New direct torque control method considering voltage vector duty ratio used in PMSM drive

Implementation of permanent magnet synchronous motor (PMSM) direct torque control (DTC) is not unique. The new DTC method considers the fastest torque response and the stator flux linkage loop in traditional DTC is removed. However, large torque ripple exists in the new method with the same in the traditional switch table DTC. Duty ratio control can adjust the time of effective voltage vector, so as to change the voltage vector strength within a sampling period. The duty ratio control mixed together with the new DTC would reduce the torque ripple and improve system performance.