Design and analysis of double-sided slotless axial-flux permanent magnet machines with conventional and new stator core

The objective of this paper is to present the design equations of the conventional double-sided axial-flux slotless brushless DC machine (BLDC) and the new one with the trapezoidal cross-section core as well as performances comparison based on the proposed design algorithm. Direct search method is used to find the optimum designs, whereas machines with the rated power of 0.25-10 kW are compared. Efficiency and size of the optimum designed machines are presented to make a comprehensive study for choosing the best topology from the viewpoint of electrical and geometrical characteristics. Finite element analysis and experimental results are presented to show the validity of the derived equations and the design outcomes.