Patent ID: 6282103
Filing Date: 2001-08-28
Classification: H02M,Y02B

Abstract:
A switching power supply apparatus comprising:a first rectifying circuit for rectifying an AC input signal of an ordinary frequency from an AC power source into a DC signal, said first rectifying circuit comprising a positive output terminal;a smoothing circuit for smoothing the rectified DC signal from said first rectifying circuit, said smoothing circuit having a positive terminal and a negative terminal;a DC/DC converter for converting the smoothed and rectified DC signal from said smoothing circuit into an output DC signal, said DC/DC converter comprising:a switching device operable at a high frequency;a first transformer comprising a primary winding having a first terminal connected to said positive terminal of said smoothing circuit, a center terminal, and a second terminal connected to said switching device and therethrough to said negative terminal of said smoothing circuit, and a secondary winding for providing an output signal;second rectifying circuit connected to a terminal of said secondary winding of said first transformer for rectifying said output signal from said secondary winding of said first transformer into said output DC-signal, andcontrol circuit connected to said secondary winding of said first transformer and to said switching device for monitoring and controlling frequency of said switching device and said output DC signal from said second rectifying circuit; andan inductor device disposed between said first rectifying circuit and said DC/DC converter and comprising:a first inductor,a second inductor connected to said first inductor,a first terminal,a second terminal,a third terminal, whereinsaid first, second and third terminals are connected to said first and second inductors, and wherein said first terminal is also connected to said positive output terminal of said first rectifying circuit, said second terminal is also connected to said positive end of said smoothing circuit and to said first terminal of said primary winding of said first transformer so as to supply the smoothed and rectified input signal of ordinary frequency as inductor influenced to said primary winding,and said third terminal is also connected to said center terminal of said primary winding of said first transformer, wherein said switching device under control of said control circuit selectively controls frequency of the rectified and smoothed input signal provided to a part of said primary winding of said first transformer located between said center terminal and said second terminal so that said rectified and smoothed input signal is made to be of a high frequency, whereby inductor influenced input signal of an ordinary frequency and inductor influenced input signal of a higher frequency are concurrently supplied to said primary winding of said first transformer to cause output signal to be generated in said secondary winding of said first transformer which is substantially free of harmonic current, and whereby power factor of said apparatus is increased.