A synchronous electrical machine configured to drive a rotating element in rotation around an axis of rotation of the electrical machine or to generate electrical energy from the mechanical energy transmitted by said rotating element, comprising: - a stator (20, 20') disposed around the axis of rotation of the electrical machine, comprising a ring extending along a preferred plane perpendicular to said axis of rotation and comprising a winding and a denture comprising teeth extending parallel to the axis of rotation from the ring, said winding being coiled around the denture according to the preferred plane and the denture delimiting an inner zone of the stator around the axis of rotation, - a rotor, comprising a first portion extending in p first preferred directions parallel to the preferred plane, a second portion extending in p second preferred directions angularly shifted by π/p with respect to the first preferred directions of the first portion and parallel to the preferred plane, and an intermediate portion linking the first portion to the second portion, the rotor being arranged in such a way that at least the second portion and the intermediate portion, extending in parallel to the axis of rotation, are in the inner zone of the stator and that the second portion is located on the side of the ring, and - an excitation coil for exciting the rotor, fixed with respect to the stator, supplied with DC electric current, positioned around the intermediate portion of the rotor and configured so as to generate a magnetic flux in the rotor through magnetic induction, such that the first portion of the rotor constitutes p north magnetic poles of the rotor and the second portion of the rotor constitutes p south magnetic poles of the rotor. - a stator (20, 20') disposed around the axis of rotation of the electrical machine, comprising a ring extending along a preferred plane perpendicular to said axis of rotation and comprising a winding and a denture comprising teeth extending parallel to the axis of rotation from the ring, said winding being coiled around the denture according to the preferred plane and the denture delimiting an inner zone of the stator around the axis of rotation, - a rotor, comprising a first portion extending in p first preferred directions parallel to the preferred plane, a second portion extending in p second preferred directions angularly shifted by π/p with respect to the first preferred directions of the first portion and parallel to the preferred plane, and an intermediate portion linking the first portion to the second portion, the rotor being arranged in such a way that at least the second portion and the intermediate portion, extending in parallel to the axis of rotation, are in the inner zone of the stator and that the second portion is located on the side of the ring, and - an excitation coil for exciting the rotor, fixed with respect to the stator, supplied with DC electric current, positioned around the intermediate portion of the rotor and configured so as to generate a magnetic flux in the rotor through magnetic induction, such that the first portion of the rotor constitutes p north magnetic poles of the rotor and the second portion of the rotor constitutes p south magnetic poles of the rotor.