A simulation method for the electromagnetic railgun based on equivalent circuit

Ruihu Wen^1,2

¹ School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China
² Science and Technology on Electromechanical Dynamic Control Laboratory, Xi'an 710065, Shaanxi, China

Abstract
As a typical electromagnetic launcher, electromagnetic railguns have attracted widespread attention for their broad military application prospects. It is known that skin effects occur during electromagnetic railgun launch. How to quickly and accurately simulate these skin effects is of importance for the application of electromagnetic launch technology. This paper proposes a static two-dimensional finite element model in series with one variable equivalent inductance and three resistances for simulating the dynamic electromagnetic railgun launch. Two skin effects are presented by changing equivalent inductance and resistances. For an electromagnetic railgun including two rails of length of 2 m and width of 0.3 m and square armature of 0.3 m long, after 4.23 ms under a pulse current of a peak of 1 MA, the simulation results based on this proposed static 2D model show that the armature can leave the rails with a velocity and acceleration increasing to 1,464 m/s and 614,876 m/s², respectively. For an equivalent circuit connected in series, the equivalent inductance, AC resistance, velocity skin effect resistance, and back EMF resistance are 0.49 μH, 2.5 mΩ, 7.1 mΩ, and 4.44 mΩ, respectively, whereas the breech voltage can increase to 1.36 kV. The proposed method simplifies the meshing in the finite element model, saves computational cost, and is conducive to study electromagnetic railgun design and projectile magnetic field shielding. Key words: Electromagnetic railgun, equivalent inductance, equivalent resistance. Tables 1, Figs 7, Refs 10.