Analysis of magnetic characteristics of a brushless DC motor taking into account the distribution of magnetization

Magnetic characteristics of a brushless d.c. motor have been analyzed taking into account the magnetization distribution in the rotor magnet. The magnetization is calculated taking into account the magnetizing process of a magnet. This paper describes a method for calculating the magnetization in the magnet, and the effects of the pattern of magnetization distribution and the shape of the coil on torque ripples. The calculated results are in good agreement with the results measured. Because the flux distribution and the torque characteristics can be calculated, the optimum design of the brushless d.c. motor will be possible without repeating a trial manufacture.