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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]

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]

Marx generator using all-solid-state devices has been studied for many years. Higher parameters are always the demand for new applications. Traditional all-solid-state Marx generator can output high voltage due to its series topology, but the current is always limited by the switch. In this paper, a stage-stage paralleled topology of Marx generator for high current has been proposed. Topology structure and driving mode comparison for current balance have been analyzed. The paralleled driving mode for the current balance and the shaping waveform has been proposed. For experiment, a four-stage-four-paralleled Marx generator with metal–oxide–semiconductor field-effect transistors (MOSFETs) has been constructed with output pulses 2.2 kV, 730 A (depending on the load), rise time of 31 ns, fall time of 56 ns, and adjustable pulsewidth from 400 to 800 ns. [ABSTRACT FROM AUTHOR]

One of the critical components of high energy density pulsed power systems used to generate short high-voltage and high-power impulses is gas-filled plasma closing switch (PCS). In recent years, significant research efforts have been aimed at finding environmentally friendly gases which can be used in the PCSs, and several gases including dry air, nitrogen, carbon dioxide, argon, and their mixtures have been considered as potentially suitable working fluids in such switches. However, the lack of knowledge of the breakdown characteristics of complex switching topologies filled with these gases limits their practical applications. Therefore, further investigation of the breakdown performance of PCSs is required, in order to establish their applicability for practical use in high-voltage pulsed power systems. This paper reports on the investigation of the breakdown characteristics of a triggered PCS topology with corona discharge electrodes. The self-breakdown voltage of the switch, variation in the self-breakdown voltage, time to breakdown, and jitter have been obtained for the switch filled with “zero grade” air, N2, CO2, and an Ar/O2 mixture up to a pressure of 10 bar (abs). It was shown that the switch can provide a stable breakdown performance with jitter as low as ~1 ns. [ABSTRACT FROM AUTHOR]

The trigger voltage is usually high in traditional three-electrode gas switch, which makes the trigger system large and complex in large-scale pulsed power system such as linear transformer driver. In this paper, a three-electrode gas switch triggered by microhollow cathode (MHC) discharge is put forward, which can be operated stably under low trigger voltage. MHC discharge is a kind of microplasma with the characteristics of low trigger voltage (several thousand volts), high electron density, and high gas pressure discharge. In this switch, three MHC triggers sharing the same cathode are designed as the third electrode of the switch in the middle. Positive and negative high voltages are applied to two main electrodes, respectively. The breakdown characteristics of MHC discharge triggered by pulse voltage are first studied. The trigger voltage can be as low as 8 kV at 0.3 MPa in pure N2 with the discharge peak current up to 80 A. A circuit simulation model describing breakdown process of MHC is also built. Then two operating modes of the switch, three-electrode mode (T-mode) and two-electrode mode (D-mode), are analyzed. The stable operation with the charging voltage from ±35 to ±50 kV is realized under different working coefficients from 64% to 92% and different trigger voltages from 8 to 15 kV. The turn-on parameters including delay time, jitter, and turn-on time are studied that the delay time and jitter of D-mode are longer than that of T-mode under the same condition. At last, the improvement of MHC trigger for the stable operation of D-mode with shorter delay time is described. [ABSTRACT FROM PUBLISHER]

In this paper, we present the first implementation of our 0–60-kV picosecond rise time 1–10-ns pulse generator. The pulse generator will be used in future work to generate a (sub-)nanosecond streamer plasma for air purification research. The first implementation of the pulse generator is a single-line pulse generator with an oil spark-gap, which generates 5 ns pulses with a 200 picosecond rise time and can operate at repetition rates of over 1 kHz into a 50 \Omega load. In this paper, we evaluate its performance and describe how we measure the very short pulses with an integrated and calibrated D-dot sensor. Furthermore, we present 3-D EM simulations of the 5 ns pulse generator and show that the simulations are in good agreement with the measurements. We previously described methods to flexibly vary the pulse duration of the pulse source by (artificially) changing the length of the pulse forming line (PFL). Here, we test these methods and find that changing the length of the outer conductor of the PFL and inserting magnetic material at the end of the PFL is a suitable method to change the pulse duration. Finally, we measure the breakdown voltages of the oil spark-gap and discover that higher pulse repetition rates are possible at higher oil pressures and smaller gap distances. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique for the voltage droop compensation of long pulses in solid-state bipolar high-voltage Marx generators. Considering the modularity of Marx generators the compensation consists in adding one extra stage to perform as a pulsewidth modulation circuit. This stage voltage is added to the output positive or negative pulses, and an output LfCf filter is included to smooth the voltage pulse waveform. A five-stage laboratory prototype of this circuit has been assembled using 1200-V Insulated Gate Bipolar Transistors and diodes with 1000-V dc input voltage. The circuit was operated at 50-Hz bipolar pulse rate, giving 4-kV bipolar pulses, into a resistive load, with 100- \mu \texts pulsewidth and 9.5-ms relaxation time. The circuit was able to compensate 10% of bipolar pulse voltage droop. [ABSTRACT FROM PUBLISHER]

This paper presents a power electronics converter to generate bipolar high-voltage pulses using low-voltage dc source. Converter is designed based on charging of different capacitors by a predetermined switching pattern and their discharging on the load for pulsed power applications. Low number of power electronics devices and bulky transformer elimination are main advantages of the proposed converter. According to new findings, bipolar high-voltage pulses may lead to higher efficiency in many applications, such as food sterilization industry. The proposed pulse generator generates bipolar controllable pulses with a modular circuit structure based on a capacitor-switched network. Experimental results are presented to verify the analysis. [ABSTRACT FROM AUTHOR]

The acceleration grid power supply (AGPS) is an important part of the neutral beam injector (NBI) system. With the increase in NBI power, the requirement for output voltage of the AGPS is becoming higher and higher, even reaching to 1000 kV. As the inverter-type high voltage power supply uses inverters located at the lower voltage side to regulate and cut off the output voltage, it is very suitable for high-voltage applications. The proposed scheme for the AGPS of the International Thermonuclear Experimental Reactor (ITER) NBI system comprises five stages, where each stage has an inverter-type power supply with an output voltage of 200 kV. This paper investigates the inverter-type power supply based on neutral point clamped three-phase three-level (TPTL) inverter and three-phase step-up transformer, which is equivalent to an insulated TPTL dc–dc converter connected with a dual dc link. In order to design a preferable controller for the inverter-type power supply, the topology and principles of the TPTL dc–dc converter with duty cycle modulation have been analyzed. It indicates that only when the converter operates at a large duty cycle, the output voltage ripple can be limited to ±5%. Hence, the small signal model of the converter at a duty cycle larger than 2/3 is established. Following the mathematical model, a single-loop PID controller has been designed and a 400 V/6 A prototype has been built. Simulation and experimental results verify the correctness of the theoretical analysis. The system achieves a lower output voltage ripple and fast dynamic response. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate an influence of high-frequency high-voltage impulse conditioning on the back-to-back capacitor bank switching performance of vacuum interrupters (VIs). Nine identical 7.2-kV VIs were tested by 80 CO operations after the proposed conditioning. Test inrush currents were set to 0-, 2-, and 5-kA peak. The experimental results showed that this conditioning technology could make an impact on both prestrike and restrike characteristics of VIs. The complementary cumulative distribution function (CCDF) of the prestrike gap d\textrm {pre} followed complementary Weibull distribution. In contrast to VIs without conditioning, three typical prestrike gaps, i.e., CCDF 10% prestrike gap d\overline {10} , CCDF 50% prestrike gap d\overline {50} , and CCDF 90% prestrike gap d\overline {90}\vphantom {\sum RRR} , decreased by 39%, 19%, and 4% at most, respectively. Besides, the scattering of d\textrm {pre} decreased by 52% at most. Furthermore, the conditioning technology had an influence on the feature of restrike waveform through variation of field emission current. It could also reduce the restrike probability by 22.5% at most and made the entire restrikes occur between $0.5T$ and $5T$ during recovery voltage period ( $T=20$ ms). [ABSTRACT FROM AUTHOR]

This paper describes the design and implementation of a three-phase resonant converter with low ripple and high control accuracy. Based on a three-phase LCC-type resonant converter—which has advantages of low ripple, high-efficiency, and high-power density compared with a single-phase converter—a high-voltage power supply with low ripple (<0.1%) was designed. In addition to the general merits of an LCC-type resonant converter operating at continuous conduction mode—including soft switching, low conduction loss, and current source characteristics—the proposed scheme uses only one phase under a light-load condition by having different leg designs of the gate drive circuit and snubber parameters. This allows the design to overcome the operational constraints of the general LCC-type resonant converter. The distinctive design of the three-phase converter structure provides high efficiency and low ripple not only during rated operation, but also under light-load conditions. In order to analyze the high performance of the proposed scheme from no load to rated load, a PSPICE simulation was carried out. Comparison results with a conventional LCC-type resonant converter based on a single-phase structure are analyzed from the viewpoints of output ripple, losses, and operable load range. Using the proposed converter, a 20-kV, 20-kW high-voltage dc power supply design and implementation was presented with a superior gate drive circuit. Finally, the superiority of the proposed converter was verified through a simulation and experimental results. It was experimentally confirmed that the developed power supply achieves high performance in terms of efficiency (98%), operable load range (0.5–20 kV), and low ripple (0.05%), with a high power density. [ABSTRACT FROM PUBLISHER]

This paper describes a modular solid-state switching cell derived from the Marx generator concept to be used in topologies for generating multilevel unipolar and bipolar high-voltage (HV) pulses into resistive loads. The switching modular cell comprises two ON/OFF semiconductors, a diode, and a capacitor. This cell can be stacked, being the capacitors charged in series and their voltages balanced in parallel. To balance each capacitor voltage without needing any parameter measurement, a vector decision diode algorithm is used in each cell to drive the two switches. Simulation and experimental results, for generating multilevel unipolar and bipolar HV pulses into resistive loads are presented. [ABSTRACT FROM PUBLISHER]

The main characteristics of reversely switched dynistor (RSD) are infinite series, long lifetime, turning on in microseconds to nanoseconds, high-current rise rate (100 kA/\mus), and ability of passing through large current (several kiloamperes). With these advantages, RSD has a great potential of application in repetition rate pulsed power technology and the future HVdc field. To resolve the problem of residual voltage of RSD caused by insufficient precharge, which leads to nonuniform turn-on of RSD, this paper, based on the conduction mechanism of RSD devices, describes precharge circuit design requirements and establishes a second order circuit model to study the resonant triggering circuit of RSD. It is found that reducing precharge inductor can effectively increase precharge current, resulting in reducing the turn-on voltage of RSD. Finally, design for three improved circuit topologies (full-bridge, intense pulsed, and two-step triggering circuit) are presented and experiments show that these improved circuit topologies can enhance the precharge efficiency and reduce the turn-on voltage of RSD. [ABSTRACT FROM PUBLISHER]

In this paper, we present a solid state 0–120 kV microsecond pulse charger for our nanosecond pulse generator refid="ref1"/. The pulse-forming line (PFL) of our nanosecond pulse generator must be charged with microsecond pulses to prevent pre-firing of its oil spark gap. The pulse charger consists of two identical compact pulse charger modules with integrated electronics. The electronic circuits are mounted on a compact printed circuit board and consist mainly of a number of parallel connected insulated-gate bipolar transistors (IGBTs) that switch a primary capacitor bank into a pulse transformer. Each pulse charger module can generate 60 kV microsecond pulses at 1 kHz repetition rate. When connected in series, they are able to deliver up to 120 kV into a 100 pF load. This 100 pF load is the PFL of our nanosecond pulse generator at its maximum length of 1 m. The pulse charger is able to operate in a harsh electromagnetic interference environment as a result of its compact layout and optical triggering of the IGBTs. [ABSTRACT FROM PUBLISHER]

Modern pulsed power technology has its roots in the late 1950s and early 1960s, and it was driven overwhelmingly by applications in national defense carried out by several countries, especially the U.S., U.K., Russia, and China. The following decades, particularly the early 1990s, witnessed an increased interest in compact systems with pulse repetition rate that could be used in nondefense applications such as treatment of material surfaces by plasma and beam interactions, treatment of pollutants, food sterilization, medical applications, etc. This spawned a new generation of pulsed power components (solid-state switches) that led to completely solid-state modulators. This paper describes how the pulsed power technology used originally in beam sources and cathodic arcs has converged to produce power sources for plasma-based ion implantation (PBII) and related technologies. The present state of the art is reviewed, and prospects for future advances are described, especially for PBII. [ABSTRACT FROM AUTHOR]

In this paper, a new way for high-voltage \mu\s -range quasi-square pulse generation based on a ns source pulser and a chopping spark gap is introduced. The source pulser delivered high-voltage source pulse with front edge at ns range to the chopping gap, and the chopping gap chopped the long flat back edge of the source pulse, so that a quasi-square pulse was formed on a high-impedance load. The breakdown-delay characteristics of the chopping gap, which was the most important, were studied in detail. Results of the experiments showed that when the pulse voltage peaked by the first peaking gap was a little lower than or approximate to the breakdown voltage of the chopping gap, the chopping gap broke down at the back edge of the peaked pulse so that the breakdown-delay time can increase from 30 ns to several \mu\s. The breakdown-delay time of chopping gap is confined to the flat top of the peaked pulse. By using this mechanism of breakdown delay, a quasi-square pulse with pulse width of 1.95 \mu\s, amplitude of 55 kV, and front edge of 22 ns was produced on a 1.15-\k\Omega load. Repetitive chopping pulses at 0.2 Hz were provided to demonstrate the feasibility of the chopping gap. By contrast to the conventional chopping, four essential conditions were concluded. Based on these results, a controllable trigatron-type chopping gap system is introduced to ensure chopping stability. It provides an important new way for \mu\s-range high-voltage square pulse generation. [ABSTRACT FROM AUTHOR]