Asynchronous linear machine as booster for railway vehicles

An asynchronous linear machine as a booster for railway vehicles is presented. The short stator is mounted on the locomotive, the secondary is fixed to the track. This machine is to be used at steep slopes and should substitute the pushing locomotive which is used to push heavy trains at steep slopes. For the German heavy rail loco BR 152 the asynchronous linear machine as booster drive (ALIM) is investigated to increase the tractive effort especially under wet rail conditions. The primary with the three-phase armature is mounted on the bogie, the secondary linear cage is fixed in the middle of the track. Two solutions are pointed out: the ALIM is fed by the PWM inverter of the locomotive in parallel with the traction motor; and the ALIM is supplied by an extra inverter fed from a DC link of the locomotive traction drive. Investigations on the requirements such as the mounting space for the ALIM or the use of an extra inverter for the ALIM and the calculation of the forces are presented. The increase of tractive effort under wet rail conditions is estimated