I'm playing around in Femm, learning it. I'm trying to design a DC solenoid with a steel shell and an encapsulated plunger. The solenoid should be quite a bit longer than the plunger and I'd like the forces acting on the plunger to vary fairly linearly with plunger displacement (with 0 force when the plunger is centered), over a fairly large displacement.
I'm finding the forces increase exponentially as the plunger approaches the ends of the solenoid and I'm struggling to make the curve more linear.
I've found that increasing the # of turns and decreasing current (increasing voltage) makes things more linear but I'm at the practical maximum of turn count and still far from desired linearity. The forces I'm getting at the ends of the solenoid are sufficient for my design, it's the middle region I'm stuck on.
Any design tips appreciated!
PS I'm not married to a solenoid design, if there's some other electromagnet approach that's fairly power efficient and gives linear force vs displacement I'm all ears.
I'm finding the forces increase exponentially as the plunger approaches the ends of the solenoid and I'm struggling to make the curve more linear.
I've found that increasing the # of turns and decreasing current (increasing voltage) makes things more linear but I'm at the practical maximum of turn count and still far from desired linearity. The forces I'm getting at the ends of the solenoid are sufficient for my design, it's the middle region I'm stuck on.
Any design tips appreciated!
PS I'm not married to a solenoid design, if there's some other electromagnet approach that's fairly power efficient and gives linear force vs displacement I'm all ears.
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