A simplified determination of the permanent magnet (PM) eddy current losses due to slotting in a PM rotating motor

The paper presents a simplified determination of the eddy current losses in the permanent magnets (PM) in PM rotating motors, caused by the slotting. The main assumption is that the eddy currents are resistance limited (weak diffusion effect). The procedure is as follows: at first, a rectangular geometry corresponding to the given rotating one is introduced; the PM field is determined in the slotless case, and then modulated due to the slots. The modulation function is obtained by applying the conformal mapping method. From the obtained magnetic field, the induced eddy currents are derived. Finally, the eddy current losses are determined by the integration of the eddy current density.