Research On Disturbance Suppression Methods Of Permanent Magnet Synchronous Linear Motor Drive System

Permanent magnet synchronous linear motor(PMSLM)has the characteristics of simple structure,low losses,and high efficiency,thus having broad application and development prospects.However,there are various complex disturbances in the operation of permanent magnet synchronous linear motors,which can lead to a decrease in system control accuracy.Therefore,in-depth research on disturbance suppression methods is of great significance for achieving high-performance permanent magnet synchronous linear motor drive systems.At present,there are still some core technical difficulties that need to be overcome to achieve high-precision and strong robustness operation of permanent magnet synchronous linear motors:(1)The permanent magnet synchronous linear motor drive system faces periodic positioning force disturbances as well as non periodic equivalent load disturbance such as friction,mechanical parameter perturbations,and load changes.The multiple-sources disturbance composed of these two types of disturbances will cause a decrease in positioning accuracy and cause mechanical vibration and noise.(2)During the operation of the permanent magnet synchuronous linear motor,the motor parameters will inevitably change.This will result in calculation bias in the predictive current control method,leading to a decrease in current control accuracy and,in severe cases,system divergence.(3)Due to the single model and fixed observer parameters,conventional disturbance estimation methods are difficult to apply to various operating conditions,and the disturbance estimation effect is not ideal.Breaking through the core technical barriers mentioned above has important theoretical and practical significance for expanding the application of permanent magnet synchronous linear motor drive systems.The modeling and disturbance analysis of the permanent magnet synchronous linear motor drive system are the prerequisite and foundation for subsequent research on disturbance suppression methods.Firstly,a mathematical model of permanent magnet synchronous linear motor is established using the principle of coordinate transformation.Secondly,by analyzing the cogging effect and end effect,the mechanism of periodic positioning force disturbance is modeled and analyzed.In addition,the composition of multiple-sources disturbance in the speed loop of permanent magnet synchronous linear motor and the mechanism of their impact on the motor drive system are analyzed.Finally,the current loop of the permanent magnet synchronous linear motor is modeled,and the uncertainty of the current loop parameters is analyzed.The dynamic characteristics of the current loop parameter uncertainty disturbance are studied.The above analysis has laid a theoretical and practical foundation for the subsequent research on disturbance suppression methods for permanent magnet synchronous linear motors.Affected by the structural characteristics of permanent magnet synchronous linear motor,periodic positioning force disturbance is the main factor causing thrust fluctuation and speed fluctuation,and can further cause mechanical vibration and noise,increase motor losses,and affect motor system performance,especially at low speeds.A periodic positioning force disturbance suppression method based on enhanced internal model control is proposed to address this issue.Firstly,a composite speed controller based on internal model control is adopted to suppress periodic disturbances of a single frequency.However,in the actual operation of permanent magnet synchronous linear motor drive systems,there is more than one periodic positioning force disturbance frequency,so it is necessary to suppress the periodic disturbances of multiple frequencies.Thus,an enhanced internal model control method is proposed,which extends the composite speed controller that suppresses single frequency periodic disturbances to suppress multiple frequency periodic disturbances,and analyzes the anti-interference and stability of the closed-loop system.Finally,the effectiveness of the periodic positioning force disturbance suppression method based on enhanced internal model control is experimentally verified,with significant reduction of thrust and velocity fluctuations and effective improvement of system control accuracy.In practical industrial applications,the permanent magnet synchronous linear motor drive system is not only affected by periodic positioning force disturbances,but also by multiple-sources disturbance including non periodic equivalent load disturbances such as mechanical parameter perturbations,friction torque,and load changes,resulting in a decrease in control performance.To address this issue,a multiple-sources disturbance suppression method is proposed that can simultaneously observe periodic disturbances of multiple frequencies components and equivalent disturbances of non periodic loads.Firstly,a generalized proportional integral load thrust observer is designed and disturbance tracking error convergence analysis and noise suppression performance analysis are performed.Secondly,a multiple-sources disturbance suppression method based on an enhanced internal model collaborative generalized proportional integral load thrust observer is proposed,and the anti-interference and stability of the closed-loop system are analyzed.Finally,the effectiveness of the multiple-sources disturbance suppression method using an enhanced internal model collaborative generalized proportional integral load thrust observer is verified through experiments.A robust predictive current control method based on an augmented internal model disturbance observer is proposed to address the problem of parameter uncertainty disturbance causing a decrease in current control accuracy and even system instability in the predictive current control method of permanent magnet synchronous linear motors.Firstly,a predictive current controller for permanent magnet synchronous linear motor is designed using the principle of predictive current control.Secondly,an augmented internal model disturbance observer is proposed to estimate parameter uncertainty disturbances in predictive current control systems online and perform real-time compensation,effectively solving the problem of current control performance degradation caused by parameter changes and model mismatch.Finally,the experimental results show that compared with traditional predictive current control methods,the robust predictive current control method combined with an augmented internal model disturbance observer has superior current response performance while significantly improving the robustness of the system to parameter perturbations and model mismatches.A multiple-models adaptive disturbance observer is proposed to solve the problem that the traditional single model disturbance observer has fixed parameters,which is difficult to apply to multiple operating conditions and has poor disturbance estimation effect.Firstly,using the principle of multiple-models adaptation,a disturbance adaptive model is designed,and multiple disturbance estimation models are established based on the identification model to approximate the dynamic characteristics of complex operating conditions and cover the uncertainty of the system.Secondly,a weight adaptive model is designed,and the outputs of each model are weighted and fused according to the scheduling mechanism to obtain the estimated values of parameter uncertainty disturbances.Next,a multiple-models adaptive disturbance observer is combined with a predictive current control method to achieve real-time compensation of disturbance.On the basis of improving disturbance estimation performance,the problem of strong dependence on parameter accuracy in conventional predictive current control methods has been solved.Finally,the effectiveness of the multiple-models adaptive disturbance observer is experimentally verified.