I'm trying to figure out how to solve the equivalent circuit for two identical transformers connected in series or parallel on the primary and secondary. Mainly I want to know what the equivalent leakage and magnetizing inductance will be for each different type of connection (Pri in parallel/sec in parallel, pri in parallel/sec in series, pri in series/sec in parallel and pri in series/sec in series).

I know you can create a T model for the transformer but how does this model change depending on the primary and secondary connection? I understand how the equivalent turns ratio will change but I don't know how to simplify the model to represent it as one concise T model. This is similar to a matrix transformer but in this case there are discrete transformers with separate cores not one core and multiple windings on the core.

Matrix Trans Examples

This is what I meant. Using this to create the T model.


1 Answer 1


For an ideal transformer (no saturation) one could combine the inductance's of some elements by paralleling the T-models.

T-models in parallel are reducible as the primary and secondary are in series with both mutual inductance's of each T-model, and the whole thing reduces to another T-model.

The series model would be reducible if one used Kirchhoff's laws, I am uncertain if it could be reduced to a T-model.


simulate this circuit – Schematic created using CircuitLab

  • 2
    \$\begingroup\$ Are you sure you have connected the T model correctly for series and parallel ? It seems like the parallel connection is actually in series. And your series connection appears wrong as well. This is more of what I meant. \$\endgroup\$
    – DSho3
    Oct 30, 2019 at 22:40
  • \$\begingroup\$ 100% sure the VIN and vout points are connected in the series model. The parralel model is also correct, I'm going of if a CRC book \$\endgroup\$
    – Voltage Spike
    Oct 31, 2019 at 1:53

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