Abstract: A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters in a full-bridge topology. The invention takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side. The invention further discloses means to use one drive transformer winding to control two switches completely out of phase.

Abstract: The invention employs a coreless isolated transformer, with associated electronic circuitry, for providing an initial bias and enable signal for control and drive circuitry that is referenced to the output of a converter. The improvement is accomplished by embedding the transformer primary and secondary windings into a multi-layer PCB so that the transformer does not occupy space on the top and bottom surfaces of the PCB The initial bias voltage is used to initialize operation of the control circuit when referenced to the output side of the converter. Thus, complete regulation and drive signals are generated on the output side.

Abstract: A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters in a full-bridge topology. The invention takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side. The invention further discloses means to use one drive transformer winding to control two switches completely out of phase.

Abstract: A bias circuit with a coreless transformer to provide isolated initial bias and enable signal for a switch-mode power converter with the control circuit located on the output side. A coreless transformer is used for initializing operation of the control circuit, because of its simplicity and low profile on a printed circuit board due to lack of a magnetic core. Exemplary embodiments are further disclosed that provide a means to enable or disable the power converter using input signals from the input side, such as an ON/OFF feature, as well as from input signals from the output side, such as secondary protection logic.

Abstract: A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters in a full-bridge topology. The invention takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side. The invention further discloses means to use one drive transformer winding to control two switches completely out of phase.

Abstract: An ac-to-dc switching full-bridge converter employing voltage bidirectional switches as controllable series input switches, preferably implemented with magnetic amplifiers, that couple ac rectifiers to a single-stage full-bridge dc-to-dc converter in order to provide unity power factor operation by control of input current using a fast current loop to modulate the duty ratio d1 of the voltage bidirectional amplifier switches while independent output voltage regulation is maintained by voltage feedback to the full-bridge converter switches through modulation of the switch duty ratio d of the converter (where d1<d) using an independent fast output regulation loop.

Abstract: Ac-to-dc switching converters employ bidirectional voltage switches, preferably magnetic amplifiers in series with a fast recovery diode, as controllable series input switches that couple ac rectifiers to single-stage dc-to-dc converters in order to provide unity power factor operation by control of current through the input inductor achieved by modulating the duty ratio d1 of the bidirectional voltage switch while independent regulation of load voltage is maintained by voltage feedback to modulate the switch duty ratio d of the converter (where d1<d) in an independent fast output regulation loop.

Abstract: A soft-switching dc-to-dc converter for providing regulated voltage to a load combines the functions of loss-less soft switching at zero voltage and at a constant switching frequency on the primary side and soft switching at zero current on the secondary side of an isolation transformer for all load currents from full load to no-load and PWM output voltage regulation on the secondary side. This is made possible by using voltage bidirectional switching element in series with a low-pass filter on the secondary side and current bidirectional switching element on the primary side driven at close to 50% duty ratio with adjustable dead time between switching. The adjustable dead-time is realized by sensing voltages across paired primary side current bidirectional switching element in order to enable alternate turn ON of said pair only at zero voltage, thereby eliminating or greatly reducing switching losses under all load current conditions.