Advances in locomotive Power Electronic systems directly fed through AC lines

High-power converters with a medium frequency inductive coupling, commonly referred as Power Electronic Transformers, Medium Frequency Topologies, Solid-State Transformers (SST), or other similar acronyms, have been certainly one of the most important innovations expectations - for many years - in the field of electrical equipment of the railway rolling stock. The main purpose of these topologies is to replace the usual line-frequency on-board transformer on the AC powered rolling stock (25 kV - 50 Hz and 15 kV - 16 2/3 Hz), bulky, heavy and characterized by rather poor efficiency.