Research On Key Technologies Of Predictive Torque Control For SMPMSM Drive System

Energy security and environmental protection make electric vehicles become the main development direction of automobile industry in the future.As the main power source of electric vehicles,the control performance of electric drive system directly affects the economy,power,safety and comfort of electric vehicles.Surface Mounted Permanent Magnet Synchronous Motor(SMPMSM)is widely used in the field of electric drive system because of its simple structure,high power density,small size and high efficiency.This paper focuses on the improvement of steady-state control performance and robustness of SMPMSM drive system,focusing on the extended control set double gradient optimization predictive torque control,model-free stator flux observer,model-free predictive torque control technology.It has important theoretical research significance and engineering application value to improve the torque control performance of electric vehicle SMPMSM drive system.Firstly,the mathematical model of SMPMSM is established,and the basic principle of model-based predictive torque control strategy is introduced.Based on this,Extended Control Set-Model Predictive Torque Control(ECS-MPTC)is proposed to improve the steady-state performance of finite control set predictive torque control.The cost function is transformed into a single objective cost function by eliminating the weight factor with flux vector.Based on the spatial distribution characteristics of the single objective cost function,the generation method of Quasi Longitude and Latitude Line(QLLL)virtual voltage vector extended control set is proposed,and the optimal vector sector is determined by fast optimization.In the optimal sector,the extended control set is matched and the optimal voltage vector is obtained by double gradient descent method.Compared with the existing enumeration scheme of generating virtual voltage vector by Discrete Space Vector Modulation(DSVM).It is proved that the proposed control scheme can reduce the computational load and improve the steady-state performance of the motor.Secondly,starting from the full order stator flux observer,based on the super local model,a model-free stator flux observer is proposed to achieve the accurate acquisition of stator flux.Combined with the model-free technology,the model-free predictive controller of current and flux linkage is designed.The model-free stator flux observer is combined with the model-free current and flux predictive controller to form a complete model-free predictive torque control scheme.The flux observer is used to obtain the accurate estimated flux,and then the flux estimation and current measurement are sent to the model-free predictive controller to generate predictive variables,so as to improve the robustness of predictive torque control.On the basis of theoretical analysis,through the simulation and experimental study of SMPMSM drive system,the rationality and effectiveness of the proposed extended control set double gradient optimization predictive torque control,model-free stator flux observer and model-free predictive torque control scheme are verified.