Patent ID: 7046525

Claim:
A method of operating a bidirectional flyback switch mode power supply (SMPS), comprising the steps of: (1) closing a primary switch when the voltage across the primary switch is substantially in a valley less than zero, thereby ramping up current in a first direction through a primary winding of a transformer at the primary side of the converter; (2) opening a primary switch which is in series with said primary winding, thereby driving current through a secondary winding of said transformer at a secondary side of the converter which is inductively coupled to said primary winding; (3) controlling a secondary switch which is in series with said secondary winding, to permit said secondary winding to pass current in a first direction, and, subsequently, to permit said current to pass through said secondary winding in a second direction which is opposite to said first direction, so as to drive current through said primary winding in a second direction which is opposite to said first direction; wherein the secondary switch is further controlled in order to provide a controlled output power on the secondary side; and wherein the primary switch is further controlled in order to compensate input voltage variations.