Minimizing Wheel Slip in Railway Locomotives with Coupled Permanent   Magnet Synchronous Motors
  In this work I consider control strategies of permanent magnet synchronous motors in which the back-emf signal from the motor is used to achieve commutation of the six step driving circuit. I show that if the strategy is modified to connect multiple motors in a cyclic chain, then a collective synchronized state is favoured. The stability of this state can be exploited in the bogies of a railway locomotive to automatically terminate wheel slipping episodes. 
Shayak Bhattacharjee
nlin.CD