Finite element analysis of Electro-Machanical Devices

This paper will review basic concepts used in the formulation and solution of the finite element model, as well as the results that are obtained from the finite element method. Included is a brief review of magnetics leading to the partial differential field equation that is solved. Formulation of the finite element problem and solution techniques used in both the linear and nonlinear aspects of the problem will be discussed.

Once the field vector potential has been determined, it is possible to evaluate many characteristics of the device that has been modeled. These characteristics include flux densities, magnetic fields, and inductances, both self and mutual. Torques or forces can be calculated from B cross I as well as from the virtual work method and the Maxwell stress tensor.

The types of problems discussed will be limited to those usually thought of as two dimensional. These problems are really three dimensional with certain constraints. These problems are restricted to ones that can be modeled by assuming that the geometry varies in the x and y directions only. His constrains the flux to have components that lie in the x-y plane only. In addition, the device to be modeled must have sufficient depth that end-turn effects can be ignored. In general, all discussion will also be limited to finite elements of the first order triangular type.