Abstract：Brushless DC motor has the advantages of high reliability and high efficiency，but due to its own

structural characteristics and driving characteristics，it will produce large torque pulsation during operation. In light

of this operation problem，an improved direct torque control strategy for brushless DC motor was proposed，which

adopts a new space vector pulse width modulation technique to replace the switching table module in the traditional direct torque control，and combines it with the sliding mode controller. The arithmetic process of the spatial pulse width modulation technique was improved to simplify the calculation process. The sliding mode controller was introduced to replace the traditional PI controller，and the control process was optimized using the super-helix algorithm. Under the simulation environment，the traditional direct torque control and the new direct torque control strategy were compared，and the results show that the new direct torque control strategy has significant improvement in motor response time，speed overshoot and torque fluctuation amplitude.

      Key words：brushless DC motor（BLDCM）；direct torque control（DTC）；torque ripple reduction；space

vector pulse width modulation（SVPWM）；sliding mode control