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Conservation of energy AC/DC
Posted 22.10.2016, 16:53 GMT-4 Low-Frequency Electromagnetics Version 5.2 0 Replies
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I have built a model of a voltage driven coil with a steel plunger (nonlinear material). It is based on the example here: www.comsol.com/blogs/part-1-how-to-model-a-linear-electromagnetic-plunger/
I calculate input Energy as the time integral of U*I , where U is the voltage driving the coil and I is the current in the coil.
I calculate Kinetic energy as E_k = 0.5*m*v^2, where m is the mass of the plunger and v its velocity.
I calculate electromagnetic (resistive) losses as time integral of volume integral of "mf.Qh", which is "Electromagnetic losses" as defined by comsol.
I calculate magnetic field energy as volume integral of HdB in the nonlinear plunger and volume integral of mf.W in the rest of space
I would expect input energy to equal the sum of the other energies but it doesn't!
I have attached a plot of the mentioned energies. Energy output is the sum, and as you can see it is somewhat larger than the input energy. What am i missing?
Thank you for your time!
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Hello Max Cedercreutz
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