Abstract: An electric current regulation, commutation and conversion device, which is particularly adapted for current regulation and commutation in rotating direct current electrical machines and for converting alternating current into direct current or vice versa. At least one conductor is disposed in at least one slot in a ferromagnetic lamination pack, the shape of the conductor cross-section and its arrangement in the slot being such as to intensify the additional resistance caused by the dispersion flow due to the current running therethrough. The magnetic circuit constituted by the lamination pack and linked to the current in the conductor is such as to minimize the inductance of the conductor, and the walls of the conductor containing slot are of such a form and arrangement as to be able to be saturated by an external magnetic control field superimposed on the magnetic field due to the current in the conductor.