A three-phase-two-phase transformer comprising a magnetic circuit , three-phase windings, and two-phase windings, wherein: the magnetic circuit comprises a first column (3; 4), a second column (4; 3), and a third column that are magnetically connected together; and the three-phase windings consist in a first winding of n 1 turns around the first column (3; 4), a second winding of n 1 turns around the second column (4; 3), and a third winding of n 1 turns around the third column ; the transformer being characterized in that : the two-phase windings consist in a fourth winding of n 2 turns around the first column (3; 4), a fifth winding of n' 2 turns around the first column (3; 4), a sixth winding of n 2 turns around the third column , and a seventh winding of n' 2 turns around the third column ; the fourth winding and the seventh winding are connected in series and form a first two-phase phase, and each of the fourth and seventh windings presents a corresponding winding direction for a current (I 1 ) flowing in the first two-phase phase, with magnetic potentials (n 2 I 1 , n' 2 I 1 ) in the same direction; and the fifth winding and the sixth winding are connected in series and form a second two-phase phase, and each of the fifth and sixth windings presents a corresponding winding direction for a current (I 2 ) flowing in the second two-phase phase, with magnetic potentials (n 2 I 2 , n' 2 I 2 ) in the same direction. the magnetic circuit comprises a first column (3; 4), a second column (4; 3), and a third column that are magnetically connected together; and the three-phase windings consist in a first winding of n 1 turns around the first column (3; 4), a second winding of n 1 turns around the second column (4; 3), and a third winding of n 1 turns around the third column ; the transformer being characterized in that : the two-phase windings consist in a fourth winding of n 2 turns around the first column (3; 4), a fifth winding of n' 2 turns around the first column (3; 4), a sixth winding of n 2 turns around the third column , and a seventh winding of n' 2 turns around the third column ; the fourth winding and the seventh winding are connected in series and form a first two-phase phase, and each of the fourth and seventh windings presents a corresponding winding direction for a current (I 1 ) flowing in the first two-phase phase, with magnetic potentials (n 2 I 1 , n' 2 I 1 ) in the same direction; and the fifth winding and the sixth winding are connected in series and form a second two-phase phase, and each of the fifth and sixth windings presents a corresponding winding direction for a current (I 2 ) flowing in the second two-phase phase, with magnetic potentials (n 2 I 2 , n' 2 I 2 ) in the same direction. the two-phase windings consist in a fourth winding of n 2 turns around the first column (3; 4), a fifth winding of n' 2 turns around the first column (3; 4), a sixth winding of n 2 turns around the third column , and a seventh winding of n' 2 turns around the third column ; the fourth winding and the seventh winding are connected in series and form a first two-phase phase, and each of the fourth and seventh windings presents a corresponding winding direction for a current (I 1 ) flowing in the first two-phase phase, with magnetic potentials (n 2 I 1 , n' 2 I 1 ) in the same direction; and the fifth winding and the sixth winding are connected in series and form a second two-phase phase, and each of the fifth and sixth windings presents a corresponding winding direction for a current (I 2 ) flowing in the second two-phase phase, with magnetic potentials (n 2 I 2 , n' 2 I 2 ) in the same direction. <EOS>