Search

In inductive pulsed power supplies (IPPSs), the toroidal circular disk-type inductors have the advantages of high energy density, good symmetry, and slight magnetic field interference. However, the inductance calculation of the toroidal coils with a different geometric structure and electrical connection is very complicated, let alone the overall optimization of the IPPS system using structure parameters as variables. In this article, a systematic quick calculation method for the toroidal circular disk-type inductor with any geometric structure and electrical connection has been summarized and elaborated. Some improvements in accelerating the calculation speed have been proposed and verified. The error between the proposed calculation method and measurement is less than 1.1%. Finally, with the quick calculation methods, the genetic algorithm (GA) is used to optimize a 20-stage inductor for an XRAM generator with a total energy of 1.25 MJ. After 12 400 calculations, the energy density of the obtained optimal toroidal coil reaches 14.54 MJ/m3. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS) is a competitive type of power supply for electromagnetic launch (EML). Compared with the capacitive type, the structure and working process of IPPS are more complicated, which make the design of the IPPS module difficult. In this article, the method of calculating the module performance from structural and electrical parameters is proposed. Based on that, the biobjective optimization of a 100-kJ module is carried out. With the help of genetic algorithms, the optimization results are 2500 nondominated solutions on the Pareto front, and one of the representative solutions is verified by experiments. The performance of the built module is in good agreement with the calculated value. Its energy density reaches 3.98 MJ/m3, the peak output current reaches 23 kA with 8.1-ms pulsewidth. [ABSTRACT FROM AUTHOR]

High energy density makes inductive pulsed power supply (IPPS), a research focus of supplies for electromagnetic launch (EML). However, in existing IPPS topologies, the charging and discharging stages of the inductors cannot be separated, so the response time of IPPS can be as long as ten or even tens of milliseconds. For this reason, the real-time closed-loop control of the output current and muzzle velocity based on IPPS is nearly impossible, which might be one of its biggest drawbacks compared to the capacitive pulsed power supply (CPPS). In this article, a novel current maintainable meat grinder (CMMG) circuit capable of fast response for EML applications is proposed, in which the antiparallel diode can provide a current maintaining path. After the inductor completes its charging process, the current can be maintained for a period of time. Thus, the circuit can be in a hot standby state and can be triggered with a very short delay. Subsequently, two commutation methods for the CMMG circuit are explored. The first one is to introduce the inverse current commutation with semiconductor device (ICCOS) branch. In its experiment with an inductance energy of 22 kJ, the circuit maintains 77% of the charging energy in the first 10 ms and is triggered successfully after 28 ms with almost zero response delay. The second method is the superconducting switching technology, based on which the CMMG with self-shutdown circuit is proposed and simulated. [ABSTRACT FROM AUTHOR]

The performance of inductive pulsed power supplies (IPPSs) is limited by excessive joule heat loss and low energy transfer efficiency. A significant reduction in the coil resistance can fundamentally ameliorate this problem. This article takes the meat grinder with self-charge capacitor and thyristor (SECT) circuit as an example to study the performance improvement caused by the reduction of the coil resistance. The influence of coil resistance on several performance indexes is analyzed by circuit analysis and simulation. Then, the experiment with an energy level of 40 kJ is carried out, in which the inductors have very low resistance due to immersion in liquid nitrogen. With low temperature, the charging energy and the output current peak value are increased by 37% and 19%, respectively, the pulsewidth of output current is increased by 257%, and the energy transfer capacitor is successfully self-charged compared to the performance of the same SECT circuit with room temperature. Thus, the feasibility of applying nitrogen cooling to IPPS is validated. [ABSTRACT FROM AUTHOR]

The inductive pulse power supplies attract researchers’ attention as an important part of the electromagnetic launch system. However, in each topology of the meat grinder class circuits, the precharging of the auxiliary capacitor may cause many problems: the time-consuming precharging severely limits the repetition operating frequency, the charging devices and charging ports increase the complexity of the system, and there is a short-circuit safety hazard in actual operation. In order to solve the above problems, the meat grinder with an auto-charged commutating capacitor (ACC) circuit is proposed, in which the auto-charging of auxiliary capacitor is realized through topology design. Its working process is analyzed stage by stage, and the experiment of this circuit with 43 kJ is carried out. The experimental results are well fit with the simulation waveform, and the repeated operation is realized without precharging. [ABSTRACT FROM AUTHOR]

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]

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 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]

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]

A novel two-objective optimization design model for pulsed power supply (PPS) is proposed in this paper. The objectives are the muzzle velocity and the stored-to-kinetic energy efficiency. The design variables include the operating voltage and the trigger delay times between segments. The acceleration of the armature is constrained to lower than 106 m/s². The optimization results for the muzzle velocity and the efficiency separately show the following: 1) The acceleration constraint has great influence on the performance; 2) wide current pulse yields high velocity but low efficiency; and 3) the operating voltage has to be increased to accelerate a heavier projectile to a certain velocity or at a certain efficiency. Pareto solution fronts for various projectile masses are found using the nondominated sorting genetic algorithm (NSGA-II) under the integration environment of iSIGHT software. Numerical results show that the NSGA-II can provide a set of feasible Pareto solutions for the two-objective optimization design model of PPS, among which the "best" one is to be extracted according to the designer's requirements. [ABSTRACT FROM AUTHOR]