Structure design, analysis, and optimization of 12-pole radial magnetic bearing

Active magnetic bearings (AMBs) are widely used in high-speed turbines, precision machining, and energy storage systems due to their non-contact operation, high rotational speeds, and low maintenance. The 8-pole radial magnetic bearing (RMB), commonly adopted in AMB systems, faces limitations in load-carrying capacity and space utilization under heavy loads. To address this, a 12-pole RMB with E-type magnetic poles is proposed, enhancing stator space utilization and electromagnetic force generation. However, optimizing the 12-pole RMB is challenging due to the trade-off between maximizing electromagnetic force and minimizing stator volume, with limited research on its multi-objective optimization. This study fills this gap by systematically investigating the structural design and optimization of the 12-pole RMB. A mathematical model using an equivalent magnetic circuit is developed, validated by Finite Element Method (FEM) simulations, showing strong agreement. FEM further assesses magnetic flux density, dynamic performance, and structural parameter effects. Using the NSGA-II algorithm, a multi-objective optimization framework optimizes the conflicting objectives, selecting six key variables based on their Pareto effect. A prototype of the optimized 12-pole RMB is fabricated and tested, demonstrating stable levitation and confirming the design's effectiveness. This study offers a systematic approach for designing 12-pole RMBs, providing valuable insights for industrial applications.