3D numerical calculation method of electrical machines with time efficient air gap coupling and stabilized torque and force calculation

A calculation method, which allows a time efficient coupling of the machine stator and moving rotor parts and force calculation in electrical machines, dedicated to 3D Finite Element (FE) models, is presented in this paper. The method requires only a single mesh generation at the beginning of the simulation. The applied force calculation method is stabilized, using a whole air gap averaging method, which does not require a special air gap mesh. Standard tetrahedral mesh elements can be used in the air gap, without affecting the torque or force calculation results even for the numerically demanding cogging torque calculation.

I. Introduction

THE numerical simulation of electrical machines, mostly with the Finite Element Method (FEM), is an important design tool, which is used intensively during the design process or during the optimization of existing electrical machines. In order to simulate these electrical machines accurately, it is required to simulate the relative movement of the primary and secondary electrical machine parts in order to calculate position dependent parameters. Thus a coupling between the stator and rotor is necessary, which allows a relative movement with a fixed step size. The calculation of the forces between primary and secondary is usually done in the air gap. For these reasons special care is taken for the modelling and mesh generation of the machine air gap.