Direct control of the synchronous motor stator flux linkage based on PWM

A new torque control strategy on the direct control of stator flux linkage based on PWM is introduced due to the disadvantage of synchronous motor current vector control and traditional torque control. Flux linkage and torque control are achieved through controlling the trajectory of stator flux linkage vector, thus permanent switching frequency and small flux linkage pulse are obtained. The necessary condition of the direct flux linkage control is also given in this paper. The experimental result indicates that the strategy is applicable to the weak sector control in the permanent torque area, which is better than the traditional current control strategy. Further more, it improved the dynamic response of speed and torque control in a wide velocity range.