Electropermanent magnet relay

QuickField simulation example

A relay of conventional design develops a pull-in force for any polarity current. By adding a permanent magnet to the structure, a polarized relay is obtained. It can develop both pulling and pushing forces.

Problem type:
Axisymmetric problem of DC magnetics.

Geometry

Given
Permanent magnet coercive force H_c = 500 kA/m;
Winding number of turns: 600, nominal current I = 1 A.
The core and plunger material is steel with a nonlinear dependence B(H):

Task
Determine the force acting on the anchor of the relay, with the nominal current and in the absence of the electric current in the winding.

Solution
Using the integration contour, QuickField calculates the force acting on the ferromagnetic object. The calculation is carried out by integrating along the contour which surrounds the object. At the transition between ferromagnetic and air where the magnetic properties change significantly, field calculation error is relatively high. Therefore, in order to reduce the computational error, the contour should be shifted away from the ferromagnetic-air boundary and drawn through the air, around the anchor.

Results

The magnetic field picture and anchor expelling force value at rated current:

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