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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]

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 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]

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]