A Three-vector-based Model Predictive Flux Control For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)is widely used in aerospace,transportation track,industrial robots,due to its simple structure,small size,high efficiency.The model predic-tive torque control has attracted more and more attention due to its advantages of fast dynamic response,simple and easy implementation,and multi-objective control.However,but there still are some significant problems that the weighting factor is difficult to adjust and the steady-state performance is poor.The model predictive flux control strategy is an improved method for the weighting factor that is difficult to adjust.By analyzing the relationship of load angle,reference stator flux and reference torque,the equivalent reference stator flux vector is obtained,the new cost function only contains the error terms of the equivalent reference stator flux vector and flux prediction,eliminating directly the weighting factor,but the problem of large torque and flux ripple still exists.The optimal duty cycle model predictive flux control strategy is an improved scheme to improve the steady-state performance of the model predictive flux control strategy,the duty cycles of every active voltage vectors are calculated in advance by the cross-axis deadbeat flux principle,then the cost function is used to optimize the active voltage vector and the duty cycle combination.Although the magnitude of the candidate vector can be adjusted,the direction is still fixed,resulting in limited steady-state performance improvement.In order to further reduce torque and flux ripple,a three-vector-based model predictive flux control strategy for permanent magnet synchronous motor is studied in this paper.In this method,two adjacent active vectors and zero vector are used to synthesize the desired voltage vector with adjustable amplitude and variable direction,and the action time of the three vectors is obtained by the orthogonal axis deadbeat flux principle.When the selection range of candidate voltage vectors is expanded,the selection of optimal voltage vectors will be more accurate,which is conducive to improving the steady-state performance.In order to prove the feasibility and effectiveness of the three-vector-based model predictive flux control strategy,the simulation research is carried out by using MATLAB simulation soft-ware,and the experimental research is performed on a two-level inverter-driven permanent mag-net synchronous motor.The simulation and experimental results demonstrate that,the model prediction flux control strategy can eliminate the weighting factor,both the optimal duty model predictive flux control strategy and the three-vector-based model predictive flux control strategy can reduce the torque and flux ripple,while maintaining the good dynamic response performance of the model predictive flux control strategy,and the three-vector-based model predictive flux control strategy is more significantly in improving steady-state performance.