| As a large manufacturing country in China,improving the intelligence and efficiency of manufacturing has always been one of the major strategies of our country.The motor plays a very important role in the manufacturing industry chain.The traditional rotary motor needs to cooperate with gears,ball screws and other transmission devices to realize linear motion.Due to the limitation of the transmission device and the structure,the rotating motor has some problems such as complex structure,low speed,low precision and high noise.With the rapid development of industrial science and technology,precision and intelligence are the inevitable trend of modern industry.The electromagnetic thrust generated by the PMLSM is horizontal,so it can directly produce linear motion without an intermediate transmission device,thus greatly reducing the mechanical loss.Compared with the traditional rotary motor,PMLSM has the advantages of fast speed,high accuracy,simple structure,fast response and low noise.It has attracted wide attention and has been used more and more widely in industrial robots,semiconductor manufacturing and CNC machine tools and other fields.The direct drive structure of PMLSM has a shortcoming,when it subjected to uncertain disturbances such as thrust fluctuations and external disturbances,the disturbances will be directly transmitted to the motor and affect the accuracy of the system.And PMLSM is a multi-variable,highly coupled complex nonlinear system,so it becomes very difficult to achieve high-precision PMLSM control.In this paper,a series of studies on position tracking control of PMLSM are carried out.First,the basic structure and characteristics of PMLSM are analyzed,and its working principle is introduced.The principle of vector control and some specific implementation methods has been described.The mathematical model of PMLSM in the synchronous rotating coordinate system is obtained by coordinate transformation,and the dynamic model of PMLSM is listed.According to the principle of vector control,the PMLSM control system is divided into position loop,speed loop and current loop,and the basic PMLSM control structure based on vector control is built.Then,in order to achieve high-precision PMLSM position tracking control,a NTSM control based on NDO is proposed.Sliding mode control is insensitive to system parameters and has the advantage of high robustness.NTSM adopts nonlinear sliding surface,which can make the system state converge to zero in finite time and improve the dynamic response performance of the system.In order to alleviate chattering caused by sliding mode control,saturation function is introduced instead of switching function.In order to further improve the anti-interference performance of the system and eliminate the steady-state deviation error,an NDO is designed to estimate the system disturbance,and a feed-forward method is used to compensate the sliding mode controller.Finally,the effectiveness of the proposed control method is verified by simulation.Then,in order to further improve the tracking performance of PMLSM system,a NFTSM control strategy based on HOSMO is proposed.NFTSM can make the error converge faster.Aiming at the incomplete state information caused by disturbance,a HOSMO is proposed to estimate the state and disturbance of the system,and the estimated values are introduced into the design of sliding mode controller to improve the tracking performance of the system.The effectiveness of the proposed control method is verified by simulation.Considering that the simulation is difficult to simulate the actual hardware and can’t fully reflect the advantages and disadvantages of the control method.In order to verify the proposed control method,a PMLSM experimental platform based on d SPACE DS1104 is built.Then the designed control is applied to the experimental platform,and the experimental results are basically consistent with the simulation results,which verifies that the proposed control strategy has excellent tracking performance. |
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