Design optimization of surface permanent magnet machines with fractional slot concentrated windings

This paper presents a closed-form design optimization of surface permanent magnet (SPM) machines using concentrated windings layout. Over the last few years, the interest in the use of SPM machines with a high pole number for low speed direct-drive applications has significantly increased. In this paper, the analytical design model is developed and particle swarm optimization (PSO) is applied for achieving optimal specific power and efficiency. In particular, a penalty function is added to the objective function in order to avoid unwanted results. PSO results show that pancake type motor is suitable for high specific power. The performance characteristics of machine designed by closed-form analysis are verified using finite element analysis (FEA). Finally, results of the closed-form analysis and FEA have been validated using experimental data, demonstrating a strong correlation between key machine parameters.