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Relay dynamics simulation using Microsoft Excel and QuickField API - QuickField simulation example

Relay-plunger motion under electromagnetic and spring forces, with Microsoft Excel VBA integrating the mechanical motion from position-dependent forces..

To combine the electromagnetic field analysis with the moving core dynamics both Microsoft Office (Excel) and QuickField are used. Interaction between QuickField and Microsoft Excel is performed using ActiveField application programming interface.

Engineering question

How is the relay's plunger motion calculated using QuickField and Microsoft Excel VBA?

Answer
Set up an axisymmetric QuickField DC Magnetics problem and replace the multi-turn coil with an equivalent total current. Use Microsoft Excel VBA to integrate the plunger's equation of motion, invoking QuickField at each step to get the electromagnetic force.

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Typical applications
electromagnetic relays, relay armatures, electromechanical switching devices

Relay dynamics simulation using Microsoft Excel and QuickField API

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Simulation problem

Problem Type
Axisymmetric problem of DC magnetics.

Geometry
Relay dynamics simulation The electromagnetic and spring forces act on the plunger. Both forces depend on the plunger position Coil Plunger Spring 20 mm x Ø 7.2 mm

Given
Current I = 400 Ampere*turns;
Plunger pull-out position xmax = 10 mm.
Plunger pull in position xmin = 6 mm.
Plunger weight m = 4.5 g;
Spring constant k = 4 N/m
Spring free position xspring.free = 15 mm.

Task
Relay-plunger motion under electromagnetic and spring forces, with Microsoft Excel VBA integrating the mechanical motion from position-dependent forces..

Solution
The multi-turn winding is replaced with the equivalent total current.

The motion function can be found from second-order differential equation
m · d²x/dt² = f(x),
where m - is a plunger weight (kg),
x - is a plunger position (m)
f(x) - is the force acting on the plunger (N).
The force acting on the plunger is a sum of spring force fspring(x) = k·(xspring.free - x) and electromagnetic force.

The equations are solved in Microsoft Excel VBA. The dynamic link is used to invoke QuickField and calculate the electromagnetic force at each step.

The calculations are stopped when x=xmin (pull in position, plunger hits damper).
Microsoft Excel VBA to QuickField link The equations are solved in Microsoft Excel VBA. The dynamic link through COM is used to invoke QuickField and calculate the electromagnetic force at each step Microsoft Excel VBA QuickField Initial conditions x0 = xmax, v0 = 0 m/s Invoke QuickField to calculate Force(xi) vi+1 = vi + Force/mass*Δt xi+1 = xi + vi+1* Δt x>xmin ? true false EXIT

Results
The plunger hits initial position (0.006 m) at 0.055 s.
Plot of the plunger position in meters vs time in seconds.

Video

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