Optimization Design Of Electromagnetic Shielding Structure For Magnetic Levitation Vehicle Recorder

The ultra-high speed and low vacuum pipeline maglev transportation system is a complex system engineering.The train runs at ultra-high speed in the environment of low vacuum,strong magnetic field and confined space.In order to test the performance parameters of the train superconductor structure,the on-board recorder needs to work in the strong electromagnetic environment.The metal shielding cavity can ensure its normal operation in strong electromagnetic environments,but opening holes such as cables can reduce the shielding effect of the cavity,and structural optimization is needed to improve the shielding efficiency.It is very important to quickly and effectively optimize the parameters of electromagnetic shielding structures.Firstly,based on the study of electromagnetic shielding theory and transmission line theory,an analytical formula for the shielding effectiveness of a single-layer shielding cavity with mixed openings such as hole arrays,circular holes,and non central holes is derived to address the complexity of the shielding structure of multi-layer materials with mixed openings.Among them,the impact of different square hole positions on shielding performance is mainly analyzed,and the effectiveness of the analytical formula for shielding effectiveness is verified in subsequent simulations.Based on the similarity between the cross-section of a rectangular cavity and the axial cross-section of a cylindrical cavity,an analytical formula for the shielding effectiveness of the shielding structure used in this paper is derived by analogy,and numerical simulation analysis is conducted on the factors affecting the shielding effectiveness.Secondly,in view of the problems of simple calculation and insufficient accuracy of analytical method,high accuracy and low efficiency of numerical method,combined with the advantages of high efficiency of analytical method and accurate calculation of numerical method,the combinatorial optimization method of "analytical method+numerical method" is selected to maximize the shielding effectiveness.On the basis of comparing genetic algorithm and particle swarm optimization algorithm,and combining the advantages and disadvantages of the two algorithms,GA-PSO algorithm is used to optimize the shielding structure.Finally,the 17 parameters to be optimized in the electromagnetic shielding analytical formula are optimized by analytical method,numerical method and combinatorial optimization method respectively.The results show that the optimization effect of the achievable numerical optimization scheme is the worst due to the large step size setting.Although the combinatorial optimization method has more computation than the analytical method,it can further improve the shielding effectiveness by 1.35% on the basis of the same structure volume;Compared with the numerical method,the structure volume is reduced by 11.09%,the calculation amount is reduced by 64%,and the shielding effectiveness of the structure is increased from 86.79 d B to90.35 d B.It can be seen that the proposed combinatorial optimization method can significantly improve the design efficiency while improving the optimization effect.