Research On Fractional-order Control Of PMSM Servo System

PMSM servo system has the advantages of lightweight,high efficiency,low loss and high reliability.It is widely used in rail transit,aerospace,computerized numerical control(CNC)lathe and other occasions requiring high precision control,and occupies an important position in the field of industrial automation.However,PMSM is a timevarying system with multivariable,strong coupling,nonlinear,variable parameters characteristics.To achieve high performance control of PMSM,the effects of parameters,load,friction,dead zone,torque ripple,unpredictable actuator failure,internal and external disturbances must be overcome.Therefore,in order to ensure that PMSM still has high driving performance under the influence of the above factors,the work considers the nonlinear and uncertain characteristics of PMSM,and establishes a fractional-order robust adaptive fault-tolerant control method,which improves the PMSM mechanical angular position and velocity tracking performance.The specific research contents of this paper are as follows:(1)This paper comprehensively analyzes the effects of torque ripple,friction,load moment,dead-zone effects,unpredictable actuator failures and unknown internal and external interferences on PMSM driving performance,and studies their relationship with system state variables,based on which,a mechanistic model of PMSM with uncertain and nonlinear features is developed.(2)Combining fractional integral and differential theory,a set of fractional-order robust adaptive fault-tolerant control methods for PMSM with various nonlinear and uncertain characteristics are developed,and the stability of the controllers is demonstrated with using correlation theorems and lemmas.The designed controllers does not rely on the system parameter information,and with the genetic attenuation characteristics of fractional calculus,it can effectively suppress the uncertainty and nonlinear disturbance of PMSM,improve the anti-interference ability of the system and its robust;and the controllers have the ability to actively prevent the actuator failure and guarantee the PMSM mechanical angular position and velocity tracking performance when the failure is within a certain range,which is more practical.(3)The co-simulation model of PMSM was built with MATLAB / Simulink and ADAMS software to verify the effectiveness and superiority of the designed fractionalorder control methods.The co-simulation results show that compared with traditional PI,PID and integer-order robust adaptive control method,the designed fractional-order controllers can make the system with high tracking accuracy,small overshoot,strong antidisturbance ability and fault-tolerant.Besides,the electromagnetic torque of PMSM is more stable and small energy consumption.Co-simulation also show that,consistent with the traditional integral and differential regulation,the controllers designed based on integer and fractional order integration have higher control precision,and the controllers designed based on integer and fractional order differentiation make the overshoot of the system smaller,which provides more choices and theoretical guidance for different applications of PMSM and has higher practical application value.This paper mainly studies PMSM servo control algorithm with considering the actual influencing factors such as PMSM characteristics and operating conditions,which provides theoretical and technical support for the realization of high-performance servo control,and has certain theoretical research significance and engineering practical value to improve the level of industrial automation equipment.