Research On Current Loop Control Strategy Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)has the advantages of high speed,high precision and high reliability.It is widely used in the field of cutting-edge technology.With the continuous progress of modern industry,permanent magnet synchronous motor control technology is gradually developing to the high-performance control.In the actual operation of permanent magnet synchronous motor,time-delay,external disturbance and load mutation will affect the stability and control performance of the whole system.Therefore,the design of a current loop controller with excellent performance is an important link to realize high-performance control of servo motor.Taking the permanent magnet synchronous motor as the controlled object,this study mainly studies the current loop control strategy of permanent magnet synchronous motor.On the basis of literature research,aiming at the problems that the current loop control performance of permanent magnet synchronous motor is affected by coupling,time delay and other factors,this thesis carries out the research on the improved design of current loop controller.Relevant research shows that the inherent time-delay in the permanent magnet synchronous motor servo control system will affect the stability of current control,and even lead to instability.Therefore,firstly,the estimation research on the inherent time-delay of permanent magnet synchronous motor servo control system is carried out for the research on time-delay compensation.The estimation model of permanent magnet synchronous motor servo control system considering time-delay is established,and the time-delay estimation algorithm based on recursive least square method and data fitting solution method is designed.The effectiveness and accuracy of the method are verified by simulation.Secondly,for the current loop of permanent magnet synchronous motor,the fractional order control technology is applied to design the current loop controller.Aiming at the design defects in the application of the robustness criterion of system gain,which limits the application scope of the algorithm,the correction transfer function is adopted to improve the traditional fractional order PI control structure,an improved fractional order PI(FO-PI)current loop controller is designed,and the three-dimensional drawing method is designed to realize parameter tuning,The flexibility and margin of parameter selection are increased,and the design defects of the traditional method are eliminated.Then it is compared with the traditional integer order current loop controller by simulation.The simulation results show that the improved FO-PI current loop controller has better dynamic performance,stability,anti-disturbance and robustness.Finally,aiming at the problem that the ideally designed FO-PI current loop controller is affected by the time-delay characteristics in the actual permanent magnet synchronous motor servo system,which leads to the tracking current vibrates,the Smith predictor principle is proposed to improve the design of FO-PI current loop controller,and the rationality of the design is verified by analyzing the frequency characteristics of the closed-loop transfer function of the system.The simulation results show that the FO-PI current loop controller with Smith predictor can improve the influence of system time-delay on control performance and has certain robustness to parameter mismatch.