Design and analysis of fractional slot direct drive motor with low speed and high torque

In recent years, low speed and high torque direct drive motor is increasingly used in many application for industrial drive for the improved performance, especially for replacing the motor with structure of reducer which possess some shortcomings, such as complex structure, big volume and low efficiency of transmission . In this paper, we designed a 32poles/30slots fractional slot direct drove motor with surface mounted permanent magnet structure for low speed and high torque . We put the UDLR (up, down, left, right) four layers winding designing method into use to decrease the torque ripple . With two permanent magnet materials combined in the rotor, we can decrease harmonic components in electromotive force (later shows EMF) and attain more perfect sinusoidal waveform in EMF .