4. Conclusion

The study of the iron-core coil remains a delicate problem, due to the non-linear phenomena it is the seat of and the interweaving of these problems.

Two tools are available to study its behaviour:

• an equivalent diagram where all elements are constant; this allows the problem to be solved in literal form;

• a numerical model that takes non-linear phenomena into account.

The choice between one or other of these methods depends on the accuracy required and the calculation resources available. This choice is not exclusive. Initially, an approximate behavior can be obtained from the equivalent diagram, and the results can then be refined with the help of a computer tool, which is also an analysis and development tool well suited to the development phases...