Transient 3-D FEM computation of eddy-current losses in the rotor of a claw-pole alternator

The three-dimensional finite-element method (FEM) allows for the calculation of eddy currents in the claws of synchronous claw-pole alternators taking the rotational geometry movement into account. A transient edge-based vector formulation is utilized to compute the induced eddy-current losses in the rotor caused by the stator slotting. The theory of this formulation is outlined and the FEM model of the alternator is described. On a model built in series-production the local loss distribution on the rotor claw is discussed as well as the speed characteristics of the eddy-current losses. The use of adaptive mesh optimization leads to corrected results which are compared to local temperature measurements.