Brushless DC motor design using harmony search optimization

This paper presents the design and optimization procedure for slotless brushless DC (BLDC) motors. The motor optimization is achieved using a modified harmony search technique, though other optimization methods can also be used. The expressions of motor electromagnetic torque, speed, voltage, current, power losses, volume and cost are analytically represented as functions of motor geometric parameters. The objective function is a combination of motor power losses, volume and cost, and needs to be minimized subject to a set of electrical and mechanical requirements and limitations. Ten design parameters are considered including the number of poles, current density and the dimensions of magnet, stator, rotor, winding and air-gap. The effects of each design parameter on the brushless DC motor performance have been investigated. The method was originally conceived for the design of a small motor for a biomedical application, but in this paper one sample case of a larger motor illustrates the general use of the technique.