Setting Coil and Mechanical Terminals

There are currently two types of terminals:

For models with motion, the mechanical terminal setup determines which force (or torque) causes the motion and which position (or rotation) is affected.

When setting up coil terminals, flux and current are used for magnetic models, and charge and voltage are used for electric models.

In the coil terminal setup, there is one row for each flux (or charge) group. In the Current (or Voltage) column, each cell is a selection box where you can choose the current (or voltage) that applies to that flux (or charge) group. Usually the software can choose the correct current by default, based on the source setup in the design. The Resistance column is set to 0 by default; you can enter any value here. The Turns and Branches columns only appear for magnetic models where current variables represent Ampere-turns. These columns are initialized with the turns and branches specified in the inductance matrix setup.

In the Current column, in addition to each current, there is another choice, <Dependent>. This feature allows you to solve some problems using fewer parametric rows. This is explained using the following example:

Suppose you are working on a three-phase machine. You create three sources: CurrentA, CurrentB, and CurrentC. In Maxwell, you can create only variables iA and iB and then set the value of CurrentC to -(iA + iB). The parametric table will have ten values each for iA and iB, so it will only have 100 rows. When exporting the circuit, you would set the current for Flux[CurrentA] to iA, Flux[CurrentB] to iB, and Flux[CurrentC] to <Dependent>. In the circuit model, the PWL table will contain two input currents (iA and iB), but it will contain all three fluxes. So it will look up all three flux values based on only the two current values. As long as you always connect a current of -(iA + iB) to CurrentC, this model will be valid.

Note: A dependent source can have a different number of turns from the sources that it depends on (in the example above, CurrentA, CurrentB, and CurrentC can all have different numbers of turns). But in this case, you would have set up the current variables as Amperes instead of Ampere-turns — otherwise there would be no way to obtain the correct scaling of currents iA and iB for both their own current sources and for CurrentC. Therefore, this is another case where specifying current variables in Amperes (rather than in Ampere-turns) is useful.