Patent ID: 8027174

Claim:
An adapter power supply, comprising: an AC/DC converter for converting an AC power into a DC power; a DC/DC converter including a transformer having a primary terminal and a secondary terminal for converting a link voltage of the DC power into an output power; and a controller for estimating a load current of the output power through a primary current of the transformer and varying the link voltage of the DC power according to variation of the estimated load current, wherein the controller includes: a first coupler for outputting a difference between an output voltage of the output power and a reference output voltage; a gain controller connected to the first coupler; an Opto coupler connected to the gain controller; a current sensor for sensing the primary current; a variation controller connected to the current sensor for outputting an output voltage control signal and a link voltage control signal; a second coupler for coupling a control signal passing the Opto coupler with the output voltage control signal; an integral controller connected to the second coupler; a frequency modulator connected to the integral controller for controlling switching of the DC/DC converter; a third coupler for coupling the link voltage control signal with a difference between the link voltage of the DC power and a reference link voltage; a gain/integral controller connected to the third coupler; and a pulse width modulator connected to the gain/integral controller for controlling switching of the AC/DC converter.