Patent ID: 7351931

Claim:
A switching power supply unit, comprising: two or more switching power supplies each including: two capacitors connected in series; a transformer having a primary winding whose one end is connected to a connection point of the two capacitors; two switching elements connected to the other end of the two capacitors and the other ends of the primary winding of the transformer; a rectifier for rectifying an output of a secondary winding of the transformer; and a choke coil for smoothing an output of the rectifier, and a common control circuit for controlling the plurality of switching elements, wherein the two or more switching power supplies are connected to an input power supply so that the capacitors are connected in series, output voltages generated by the two or more switching power supplies are outputted to a common output terminal, the control circuit switches the plurality of switching elements in the plurality of switching power supply units at regular intervals and regular time ratios, and the windings of the transformer are made of stacked plate-shaped conductors.