Design Optimization of Primary Core in Induction Heating Roll by the Combination of 2D Level-set Method and 3D Coupled Magnetic-Thermal FEM

Abstract

We present a novel practical design optimization for the primary core in an induction heating roll, which significantly affects the heating performance. To optimize the 3D eddy current field problem within an acceptable CPU time, we effectively combine 2D magnetostatic optimization and 3D coupled magnetic-thermal FEM. For the 2D optimization, we adopt the level-set method, which has an advantage of being able to derive a feasible shape. However, the disadvantage is that its result occasionally falls into a local optimal solution. To overcome this disadvantage, we propose conducting the initial conceptual design with the linear level-set method before using the nonlinear level-set method to expand the search domain. Furthermore, we incorporate the parallelized move-limit strategy into the level-set method to prevent the configuration from undergoing excess deformation by the operation for the area constraint. Finally, the 2D optimal shape obtained using our new level-set method is converted into a straight line cross-sectional configuration to improve manufacturability, and the final 3D design is created with slits. The final 3D design obtained as a result of the 3D FEM successfully improves both the heating speed and temperature uniformity on the surface of the heating part under the same conditions of input AC current and material volume.

Evaluation of localized heat transfer coefficient for induction heating apparatus by thermal fluid analysis based on the HSMAC method

“…As a simulation technique to evaluate the temperature rise in the actual driving state of electrical machines, coupled electromagnetic-field and heatconduction analysis using the heat-transfer boundary set on the surface of the heated target has been frequently carried out [1,2]. However, because the heattransfer coefficient changes depending on location owing to various factors (e.g., shape, material of the heated target, and temperature of the surroundings), it is often determined such that the discrepancy between the measurement data and numerical result is minimized [3].…”

Multistage topology optimization of induction heating apparatus in time domain electromagnetic field with magnetic nonlinearity

“…The heating performance of the apparatus is evaluated by the heating rate of the roll surface and the temperature uniformity, and its heating performance depends on the magnetic circuit structure. Therefore, to improve the heating performance, a design method using structural optimization that can automatically change the magnetic circuit structure of the roll has been investigated (Hirono et al, 2018). Structural optimization is mainly classified into size and shape optimization and topology optimization (TO) (Bendsøe, 1989) in terms of the degrees of freedom of the obtained structure.…”