This project involved the simulation and analysis of an electromagnetic actuator using COMSOL Multiphysics to evaluate force production and optimise the actuator's performance. The objective was to model and simulate the behaviour of the actuator under various conditions, particularly focusing on material choices and geometrical configurations.
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Analytical Modelling: The magnetic flux in the air gap and driver core was analytically derived, focusing on the magnetic circuit of the actuator. The model provided insights into how magnetic flux density and reluctances influence the force output of the actuator.
FEA and Mesh Analysis: COMSOL Multiphysics was used to create a finite element model of the actuator. A mesh refinement approach was applied, particularly in the air gap between the plunger and core, where precision was paramount. The simulations demonstrated that refining the mesh to 0.05mm produced stable results with minimal variance in force approximation.
Material Selection: Both linear and non-linear material models were compared. The non-linear model utilised soft iron, which showed magnetic saturation at 1.9 Tesla. This gave the non-linear model a distinct advantage at larger air gaps, while the linear model exhibited unrestricted magnetic flux but produced higher forces at smaller gaps.
Plunger Designs: Two plunger designs were tested—cylindrical and conical. The cylindrical design produced stronger magnetic fields at small air gaps, while the conical plunger demonstrated better force consistency at larger air gaps by reducing magnetic fringing.
The simulations showed significant differences between the linear and non-linear models across a range of air gaps. For a 1mm air gap, the force output was 1,407 N with the conical-headed plunger, compared to 2,320.7 N for the cylindrical design. However, at larger air gaps, the conical plunger outperformed the cylindrical one, generating 489.9 N at a 10mm air gap compared to 301.64 N for the cylindrical design. The conical plunger’s 45° angle reduced magnetic fringing, improving force efficiency over larger distances.
The primary challenge was to balance force output across a range of air gaps. While the cylindrical plunger performed better at smaller gaps, its efficiency dropped significantly at larger gaps due to magnetic fringing. The conical design, however, provided a more even distribution of force over varying distances. Future improvements could include exploring alternative materials with higher magnetic permeability, such as Fe-Co, and further optimising the plunger geometry to maximise force output without compromising on material cost or complexity.
