Switching power supply apparatus for reducing common mode noise due to line-to-ground capacitances

A switching power supply apparatus comprising a switching circuit and an even number of transformers, the switching circuit including a plurality of switching elements that form a bridge circuit,

• wherein the even number of transformers include first and second transformers, and the first and second transformers comprise:
• cores having an identical shape;
• primary windings having an identical arrangement around the cores, and having first and second terminals;
• and secondary windings having an identical arrangement around the cores, and having third and fourth terminals,
• wherein the primary windings of the first and second transformers are connected to each other so that when a current flows from the first terminal of the first transformer to the second terminal of the first transformer, a current flows from the second terminal of the second transformer to the first terminal of the second transformer,
• wherein the secondary windings of the first and second transformers are connected to each other so that when a current flows from the third terminal of the first transformer to the fourth terminal of the first transformer, a current flows from the fourth terminal of the second transformer to the third terminal of the second transformer, and when a current flows from the fourth terminal of the first transformer to the third terminal of the first transformer, a current flows from the third terminal of the second transformer to the fourth terminal of the second transformer,
• wherein the third terminal of the first transformer and the fourth terminal of the second transformer are connected to each other, and are further connected to an output terminal of the switching power supply apparatus;
• and
• wherein the fourth terminal of the first transformer and the third terminal of the second transformer are connected to each other, and are further connected to another output terminal of the switching power supply apparatus.