Study On Direct Thrust Control Of PMLSM With Speed-Sensorless

Direct thrust control(DTC)has become a research hotspot in the field of linear motor servo system due to its simple control structure,fast dynamic response and less dependence on motor parameters.Because the traditional direct thrust control has problems of thrust ripples,and poor robustness,this thesis proposes a method of DTC based on integral backstepping with extended state observer,combining the space vector pulse width modulation(SVPWM)technology to optimize the system design.The speed sensorless technology can reduce the cost and improve the reliability of the system.Therefore,the combination of the speed sensorless and direct thrust control is one of directions in the the development of Linear servo technique.In this thesis,the permanent magnet linear synchronous motor(PMLSM)is taken as the control object,and the investigated contents are shown as follows:Firstly,the principle of permanent magnet linear synchronous motor and mathematical model are introduced,on the basis of this,the traditional direct thrust system in all parts of the constitution and the basic principle has been analyzed.Finally,according to the simulation,the problems of traditional direct thrust control are analyzed.Secondly,this thesis propose a method of integral backstepping control,the system is divided into two subsystems according to the backstepping method.Then the speed regulator,thrust and flux regulator was designed respectively.The SVPWM principle is also employed to make the inverter switching frequency to be fixed.At the same time,in order to enhance the robustness of the system,an extended state observer(ESO)is used to estimate the load disturbance so as to obtain forward compensation.The simulation of DTC based on integral backstepping with ESO was established,and the simulation results has been compared with the traditional direct thrust control system.Finally,based on the analysis of traditional sliding mode speed observer,this thesis proposes an improved sliding mode observer,which makes improvement in switch function,sliding mode observer coefficient and the processing of back EMF filtering.The new sliding mode observer is combined with DTC system based on integral backstepping with ESO,which realize the speed sensorless control.Then the simulation of whole system is established and the feasibility of the control strategy is verified.