The present invention discloses a synchronous rectification control circuit, comprising at least one switch unit, a pulse width control unit, a transformer, a first rectification unit, a second rectification unit, a plurality of driving units, a logic operation unit and a signal transmission unit. The logic operation unit is used for receiving a working cycle signal generated by the pulse width control unit. When the working cycle signal is changed, the signal transmission unit transmits a switching signal for changing the working conditions of the first and second rectification units at a secondary side of the transformer, so as to switch the first and second rectification units before the switch unit operates and prevent possible short circuits or overlaps.

A DC/DC converter includes an input filter, a half-bridge converter without PWM (Pulse Width Modulation) control function, a synchronous rectifier, an output capacitor, and a DC transformer. The DC transformer includes a magnetic core, a primary winding, a first secondary winding, and a second secondary winding. The magnetic core of the DC transformer includes a first leg, a second leg having a first air gap, and a third leg having a second air gap. The first secondary winding is wound on the first leg and the second leg, and induces a first inductance by the first air gap. The second secondary winding is wound on the first leg and the third leg, and induces a second inductance by the second air gap.

To demagnetize a transformer (TR) in a single-ended forward DC/DC converter with self-driven synchronized rectifiers (V1, V2) connected across the secondary winding (N2) of the transformer (TR), a diode (D1) is connected in series with a capacitor (C1) across the primary winding (N1) of the transformer. The diode (D1) transfers magnetization energy stored in the transformer to the capacitor (C1) every time a primary switch (V3) of the converter is turned off. To ensure optimum efficiency of the synchronized rectifiers, a discharging circuit is connected to the capacitor (C1) for discharging the magnetization energy stored therein by drawing a DC current (I) from the capacitor (C1) in response to varying input DC voltage such that complete demagnetization of the transformer (TR) always is attained just before turn-on of the primary switch (V3).

A power converter includes an input circuit that receives DC input power and creates high frequency pulses. A transformer transforms the high frequency pulses into at least two sets of transformed pulses having alternating and opposite polarity. An output circuit connected to the transformer includes a plurality of switches for blocking undesired pulses. A controller controls the switches so that they are on except when blocking undesired pulses, so that a continuous current path is provided through the output circuit.

There is disclosed a core structure with a very low profile, high power density and lower losses. The disclosed design allows for a larger core area where the DC fluxes are added, thereby reducing the air-gap requirements in the cores derived from low saturation density materials such as ferrites. The cellular nature of the design can be effectively employed in vertically packaged power converters and modules. Also disclosed is a DC-DC converter topology which preferably employs the disclosed core. N AC drive voltages drive N current doubler rectifiers (CDRs) in accordance with the symmetric modulation scheme; each CDR provides two rectified output currents to an output node. Each AC drive voltage has a switching period T.sub.s. The drive voltages are phase-shifted by T.sub.s/(2*N), such that the rectified output currents of the CDRs are interleaved, thereby reducing output voltage ripple.