An annular magnetic power unit including: an annular magnetic core defining an inner passage and a annular groove, said annular magnetic core comprising a first partial magnetic core and a second partial magnetic core, overlapped and facing to each other, at least said first partial magnetic core having a first annular groove constitutive of said annular groove, accessible through a surface of the first partial magnetic core facing the second partial magnetic core, said first annular groove surrounding the inner passage; at least one electro-conductive inner coil included within the annular groove; at least one electro-conductive outer coil wound around the annular magnetic core passing through the inner passage; wherein said at least one electro-conductive outer coil are two independent electro-conductive outer coils named left and right independent electro-conductive outer coils (43, 44); the first partial magnetic core is divided by two parallel air-gaps in three independent parts corresponding to a first central magnetic core portion, defined between said two parallel air-gaps, to a first left-side core portion and to a first right-side core portion placed on both sides of said first central magnetic core portion; the second partial magnetic core is also divided by said two parallel air-gaps in three independent parts corresponding to a second central magnetic core portion, defined between said two parallel air-gaps, to a second left-side core portion and to a right-side core portion placed on both sides of said second central magnetic core portion; the two-parallel air-gaps are defined by two parallel gap planes perpendicular to a surface of the first partial magnetic core facing the second partial magnetic core, both parallel gap planes passing through the inner passage; the first central magnetic core portion and the second central magnetic core portion define correspondent first and second bridges across the inner passage, dividing said inner passage in a left inner passage and a right inner passage; and wherein the left electro-conductive outer coil passes through the left inner passage and surrounds the first and second left side core portions (13, 23); and the right electro-conductive outer coil passes through the right inner passage and surrounds the first and second right side core portions (14, 24). an annular magnetic core defining an inner passage and a annular groove, said annular magnetic core comprising a first partial magnetic core and a second partial magnetic core, overlapped and facing to each other, at least said first partial magnetic core having a first annular groove constitutive of said annular groove, accessible through a surface of the first partial magnetic core facing the second partial magnetic core, said first annular groove surrounding the inner passage; at least one electro-conductive inner coil included within the annular groove; at least one electro-conductive outer coil wound around the annular magnetic core passing through the inner passage; wherein said at least one electro-conductive outer coil are two independent electro-conductive outer coils named left and right independent electro-conductive outer coils (43, 44); the first partial magnetic core is divided by two parallel air-gaps in three independent parts corresponding to a first central magnetic core portion, defined between said two parallel air-gaps, to a first left-side core portion and to a first right-side core portion placed on both sides of said first central magnetic core portion; the second partial magnetic core is also divided by said two parallel air-gaps in three independent parts corresponding to a second central magnetic core portion, defined between said two parallel air-gaps, to a second left-side core portion and to a right-side core portion placed on both sides of said second central magnetic core portion; the two-parallel air-gaps are defined by two parallel gap planes perpendicular to a surface of the first partial magnetic core facing the second partial magnetic core, both parallel gap planes passing through the inner passage; the first central magnetic core portion and the second central magnetic core portion define correspondent first and second bridges across the inner passage, dividing said inner passage in a left inner passage and a right inner passage; and wherein the left electro-conductive outer coil passes through the left inner passage and surrounds the first and second left side core portions (13, 23); and the right electro-conductive outer coil passes through the right inner passage and surrounds the first and second right side core portions (14, 24).