Electromagnetic Coil Launcher Research Articles

Damage and Failure Analysis of Insulation Structure of Electromagnetic Coil Launcher in Multiphysics Environment

Damage and Failure Analysis of Insulation Structure of Electromagnetic Coil Launcher in Multiphysics Environment

Analysis of the Influence of System Parameters on Launch Performance of Electromagnetic Induction Coil Launcher

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes a pulse power supply and launcher. The parameters of the pulse power supply mainly include the discharge voltage and the capacitance value of the capacitor bank. The structural parameters of the launcher mainly include the bore size of the launcher, the air gap length between the armature and the drive coil, the length and width of the drive coil, and the trigger position of the armature. Change in single or multiple parameters in the launch system will influence the launch performance. The influence of single or multiple parameters on the launch performance was summarized, and the physical law as analyzed. The influence law of the EICL system parameters on the launch performance was obtained, which lays a theoretical foundation for the optimization design of EICL. Finally, experimental verification was carried out by a single-stage test platform.

Study on the influence of different thickness of armature structure on the emission performance of electromagnetic induction coil launcher

In the armature structure of traditional electromagnetic induction coil launcher, the armature tail melted due to heat accumulation. In this paper, three new armature structures are proposed. Based on the finite element software maxwell2D, the single-stage electromagnetic induction coil launcher, model is established. The performance indexes of traditional and new armature structures are compared, and the influence of the thickness of traditional armature structure and the side thickness of new structure on temperature rise and electromagnetic performance is studied. On the basis of Maxwell-thermal finite element, the correctness of the temperature field conclusion is verified. The simulation results show that the traditional armature structure has the optimal thickness and the armature performance remains unchanged when the weight ratio and the mechanical strength of the armature are considered. Structure 3 and Structure 4 of the new structure significantly improve the temperature rise of the armature and enhance its emission performance. Due to the eddy current, the optimum side thickness of the new structure 3 and structure 4 is slightly larger than 1/2 of the armature length.

Research on Adaptive Design and Optimization of High-Speed Coil Launcher

With the increase of coil stages of the high-speed electromagnetic coil launcher, the mutual coupling between the parameters and the increase of the variables to be designed make the design of the multistage high-speed electromagnetic coil launcher more difficult. In this article, an adaptive design method of electromagnetic coil launcher based on the current filament model is proposed. Its feasibility is verified by a 25-stage coil launcher design scheme calculation example. However, the coil temperature rise cannot be restricted with the traditional step-by-step trial method and adaptive design method alone. The use of traditional optimization algorithms will consume a lot of time to get a result. Therefore, this article adopts the genetic algorithm (GA) based on the predictive model to obtain constrained optimization results. With the predictive model of support vector regression (SVR), the average prediction error of the armature peak speed can be controlled below 5%. Using the established predictive model, GA is used to optimize the adjustable parameters in the adaptive design. The peak velocity of the predictive model output is selected as the fitness function, and the coil temperature rise and acceleration stability are constrained. Sixteen sets of optimization results are obtained by repeated optimization calculation. The peak speed of the armature can reach 1083 m/s, the launch efficiency of the launcher is 25.78%, and the maximum temperature rise of the coil is 76.88°C. Compared with ordinary optimization algorithms, the calculation time is greatly reduced.

Optimization Calculation of Single Stage Coil Launcher Based on Prediction Model

At present, the optimization design method of electromagnetic coil launcher mainly includes of manual trial and error method and intelligent algorithm. The former has low optimization efficiency and poor effect, while the latter can obtain optimization results, but the calculation time is longer. In order to improve the calculation efficiency and obtain the global optimal solution of the coil launcher, the optimization process of the coil launcher must be improved. In this article, a genetic algorithm based on a predictive model is adopted. By using the output of the predictive model as the optimization target and constraint target of the optimization algorithm, it avoids calling the full model of the coil launcher during the optimization process and effectively reduces the calculation time. The orthogonal test method and the current filament method are used to establish 49 sets of orthogonal sample data of the single-stage coil launcher. The optimal armature speed of the coil launcher obtained in the orthogonal test is 59.81 m/s; the support vector regression (SVR) prediction model is obtained by training on the orthogonal test results, and the prediction error of the test data is 0.39%; the genetic algorithm based on the prediction model is used to optimize the single-stage coil launcher. The calculation result shows that, without constraints, the peak speed of the armature is 60.17 m/s. After the temperature constraint is added, the peak speed of the armature is 59.86 m/s.

Modeling and Simulation of Electromagnetic Field of Electromagnetic Coil Launcher

Electromagnetic coil launcher is a kind of special linear motor. In order to study the trigger principles of multi‐stage electromagnetic coil launcher, based on the electromagnetic field theory, the paper deduced the field‐circuit coupling magnetic field control equations of multi‐stage synchronous inductive coil with the consideration of inter‐stage coupling, and analyzed the distribution law of magnetic lines of force, air‐gap magnetic field and current density for multi‐stage electromagnetic coil launcher. The following conclusions were reached: the largest part of magnetic flux was at the intermediate stages of multi‐stage electromagnetic coil launcher; each stage of drive coil compensates for the magnetic field of the upper coil, thus making a stable air‐gap magnetic field; the induced current density was mainly distributed in the tail and surface of the armature; according to anti‐electromagnetic shock design principle of multi‐stage electromagnetic coil launcher (namely, the requirement for small fluctuation of electromagnetic force), the basic principle of multistage trigger was summarized, that is the principle of keeping air‐gap magnetic field and induced current constant. Thus, the design foundation was laid for the operation of multistage electromagnetic coil launcher. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Design and Implementation of a High-Speed Real-Time Position Detection System in Electromagnetic Coil Launcher

Electromagnetic coil launcher (ECL) is a specific application of electromagnetic launching technology and has broad prospects in the fields of new weapon systems and launching microsatellites. The acceleration force of the projectile in the ECL depends on the current of the driving coil and the projectile together with the mutual inductance between them, and to maximize the launch coefficient, each drive coil should be energized according to the projectile’s movement position. In order to realize the closed-loop control of the ECL and improve the energy utilization, a new position detection system (PDS) based on fiber optic sensor (FOS) is designed in this article, which can obtain the armature displacement and velocity in real time during the launch process. Then, the main factors influencing the detection results are analyzed and studied. Finally, after experimental verification, the PDS designed in this article has an error of 4.2% and 1.41% in the measurement of the armature position and velocity, respectively. The results are of great significance to the realization of ECL engineering.

Research on Armature Recovery of a Coil Launcher

At present, the boost payload of electromagnetic coil launcher mainly adopts integrated launching mode; that is, the armature and payload are integrated into a projectile to shoot out of the bore together. There are some problems with this kind of launching form, such as high parasitic mass and low efficiency of payload launching. In this article, a payload projection scheme of armature–load separation launching is proposed. When the armature and payload reach the peak velocity, the armature is separated from the payload by electromagnetic capture force, and the armature can be recovered and reused under certain conditions. A model of five-stage coil launcher is established and the interior trajectory characteristics of armature under the integrated launching and separation launching modes are compared by simulation. It is shown that the mass of armature will exaggerate the launching performance. The armature–load separated launching mode can effectively improve the launching efficiency. Then the armature recovery method is further proposed. The armature velocity is related to many factors such as mass ratio of armature and payload, driving voltage, and turns of the last coil stage. The study proves that under certain conditions, the armature can be recovered, which could improve the safety of launch.

Study on temperature rise of electromagnetic coil launcher

Synchronous induction coil launcher mainly uses pulse current to supply power directly to the coil. The temperature rise of armature and coil will occur in the actual working process, and it is a major factor restricting the development of coil launcher to miniaturization and high speed. In this paper, the temperature rise model of electromagnetic coil is established. For single trigger, Comsol and self-programmed Coilgun are used to calculate, and the corresponding test platform is built to verify the temperature rise. The Comsol method with direct coupling is the most accurate method, and the change of material parameters with temperature can also be considered. The simulation results show that the temperature rise of armature is about 4.2 ℃ and the maximum temperature rise of coil is 7.7 ℃. Because of the limitation of measurement delay and sampling frequency of thermocouple temperature sensor, the armature temperature test curve can not measure the maximum temperature point in the simulation curve, it can record the temperature change curve in the whole test process. The change of temperature and the final stable temperature are basically consistent with that of the simulation. The maximum error is 6.1%, which shows the accuracy of the simulation. This study lays a foundation for subsequent multi-stage coil continuous launching.

Research on Driving Circuit Improvement of Coilgun

Theoretically, the energy conversion efficiency of the synchronous induction coil launcher (SICL) can reach 100%, but at present, the test data show that the highest current is only a little higher than 20%, which shows that the efficiency of the coil launcher has a lot of room for improvement. In this paper, three improved schemes are proposed for the topology of the traditional crowbar circuit based on the pulse capacitor to improve the electromechanical energy conversion efficiency of the electromagnetic coil launcher. They are main circuit breaking, crowbar break-off circuit, and crowbar circuit with inductor, respectively. In order to verify the feasibility of the above three methods, a five-stage coil launcher was simulated and analyzed. Then, based on the model, three improved circuits were calculated and analyzed by the finite-element simulation software. The results show that all of the three methods can improve the efficiency of energy conversion to a certain extent. Both the first and second methods have limited effect on increasing efficiency. In addition, they need to add some expensive equipment such as circuit breaker. So, they are not recommended. The third way of increasing an inductor in the crowbar circuit could increase the muzzle velocity and efficiency obviously. The muzzle velocity increased from 30.6 to 35 m/s. The effect of armature capture is reduced which is worthy of recommendation.

The Launch Performance Analysis of the Electromagnetic Coil Launcher Continuous Launch Process With Multiple Armature

In this paper, it is mainly aimed to study the working condition when there exists multiple armatures in launch tubes in the process of hyper velocity launching of the electromagnetic coil launcher. On the basis of understanding the single stage induction coil launch principle, this article expounds the working process of this kind of condition, and based on the circuit principle, an electrical and mechanical model for continuous emission of electromagnetic coil launcher with multiple armatures is set up. Through systematic description to the launcher equivalent circuit and the control equation, thrust equation and equation of motion, it further expounds the mechanism of the launcher. Dynamic simulation and structural design of electromagnetic coil launcher is conducted based on established parameters. Finally, the results of theoretic analysis and simulation design were further verified by the experiment, and the results of this paper are achieved.

Trigger Control Research of Electromagnetic Coil Launcher Based on Real-Time Velocity Measurement

In order to avoid the inherent defect of the traditional position trigger and time trigger, reduce launch error accumulation, and improve the launch efficiency of the electromagnetic coil launcher, a new trigger control method based on real-time velocity measurement is provided in this paper. By the simulation of the launcher whose structural parameters are given, the optimal trigger time corresponding to the different initial velocity could be achieved and preset to the host computer. First, the initial velocity of each stage is measured in real time, and a new time reference is set. Second, the measured data are matched with the preset data, and then the final control time of trigger can be fixed by the interpolation method. Finally, the validity of the method is verified by the experiment.

Comparison of Electromagnetic Coil Launcher Model with Real-Device Characteristics

In this paper we describe a numerical model and a construction of an electromagnetic launcher (EML) consisting of ten copper coils located serially. The solenoids were mounted on the pipe-shaped slideway, inside which, the ferromagnetic core was moved driven by the coils magnetic force. The paper presents the model of an EML based on circuit approach involving lumped parameters which were obtained by means of a finite element methods (FEM). The numerical representation contained a mechanical part with introduced friction coefficients. In the article we proposed an algorithm which enabled us to fit the numerical model to the constructed device by selection of these friction parameters values. Thus, we were able to compare the signals from computer simulations and measurements which were taken during laboratory tests.

Research on the Scaling Model of Electromagnetic Coil Launcher

A model experiment is an effective method to investigate the working characteristics of electromagnetic coil launcher (EMCL). Results from the model experiment are applied to the prototype study of EMCL, after the scaling relations of physical quantities between model and prototype are determined. A new type of EMCL is designed, and the scaling factor relations of the physical quantities between model and prototype of the EMCL are deduced based on its mathematical model and similarity theory. The scaling model is investigated by simulation. It is shown that the scaling factor relations of the physical quantities are expressed as length-scaling factor, and the scaling model is feasible.

Multipole Field Electromagnetic Launcher

A conventional electromagnetic coil launcher has some inherent problems and technical limitations. We present a novel multipole field electromagnetic launcher based on eddy-current catapult and multipole induction acceleration. We introduce the operation principle and conception model. We analyze the electromagnetic acceleration force of eddy-current catapult and induction acceleration. We establish the system circuit equation and dynamics equation. Using electromagnetic field finite-element analysis coupling with the circuit, we simulate and compute the transient launch process of multipole field electromagnetic launcher. The simulation result indicates that the multipole field electromagnetic launcher has the potential of developing huge thrust force, large driven mass, supervelocity launch, and steady maglev.

High velocity linear induction launchers

Electromagnetic launchers (EMLs) have received great attention in the last decades because of their potential application to a variety of energy, transportation, space, and defense systems. Particularly, they can serve as kinetic weapons, such as ground-based and naval artillery, space-based anti-missile guns, Earth-to-Orbit launcher, and mass transportation. The main advantage is that EMLs can accelerate projectiles to hyper velocities, i.e. velocities greater than those achievable with conventional cannons. The Linear Induction Launcher (LIL) is an air-cored electromagnetic coil launcher operating on the principle of the induction motor. Polyphase excitation of the coils constituting the barrel is designed to create an electromagnetic wave packet, which travels with increasing velocity from the breech to the muzzle. The projectile is a hollow conducting cylinder (sleeve) carrying the payload within it. Relative motion (slip) of the wave packet with respect to the projectile induces azimuthal currents in the sleeve that interacts with the exciting magnetic field to produce both propulsive and centering forces. This paper deals with the design of a high velocity linear induction launcher with muzzle velocity up to 6000m/s. It addresses the design specifications of the launcher and utilizing a projectile weighing 1kg. In the paper, the design specifications with simulation results for the phase voltages, the currents, the velocity, and the temperature rise of the sleeve are presented.

Use of electromagnetic coil launcher to increase muzzle velocity of conventional cannons

The paper deals with the design and operation of an experimental hybrid cannon consisting of a 60 mm bore gas cannon using standard propellant and a traveling-wave induction accelerator. The projectile, consisting of an aluminum cylinder weighing 120 grams, is initially brought up to a speed of 600 m/s in the gas cannon. The pulsed-power stage is designed to accelerate the projectile further to a velocity of 700 m/s.