Research On Disturbance Rejection Strategy Of Pmsm Based On Active Disturbance Rejection Control

Permanent magnet synchronous motor(PMSM)has been widely used in industrial production,locomotive traction,aerospace and other fields due to its advantages of simple structure,small size and high power density.With the development of science and technology,higher requirements have been put forward for speed and torque quality of PMSM by high precision industrial occasions.It is not only necessary to suppress the dynamic speed mutation caused by the load torque,but also to reduce the steady state fluctuation of speed and torque caused by the periodic disturbance.However,the non-ideal factors inherent in the PMSM drive system are bound to affect the quality of speed and torque.To restrain the influence of these disturbances,the mechanism of the intrinsic disturbance is analyzed and its internal relation with the speed and torque is discussed in this paper.According to the characteristics of the disturbance in the current loop and the speed loop,the corresponding disturbance suppression strategies are designed respectively.By applying the proposed control strategy,the quality of PMSM speed and torque is improved comprehensively.The specific contents of the paper are as follows:The disturbance mechanism inherent in the PMSM drive system is explored to provide a theoretical basis for restraining its influence.There are various disturbances in the PMSM drive system,which can be divided into aperiodic and periodic disturbances according to their characteristics.Aperiodic disturbance includes load torque and motor parameter perturbation.While periodic disturbances include magnetic flux harmonics,dead time effect,and current sampling errors.Among them,the load torque and current sampling error deteriorate the speed quality.The load torque results in the aperiodic speed fluctuation,while the current sampling error lead to the periodic speed fluctuation of frequency which is 1 and 2 times of the rotor angular velocity.The magnetic flux harmonics and dead time effect deteriorate the current quality,which can cause 6n current periodic harmonic.Because of the linear correlation between torque and current,the disturbance could lead to the periodic torque fluctuation.A control strategy based on an optimized linear active disturbance rejection control(LADRC)is proposed to solve the problem that the current loop is affected by both aperiodic and periodic disturbances in this paper.Compared with PI controller,LADRC can effectively reject the aperiodic disturbance in current loop.However,two problems inherent in LADRC are found through theoretical analysis.The one is that the coupling of anti-disturbance performance and tracking performance makes parameter setting difficult.The other is the incapable to reject periodic disturbances in the middle frequency band.Therefore,a repetitive controller-ADRC(RC-ADRC)is proposed in this paper.The proposed algorithm makes two optimizations for the LADRC: For the first problem,a decoupled LADRC is designed by optimizing the structure of the extended state observer.Aiming at the second problem,the bandwidth of the control rate is broadened by introducing the RC.The optimized control law can realize the purpose of suppressing the periodic disturbance.Simulation results show that the algorithm can improve the current quality by simultaneously suppressing the aperiodic and periodic disturbance in current loop.Another control strategy based on optimal LADRC is proposed to solve the problem that the speed loop is affected by both aperiodic and periodic disturbance in this paper.Since the repetitive controller can suppress many kinds of periodic disturbances simultaneously,the application of the repetitive controller in the speed loop can easily amplify other periodic signals,resulting in the instability of the system.The RC-ADRC proposed for the current loop is not suitable for speed loop application.One resonant regulator can suppress one kind of periodic disturbance,and two parallel resonant regulators can satisfy the demand of the speed loop.Therefore,this paper introduces a proportional resonance controller to widen the bandwidth of the control rate and realize the purpose of suppressing the periodic disturbance.The simulation and experimental results show that the proposed algorithm can improve the quality of the speed by suppressing both aperiodic and periodic disturbance simultaneously.