Patent ID: 7199569
Filing Date: 2007-04-03
Classification: H02M

Abstract:
1. A switching power supply unit comprising: a transformer having a primary-winding group including a first primary-winding group and a second primary-winding group connected in series to each other, and a secondary-winding group including a first secondary-winding group and a second secondary-winding group connected to each other; a switching circuit performing switching operation to allow a current direction of the primary-winding group to be changed in a time-divisional manner; and a rectifier-and-smoother circuit rectifying and smoothing AC voltage induced on the secondary-winding group in response to operation of the switching circuit, wherein the first secondary-winding group and the second secondary-winding group are driven in a time divisional manner in phases opposite to each other in response to operation of the switching circuit, magnetic coupling between the first primary-winding group and the secondary-winding group is relatively strong when the first secondary-winding group is driven, while it is relatively loose when the second secondary-winding group is driven, and magnetic coupling between the second primary-winding group and the secondary-winding group is relatively loose when the first secondary-winding group is driven, while it is relatively strong when the second secondary-winding group is driven.