Sensorless Control Of Permanent Magnet Linear Synchronous Motor In Low-speed Domain

Permanent magnet linear synchronous motor(PMLSM)has attracted the attention of scholars and manufacturers because of its advantages of high operating efficiency,fast dynamic response and high thrust strength,and has become a research hotspot in direct drive technology.In the vector control of permanent magnet linear synchronous motor,the accuracy of the real-time position and speed of the mover fed back to the control system will directly affect the performance of the control system.The usage of the traditional instrument called position sensor will increase the system cost,increase the system complexity and limit the use environment of linear motor.Therefore,the position estimation technology without position sensors is applied to the closed-loop motion control system of PMLSM,which is stable and low-cost closed loop motion control is of great significance.In order to achieve high performance control of PMLSM without position sensor in low-speed domain,this paper studies an improved flux calculation method based on back electromotive force compensation and a high frequency pulsating sinusoidal voltage injection(HFPSVI)based control method of PMLSM without position sensor,which overcomes the inherent shortcomings of fundamental wave model method.Firstly,the mathematical model is elaborated,and the mathematical model of ripple thrust is derived.Secondly,the error analysis of flux calculation method is carried out,and an improved flux calculation method based on back electromotive force compensation is studied to improve the performance of low-speed field position estimation of PMLSM.Because of the inherent disadvantage of low signal-to-noise ratio in low-speed domain of sensorless control technology based on fundamental wave model,it is difficult to overcome.Therefore,using pulse vibration high-frequency sinusoidal voltage injection method to improve the estimation performance of sensorless algorithm in low-speed domain,to obtain more accurate mover position.In the study of HFPSVI algorithm,the basic principle of this sensorless method is elaborated in detail,and the signal demodulation process of HFPSVI is analyzedFinally,the performance of the flux calculation method based on back EMF cross compensation and the high frequency sinusoidal voltage injection method are verified on the single side short primary PMLSM.The two methods can accurately estimate the velocity and position of the mover in the low speed domain.