A Closed-Loop Velocity Control System for Electromagnetic Railguns

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-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, CPFU, 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.