Design And Research Of Permanent Magnet Synchronous Linear Motor

Linear motor is a kind of transmission device,which can directly convert electrical energy into mechanical energy and output linear motion.It has the characteristics of low noise,simple structure,high positioning accuracy and short response time.With the development trend of modularization,intellectualization and integration in manufacturing industry,linear motors are widely used in military electromagnetic catapults,light rail trams and automatic processing centers.In recent years,they are also used in some high-grade intelligent furniture.Because the magnetic circuit is disconnected at the front and rear ends of the stator core of linear motor,the distorted magnetic field is produced,which makes the motor affected by the magnetic resistance in the operation process,brings the thrust fluctuation,and affects the operation of the motor.In addition,due to the strong magnetic field at the core teeth of the mover,when the relative position of the core teeth and the permanent magnet changes,the attraction also changes,which brings about the cogging effect and affects the positioning accuracy of the motor.In this paper,starting with the design of permanent magnet synchronous linear motor,the simulation analysis and structure optimization of the motor are carried out,including the following aspects:1.Through theoretical derivation and empirical formulas,a set of overall design flow of permanent magnet synchronous linear motor(PMSLM)is given,the magnetic field and the matching between the number of slots and the number of poles of the motor is analyzed.2.The mathematical models of the end thrust fluctuation and the end normal force fluctuation of PMSLM are established.According to the model,a method to suppress the thrust fluctuation of motor with multi-teeth structure is proposed and verified by simulation analysis.Taking a 12-slot10-pole linear motor as an example,the end thrust fluctuation is reduced to 22.4 %.By comparing the magnetic field distribution and working conditions of multi-teeth structures,the optimization theory of end structures is further improved.3.The structure of skewing permanent magnet is analyzed.The influence of the inclination angle of permanent magnet on the average thrust and thrust fluctuation of the motor is studied.Under the condition of 95 % or 90 % average thrust of the motor,the selection range of the electric angle of the skewing permanent magnet is determined.The relationship between the inclination angle and the electric angle of the permanent magnet is given,which provides a basis for the selection of skewing permanent magnet.On this basis,combined with the three-dimensional temperature field of permanent magnet,the optimal inclination angle of permanent magnet is given as 81 degrees in a 6-slot 5-pole linear motor.4.A linear motor with translation automatic door is designed.According to the design flow ofPMSLM and the optimization analysis of restraining motor thrust fluctuation,a specific design example is given.