Research On Thrust Of Permanent Magnet Linear Motor Based On Magnetic Network Method

As a kind of gearing, linear motor can be directly converted electrical energy into mechanical energy.It is widely used because of its simple structure and high efficiency.As an important parameter of linear motor, it is necessary to study on thrust and thrust of the fluctuation.Traditional calculation methods for motor thrust are the magnetic circuit method and finite element method in two categories, the magnetic circuit method fail to consider the effect of the motor flux and leakage flux, so it is lacking in accuracy.By using the finite element method in the analysis of the motor, we need to redistricting for motor when the motor state is changed, therefore the method is high time-consuming. In this paper, by conbination the advantages of the two methods, we using equivalent magnetic network method to establish a equivalent model of permanent magnet linear motor. And considering the influence of end effect on motor thrust,the influence of structure parameters on the motor thrust, finally through finite element method verified that the method has better reference value for the electromagnetic field analysis.The main research contents of this paper:1)Firstly,according to the similarity of the magnetic circuit and the electrical circuit,the motor can divided into several parts,by calculating the equivalent reluctance of different parts of the motor to establish a magnetic network model of permanent magnet linear motor. Verified that end effects can generate fluctuation influence on motor thrust. And then analyzes the roots of thrust fluctuation, points out that the ripple effect, the slot effect and end effect is the main reasons. Through theoretical elaboration how to restrain thrust fluctuation.The result indicated that through control of the load current can decrease the ripple effect caused by harmonic current, explaining that the motor adopts a multi-pole structure、increasing the air gap length can reduce thrust ripple caused by the end effect.Considering different parameters of permanent magnet linear motor influence on thrust size and thrust fluctuation based on magnetic network model. 2)Then, build the finite element model of permanent magnet linear motor,. analysis of the size and the fluctuation phenomena of electromagnetic thrust and normal force, indicated that the electromagnetic thrust and normal force with periodic fluctuation in a polar distance. By compared with the magnetic network model, to validate the correctness of the magnetic network method.