Patent ID: 6396719
Filing Date: 2002-05-28
Classification: H02M,Y02B

Abstract:
A d.c.-to-d.c. converter to be connected between a d.c. power supply and a load, comprising:(a) a pair of input terminals to be connected to a d.c. power supply; (b) a transformer having a primary winding, a secondary winding, a tertiary winding, and a quaternary winding which are all electromagnetically coupled together, the primary winding having one extremity thereof connected to one of the pair of input terminals; (c) a pair of output terminals to be connected to a load; (d) a rectifying and smoothing circuit connected between the secondary winding of the transformer and the pair of output terminals; (e) a first switch connected between the other extremity of the primary winding of the transformer and the other of the pair of input terminals; (f) resonant capacitance means connected in parallel with the first switch; (g) resonant inductance means; (h) a first diode; (i) a second switch, the tertiary winding and quaternary winding of the transformer and the resonant inductance means and the first diode and the second switch being all connected in series with one another and in parallel with the serial connection of the primary winding of the transformer and the first switch, the first diode being so oriented as to be forward-biased by a supply voltage to be applied from the pair of input terminals; (j) a second diode connected in parallel with the serial connection of the quaternary winding of the transformer and the resonant inductance means and the first diode and the second switch, the second diode being so oriented as to be reverse-biased by the supply voltage to be applied from the pair of input terminals; and (k) a switch control circuit connected to the first and the second switch for making on-off control of the first and the second switch, the switch control circuit including means for turning on the second switch at a first moment that is earlier than a starting moment of each conducting period of the first switch and turning off the second switch at a second moment that is equal to or earlier than an ending moment of each conducting period of the first switch.