Is there experience in modelling reluctance force behaviour with variable excitation current. The intention is for a lifting magnet to open a latch by forcing the current while the airgap is still significant.

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Magnetomotive device based on reluctance force Library Magnetic Elements

Description The Reluctance Force Actuator block models a generic magnetomotive device based on reluctance force.

The block is based on the following equations:

F=−0.5⋅Φ 2 ⋅ dℜ dx ℜ(x)= x μ 0 ⋅μ r ⋅A u=dx where

F Reluctance force Φ Flux in the magnetic circuit ℜ Reluctance x Thickness or length of the air gap μ0 Permeability constant μr Relative permeability of the material A Cross-sectional area of the section being modeled u Velocity Connections N and S are magnetic conserving ports, and connections C and R are mechanical translational conserving ports. The magnetic force produced by the actuator acts to close the gap, therefore the resulting force is negative when it acts from C to R.

Basic Assumptions and Limitations The current excitation in the system is constant. Only axial reluctance is modeled.

Answer 1

[Steve Miller]

You have already found the block you need to use - the Reluctance Force Actuator.

The closest example that I can find is this one: Solenoid with Magnetic Blocks. Use this example as a starting point to model your system.

For a more advanced example, see Magnetic Bearings for Electric Machines on the MATLAB Central File Exchange.

--Steve

Answer 2

[Bob Masterman]

Steve, Thanks for the reference which we will examine with interest.

Our project of designing a system to handle rigid covers on and off rail wagons robotically is progressing. We are using electromagnets for lifting and need to transmit AC power through the magnet to unlatch the passive cover before applying DC to lift.