| The technology of electromagnetic launch is a leap in the fields of the propulsion technology in recent years. It has opened up a new avenue to meet the special requirements of propulsion, such as ultra high speed and big mass. Its merit of low propulsion cost has especially attracted the attention of all countries. The electromagnetic launch is that when the electromagnetic force works, the electromagnetic energy is transformed into kinetic energy which is used to launch projectile (armature). The coil-type electromagnetic propulsion technology in essence is that the varied magnetic field produces eddy-current in projectile, and then the eddy-current and the varied magnetic field interact to generate the electromagnetic force to promote projectile motion. The technology of electromagnetic launch is a kind of new technology that objects are launched by the electromagnetic energy instead of the conventional chemical energy. The technology of electromagnetic launch is applied in the field of the national defense and civilian industries, such as aircraft launch system, electromagnetic gun, linear electromagnetic induction pumping units, ramming machine and so on.Nowadays traditional launch technologies can hardly meet people's special demands towards driving apparatus in the aspect of velocity and safety, while the EML technology, which has been revived only in recent years, casts a new light on solving the above-mentioned problems. Potential and advantageous as it is, EML technology is relatively more complex to be applied than traditional launching technologies. The process of the electromagnetic launch is a transient process, so the interaction between the stator windings and projectile changes with the change of time. Consequently, to design an electromagnetic launch system which has good working conditions, it is rather necessary to build a numerical simulation model. In the course of the electromagnetic launch development, there are three basic types of the electromagnetic launcher: the track gun, the coil gun and the reconnection gun. The coil gun, also named coil electromagnetic launcher, can be interpreted as a cylindrical linear motor. Its characters are as follows: Because of the magnetic suspension effect, there is no fiction between tube and projectile in acceleration process; simple structure; wide range of launch quality; different shapes of the projectile; simple energy source; high initial velocity; good controllability and excellent performance. Therefore, only the coil electromagnetic launcher is researched in this paper.After analyzing the characteristics of driving coil circuit and kinematics, the system equation of the multistage electromagnetic launcher is built. The system equation is a nonlinear differential equation. The projectile is equivalent to some slices, which make the self-inductances, mutual inductances and mutual inductance gradient closer to the actual situation. According to the symmetry of the parameters, the assignment table is used to decrease the calculation time. The Treanor algorithm, which has better stability, is used to solve the nonlinear constant differential equations, and a stable solution is obtained. A computer simulation program which is especially appropriate to the multistage coil gun is designed, and the simulation results satisfactorily agree with the experimental data.The obtained parameters are used to design the 3-stage coil launch system model. Many experiments have been done to validate the results. To improve the projectile launch times per unit time, a series resonant constant current charge power is designed, and the work circuits are simulated with the PSPICE software. According to the simulation results, the charge power is manufactured, which raises the capacitor charge speed and improves the battery charge performance.Both theoretical analysis and experimental study show that the proposed model and the analysis method are reasonable and have laid a foundation for further research.
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