Analysis of the Triggering Instants of the Solid-State Switches of the Pulsed Power Sources for Achieving Optimal Projectile Velocity in a Multistage Induction Coilgun

The coils of each stage of a multistage induction coilgun must be precisely and appropriately synchronized to achieve a higher launch velocity (vp) of the projectile. Hence, the optimum triggering instant of the solidstate switch of the pulsed power source (PPS) with respect to the position of the projectile inside each coil plays a vital role in achieving a higher vp of the projectile. The several stages of a multistage induction coilgun can typically be energized in two ways: (1) positive-positive (“PP”), where the direction of the excitation currents in the subsequent coils is kept the same, and (2) positive-negative (“PN”), where the direction of the excitation currents in the subsequent coils is reversed alternatively. The optimum triggering instant for the projectile inside each coil of the subsequent stages changes accordingly in these two launching configurations. This paper investigates and compares the difference between triggering instants for the projectile inside each coil in “PP” and “PN” launching configurations. A computer simulation-based analysis is carried out with a four-stage induction coilgun. The input electrical energy to each stage is kept constant at 252 J. The triggering instant for the projectile inside each coil is then set such that the projectile position is anywhere between the corresponding coil's rear and front ends with a linear step of 1.6 mm. The analysis presented in this paper will help better understand the operation of a multistage induction coilgun.