Power conversion device, multilayer board included in the same, and vehicle having power conversion device mounted therein

A power conversion device comprising:

• a multilayer board including conductive layers that form a primary-side coil and a secondary-side coil of a transformer;
• and
• a circuit board electrically connected to the multilayer board, the circuit board having a first conversion circuit formed therein or thereon,
• wherein the multilayer board includes
• a transformer region in which the transformer is formed,
• a core member which is disposed in the transformer region and around which the primary-side coil and the secondary-side coil are wound,
• a circuit formed region which is adjacent to the transformer region and in which a second conversion circuit is formed, the second conversion circuit being electrically connected to one coil of the primary-side coil and the secondary-side coil, and
• a terminal portion which is electrically connected to the other coil of the primary-side coil and the secondary-side coil,
• wherein the first conversion circuit is electrically connected to the transformer via the terminal portion, and
• wherein the one coil connected to the second conversion circuit has a smaller number of turns than the other coil connected to the terminal portion.