Lumped Parameter Calculations
All the types of coil domains define lumped variables during the solution. These variables are defined in the global scope and have the template <variable>Coil_<name>, where <variable> is the basic variable name (V for voltage, Z for impedance, and so forth) and <name> is the string specified in the Coil name field. These variables can be evaluated during the analysis phase or used in expressions; in this case, the scope of the physics interface (for example, mf. for the Magnetic Fields interface) must be added to the beginning of the variable name — for example, mf.ICoil_1 is the total coil current flowing in the coil 1 in the physics interface identified by the name mf. A brief description of each of the variables follows.
The Voltage, Current, and Power Variables
The coil nodes define the variables Vcoil, Icoil and Pcoil. The variable corresponding to the quantity used for the coil excitation contains the input value, while the others have values computed from the solution according to the coil model.
Stationary and Time Dependent Studies
In Stationary and Time Dependent studies, the coil feature defines the coil resistance variable, Rcoil, with the formula:
Frequency Domain Studies
In frequency domain studies, the following lumped variables are defined.
Frequency Domain, Perturbation Studies
In frequency domain perturbation studies (small-signal analysis), the parameters defined are the same as in the frequency domain study, but the impedance is computed using the harmonic voltage and current around the linearization point:
lindev in the COMSOL Multiphysics Reference Manual