Optimization of EM railgun based on orthogonal design method and harmony search algorithm

The muzzle velocity is a key index to reflect the performance of electromagnetic(EM) railgun. In order to obtain an optimal solution of muzzle velocity accurately and quickly in numerical simulation, an approach of combining orthogonal design method(ODM) and harmony search(HS) algorithm is presented. There are up to 11 factors to be considered in affecting 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 projectile. By ODM analysis, the best level combinations of these factors are selected and the significant degree of these factors is ordered. Therefore, the varying ranges of these factors are decided and a hierarchical factor optimization model is built. The optimization model is solved by HS algorithm with the penalty function method added to satisfy process constraints, such as the peak of current is bounded under 420KA. Finally, the proposed approach and the simple HS algorithm are compared. The results indicate that, by using the proposed approach, the average of original velocity is increased by 43.53%, and the average of best velocity at last, is increased by 1.34%.