Switching power supply apparatus

摘要

In accordance with the present invention, there is provided a power supply apparatus comprising a primary winding of a main transformer and a semiconductor device with a control electrode connected in series between both electrodes of a DC power source, a drive current being fed to said control electrode of said semiconductor device via an auxiliary transformer, and output being obtained on a secondary winding of said main transformer by turning on and off of said semiconductor device, wherein a tertiary winding is provided on said main transformer and a negative polarity drive current is flowed into said semiconductor device via said tertiary winding when said semiconductor device is to turn off.