A novel duty ratio control to reduce torque ripple for DTC of IM drives with constant switching frequency

摘要

The conventional switching-table-based direct torque controlled (DTC) induction motor drives are usually afflicted by large torque ripple as well as inconstant switching frequency in a low speed range. A novel DTC strategy of induction motor with duty ratio control is proposed based on the detailed analysis of effect factors of flux linkage and torque ripples. In this method the pulse duration of active vector is calculated according to equalizing the mean torque with its desired value over one control cycle. The proposed scheme is able to reduce the torque ripple significantly while maintaining the simplicity and robustness of conventional DTC at the most. Simulations and presented experimental results validate the effectiveness of the proposed scheme as compared with the conventional method.