External I-Terminal
The External I-Terminal () feature connects an arbitrary voltage-to-ground measurement (for example, a circuit terminal from another physics interface) as a voltage-to-ground assignment to a node in the electrical circuit. The resulting circuit current from the node is typically coupled back as a prescribed current source in the context of the voltage measurement. This node does not apply when coupling to inductive or electromagnetic wave propagation models because then voltage must be defined as a line integral between two points rather than a single point measurement of electric potential. For such couplings, use the External I vs. U node instead.
Node Connections
Set the Node name for the connecting node for the voltage assignment.
External Terminal
Enter the source of the Voltage. If circuit- or current-excited terminals are defined on boundaries in other physics interfaces, these display as options in the Voltage list. Also select the User defined option and enter a voltage variable, for example, using a suitable coupling operator.
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Except when coupling to a circuit terminal, the current flow variable must be manually coupled back in the electrical circuit to the context of the voltage measurement. This applies also when coupling to a current excited terminal. The name of this current variable follows the convention cirn.termIm_i, where cirn is the tag of the Electrical Circuit interface node and termIm is the tag of the External I-Terminal node. The tags are typically displayed within curly brackets {} in the Model Builder.
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When connecting the finite element model between two circuit nodes that both are not grounded, the External I-Terminal node cannot be used. In this case, use External I vs. U or External U vs. I instead.
Connecting to Electrical Circuits
Nonlocal Couplings and Coupling Operators in the COMSOL Multiphysics Reference Manual.