Hierarchical Multi-Objective Optimization of a Multi-Sided Permanent Magnet Linear Synchronous Motor with Ring Structure Winding for Conveyor Systems

This paper proposes a multi-sided permanent magnet linear synchronous motor (MSPMLSM) with Ring Structure Winding to meet the high thrust requirements of intelligent circular conveying systems. This motor adopts a three-sided mover structure with three working air gaps: the upper and lower air gaps are composed of parallel permanent magnets and fan-shaped primary teeth, resulting in incomplete primary-mover coupling; the side air gap consists of a Halbach permanent magnet array and arc-shaped primary teeth, leading to uneven air gap length. Firstly, this paper analyzes the magnetic field generated by the special air gap and derives the thrust expression. To simplify the optimization process, the motor is divided into two parts for optimization: Motor I is composed of the side mover and primary, and Motor II is composed of the upper and lower movers and primary. After performing a sensitivity analysis on the main structural parameters of Motor I, a hierarchical optimization is conducted using central composite design (CCD) and box-Behnken design (BBD), and the final parameters are determined using the Non-dominated sorting genetic algorithm II (NSGA-II). For Motor II, the mover parameters are determined through single-objective optimization. Finally, Motors I and II are combined and validated through finite element simulation, with results showing that the new motor significantly improves thrust performance.