Investigation of Torque Ripple in Servo Motors with Different Magnet Geometries

Abstract

Servo motors are among the most efficient and precise performers within the category of permanent magnet synchronous motors. These motors stand out for their high power density, quiet operation, low maintenance, and wide operating speed range advantages. One of the disadvantages of these motors, which is also the subject of this study, is their high torque ripple. Torque ripple is critical in applications requiring precision, as it can affect operational performance and contribute to vibration and noise issues. Torque ripple can be reduced through design methods such as different winding layouts, slot openings, stator/rotor skewing, or pole offset. In this study, torque ripple of servo motors was investigated through various magnet geometry designs and analyses using the finite element method. Design and analysis studies were conducted for a reference servo motor, and alternative designs were obtained by modifying the rotor structure of the reference motor. In the studies conducted, it has been observed that the torque ripple, initially at 2.17 Nm, can be improved to as low as 1.23 Nm. This indicates that the torque ripple, which was initially at 3.75%, can be reduced to around 2.08%. However, performance losses may occur depending on the extent of improvement.