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Inductive pulsed power supplies have become a promising option for the power supplies of electromagnetic launchers, because they can reach a good balance between the energy storage density and the power density. This article presents a status for our research work, namely an integrated pulsed power module. The length, width, height, and volume of this module are 0.48 m, 0.3 m, 0.24 m, and 0.034 m3, respectively. In the so-far conducted highest energy-level experiment, this module reached 4.91-kA inductor charging current, 77.6-kJ inductor charging energy, and 2.36-MJ/m3 module energy density. The output current pulse reached 15.0-kA first peak value, 15.4-kA second peak value, and 14.1-ms half-peak value pulsewidth. The performance of this module has been confirmed to be stable and consistent within the range of 0–80 kJ. [ABSTRACT FROM AUTHOR]

The electromagnetic railguns possess the characteristics of active and accurate control of the muzzle velocity. As to our understanding, the muzzle velocity control has two levels. One is to design the triggering strategy of the pulsed power supplies before the launching process, while the other is to adjust the triggering strategy during the launching process. The objective of the first one is to realize the desired muzzle velocity with ideal system parameters, and the target of the second one is to design a closed-loop adjusting system for the precalculated triggering strategy, so as to keep the actual muzzle velocity equal or closed to the desired value when the launching process has some kind of turbulences, e.g., nonideal charging voltage and errors of the armature mass. This paper proposes a closed-loop velocity control system and four different methods to adjust the actual muzzle velocity in real launching time. The core idea of this system is to detect the armature velocities at key points along the rails and adjust the following triggering pulsed forming unit (PFU) number of the pulsed power supplies. In simulations, the desired muzzle velocity is 2000 m/s, the capacitance of the energy storage capacitors $C_{\mathrm {PFU}}$ is 2 mF, the precharged voltage $U_{0}$ is 5 kV, and the armature mass ${m}$ is 0.15 kg. Without the closed-loop adjusting, if $U_{0}$ , $C_{\mathrm {PFU}}$ , and ${m}$ simultaneously and randomly change within [−2%, 2%] in actual operations, the muzzle velocity relative errors are within [0%, 2.1346%]. However, after using this closed-loop system, the results show that the muzzle velocity errors can be less than 1%, even when there is ±0.5% detection error. [ABSTRACT FROM AUTHOR]

This paper at first proposes a method to calculate a trigger strategy before launching in order to control the muzzle velocity of railguns. Five triggering points are set equidistantly and six pulsed forming unit (PFU) groups are triggered in total. First, given a desired muzzle velocity, the expected uniformly accelerated rectilinear motion of the armature is calculated. Second, the module number of each PFU group is obtained according to the principle of minimizing the absolute relative error between the actual and the expected velocity at each triggering point. The results show that, when the desired muzzle velocity is within [1500, 2000] m/s, the absolute muzzle velocity relative error $\delta $ is less than 0.5%. In order to achieve a better control performance, the places of the five triggering points are then optimized by a genetic algorithm (GA). The objective function is the sum of absolute $\delta $ , when the desired muzzle velocities are 1500, 1600, $\ldots $ , 2000 m/s. After the optimization, $\delta $ is reduced to less than 0.05%. At last, based on this velocity control method, the railgun system is optimized to pursue the highest system efficiency $\eta $ by GA. The independent variables are the armature mass, the precharged voltage, and the places of the five triggering points. The constraints are that the desired muzzle velocity is 1800 m/s and the absolute $\delta $ is within 1%. The results show that $\eta $ increases from 6.57% to 25.37%. [ABSTRACT FROM AUTHOR]

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]

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]

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]

The meat grinder with SElf-charged Capacitor and Thyristors circuit is a novel circuit for inductive pulsed power supplies. The energy transfer capacitor is one of the key components in this circuit. And its capacitance C and the precharged voltage UC are key parameters worth investigating. The circuit working process and corresponding numerical calculation method are briefly introduced. And the method validity is verified through experiments. Then, the influences of $C$ and UC on circuit performance indices, i.e., the maximum voltage across the main switch $V_{{\mathrm{sopm}}} , the secondary current multiplication factor m2 , the ratio of the maximum capacitor energy over the inductor charging energy \eta C , and the self-recovery rate of the precharged capacitor voltage k\mathrm{UC} , are quantitatively analyzed through parameter sweep. Generally speaking, large C is conducive to lower $V_{{\mathrm{sopm}}} ; small m2 ; small C and low UC are conducive to lower \eta C and higher $k_{{\mathrm{UC}}}$ . Moreover, the analytical expression of $k_{{\mathrm{UC}}}$ is given. With C and UC elaborately selected, $k_{{\mathrm{UC}}}$ can achieve 100%. In addition, the balance relationship between two contradictory indices $V_{{\mathrm{sopm}}}$ and $k_{{\mathrm{UC}}}$ is obtained by solving a biobjective optimization problem and using the genetic algorithm. [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]

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 air-core flat spirals of strip coil structure is a typical type of the tightly coupled energy storage inductors used in inductive pulsed power supplies. This paper improves the speed and the parameter scope of the inductance calculation method for these inductors. Specifically, the analytical expressions using the structural parameters to represent the performance parameters, e.g., the inductance, the resistance, and the current conducting capability of the primary inductor and the secondary inductor L1 , L2 , R1 , R2 , I\mathrm{ 1limit} , I\mathrm{ 2limit} , the total volume V\mathrm{ tot} , and the energy density \omega , are given. The validity of this method is confirmed by practical measurements of a set of constructed inductors with 2.67-mH total inductance. The absolute error is within 0.02 mH. On the basis of this method, parameter optimization on energy density is conducted for the 70-kJ energy level module. Results show that the energy density can reach 11.2 MJ/ \text{m}^{3} when the total inductance is 5.07 mH and the total volume is 6.3\times 10^{-3}~\text{m}^{3}$ . [ABSTRACT FROM AUTHOR]

A fast solving method for the launching process of the electromagnetic railgun and an automatic assignment method for the trigger strategy of the capacitive pulsed power supply (CPPS) are proposed. The accuracy of the solving method and the feasibility of the assignment method are verified through an illustrative example with a 1.8-MJ initially stored energy. On the basis of these methods, parameter optimization in design phase and performance analysis in operation phase are conducted around the projectile muzzle kinetic energy Ek and the system energy transfer efficiency $\eta $ . To be specific, the single-objective optimal solutions of Ek and $\eta $ and the biobjective Pareto front of Ek – $\eta $ are acquired by evolutionary computation. And the influence relations of certain system parameters on Ek and $\eta $ are acquired by parameter sweep. The research methods and results in this paper have both theoretical and pragmatic values in improving the performance of the CPPS-based electromagnetic railgun system. [ABSTRACT FROM AUTHOR]