Simultaneous structural topology optimization of electromagnetic sources and ferromagnetic materials

For the design of electric machines such as actuators, sensors and motors, the topology optimization for EM sources as well as ferromagnetic materials (FMs) is in great request. Generally, permanent magnets (PMs) and coils serve as electromagnetic (EM) sources in electric machines. However, most of researches in relation with topology optimization in electric machinery are focused mostly on the design of ferromagnetic materials such as yokes and stators. In this paper, the topology optimization methodology for the simultaneous design of PMs and FMs is developed and it is expanded to the design of FMs with coils. The proposed method makes it possible to obtain a clear topology with little gray density elements in the design domain and shows the stable convergence history. The proposed method is applied to the optimization problem of a C-core actuator and a magnetostrictive sensor. The sensitivity analysis and the update of design variables are accomplished by the adjoint variable method and the sequential linear programming, respectively.