Design and field-weakening performance of permanent-magnet/reluctance motor with two-part rotor

A synchronous motor with two-part rotor is described whose rotor comprises a surface-magnet part and a reluctance part mounted adjacent to each other on the same axis. An axially laminated construction is used in the reluctance part to achieve a high saliency ratio. Machine parameters and physical design details are selected to obtain constant-power characteristics over a 3:1 speed range by field-weakening. Test results demonstrate the achievement of the desired characteristics, in good agreement with computed predictions. The two-part rotor construction is thus a candidate for applications such as electric vehicles.