A.C. diesel-electric drive system using consequential pole changing

The paper describes the development of a commutatorless diesel-electric drive system which uses an alternator and induction motors as the drive elements. The system provides a set of discrete final motor drive speeds at a fixed alternator drive speed, and so may be regarded as an electrical `gearbox?, a feature of the scheme being that, during normal operation, gear selection is carried out by pole changing the alternator excitation winding. Pole changing of the alternator output winding and the induction-motor stator winding is also used, but is a consequence of changing the alternator excitation pole number, and switching at full power level between the alternator and motors is thereby entirely avoided. The paper includes a sample design for a traction system having a continuous rating of 3600hp. The prediction of the performance of the sample design is substantiated by experimental results taken on a simplified laboratory model of the system.