Core piece, reactor, converter and power conversion device

A method for manufacturing a core piece that is to constitute a portion of a magnetic core, comprising the steps of:

• placing, into a mold, a composite material in which unsolidified resin and soft magnetic powder are mixed, and molding the composite material;
• and
• applying a magnetic field when molding the composite material in the step of molding the composite material,
• wherein the core piece is E-shaped and includes an end core portion, a middle core portion, and two side core portions,
• the end core portion extends in a direction orthogonal to a direction in which the middle core portion and the side core portions extend,
• the mold is provided with a magnetic field device that applies the magnetic field,
• the magnetic field device includes an iron core and a coil wound around the iron core,
• the iron core is C-shaped,
• the iron core is disposed so as to form a closed magnetic path between the side core portions and the end core portion, and
• in the step of applying the magnetic field, the closed magnetic path is formed when the coil is excited, and a magnetic field is applied to the end core portion in a direction in which the end core portion extends, while a magnetic field is applied to the side core portions in a direction in which the side core portions extend.