Multi-speed induction motor for direct drive applications

This paper presents the study of the transients for a multi-speed induction motor with toroidal stator winding and external rotor. The results prove the superiority of the toroidal winding for external rotor structures since it offers an easier way to change the coil ends connection in order to obtained more synchronous speeds. By knowing the motor mechanical characteristics, the start-up has been simulated for each pole number configuration. For two of the situations, the start-up takes into consideration both no-load and under load operation using a strategy based on the switching of poles number.