Research On Model Predictive Torque Control Of Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motor(PMSM)has the advantages of low energy consumption,wide speed range,running stable,strong overload capacity,etc.,and is widely used in modern industry.The traditional PMSM control strategy has problems,such as torque ripple,large overshoot and difficult parameter adjustment.To obtain better PMSM control performance,the Model Predictive Torque Control(MPTC)of PMSM was studied in this thesis.The main research contents of this thesis were as follows:(1)In order to solve the problems of difficult adjustment of weight coefficients,torque ripple and large calculation amount for traditional MPTC cost function,an improved MPTC PMSM control strategy was proposed.The torque and flux linkage were normalised,and the torque and flux linkage errors were converted into error rates to solve the problem of difficult selection of the weight coefficients.Simplified current prediction was used,with only one predicted current value calculated,reducing the amount of calculation.SVPWM was used instead of PWM to suppress torque ripple.The simulation results showed that the proposed method had less torque ripple and simplified calculation.(2)The improved Type Ⅰ MPTC and improved Type Ⅱ MPTC control strategies based on parameter identification were proposed to solve the problems of parameter perturbation affecting prediction error,incomplete compensation of current prediction and large torque ripple without weighting factor in the improved MPTC.The recursive least squares method with forgetting factor was used to identify the inductance and flux linkage,which were more affected by the prediction error,to improve the parameter robustness of the system.The two-step delay compensation was used in the improved Type Ⅰ MPTC to solve the problem of incomplete compensation.The improved Type Ⅱ MPTC used particle swarm optimisation algorithm on the basis of two-step compensation to achieve self-tuning of the weight coefficients,and solve the problem of large torque fluctuations.The simulation verified the effectiveness of the proposed two strategies.(3)The improved MPTC,improved Type Ⅰ MPTC and improved Type Ⅱ MPTC proposed in this thesis were experimentally verified by the RT-LAB platform.The experimental results showed that the improved Type Ⅱ MPTC can adjust the weight coefficients in real time,solving the problems of difficult adjustment of weight coefficients and large torque ripple,and the response speed and control accuracy were better than the improved MPTC and improved Type Ⅰ MPTC.