A new inverter control scheme for induction motor drives requiring wide speed range

A new control scheme to extend the speed range of four pole induction motor drives for electric vehicles is investigated. A three phase stator winding is used with each of the two coil groups per phase being independent resulting in a six coil, six terminal machine. Two inverters supply the machine with the required regulated currents to obtain the effect of either four pole or two pole windings. Four pole operation is proposed from zero speed until the end of its constant power region. Employing contactorless pole changing to obtain two pole operation extends the constant power region resulting in a doubling of the speed range for the same inverter/machine rating.