A DTC-PWM control scheme of PMSM based on 12-sectors division and speed information

This paper presents a modified DTC-PWM scheme which uses 12-side sectors and 12 voltage vectors to reduce torque and flux ripple. In the proposed control scheme, three voltage vectors can be selected in a sector with the torque and flux error conditions. The 3 voltage vectors are set as big-small, medium-medium and small-big pairs of torque and flux component according to the sign of the torque and flux error. So, the suitable voltage vector can be determined by the error magnitudes of the torque and flux. And the duty ratio to determine the switching time of the selected voltage vector is calculated by the torque, flux error and speed information. Unlike the conventional approaches, the properly selected voltage vector among three voltage vectors can increase the dynamic response of torque and flux control. And the properly calculated duty ratio based on the flux, torque error and speed information, can decrease the flux and torque ripple with the fixed switching frequency. The proposed DTC-PWM based on the 12-side sectors and duty ratio calculation method is verified by the computer simulation and experimental comparisons of PMSM.