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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]

A pulsed electromagnetic inductive valve has been developed to achieve correct initial deposition of the propellant gas puff for the planar pulsed inductive plasma thruster. This paper aims to describe the method for modeling the valve. The most significant physical effects involved in the valve operation process are described by the electrical model, the magnetic model, the mechanical model, and the pneumatic model. These physical models are then linked together based on the couplings between them to form a complete multiphysics coupling model. In order to validate the proposed model, simulations and experiments are implemented for the prototype valve at different operating conditions. Response characteristics and throughput characteristics predicted by the model agree well with experimental data. The results demonstrate that the proposed model can be successfully applied to accurately capture the main performance of the valve. The principle of the analysis procedure is applicable to other electromagnetic valves of this type. [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]

This paper presents a new capacitor bank topology for a pulsed power system to improve the efficiency of multistage synchronous induction coilgun. In the proposed method, a switch, such a gate turn-off thyristor, is inserted in parallel to a crowbar diode and load to generate an attractive force between the next stator and the armature. A mathematical model was developed, and finite-element method simulations were conducted to verify the proposed topology. The results show that the proposed method improves the energy efficiency and launch velocity. The improvement in energy efficiency is confirmed from the simulation results of a three-stage synchronous induction coilgun. [ABSTRACT FROM AUTHOR]

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]

Pulsed power supply (PPS) applied in the electromagnetic launch system must have a compact design and high reliability. In this paper, a PPS for electromagnetic launch system is built up. The main parts in a pulse forming unit (PFU) of a PPS are energy storage capacitors (8 kV/75 kJ), pulse-shaping inductor (10 \muH), pulse thyristor, crowbar diode, and a Rogowski coil for current measuring. The energy storage density of the PFU is 0.74 MJ/m^3. Eight PFUs form a pulse forming network (PFN) of 600 kJ. In many cases, the discharge current waveform of the PFN must be adjusted for lower peak value and lower electromagnetic force. On the basis of this PFN, in this paper, we analyze the effect of sequence discharge on the semiconductors. To prevent diode from overvoltage during the recovery process, different parameters of snubber circuit have been researched in the experiments. Finally, we set up a model of the serial augment rail gun in a personal simulation program with integrated circuit emphasis, and the safety of PFU can be affirmed by simulation if the voltage of the rail gun keeps positive during the course of the discharge. [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]

This paper details the experimental evaluation and simulation of a 4-kV n-type gate turn-OFF thyristor (GTO) designed for pulsed power applications. The primary criteria of evaluation are rate of current rise ( dI/dt ), turn-ON delay time ( T_{D}) , and resistance of the device during turn-ON transients [ R_{\mathrm{\scriptscriptstyle ON}}(t)$ ]. The device under test (DuT) is an n-type asymmetric-blocking GTO manufactured by Silicon Power (Part No. 14N40A10) with a rated dc blocking voltage of 4 kV. A test circuit was specifically designed to minimize stray inductance in order to capitalize on the dI/dt$ capabilities of the DuT. Experimental data collected from resistance measurements are used to develop a single-switch approximate model for use in simulation. The results of dI/dt$ experiments provide a profile of DuT dI/dt$ operation beyond rated values; specifically dI/dt were readily achieved. The turn-ON delay time of the DuT is also characterized and determined to be $\sim 225$ ns on average. [ABSTRACT FROM AUTHOR]

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]

Two-electrode graphite spark gap switch (TGSGS) is used as the main discharge switch and triggered by a reliable trigger generator in pulsed power conditioning system (PPCS). There would be 108 energy modules in PPCS working at the same time. The reliable operating and jitters of the trigger generators will have impact on the PPCSs performance. In this paper, the working modes of the TGSGS are discussed and the performance of trigger generators in PPCS is tested and presented. A protection strategy of the trigger generator in PPCS is introduced, and effect of the blocking capacitor on the trigger pulse transmission is analyzed and tested. The protection strategy of the trigger generator based on blocking capacitor and fuse can effectively prevent the energy anti-irrigation failure when the pulse transformer core saturated. The blocking capacitor has some effect on the trigger pulse transmission, and has the larger capacitance, getting the higher peak amplitude on the cathode of the TGSGS. It is tried to discuss the working characteristics of the thyristors, and proposes a selection reference of the thyristors in this and other similar applications. The combination of analysis and measurement would be useful for the selection of thyristors and other components. [ABSTRACT FROM PUBLISHER]

A 600-kJ pulsed power system (PPS) was built for various applications. The PPS consists of six 100-kJ unit modules. A single unit module is composed of a capacitor, a thyristor switch stack, a crowbar diode stack, and a pulse forming inductor. The module was designed to be operational for a maximum charging voltage of 10 kV and a peak current up to 75 kA. Each module can be triggered and controlled independently by a control computer via fiber optic communication. The six modules are combined into one frame and are charged to the same voltage by one capacitor charger. The design, fabrication and test results of the unit modules, and the 600 kJ PPS are presented in this paper. [ABSTRACT FROM AUTHOR]

The French-German Research Institute of Saint-Louis obtained essential parts of a 30-MJ energy supply formerly installed at Rheinmetall in Unterlüß, Germany. This paper describes the original state of the energy supply and the refurbishment of one rack with a stored energy of 1.28 MJ and its testing, taking into account worst-case conditions. The rack was split into two subunits of 675 and 608 kJ, which were upgraded with newly developed high-power thyristor and crowbar diode assemblies. The subunits were successfully tested individually and in the pulse shaping mode by connecting them to a common load. Several tests with voltages up to 22 kV, currents up to 267 kA, and a different trigger delay proved the reliability of the modified rack and its suitability as a prototype for the remaining 23 racks. [ABSTRACT FROM PUBLISHER]

In this paper, we describe a novel multiple-switch pulsed-power technology. The basic idea is that the heavy switching duty is shared by multiple switches. The multiple switches are interconnected via a transmission line transformer, in such a way that all switches can be synchronized automatically and no special external synchronization trigger circuit is required. It can produce either exponential or square pulses, with various voltage and current gains and with a high degree of freedom in choosing output impedances. The topology has been implemented on a prototype with ten spark-gap switches. Pulses with a rise time of 10 ns, a width of 55 ns, a peak power up to 810 MW, a peak voltage of 77 kV, and a peak current of 11 kA have been achieved at a repetition rate of 300 pps. The energy efficiency of the circuit is about 93%. In addition to spark gaps, any overvoltage-controlled switch can be applied in this topology. As an example, we demonstrate the synchronous switching of multiple thyristor switches for current multiplication. The proposed multiple-switch topology can also be applied in a Blumlein configuration for an inductive voltage adder and a linear transformer driver. [ABSTRACT FROM AUTHOR]

A 3.2-MJ pulsed power supply system for railgun has been built. The power supply system consists of 32 pulse forming units (PFUs) of 100 kJ each. Each PUF can be triggered and controlled independently by the center computer by fiber optic transmitters. The maximum total current of the 3.2-MJ supply system reaches 500 kA. The new PFU is smaller than the former one. The PFU is composed of two capacitors, a set of semiconducting switches (thyristor and crowbar diode), an inductor, a safety device, a local controller and data acquisition circuit, a current coil, and coaxial cables. The modular PFU is designed for a maximum charging voltage of 10 kV and the peak current up to 50 kA/module. In order to reduce the influence of the electromagnetic interference and the electromagnetic force and to provide the high flexibility reliability, the arrangement of components and the configuration of the pulsed power module have been improved. A local data acquisition circuit in each PFU can record and save the discharging current and the voltage of the capacitor itself and upload test data to the computer by fiber optics. This paper describes the stack configuration, the test facility, and the prototype arrangement of 32 modular pulsed power units. [ABSTRACT FROM PUBLISHER]