Optimization of composite Helmholtz coils towards high magnetic uniformity

Abstract

Helmholtz coils are widely used in biomedicine, aerospace, and other fields due to their simple structure and remarkable magnetic properties. However, the uniform areas they generate are not suitable for conducting scientific experiments with large equipment. In order to improve the uniformity and scale of the uniform magnetic field, a novel scheme is proposed in this paper. Two auxiliary coils are added on both sides of the Helmholtz coils to optimize the magnetic field. The non-dominated Sorting Genetic Algorithm (NSGA-II) was used to optimize the structural parameters of the improved model, while orthogonal experiments were conducted to obtain initial values for better adaptability of influencing factors. A comparison was made between the magnetic field deviation rates of the coil optimized by traditional derivative algorithms within a range of 0.2 m ∼ 0.8 m from the central axis of the magnetic field. Finally, finite element simulation was employed to verify the calculated results. The results show that the magnetic field deviation rate of the coil is less than 0.5% when the intelligent algorithm is used for optimization in the range of 0.6 m from the central axis. In addition, the structure can be extended to a three-dimensional structure, which can achieve a constant magnetic field in any direction by controlling the size and direction of the current, making it a potential application prospect in magnetic navigation technology.

Keywords

• Uniform magnetic field
• Maclaurin expansion method
• Non-dominated Sorting Genetic Algorithm II
• Effective coverage rate
• Finite element simulation