This paper presents a method for the optimal design of a slotless permanent magnet brushless DC
(BLDC) motor with surface mounted magnets using a genetic algorithm. Characteristics of the motor
are expressed as functions of motor geometries. The objective function is a combination of losses,
volume and cost to be minimized simultaneously. Electrical and mechanical requirements (i.e.
voltage, torque and speed) and other limitations (e.g. upper and lower limits of the motor
geometries) are cast into constraints of the optimization problem. One sample case is used
to illustrate the design and
optimization technique.