Optimization of Electromagnetic Railgun Based on Orthogonal Design Method and Harmony Search Algorithm

Muzzle velocity is a key performance metric of the electromagnetic railgun. To obtain the optimal value of the muzzle velocity in terms of the parameters affecting it, an approach combining the orthogonal design method (ODM) and the harmony search (HS) algorithm is presented. There are up to 11 factors that affect the muzzle velocity, including eight trigger delay times of pulsed power supply (PPS), the operating voltage of PPS, the length of rail, and the mass of the projectile. The optimal values of these factors are computed and the degree of significance of these factors is ordered by the use of ODM analysis. Based on the significance order, the varying ranges of these factors are decided and a hierarchical optimization model is established. The optimization model is solved by the HS algorithm with the penalty function method, which is used to satisfy the process constraints. For example, the peak of current is bounded under 420 kA. Finally, the optimization result using ODM analysis along with the HS algorithm is compared with that using the HS algorithm alone. It is noted that by using ODM analysis along with the HS algorithm, the average of initial muzzle velocity is increased by 43.53%, and the average of best final muzzle velocity is increased by 1.34%.