Improvement of the performance of electric drives with concentrated windings: reduction of torque ripple through non-standard stator slot numbers

Abstract Torque ripple is an important factor in the design of concentrated winding servo motors, as it can determine their suitability for certain processes. We present an approach to reduce torque ripple by choosing an amount of stator slots not divisible by the number of strands, thus greatly increasing the least common multiple between rotor poles and stator slots. A method for generating the desired rotating stator field with an unconventional winding configuration is described: In a concentrated 4‑layer winding, it can be achieved by varying the number of turns contributed by two different phases for each tooth. Comparable designs with 8‑pole 10-slot (8p10s), 8p13s, and 8p14s configurations based on this approach are studied. For comparison, an example of a conventional concentrated winding motor with an 8p12s configuration is considered. Skewing is a common means to reduce torque ripple. Therefore, two skewed variants with two and four slices are investigated as well. All designs are simulated using 2D Finite Element Method (FEM) software and examined in terms of torque ripple. The torque ripple is reduced from 14% of the rated torque in the non-skewed 8p12s configuration to below 1% in the 8p13s configuration. This could, for example, enable the use of such a design for textile spindle drives. In the 8p13s design, a radial force of approximately 1 newton is introduced.