Research On Finite Control Set Model Predictive Current Control For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors are widely used in aerospace,high-precision servo drives,robots and other fields,and have the advantages of good dynamic performance,compact structure,and high power density.The traditional control method of permanent magnet synchronous motor has been difficult to meet the high-performance control requirements in some applications.The finite set model predictive current control strategy of permanent magnet synchronous motor has also become one of the research hotspots.The permanent magnet synchronous motor finite set model predicts the current control strategy to act on a basic voltage vector with a fixed direction and a fixed amplitude in a control cycle,resulting in large d and q-axis current pulsations and poor steady-state characteristics of the control system.Aiming at this problem,a three-vector finite set model predictive current control strategy for permanent magnet synchronous motors is proposed.Two effective voltage vectors and one zero-voltage vector are applied in each control cycle.The reference voltage vector is calculated by using the d and q axis current deadbeat method,and the effective voltage vector of the sector where the reference voltage vector is located is directly selected as the first optimal voltage vector,and then the first optimal voltage vector is compared with the unselected effective voltage The vectors are combined,and a zero-voltage vector is combined according to the principle of minimizing the switching frequency to synthesize 5candidate voltage vectors.The direction and amplitude of the combined candidate voltage vectors are adjustable.The deadbeat method of the d and q axis currents is used to calculate the time when the three voltage vectors act separately to realize deadbeat control of the d and q axis currents,effectively reduce the d and q axis current pulsation,and improve the steady-state characteristics of the control system.The predictive current control strategy of permanent magnet synchronous motor finite set model needs to predict and optimize the current under the action of all basic voltage vectors.The calculation amount of the algorithm is relatively large.After the introduction of three vector control,it is necessary to calculate the time for the three voltage vectors to act separately.The computational complexity of the algorithm has risen again.In response to this problem,a permanent magnet synchronous motor optimized three-vector finite set model predictive current control strategy is proposed,and the voltage vector cost function is constructed.The cost function is used to conduct in-depth analysis of the error between the reference voltage vector and the effective voltage vector,and the reference voltage is selected.The two adjacent effective voltage vector and the zero voltage vector of the sector are combined into the optimal voltage vector,which simplifies the selection process of the basic voltage vector.The optimal voltage vector can be selected with only one prediction,which guarantees good steady-state characteristics of the control system.On this basis,it effectively reduces the computational complexity of the algorithm.Finally,the two control strategies proposed in this article are simulated and experimentally verified.The simulation and experimental results show that the proposed permanent magnet synchronous motor three-vector finite set model predictive current control strategy can effectively reduce the d and q axis current ripple and improve the control System steady state characteristics.The proposed permanent magnet synchronous motor optimized three-vector finite set model predictive current control strategy can effectively reduce the calculation amount of the algorithm on the basis of ensuring the good steady-state characteristics of the control system.