Stochastic estimate of redundancy effects for non conventional ac locomotive traction drives

The direct connection of locomotive power electronics equipment to medium voltage ac overhead lines seems to be a practicable option today. Low frequency onboard transformers could therefore be eliminated, thus resulting in more efficient and lighter rail vehicles drive chains. However, the removal of the conventional transformer requires the development of innovative power conversion architectures, which should be carefully analyzed in all respects. Aim of this paper is to evaluate, through a comparative analysis, the effectiveness deriving from the adoption of redundant configurations in a non-conventional ac loco traction drive, which allows the use of transformers of greatly reduced size. Playing power electronics a fundamental role in the solutions analysed by the authors, a detailed analysis based on the Monte Carlo procedure has been carried out to compare the stochastic performances of the loco electrical drive systems under analysis, as a function of the reliability characteristics of their basic components.