An Improved Model Predictive Torque Control Strategy of a Shearer Semi-direct Permanent Magnet Synchronous Motor Based on Duty Cycle

In order to improve the stability of low-speed and high-torque permanent magnet synchronous motor control in the shearer semi-direct cutting system under large load fluctuation and strong impact conditions, an improved model predictive torque control strategy based on duty cycle is proposed which can effectively reduce the flux and torque ripples and improve steady-state control performance. This method combines the separate process of the voltage vector selection and the duty cycle calculation through the predictive model combined with duty cycle. Then, the optimal voltage vector and its duration is selected simultaneously based on minimizing the cost function. In addition, in order to mitigates the computational burden of the proposed method, the voltage vectors in the finite control set is pre-selected using hysteresis comparator according to the motor operating status. Furthermore, the duty cycle pulse width modulation is introduced to obtain a fixed switching frequency of the inverter. The results of simulation experiments confirm that the proposed strategy can significantly reduce the flux and torque ripples and improve the steady state performance while maintaining fast dynamic response.