Sensorless Control Strategy Of Linear Permanent Magnet Vernier Motor Based On New Back EMF Observers

Linear permanent magnet vernier(LPMV)motors have the advantages of low cost,small size,high positioning accuracy,and high efficiency,and are suitable for long-stroke applications such as rail transit.However,the use of position sensors still has problems such as cost and reliability,which limits the application of LPMV motors.In this paper,the electromagnetic characteristics of the LPMV motor are analyzed.The mathematical modeling is deduced.A new disturbance observer is proposed for identifying back electromotive force.The estimation block based on this observer is used for estimating the position of the mover.From the aspects of theory,simulation and experiment,the feasibility of the new position sensorless LPMV motor instead of position sensor is verified.It is of great significance to widen the application range of LPMV motor and other permanent magnet linear motors.The main research contents of the paper are as follows:1.The structure and characteristics of a three-phase LPMV motor are studied.Based on Ansoft finite element simulation software,the magnetic field distribution,positioning force and other characteristics are studied.The mathematical model of LPMV motor is established and the voltage,flux linkage,thrust and mechanical equations are deduced.2.Based on the vector control,the core control strategy of this study,the voltage vector,SVPWM wavelet method and vector control strategy with i_d=0 are analyzed.Under the Matlab/Simulink simulation environment,the LPMV motor vector control system is modeled and the control parameters are optimized.The system has good speed tracking effect and dynamic performance.3.A disturbance observer with a new structure,a phase-locked loop module,and a compensation link constitute a position estimation module.The simulation results verify the feasibility of the position estimation module instead of the mechanical sensor.4.The LPMV motor experiment platform based on DSP is designed.The function of each module of the hardware system and the development process of the software system are introduced.The system experimental research is carried out to verify the feasibility of the position sensorless operation strategy proposed in this paper and tested the accuracy and dynamic performance under different working conditions.