Numerical Investigation of Eddy Current Losses in Airgap PCB Windings of Slotless BLDC Motors

Replacing classical wire windings with windings printed on flexible circuit boards is a way to improve the performances of slotless BLDC motors. However, these printed windings bring about new design limitations, as they are more subject to eddy current losses than conventional wire windings. This paper aims at evaluating these losses. It proposes a numerical approach to investigate the influence of geometrical parameters like height, width and skewing of the printed copper tracks. The impact of the operating speed is also analyzed, and a heuristic formula to estimate eddy current losses in the case of zigzag and rhombic winding shapes is finally proposed.