Three coupled inductors
Simscape / Electrical / Passive / Transformers

The Three-Winding Mutual Inductor block represents a set of three coupled inductors or windings. The voltage across the three windings is
where:
Vi is voltage across the ith winding.
Ii is current through the ith winding.
Li is self inductance of the ith winding.
Mij is mutual inductance of the ith and jth windings, .
In the preceding equations, currents are positive when flowing into the positive node of their respective inductor terminals.
When you run a simulation that includes this block, the software checks the specified parameter values to ensure that the resulting device is passive. If it is not, the software issues an error.