Two-vector Based Model Predictive Current Control For Permanent Magnet Synchronous Motor

The application of permanent magnet synchronous motor (PMSM) is gradually expanding with permanent magnet material performance improvement and cost reduction. In the tradition-al model predictive current control (MPCC) for PMSM, the optimal voltage vector is se-lected by the cost function in each sampling period and applied in the next sampling period,and the steady-state performance is limited by finite set of control. To improve the steady state performance, the concept of duty cycle control was introduced in MPCC by inserting a zero voltage vector along with an active voltage vector during one sampling period. In the duty cycle MPCC, there are still large current ripples because the second voltage vector is always zero voltage vector and the voltage vector is selected in six fixed directions in each sampling period. In this paper, a two-vector based MPCC method is proposed by making two voltage vector selections in each sampling period, and the range of voltage vector selection is expanded to adjustable directions and amplitudes because the second voltage vector is not fixed to zero-voltage vector yet. Besides, the durations of voltage-vector is evaluated simul-tanecously in cost function, and the selection of voltage vector is more accurate.In order to verify the feasibility and effectiveness of the two-vector based MPCC, simula-tion and experimental verification were carried out on MATLAB/Simulink and two-level inver-ter platform respectively. Simulation and experimental results show that the two-vector based MPCC has good parameter robustness. Compared with the duty cycle MPCC at the same sam-pling frequency, the two-vector based MPCC improve the steady-state performance effectively and maintain a small current ripples in the wide speed range. This is because the two-vector based MPCC can select a more accurate voltage vector within the larger vector selection range.In addition, compared to the duty cycle MPCC with the sampling frequency of 20kHz, the two-vector based MPCC with a sampling frequency of 10Hz still has a small current ripples and a low switching frequency.