Patent ID: 8004867
Filing Date: 2011-08-23
Classification: H02M,Y02B

Abstract:
1. A switching power supply unit which generates a DC output voltage through performing voltage conversion on a DC input voltage inputted from an input terminal pair and outputs the generated DC output voltage from an output terminal pairs, comprising: a switching circuit of full bridge type disposed on a side near the input terminal pair and including four switching elements which configure two arms of the full bridge switching circuit; a rectifier circuit disposed on a side near the output terminal pair and including a plurality of first rectifier devices; a transformer disposed between the switching circuit and the rectifier circuit and including a first winding on a side near the input terminal pair, a second winding on a side near the output terminal pair, and a third winding; a surge voltage suppressing circuit connected in parallel with the switching circuit and including a full bridge circuit configured of four second rectifier devices which configure two arms of the surge voltage suppressing circuit, each of the four second rectifier devices being disposed so as to be applied with a voltage of reverse direction; and a driving circuit driving the switching circuit, wherein the third winding is connected to the full bridge circuit to form a H-bridge configuration; and magnetic coupling between the first and second windings and magnetic coupling between the first and third windings are both looser than magnetic coupling between the second and third windings.