Combined-Vector Model Predictive Current Control for PMSM Based on Speed Difference

According to the number of voltage vectors used in the control period, the model predictive current control (MPCC) of permanent magnet synchronous motor (PMSM) can be divided into single-vector-based MPCC (SV-MPCC), double-vector-based MPCC (DV-MPCC) and three-vector-based MPCC (TV-MPCC). The average switching frequency, algorithm computation time and steady-state performances of the three control methods are different. So, each method has its own advantages and disadvantages. This paper presents combined vector MPCC (CV-MPCC), which makes use of the advantages of the three methods and can improve the overall performance of the drive system. Firstly, one method is selected based on operating state, which is determined by difference between the given speed and the actual speed. If the speed difference is greater than the threshold, the system is considered to be in dynamic state; otherwise, it is in steady state. Then, SV-MPCC method is applied when the system is in the dynamic state, and DV-MPCC or TV-MPCC method is adopted when the system is during the steady state. Finally, the experimental results verify the method.