Design of Magnetic Actuator With Nonlinear Ferromagnetic Materials Using Level-Set Based Topology Optimization

In the practical design of magnetic actuators, the effect of magnetic saturation usually plays an important role. This paper proposes a new computation approach for identifying the optimal configuration of a magnetic actuator to deal with saturation of the ferromagnetic material. A level-set method for topology optimization in magnetic fields is employed to represent the material boundary considering nonlinear B-H characteristics. Design of magnetic actuators is mathematically formulated as a general optimization problem for maximizing magnetic energy in the air gap between armature and yoke under the limited usage of ferromagnetic material. The nonlinear magnetostatic finite element analysis where transient eddy current effects are ignored and the associated design sensitivity analysis are performed. The movement of the implicit boundaries of the ferromagnetic material is driven by the normal velocity derived from optimality and convergence conditions of level-set equation. The validity and effectiveness of the proposed method are illustrated with 2D examples that are widely used in the literature.