Local Electromagnetic Force Computation in the Presence of Numerical Field Errors

Several approaches exist for the evaluation of force distributions in electromagnetic devices. The local virtual work based stresses derived from the application of continuum design sensitivity analysis to the variation of system energy are equivalent to the traditional Maxwell stress tensor formulation in total force calculation. While both methods rely on local field values, they produce different force distributions for the same field. The paper reviews these results and examines the discrepancy due to the numerical errors in the field solution and the difference in the permeability of the material across the interface.