Analytical prediction of open-circuit eddy-current loss in series double excitation synchronous machines

This paper presents an analytical model for prediction of open circuit eddy current loss in armature windings and permanent magnets of series double excitation synchronous machines. The developed model can either be used in the case of internal or external rotor radial-field machines topologies. First, a 2D exact analytical solution of open circuit magnetic field distribution in an actual geometry of a series double excitation synchronous machine is established. It involves solution of Maxwell´s equations in stator slots, airgap, PM´s region and rotor slots. Results from this analytical model are compared to corresponding finite element analyses. Then, magnetic vector potential solutions in the stator slots and PM´s region are respectively used for prediction of resistance limited eddy current in armature windings and permanent magnets. This analytical model is then used to estimate eddy current loss in armature windings and permanent magnets.