Optimization of permanent-magnet DC motors using orthogonal arrays

The performance of permanent-magnet DC motor can be improved by optimization of its magnetic circuit taking into account important effects of magnetic density distribution in motor air-gap and neutral zone. The optimization can be achieved by means of finite element method in field and torque calculation and statistical analysis using orthogonal arrays. The electromagnetic torque as an objective function was calculated directly from magnetic vector potentials of moving conductors as an average value through a slot pitch shift. A fast improvement in shape of some motor parts was achieved by a very limited number of field and torque calculations. The optimization results verified this approach in modeling of DC motors with permanent magnets.