Use of star-delta switching to improve the performance of an inverter-fed induction motor drive (IM-ES-034)

Until recently, all railway electric traction systems have been based on the d.c. motor. A typical tractive effort versus speed graph for such a system is shown in figure 1. In attempting to replace the d.c. motor with an inverter-fed a.c. induction motor, a similar traction characteristic is a major...