Research On Model Predictive Current Control Strategy Of Open Winding Permanent Magnet Synchronous Motor

With the ongoing expansion of industry,the problem of energy crisis becomes more serious,causing people to pay more and more attention to increasing energy use efficiency.Efficient electromechanical energy conversion has recently emerged as a research priority.When compared to standard excitation motors,permanent magnet synchronous motors(PMSM)save a large amount of energy.In comparison to traditional PMSM,open winding permanent magnet synchronous motor(OW-PMSM)can meet the rated power of switching devices in high-power systems and realize multi energy hybrid power supply,making it useful in the field of electric traction drive industry with high power requirements.Simultaneously,the semi-controlled open winding permanent magnet synchronous motor(SOW-PMSM)has emerged as a research focus.A zero-sequence current suppression technique based on direct power control and model predictive current control(MPCC)is presented to address the problem of zero sequence current in the topology of a common DC bus type SOW-PMSM.Furthermore,a simplified MPCC strategy based on mathematical auxiliary lines is provided to address the difficult calculation problems in the system of isolated DC bus type SOW-PMSM based on MPCC strategy.Firstly,the mathematical model of OW-PMSM in the abc coordinate system is inferred by studying the topological structure of the physical model of OW-PMSM,and the mathematical model of OW-PMSM in the αβ coordinate system is inferred using the coordinates principle.Transformation mathematical model with dq0 coordinate system.The common DC bus type and isolated DC bus topology structure of SOW-PMSM are studied,the advantages and disadvantages of the two structures and the principle of the dualconverter power supply system are analyzed,and the mathematics of the common DC bus type and the isolated DC bus type SOW-PMSM are established.Secondly,aiming at the problem of zero-sequence current in the common DC bus type SOW-PMSM topology,a zero-sequence current suppression strategy based on direct power control and MPCC is proposed.The direct power control strategy is to select the appropriate voltage vector according to the direct power switch table to achieve the purpose of suppressing the zero-sequence current of the system.This control method analyzes the voltage vector distribution of the common DC bus type SOW-PMSM,the sector where the stator flux is located,and the influence of the voltage vector on the power by establishing the SOW-PMSM mathematical model,and establishes a direct power switch table.The influence of the vector on the power establishes a direct power switch table,when the power changes,select the appropriate voltage vector according to the direct power switch table to achieve the purpose of suppressing the zero-sequence current of the system.MPCC based on the zero-sequence current suppression strategy,a current-voltage double delay compensation algorithm has been proposed to overcome the negative impact on steady-state performance of the entire control system.In order to realize simultaneous control of d-axis current,q-axis current,and zero sequence current,design a cost function based on current error and at the same time design a cost function that suppresses zero sequence current.Current optimized voltage vector.The correctness and effectiveness of the proposed control method will be verified by simulation experiments.Finally,the computational complexity in the MPCC system of the isolated DC bus-type SOW-PMSM is studied,and a simplified model predictive current control strategy based on the mathematical auxiliary line method is proposed.Mathematical models of current prediction,first-order compensation and voltage prediction of uncontrollable converters are established,and the distribution and selection of voltage vectors are studied.In order to further improve the performance of the system and reduce the computational burden and complexity of the system,the predicted voltage of the controllable converter is used as the reference voltage,and a dual-voltage vector selection method based on the mathematical auxiliary line method is proposed.The first voltage is determined by selecting the sector.Then,the method of selecting the second voltage vector of the mathematical auxiliary line is introduced for optimization,which reduces the effective selection range of the reference voltage vector combination.This method omits the step of selecting the voltage vector through the cost function and reduces the system computation time.The correctness and effectiveness of the proposed prediction method are verified by simulation experiments.