I. Introduction
A world's first ever 1.2-MVA power electronic traction transformer (PETT) for 15 kV, 16 2/3 Hz railway grid, as shown in Fig. 1, has newly been developed, assembled, commissioned, and successfully installed on the locomotive [1]–[4]. It is presently in use by the Swiss Federal Railways. There are several features of PETT which make this technology advantageous over the conventional solutions and bring benefits to the society. PETTs offer substantial weight reduction at a considerable increase of efficiency and functionality, especially in terms of power quality and management at the traction line, since PETT is in essence a converter.
1.2 MVA PETT prototype for 15 kV 16 2/3 Hz railway grid.