Research On The Self-tuning Strategy Of Control Parameters For PMSM Servo System Current Controller

With the development and progress of control technology,AC servo system has been more and more widely used.As the inner loop of AC servo system,the adjustment of control parameters is the basis of the performance of AC servo system.In practical application,due to the existence of non-linear factors such as dead zone in current loop,it is impossible to accurately calculate the ideal control parameters.Generally,the parameters are adjusted manually by operators,but the efficiency is low and the effect is poor.To solve these problems,a parameter tuning strategy which combines model-based parameter self-tuning method with control parameter optimization isproposed.Based on the transfer function model of current loop in AC servo system,the influence of back-EMF and output limit of current controller on current loop is analyzed,and the restriction condition of ignoring back-EMF and output limit of current controller in the design of current controller is put forward,and the simplification of current loop is completed.The influence of non-linear factors such as dead-time in servo driver and voltage drop of power device on motor parameter identification is analyzed.The dead-time and voltage drop are approximated to compensate the output voltage of the inverters according to the actual working conditions in the process of motor parameter identification.A method to determine the amplitude of the excitation signal is proposed,and the motor parameter identification is realized based on the recursive least square method.?The single evaluation index of current loop control performance in time domain and frequency domain and the characteristics of typical type I system are analyzed.By correcting the current loop to a typical type I system,the calculation formula of control parameters is obtained.Combining with the design requirements of current loop,the optimization method of calculation formula of control parameters is designed.Based on the comprehensive evaluation index of control performance of common servo systems,a new method is proposed.The comprehensive evaluation index is combined with rising time,adjusting time and deviation integral,and the coordinate rotation method is used to optimize the current loop control parameters.Finally,based on the simulation platform and experimental platform,the current loop control parameters self-tuning strategy proposed in this paper is verified by simulation and experiment.The control parameters obtained by simulation and experiment can ensure the current loop to achieve the desired response performance,thus the effectiveness of the current loop control parameters self-tuning strategy is verified.