Motion

Oscillating Rotor

Mechanical Magnetic Coupling

When the mechanical equations for dynamics are coupled to the magnetics solution it is possible to simulate dynamic motion resulting from magnetic forces. This is done in the following example where a simple rotor is oscillating between two permanent magnets.

Eddy Currents of oscillating rotor 
The picture (click for movie) above shows the behaviour of the eddy currents that result from the time-dependent change of the fluxdensity.

The following picture shows the NX dialog that allows to define the characteristics of the joint.

Dialog Motion

Any result that is available in simple, non-moving electromagnetic solutions can also be obtained in the case of motion. Only some of them are: Fluxdensity, Fieldstrenght, Force, Moment, Eddy Current, Power Losses.

3D Enforced Motion

Analysis of Power Losses

These type of analysis with general motion can be done in 2D or 3D. Next picture shows the simple rotor between two magnets as a 3D model.

3D rotor in Motion, Flux density

Often developers are interested in the losses that result from motion because of self induction effects. That's what is done in this example: We assign a forced velocity of 5000 turns per minute and ask the system to compute the eddy current losses on the rotor and the magnets.

Power Losses on Rotor

The above picture shows the behaviour of power losses because of self induction with the rotor turning as shown above. You see the maximum losses arise in the middle and are about 70 Watts.

On the magnets there are very small losses as shown in the next picture.

Power Losses on Magnets

Linear Joints

Actuator, Pump, Relay

For the analysis of any linear motion as you may need for actuators, pumps or relais you can use the linear joint type. As with the revolute joint it is possible to include friction or the machanical magnetical coupling. By using the 2D or 3D magnetodynamic time solution type you can define currents or voltages as tabular or mathematical functions of time. The results are magnetic fieldstrenght and fluxdensity as well as eddy currents, power losses, velocity and step size.

Next picture/movie shows fluxdensity result from a 2D relay simulation. On the right coil we switch on current. A magnetic field developes timedependent as well as force on the plunger. The force pushes the plunger to the right. At 15mm displacement the plunger hits a wall and stops. Click on it to see a movie.

Flux Density on the Relay

Again the power losses because of this movement are analyzed. See the following picture/movie.

Eddy Current on moving Relay

The resulting losses are shown in a graph. Notice the peak at the position of the stop of the plunger.

Eddy Current Losses on moving Plunger of Relay