Unreasonable torque ripple of direct torque control in permanent magnet synchronous motor

In order to decrease torque ripple of direct torque control (DTC) in permanent magnet synchronous motor (PMSM), the PMSM DTC model is set up and the effect of voltage vectors on torque is analyzed based on the theory of DTC in PMSM. The conclusion that the changes in the magnitude of stator flux and torque angle (angle between stator and rotor flux vector) is opposite under some conditions (the change in torque is consistent with the change in the magnitude of stator flux), is proposed. The actual effect of voltage vectors on torque based on traditional switching table is opposite to the expectation and causes unreasonable torque ripple. The simulation shows that the conclusion is correct.