Sensorless Control Strategy Of PMLSM

Permanent magnet linear synchronous motors(PMLSM)are increasingly being used in industrial applications because they have no intermediate drive link.Vector control,direct torque control and other control methods require accurate kinematic position information,while position sensors are restricted and increase the system cost,so it is important to study PMLSM control strategies without position sensors.This paper investigates the observation of the position and end effects of motorised actuators at high speeds in PMLSM.Firstly,this paper investigates a non-linear observer based on the magnetic flux model to achieve an accurate observation method for the position of PMLSM,which can avoid the jitter problem compared to the traditional sliding mode observer.The gradient method is used to design the observer form to ensure convergence,and the position information is obtained by observing the kinematic magnetic flux.Simulation and experimental results show that this non-linear magnetic flux observer does not require complex parameter design and has good performance in kinematic position observation.Secondly,a third-order linearly expanding state observer(LESO)is designed to observe the disturbances including those caused by end effects.In this paper,the LESO design is carried out for the second-order model properties of the PMLSM system and the stability analysis of the designed LESO is carried out.The observer requires fewer design parameters and is easy to apply for engineering purposes.The observed disturbances are suppressed by means of feedforward current compensation for the observed disturbances.Simulations and experiments demonstrate that the LESO is able to observe the disturbances in the system,and that the disturbance suppression strategy is able to solve the speed fluctuations caused by the disturbances in the PMLSM and improve the system's immunity to disturbances.