Abstract: Aiming at the requirement of constant force characteristics of proportional electromagnet for external solenoid valve,a parametric model of proportional electromagnet was established in the 2D module of Maxwell software. The correctness of the simulation was verified by the proportional electromagnet test bench. The correctness of the material and the magnetic circuit segmentation method was verified from the simulation results and the armature working stroke was determined. On this basis,the single factor parameter analysis method was used to analyze the influence of the structural parameters of the magnetic isolation ring height L₂,the radial clearance δ₄,the diameter of the limit piece D₀ and the radial clearance δ₂ on the constant force characteristics of the electromagnet in the working stroke of the armature. According to the analysis results,the orthogonal test method was used to optimize the selected parameters to obtain a better parameter combination. The simulation shows that the proportional electromagnet has better constant force characteristics when L₂ =4.1 mm,δ₄ = 0.30 mm,and δ₂ =0.05 mm. The optimal combination parameters are verified by simulation. The electromagnetic force variance is 12.96 % lower than the original structure,and the constant force characteristics are significantly improved.

Key words: electromagnetic force, proportional electromagnet, orthogonal test, optimization analysis