To realize high-speed launch of reluctance coil-gun (RCG) requires the suppression of reverse electromagnetic (EM) force, when the center of the coil coincides with the center of the projectile to disconnect the coil power supply to quickly reduce the current is an effective means. In this study, the problems in the existing researches are explained in terms of circuit theory, and two technical difficulties are pointed out. One is to find the exact coincide time, which is basically estimated by the finite element method (FEM) at present, there are problems of slow calculation speed, and the results are affected by the accuracy of the input electrical parameters. Second, a sudden shutdown of a charged IGBT will create a large inductive electric potential and may be damaged. In this study, the treatment methods are proposed for these two points, respectively. On the one hand, an algorithm model is proposed to quickly estimate the coincide time based on the measured current data in the coil; compared with the FEM, it has the advantages of no need to know the electrical parameters and fast calculation speed. On the other hand, a new circuit topology is proposed, in which the IGBT is moved to the coil branch for current breaking at any time and a resistor–capacitor ( RC ) absorption circuit is connected in parallel to the coil side to protect the IGBT. The comparison of experimental and simulation results proves that the method proposed in this study is feasible, and it avoids both the tedious operation of testing component parameters and the errors caused by inaccurate parameter input, showing the convenience in application.

In this study, a method is proposed to obtain the initial voltage of the capacitor and the initial relative position of the projectile of a reluctance coil gun using a genetic algorithm to make the projectile launch at a specified muzzle velocity with high efficiency. Firstly, the equivalent inductance change during the launching process is used as a link for multi-physics field analysis, and a set of electromagnetic dynamics equations is derived to correct the effect of magnetic saturation on the inductance according to the current value in the coil. Further the set of equations is constructed as a Simulink discretized numerical computational program and called by a genetic algorithm written in MATLAB to approximate the optimal solution by generation-by-generation optimization. When the specified projectile muzzle velocity is set to 10 m/s, the initial voltage of the capacitor calculated using the genetic algorithm is 156 V, and the initial position of the projectile is -14.3 mm. We input the parameters into the finite element analysis model and the launch experiment platform, and the obtained projectile muzzle velocity is 9.67 m/s and 9.8 m/s respectively, and the efficiency is close to the optimal value, also the comparison of voltage and current waveforms also shows that the method proposed in this study is effective.

The analysis of the reluctance coil launcher (RCL) basically relies on the finite element method (FEM), but the method is time-consuming and does not meet the real-time requirements for control, which seriously hampers the expansion of engineering application areas. To address this problem, this study proposes a numerical calculation method dedicated to RCL based on the mathematical equations of electromagnetic coupling, in which the magnetic saturation problem is corrected by the inductance lookup table method, and the inductance in the coupling circuit is updated in real time according to the instantaneous current and the instantaneous position of the projectile. The accuracy of the calculation method is verified and the reasons for the errors are analyzed by establishing finite element simulation model, MATLAB/Simulink model and experimental platform for a single-stage and a three-stage RCL and comparing the obtained data. When the discharge voltage of the capacitor is 300 V, the accuracy of the projectile muzzle velocity in the single-stage and three-stage is 98.42% and 98.20% respectively, which indicates that the calculation method is correct under specific conditions. The time consumed by the method is only about 1/1000 of that of FEM, which even includes the compilation time of the software MATLAB/Simulink, illustrating the advantages of the algorithm and its application prospects.

Reluctance coil launchers usually use a pulse current formed by capacitive discharge to excite the excitation coil when launching. The pulse current peaks are high, and the projectile usually undergoes deep magnetic saturation, resulting in low launching efficiency. To address this problem, this article proposes using distributed feeder circuit to drive reluctance coil launchers, replacing the traditional single set of large-capacity capacitor discharge scheme with multiple small-capacity capacitors discharged in a time-sequential manner, so as to reduce the peak current and suppress magnetic saturation problems. The study includes two main aspects, one is to study the effect of the driving method on the launch performance and analyze the reasons; the other is to propose the calculation of the time-varying data in the launch process by the time-segmented calculation method. The efficiency of the model described in the paper is only 1.301% when using a single high-capacity capacitor for launching, while the launching efficiency is increased to 3.535% when driven by the distributed feeder circuit, indicating that the method can effectively improve the launching performance.

In view of the problem that the output thrust of solenoid actuator is affected by various factors and is difficult to calculate in actual working conditions, this paper proposes a semi-analytical model constructed by magnetic field subdomain method with internal and external boundary conditions in cylindrical coordinate system for calculation, and the general solution equations of magnetic vector potential for each subdomain are derived and solved by MATLAB. Taking a push-pull electromagnet as an example, the finite element simulation and experimental comparative analysis are carried out. The correctness and applicable conditions of the subdomain method are illustrated by comparing the gradient plot of magnetic vector potential, inductance curve and electromagnetic force. By calculating the output thrust after considering the core gravity, spring force and electromagnetic force, it is shown that this method has the advantage of computational flexibility compared with the finite element method, and it is easier to write special algorithms according to various working conditions to calculate the important parameters in engineering applications.