A magnetic integrated device, wherein the magnetic integrated device comprises: a first magnetic core base and a second magnetic core base that are parallel and a first magnetic core column, a second magnetic core column, and a third magnetic core column that are located between the first magnetic core base and the second magnetic core base; and a first winding, a second winding, and a third winding are wound on the first magnetic core column, the second magnetic core column, and the third magnetic core column respectively in a same winding manner to form a closed magnetic flux loop, wherein the first winding, the second winding, and the third winding are suitable for connection to a branch of a three-phase parallel circuit; wherein the magnetic integrated device further comprises a fourth winding, a fifth winding, and a sixth winding, wherein: the fourth winding, the fifth winding, and the sixth winding are superposed and wound on the first winding, the second winding, and the third winding respectively in a same manner; and a pair of windings on each magnetic core column of the first magnetic core column, the second magnetic core column, and the third magnetic core column are usable asa primary side and a secondary side of a transformer of a branch of the three-phase parallel circuit; wherein two side columns are further provided between the two magnetic core bases, and the first magnetic core column, the second magnetic core column, and the third magnetic core column are located between the two side columns; wherein the magnetic integrated device further comprises a third magnetic core base, a fourth magnetic core column, a fifth magnetic core column, a sixth magnetic core column, a seventh winding, an eighth winding, a ninth winding, wherein: the third magnetic core base is parallel to the first magnetic core base; the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column are located between the first magnetic core base and the third magnetic core base; the seventh winding, the eighth winding, and the ninth winding are wound on the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column respectively in a same manner. the fourth winding, the fifth winding, and the sixth winding are superposed and wound on the first winding, the second winding, and the third winding respectively in a same manner; and a pair of windings on each magnetic core column of the first magnetic core column, the second magnetic core column, and the third magnetic core column are usable asa primary side and a secondary side of a transformer of a branch of the three-phase parallel circuit; wherein two side columns are further provided between the two magnetic core bases, and the first magnetic core column, the second magnetic core column, and the third magnetic core column are located between the two side columns; wherein the magnetic integrated device further comprises a third magnetic core base, a fourth magnetic core column, a fifth magnetic core column, a sixth magnetic core column, a seventh winding, an eighth winding, a ninth winding, wherein: the third magnetic core base is parallel to the first magnetic core base; the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column are located between the first magnetic core base and the third magnetic core base; the seventh winding, the eighth winding, and the ninth winding are wound on the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column respectively in a same manner. the third magnetic core base is parallel to the first magnetic core base; the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column are located between the first magnetic core base and the third magnetic core base; the seventh winding, the eighth winding, and the ninth winding are wound on the fourth magnetic core column, the fifth magnetic core column, and the sixth magnetic core column respectively in a same manner.