Patent ID: 7142438

Claim:
A dual forward converter which comprises: four transistor switch means in two pairs; each pair is turned on for half the total switching period to impress a buck converter controlled voltage across on one primary winding of the main power transformer; said transistors in each pair are turned on simultaneously for half the switching cycle, then the transistors of the second pair are turned on simultaneously for the second half of the switching cycle; each pair of switching transistor means has a separate primary winding on the main transformer arranged in opposite polarity so as to act as a full bridge topology without the reliability issues associated with having two pairs of transistors in series across the main DC supply rails, specifically with a transformer winding between the top and bottom transistor in each pair; said action of one transistor pair turning off places a near zero voltage across the second pair by transformer action, meaning that each pair turns on in a zero voltage mode which reduces losses and high frequency switching noise; power isolation transformer means has a secondary winding to deliver output power via a current doubler circuit, thus eliminating the need for a center tapped winding, and reduces the ripple current in the secondary filter circuit.