Field-weakening scheme combined with saturated voltage control strategy

In this paper, a novel field-weakening scheme which is combined with a saturated voltage control strategy is proposed and its performance comparison with the previous scheme (without implementing the saturation strategy) is presented. Though the proposed scheme is quite simple, it is effective to provide a higher torque capability than the previous scheme does. The maximum torque is produced by increasing the flux-producing current as much as possible while the stator voltage reference is saturated. The voltage saturation condition is stimulated by adding the torque-producing current into the flux-producing current reference. Since the DC voltage utility can be improved, that hence, improve the output power in the high speed motor operation, a larger torque is produced. Experiments were carried out to verify the proposed scheme. The experimental results of the previous scheme are also presented for comparison purposes.