FE Analysis and Computer-Aided Design of a Sandwiched Axial-Flux Permanent Magnet Brushless DC Motor

In this paper, a comprehensive computer-aided design (CAD) procedure for an axial-flux permanent magnet brushless dc (PM BLDC) motor having a stator sandwiched between two permanent magnet rotors is presented. The basic output equations are derived and used for the design algorithm. The developed CAD program gives the design data and the calculated performances of the motor. The optimized ratio of outer diameter to the inner diameter is used to derive the sizing equation. The design variables such as airgap flux density, slot electric loading, winding factor, stacking factor, stator current density, slot space factor, magnet fraction, slot fraction, flux density in the stator back iron, etc., are assumed. Three different motors or rating 70 W, 2.2 kW, and 20 kW are designed using the developed program, and then three dimensional finite-element analyses are carried out to validate the designs