Techniques for Motion

The MAGNETICS solver has five different types of motion techniques:

• ’General Motion (GM)’: General Motion can be used for any kind of motion, e.g. translation or rotation in 3D, because a remeshing is performed for every step. The process is the following:

  1. An initial start solution is solved. The basic result ’Magnetic Vector Potential’ is stored in an extra file (restart-file). Following this solution is referenced as step 0.

  2. The nodes and elements of the moving body are then moved, e.g. rotated or translated corresponding to the desired displacement step. In 3D scenarios, the air mesh is recreated using function ’Solid from Shell’. This function needs a 2D boundary mesh which typically goes over all parts and also over the boundary of the air volume. Therefore, we don’t have ’Mesh Mating Conditions’ between air and the parts. In 2D scenarios said ’Solid from Shell’ meshing is superfluous, of course.

  3. In case of magneto dynamic solutions:
     To capture dynamic effects (the time derivative) it is necessary for every solution time step (e.g. step 1) to include results from one time step prior (e.g. step 0), in order to form time derivatives. Therefore, each solution step uses the result of the prior solution (e.g. step 0) as start condition. This is done automatically inside the solver.

  4. In case of magneto static solutions:
     No time derivative is necessary. Therefore, each time step is a simple magneto static analysis step.

  5. One time step is computed. Results can be as usual: Magnetic Flux Density, Force, Eddy Currents, Current Losses, Temperature and others. In case of dynamic solutions finally the Magnetic Vector Potential result is again stored in the restart file and referenced as step 0.

  6. These steps are repeated in a loop to perform the complete movement.

• ’Moving Band (MB)’: This is capable for 2D rotation only. The process is the following:

  1. The user defines the outside and inside edge of the air gap. The system creates a tri mesh between them and updates this at each step.

  2. The nodes and elements of the moving body are then moved, e.g. rotated corresponding to the desired displacement step.

  3. These steps are repeated in a loop to perform the complete movement.

• ’Sliding Surface (SM)’: Sliding Surface is very similar to ’Moving Band’ but it is made for 3D rotation. Here the air gap is made of two surfaces sliding in circular way. The mesh between the two surfaces must be structured such that, if a movement step appears, all nodes can find a new partner node again.

• ’Conductor Motion, const Shape (CM)’. This feature models the effect of moving conductors, such as water. It can also be used for motors, if the rotor shape does not change while rotating. So, there must be no change in geometry to use this feature. This is the case for instance if water flows through a tube or some induction motor types.

• ’Frequency Motion (FM)’: This feature is used for the analysis of induction motors. The principle works similar to the ’Conductor Motion, const Shape’.