Performance comparison of fractional slot concentrated winding spoke type synchronous motors with different slot-pole combinations

Fractional Slot Concentrated Winding (FSCW) Interior Permanent Magnet (IPM) synchronous motors are nowadays an attractive solution in automotive applications due to their important advantages in terms of high performance and manufacturing simplicity. Among the different topologies, the spoke type is an effective configuration when high torque density is required. On the other hand, the motor performance are heavily related to the selected slot-pole combination. This is a critical issue when there are high constraints in terms of torque quality, flux weakening performance and noise/vibration/harshness. This paper deals with the design and analysis of FSCW IPM spoke type motors, comparing eight optimal slot-pole combinations. Two different low cost PM typologies are considered. Design and optimization procedures, based upon a finite element analysis, are presented. The torque density, torque quality, electromechanical performance and deformation of the machines are compared, highlighting the advantages and the differences among the solutions.