Solenoid modelling with basic blocks and physical modelling blocks

This example shows a solenoid with a return spring. The solenoid is modelled as an inductance whose value L depends on the piston position x. The inverse EMF for a time-varying inductance is defined as:

Since L depends on x:

can be obtained using data from the manufacturer and using the ratio:

Then can be integrated to get L as a function of x.

In the model, equation (2) is recalculated to solve for i and then implemented using physical blocks. The controlled current source then limits the magnitude of the current by equating it to i.

Schematic of the model:

Simulation results:

Values of solenoid current over time, A:

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Values of the force generated by the solenoid over time, N:

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