Technical Field
The present invention relates to a magnetically coupled reactor and a power converter including the magnetically coupled reactor. The magnetically coupled reactor includes a coupled core member having a first core and a second core. The magnetically coupled reactor also includes a first coil and a second coil that are wound around legs of the coupled core member.
Related Art
There are cases where it is desired to decrease leakage magnetic flux in a magnetically coupled reactor by increasing the degree of magnetic coupling. To this end, a technique such as disclosed in JP 2009-284647 A has been conceived.
JP 2009-284647 A has disclosed a magnetically coupled reactor formed by two outer cores and an inner core disposed between the two outer cores. Two coils are wound around the outer cores and the inner core. One of the two coils is wound around one of the outer cores and the inner core, while the other coil is wound around the other of the two outer cores and the inner core. The coils are partly overlapped alternately to form a lap-winding portion, and the lap-winding portion is then disposed around the inner core.
During the use of the magnetically coupled reactor, a negative-phase-sequence current that flows in a reverse direction may flow through the two coils. In this case, magnetic flux is generated in both coils and becomes intensified at portions where the two coils face each other, which therefore may cause an increase of Joule loss. If the lap-winding portion is formed as in the structure of JP 2009-284647 A, the Joule loss could be decreased. However, such a structure may require new cores at both ends in a direction orthogonal to the axial direction of the coils, and extended windings to be wound around the two cores also become necessary. As a result of this, the size of the structure is increased. Therefore, in a power converter, improvement is desired from the view point of miniaturizing the structure in which a voltage converting operation can be performed using the leakage inductance without excessively suppressing the leakage inductance.