Reduction of torque ripples in 3-level inverter fed PMSM drive based on instantaneous voltage control technique

摘要

In this paper, an efficient speed control technique is proposed for Direct Torque Control(DTC) of Permanent Magnet Synchronous Machine(PMSM) drive in order to reduce the ripple content in torque and flux. Though conventional DTC gives fast dynamic response, it has noticeably high ripple content due to the variable operating frequency of the inverter especially at lower rpm. To enervate this issue, SVPWM method is employed in this paper thereby making the inverter operating frequency independent of rotational speed. In order to further reduce the ripple content, a 3-level cascaded inverter is used. SVM is implemented using instantaneous voltage control technique for mathematical simplicity. The proposed method is implemented in Matlab/Simulink and the results obtained are compared to those of conventional DTC. It is observed from the results that there is a significant reduction in ripple content in the proposed technique when compared to the conventional method.