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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]

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]

Based on the urgent needs for modularization and miniaturization of the inductive pulsed power supply system, this paper proposes the conceptual design and comparison of 100-kJ inductive storage power modules including four circuit topologies, three of which are proposed in our previous researches. The four circuit topologies are the STRETCH meat grinder, the XRAM with STRETCH meat grinder unit, the XRAM with strongly coupled inductors, and the XRAM with magnetic flux compression effect. The maximum load current of each constructed module is set to be 50 kA and its pulsewidth is at least 5 ms, which are the same as the main electrical properties of an existing 100-kJ capacitive module. A comparative study on energy density among the constructed inductive modules and the existing capacitive module is carried out in depth. Results show that the inductive modules, considering the volume of semiconductor switches and their control circuits, have higher energy density than that of the capacitive module. Among four constructed inductive modules, the XRAM with strongly coupled inductors module has the highest inductive energy density, and the XRAM with magnetic flux compression effect module has relatively better comprehensive performance. This paper offers the theoretical analysis foundation for investigating the inductive pulse power supply with higher energy. [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]

The role of irreversible electroporation using pulsed electric field is to generate high-voltage (HV) pulses with a predefined magnitude and duration. These HV pulses are applied to the treatment chamber until decontamination of the sample is completed. In this paper, a new topology for HV rectangular pulse generation for water disinfection applications is introduced. The proposed topology has four arms comprised of series-connected half bridge modular multilevel converter cells. The rectangular pulse characteristics can be controlled via the software controller without any physical changes in power topology. The converter is capable of generating both bipolar and monopolar HV pulses with microsecond pulse durations at high a frequency rate with different characteristics. Hence, the proposed topology provides flexibility by software control, along with hardware modularity, scalability, and redundancy. Moreover, a cell’s capacitance is relatively small, which drastically reduces the converter footprint. The adopted charging and discharging process of the cell capacitors in this topology eliminate the need of any voltage measurements or complex control for cell-capacitors voltage balance. Consequently, continuity of converter operation is assured under cell malfunction. In this paper, analysis and cell-capacitor sizing of the proposed topology are detailed. Converter operation is verified using MATLAB/Simulink simulation and scaled experimentation. [ABSTRACT FROM AUTHOR]

Theoretically, the energy conversion efficiency of the synchronous induction coil launcher (SICL) can reach 100%, but at present, the test data show that the highest current is only a little higher than 20%, which shows that the efficiency of the coil launcher has a lot of room for improvement. In this paper, three improved schemes are proposed for the topology of the traditional crowbar circuit based on the pulse capacitor to improve the electromechanical energy conversion efficiency of the electromagnetic coil launcher. They are main circuit breaking, crowbar break-off circuit, and crowbar circuit with inductor, respectively. In order to verify the feasibility of the above three methods, a five-stage coil launcher was simulated and analyzed. Then, based on the model, three improved circuits were calculated and analyzed by the finite-element simulation software. The results show that all of the three methods can improve the efficiency of energy conversion to a certain extent. Both the first and second methods have limited effect on increasing efficiency. In addition, they need to add some expensive equipment such as circuit breaker. So, they are not recommended. The third way of increasing an inductor in the crowbar circuit could increase the muzzle velocity and efficiency obviously. The muzzle velocity increased from 30.6 to 35 m/s. The effect of armature capture is reduced which is worthy of recommendation. [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]

Nonlinear transmission lines (NLTLs) have been studied over the past several years to generate high-power radio frequency signals. Their operation consists of a lumped line based on the nonlinear behavior of the LC section components, capacitors or inductors, as a function of the applied voltage or current, respectively. However, considering high-power signals, the application of these devices using nonlinear ceramic capacitors as the capacitive lumped lines are restricted to frequencies around 100 MHz since at high voltages, parasitic impedances in the line structure limit the maximum operating frequency. On the other hand, the use of variable capacitance diodes has enabled the operation of NLTLs at higher frequencies. This paper provides the results of a study of NLTLs for RF generation based on silicon carbide Schottky diodes. The principle of operation and its simplified theory are presented. Initially, the voltage dependence of the diode capacitance is modeled. Experimental and simulation results are compared. Frequency oscillations around 200 MHz were generated. The extraction of the radio frequency energy is realized, and the radiation of the electromagnetic wave is performed using double-ridged horn antennas. Finally, some parameters are analyzed, and all results discussed. [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]

Optimal design and selection of arm inductances have been as a challenging subject in the field of modular multilevel converter (MMC). The average steady-state model is generally used as the analytical circuit model that neglects the switching frequency and harmonic values. Also, most of the researchers neglect the saturation effect of inductor core to simplify the analytical model. Contrary to the transformers, choosing the maximum flux density of inductance core is a sensitive issue, in order to design and minimize the inductors. Increasing the flux density reduces the inductor size, but getting close to the saturation region might alter the performance of the converter. This paper presents a systematic optimization approach to minimize high-power MMCs with saturable arm inductance considering technical, thermal, and manufacturing constraints. An accurate steady-state analytical model of MMC converter has been proposed and verified. A combination of converter circuit model and inductance electromagnetic model is employed to find the optimal arm inductances and capacitor values. The effect of nonideal inductance core on converter outputs has been investigated. A dimensioning model of inductor consisting of electromagnetic and thermal models is presented. To compute the optimal inductor size, a novel hybrid optimization loop is proposed including the analytical model of the converter and the inductor in which circuit, electromagnetic, and thermal properties are taken into consideration. In order to increase the accuracy of the dimensioning model, an internal verification loop is employed to verify and correct the analytical model using finite-element analysis. The proposed optimization loop aims to find the minimum inductor size considering technical and manufacturing constraints. Finally, the converter mass sensitivity of MMC converter versus some important constraints, such as temperature rise and capacitor ripple, has been investigated. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS), especially superconducting pulsed power supply (PS), has been the focus of research in recent years due to its high energy density and low power requirement for the input PS. Quite a lot of fantastic work regarding two or multiple IPPS modules has been presented. But they disregard the mutual inductance between modules. This paper establishes a double-module IPPS based on two high-temperature superconducting pulsed power transformers and takes the mutual inductance between modules into consideration. The influence of the mutual inductance between two modules on three discharge modes of the system is researched. Simulations and experiments on synchronous discharge, time-delay discharge, and asynchronous discharge are carried out, respectively. The results demonstrate that taking the mutual inductance into consideration, the amplitude and the pulsewidth of the output currents are both improved a lot, especially the obtainable energy of load is improved by nearly half. For time-delay discharge, the mutual inductance makes the delay time slightly increase. However, for asynchronous discharge, the mutual inductance increases the positive maximum value of the primary current of the second module. It may exceed the critical current and lead to quench. Consequently, the mutual inductance between modules has positive impacts on synchronous discharge and time-delay discharge of the IPPS system while it brings both advantages and disadvantages to asynchronous discharge. [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 nonlinear lumped element transmission line (NLETL) that comprises an $LC$ -ladder network where either the capacitors or inductors are nonlinear is used to convert an input rectangular pulse to a series of RF pulses at the output. This paper describes the implementation and demonstration of a high-voltage nonlinear hybrid line (NLHL) where both the line components (inductors and capacitors) are nonlinear. Lines with only one nonlinear component have been described in numerous publications in simulation and experiment whereas an NLHL has been described in only a few papers in simulation. There is no report about NLHL being tested to-date according to the best of our knowledge. We have built and tested an NLHL using commercial-off-the-shelf components. Instead of using complex pulse forming networks or pulse forming lines, a storage capacitor and a fast semiconductor switch are used to provide an input pulse with good approximation of a rectangular pulse shape. The experimental results are compared with simulations predicted by the in-house developed nonlinear lumped element transmission line (NLETL) circuit model. Analyses on the voltage modulation and frequency content of the output pulses are carried out. The conditions for producing RF pulses in NLHL and its performance are discussed. [ABSTRACT FROM PUBLISHER]

This paper presents the design and experimental results of the 36-kW pulsed-power supply for the xenon flash lamp. The continuous conduction mode series-parallel resonant converter is modified. This means that not only the few hundred kilohertz of high switching frequency is introduced to replace the resonant inductor with the leakage inductor of transformer but also the high output current is accomplished by using three-phase delta-connected transformers. In addition, the snubber capacitor of the inverter switches and the power factor correction module is both omitted in the compact structure. Although these main components have changed, the efficiency and power factor of the rated dummy load reach 96% and 0.96%, respectively. Within 36-kW average power, the proposed pulsed-power supply can generate as versatile combination of output pulse. For example, it can generate 20-ms pulse with 1-Hz repetition rate or generate 1-ms pulse with 20-Hz repetition rate. The used insulated gate bipolar transistor is protected from the turn-OFF peak voltage by the snubber circuit, and the effect of the snubber circuit is shown at the actual load condition. [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]

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits. [ABSTRACT FROM PUBLISHER]

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]

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit is a widely used topology in inductive pulse power supply. Therefore, it is important to understand the relationship between the STRETCH meat grinder performances and the inductor parameters when improving the system performance and designing the inductor. From the perspective of inductor designing, this paper uses four indicators to present the STRETCH meat grinder performances, i.e., the charging current, the current amplification, the inductor energy density, and the discharge efficiency, and uses two indicators to present the inductor parameters, i.e., the total inductance and the ratio of the inductance L1 to L2 . First, the meanings of the indicators are explained or defined. Second, simulations and experiments are carried out, respectively, to analyze the trends of the four performance indicators along with the changes of two parameters indicators. Finally, both simulation and experiment results show that the increase of the total inductance leads to the decrease of the charging current and the discharge efficiency; moreover, the increase of the ratio of the inductor L1 to L2 leads to the increase of the current amplification and the discharge efficiency, but causes the decrease of the inductor energy density. [ABSTRACT FROM AUTHOR]

Low-temperature plasma treatment is a promising technology for particulate matter (PM). In this paper, the arrayed dielectric barrier discharge (DBD) plasma reactor for PM2.5 removal is investigated at atmospheric pressure. In order to reveal the interaction between experimental findings and simulation results, the equivalent electrical circuit is used. The electrical model is implemented on the PSIM software. To calculate the capacitance of the arrayed DBD reactor, the capacitor expressions are developed. Considering the experimental elements, such as plasma-generated configuration and the power source, a topological equivalent circuit is given. Finally, the simulation results are compared with the experimental ones, and they agree well. In addition, the designed DBD reactor was used to investigate PM2.5 removal. PM2.5 removal after 4 min of plasma treatment found to be about 53.8%. [ABSTRACT FROM PUBLISHER]

In this paper, a new multiple-needle-cylinder reactor is designed to study the Escherichia coli inactivation with an unstable pulsed arc discharge in water and investigate the influence of several parameters for promoting its industrial application. The results show that the inactivation rate is mainly determined by energy density. About three orders reduction can be obtained with an initial cell count of 3\times 10^5 CFU/mL and energy density around 2 J/mL. The inactivation rate can almost reach 100% when the energy density is around 8 J/mL. For reaching the maximum inactivation rate of this system, the parameters including initial water conductivity below 50~\mu \textS /cm, initial cell count over 10^4 CFU/mL, and bubbling flow rate around 3.5 L/min are recommended. The water conductivity, pH value, and concentrations of hydrogen peroxide and ozone are also measured during the treatment to evaluate their influence. The transmission electron microscopy images of E. coli indicate that the intracellular morphology changes after plasma treatment. [ABSTRACT FROM AUTHOR]

A 4.8-MJ capacitive pulsed-power system (PPS) was designed and fabricated for electromagnetic launcher (EML) experiment. The PPS consists of eight 600-kJ segments, which can be operated independently. In each segment, six 100-kJ capacitor bank modules, a charging power supply, a dump and charge panel, and control circuit were integrated. The capacitor bank modules in the segment are charged at the same voltage up to 10 kV, but the trigger time of each module can be set up differently. The overall PPS system is controlled by a control program, which sets charging voltage and trigger time of each module and monitors the states of system component. All the control signals are transmitted through fiber optic communication. The 48 unit modules are connected in parallel to EML with high-voltage coaxial cables. A current amplitude of more than 1 MA and a pulsewidth of several milliseconds were achieved by the PPS. The PPS has been applied to several tens of firing experiments of EML successfully. The design, fabrication, and the test results of the 4.8-MJ PPS were described in this paper. [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]

The energy density of the inductive energy storage systems is one order of magnitude higher than that of the capacitive ones. The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder with inverse current commutation with semiconductor (ICCOS) devices put forward by Tsinghua University is a typical inductive pulsed-power supply for electromagnetic launch system, which has remarkable current amplification ability as a single module. However, one module cannot provide enough amplitude and width for the load current of the railgun launching. Therefore, the collaborative work of multiple inductive source modules is necessary for practical usage. In this paper, the designed inductive power supply system of about 1 MJ is composed of 40 STRETCH meat grinders with ICCOS modules. All the main switches are opened simultaneously to reduce the magnetic field coupling among the modules and make the current rising edge steep. The modules are divided into several groups. The triggering delays of the thyristors between every two adjacent groups are carefully designed. After the first triggers for all the modules, the energy stored in the capacitors can be further utilized with the second triggers. The numerical simulation results show that the appropriate collaborative triggering delay can increase the adjustability of the output current width and the second triggers can further increase the current width and the system efficiency. Therefore, the load current with flat shape, appropriate amplitude, and longer duration can be provided with modular design and collaborate triggering discharge of the multiple modules. This can provide a theoretical foundation for the future study and implementation. [ABSTRACT FROM PUBLISHER]

By applying the principle of inverse current commutation with semiconductor (ICCOS) devices in a slow transfer of energy through capacitive hybrid (STRETCH) meat grinder system, a novel circuit topology called STRETCH meat grinder with ICCOS was proposed by the Tsinghua University in 2013. It can not only raise the amplitude of the opening current, but also reduce the cost of the STRETCH meat grinder circuit obviously by replacing the integrated gate-commutated thyristor (IGCT) with thyristor. This paper discusses the overall design, system implementation, and testing results of a STRETCH meat grinder with ICCOS system with roughly 1-kJ inductive energy. The load is a spiral coil with 1.4- \textm\Omega resistance and 1.4- \mu \textH inductance. With closed-loop control strategy, the system detects the charging current of the inductors. When it reaches the designated value, the triggering signal for ICCOS is delivered and after the predefined delay time, the triggering signal for discharging the voltage on the pulse-forming capacitor is delivered. The current of the inductors and the load are measured by Rogowski coils. The opening current is 1 kA and the maximum load current is close to 4 kA. All the voltages on the switches are lower than 1 kV. The experimental results are consistent with the simulated ones, which verified the correctness of the theoretical analysis and proved the applicability of the STRETCH meat grinder with ICCOS for larger energy level. [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]

This paper proposes a pulsed power supply topology based on the combination of capacitor-diode voltage multiplier and resonant circuit. It generates high output voltage pulses with low ac input voltage using power electronics switches. Based on the type of application, simple or combined mode pulses can be created by proposed topology. The combined mode pulse (wide pulses combined with narrow pulses) generation can be a very good alternative strategy for food sterilization, which can reduce the amount of consumed power and avoid side effects of wide pulses used in the food treatment process. Simulation and experimental results are presented to verify the proposed topology. [ABSTRACT FROM PUBLISHER]