Flyback transformer having coil arrangement capable of reducing leakage

Abstract

A flyback transformer comprising a magnetic core assembled by joining together a pair of first and second U-shaped core halves each having two leg portions with end surfaces respectively joined in mutually abutting confrontation with respective gap spacers interposed therebetween at first and second core joint parts and a coil wound around the core joint parts. The coil includes, as an input winding, a primary winding divided into first and second primary windings which are wound at least around the two core joint parts of the core and are connected in parallel. By this arrangement, the magnetic fluxes generated at the two core joint parts cancel each other, and reduce the leakage flux field. Optionally, the two divided windings of the primary winding are each divided further into two windings wound around the leg portions on opposite sides of the spacers. At the same time, the first primary winding on the leg portion on one side and the second primary winding on the other side are connected in series. Furthermore, the first primary winding on the leg portions on the other side and the second primary winding on one side are connected in series. The coil includes, as an output winding, a secondary winding which can be operationally divided into at least two windings wound so as to envelop each of the two joint parts to thereby reduce the leakage flux.