Modeling And Static Coupling Effect Analysis Of The 2DOF Direct Drive Induction Motor

With the development of technique,it is hard for single-degree-of-freedom motor to meet the market demand so that a great number of scholars focus on multi-degree-of-freedom motor.In this paper,a two-degree-of-freedom direct drive induction motor(2DOFDDIM)capable of rotary,linear and helical motion is investigated.It is composed of rotary and linear arc-shape stators and a shared mover,which has a good application prospect in grinding miller,helical auger,drilling machine,robot and human artificial limb field.This paper presents a composite multilayer method to evaluate the performance of the 2DOFDDIM based on the traditional multilayer theory importing propagation constants.Due to the complex magnetic field in a 2DOFDDIM,this paper mainly analyses it from the perspective of a single DOF motor.The mathematical model of 2DOFDDIM composite multilayer method is established and a transfer matrix is obtained by solving Maxwell’s equations in motor layers.A complete 2DOFDDIM composite multilayer method computer program,which takes the variation along the radial direction of magnetic field into consideration,is built and the problem to determine related parameters in the program is solved.The two-dimensional magnetic field distribution is obtained and then equivalent circuit for the rotary part of the 2DOFDDIM is then derived applying composite multilayer method.The performances of 2DOFDDIM are calculated by composite multilayer method,which are then compared with results from the finite element method(FEM)and experimental results.The computation time of the composite multilayer method is far less than that of the FEM.The acceptable accuracy confirms the effectiveness of the composite multilayer method for analysis and performance calculations of the 2DOFDDIM.Considering 2DOF mechanical motions of 2DOFDDIM,a new concept—static coupling effect—is proposed in this paper.The static coupling effect produced by linear motion(rotary motion)on rotary part(linear part)is analyzed qualitatively using analytical method and quantitatively applying FEM,respectively.The image method model and the analytical model are established to analyze its reasons and predict the main effects,which are then verified by the proposed 3D finite-element static coupling model.Then the 3D finite element method is applied to analyze the influences of the power frequency,speed of movement,thickness of air-gap and copper on static coupling effect.The research of it has a big significance in the optimization of 2DOFDDIM and its accurate control.