and the ICCOS subcircuit is introduced to turn off the main switch. To reduce the opening switch voltage and increase the current turning-off capacity for IPPS, this paper presents a novel circuit topology named the meat grinder with self-charged capacitor and thyristors (SECTs). The key idea of the SECT topology is to turn off the primary current by the energy transfer capacitor, which is precharged. The meat grinder with SECT has larger capacity than the STRETCH meat grinder because it replaces the IGCT with a thyristor and is simpler than the STRETCH meat grinder with ICCOS because it only needs one capacitor. The suggested circuit is more suitable for IPPS module with high energy density. Simulation and experiment have been carried out to validate the circuit. [ABSTRACT FROM PUBLISHER]

This paper addresses inductive pulsed power generators and their major components. Different inductive storage designs, such as solenoids, toroids, and force-balanced coils, are briefly presented and their advantages and disadvantages are mentioned. Special emphasis is given to inductive circuit topologies, which have been investigated in railgun research, such as the XRAM, meat grinder, or pulse transformer topologies. One section deals with opening switches as they are indispensable for inductive storages and another one deals briefly with superconducting magnetic energy storage for pulsed power applications. Finally, the most relevant inductor systems, which have been realized with respect to railgun research, are summarized in Table I, together with their main characteristics. [ABSTRACT FROM AUTHOR]

With inherent strengths in energy density and power density, the inductive pulsed power supplies (IPPS) have become an attractive option for the power supplies in electromagnetic launch systems. The meat grinder circuits, including the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, the STRETCH meat grinder with inverse current commutation with semiconductor devices circuit, and the meat grinder with self-charged capacitor and thyristors circuit, constitute one major branch among the IPPS circuits. This paper summarizes the fundamental research work and contributions of the meat grinder circuits from the perspectives of circuit improvements, performance analysis, inductor design, module collaboration, and efficiency promotion. The future directions of single IPPS module are higher energy level, larger energy density, and higher efficiency. [ABSTRACT FROM PUBLISHER]

This paper presents the interleaved operation of a soft-switching boost converter operated in boundary conduction mode. First, the operating principle of the converter as well as the basic concept of the interleaving is presented. Then, the dynamic behavior is modeled using the z-transform to obtain a converter model that is independent of the switching frequency. With the model, the stability of the closed-loop system with a proportional–integral (PI) controller is analyzed. It is shown that an adaptive PI controller can be easily implemented to achieve a minimal settling time over a wide operating range. Finally, the controller is validated with two converters with a 40-kW nominal output power and an output voltage of 3 kV. The tests at different output voltages under different load conditions show a stable interleaved operation. [ABSTRACT FROM PUBLISHER]

This paper describes a compact high storage density inductive–capacitive storage module. The module is based on high-power opening switches using inverse current commutation with semiconductor devices commutation principle and a high storage density Brooks inductor. These opening switches, being able to switch-OFF pulse currents up to 14.5 kA by the counter-current subcircuit, make use of the general property of a standard high-power thyristors impedance transition from closing state to blocking state. The experimental results show that with the primary capacitor and counter-current commutation subcircuit charged voltage 3 and 2.5 kV, respectively, the charged current of the Brooks-type inductor is about 14.5 kA, with a charged time of about 4.5 ms. The output peak current of the inductive storage module is about 21 kA. The total stored energy is about 54.9 kJ while the energy density of the inductor is approximately 6.69 MJ/ \textm^3 , which is not including the primary storage and commutation unit. [ABSTRACT FROM PUBLISHER]

In this paper, we investigated a water treatment method that sprays waste water droplets into a pulsed discharge space. To increase energy efficiency of this method, a pulsed power generator should output a pulsed power of a high peak and a short pulse width and be low circuit loss, high repetition rate, high power, and high stability. An inductive energy storage circuit using a semiconductor opening switch was studied to satisfy the above-mentioned requirement. Initially, effect of turn ratio of a pulse transformer (PT) in the circuit was investigated. Energy transfer efficiency and the pulsewidth of the output voltage increased with the PT turn ratio, resulting in an increase of the efficiency of the water treatment system. Then, the effect of the load impedance was investigated. The result showed that an optimum resistance to maximize the efficiency exists. From these results and a previous experimental report, we concluded that the optimization conditions are summarized below. The turn ratio and the inductance in the secondary circuit should be as high as possible under the condition, which does not output the very long pulse. The impedance of the discharge at an electrode for the water treatment should be a value that maximizes the energy transfer efficiency. Capacitance of capacitors in the circuit should be adjusted to obtain optimal peak voltage for the generation of active species. [ABSTRACT FROM PUBLISHER]