Lucent Technologies Inc.

Netpower Technologies, Inc.

Other

Virginia Tech Intellectual Properties Inc

Center for Innovative Technology

Virginia Polytechnic Institute and State University

Yimin Jiang

Hengchun Mao

Mark E Jacobs

Vijayan J Thottuvelil

Rui Liu

Feng Lin

Ning Sun

Fred C Lee

Jin He

Greg H Fasullo

Marco A Davila

Vijayin Joseph Thottuvelil

Circuit and method for controlling circuitry in a power converter device during a soft-start process is provided. Synchronous rectifier control circuitry is adapted to gradually apply a gate drive signal derived from the main switch of the power converter device to a freewheeling synchronous rectifier of the switching circuitry during the soft-start process. The control circuitry gradually releases the amplitude or the pulse-width of the gate drive signal to the freewheeling synchronous rectifier to avoid a large duty ratio in the synchronous rectifier during start-up so that a negative current does not build up in the output inductor.

Soft start for a synchronous rectifier in a power converter

A power converter device using synchronous rectifiers and method for controlling operation thereof are provided. A first synchronous rectifier is coupled to the secondary transformer winding to pass a voltage induced at the secondary winding in response to an input voltage supplied to the primary transformer winding during an on-state of a main power switch. A first drive circuit is coupled to the gate terminal of the first synchronous rectifier to selectively activate and deactivate the first rectifier in correspondence with the respective on and off states of the main power switch based on a gate voltage supplied by the first drive circuit, with at least one circuit parameter being selected in the first drive circuit for maintaining the gate voltage within a predefined range regardless of variation in the level of the input voltage.

Power converter including circuits for improved operational control of synchronous rectifiers therein

A power distribution system is provided including current sharing circuitry, current sensing and over-current protection. The system includes a plurality of power converter modules each having a current sharing signal terminal on an input side and power output terminals on an output side, the corresponding power output terminals of the several modules being connected together and adapted to power a common load; an interconnecting signal bus coupled across the current sharing signal terminals on the input side; a plurality of feedback circuits, each of which is associated with one of said modules, each feedback circuit including a comparator (error amplifier) for comparing a feedback voltage on the output side with a reference voltage to provide an error signal to the input side; the error signal conditioned to provide a current command signal to said signal bus, wherein the signal bus provides a common current command signal to drive the power converter modules.

Plural power converters with individual conditioned error signals shared on a current sharing bus

An energy recovery snubber circuit for a bidirectional power converter, a method of operation thereof and a power plant employing the bidirectional power converter. The bidirectional power converter has first and second inputs, an inductor coupled to the first input and a power switch coupled between the inductor and the second input. In one embodiment, the energy recovery snubber circuit includes: (1) a clamping capacitor coupled to the second input; (2) a clamping diode coupled between the clamping capacitor and the first input; and (3) a snubber inductor coupled to a node between the clamping capacitor and the clamping diode.

Energy recovery snubber circuit for bidirectional power converter and method of operation thereof

Circuit and method for reducing voltage level variation in a bias voltage generated in a power converter device are provided. The method allows providing a first voltage source configured to supply a first voltage during one respective mode of operation of the power converter, wherein the level of the voltage supplied by the first voltage source is directly proportional to variation in an input voltage of the converter device. The method further allows providing a second voltage source configured to supply a second voltage during another respective mode of operation of the power converter, wherein the level of the voltage supplied by the second voltage source has a generally inverse proportional relationship relative to variation in the input voltage of the converter device. At least one circuit parameter is selected in the voltage sources to adjust the respective levels of the first and second voltages. The first and second voltages are combined with one another to generate a combined voltage that comprises the bias voltage in the power converter device, the combined voltage resulting in a bias voltage level being relatively impervious to variation in the input voltage of the converter device.

Method and circuit for reducing voltage level variation in a bias voltage in a power converter

A regulation circuit for a voltage-fed power converter, a method of operation thereof and a power converter employing the circuit or the method. The power converter has an inverter switch adapted to transfer power to a transformer. In one embodiment, the regulation circuit includes a switching network coupled to a tapped winding of the transformer. The switching network is operable to vary a turns ratio of the transformer, thereby regulating an output voltage of the power converter.

Regulation circuit for a power converter and method of operation thereof

A regulation circuit for a current-fed power converter having a power switch adapted to transfer power to a transformer. In one embodiment, the regulation circuit includes a switching network coupled to a tapped winding of the transformer and operable to vary a turns ratio of the transformer thereby regulating an output voltage of the power converter.

Current-fed dc/dc converter with multilevel transformer and method of operation thereof

A circuit for, and method of, reducing a preload current required to maintain a duty cycle of an asymmetrical DC/DC converter and a DC/DC converter incorporating the circuit or the method. In one embodiment, the circuit includes an auxiliary inductor, coupled in series with an output capacitor of the converter in an output current doubler thereof, that reduces ripple current in the output current doubler and thereby maintains the duty cycle.

Asymmetrical DC/DC converter having output current doubler

For use with a flyback converter having a modulator for providing a main switch control signal thereto and main and cross-regulated output circuits, the cross-regulated output circuit subject to ringing and resulting voltage excursion, a voltage excursion controller and a method of operating the same. In one embodiment, the controller includes: (1) a delay circuit, coupled to the modulator, that generates a delay signal based on the main switch control signal and (2) an auxiliary switch, associated with the cross-regulated output circuit, that receives the delay signal and opens to isolate at least a portion of the ringing within said cross-regulated output circuit.

Multiple output flyback converter having improved cross-regulation and

For use with a power converter having a power supply control circuit, a current startup bias circuit and a method of operating the same. In one embodiment, the circuit includes: (1) a charge reservoir that receives and stores a trickle current during a startup period of the power converter, a voltage of the charge reservoir increasing as the charge reservoir stores the trickle current and (2) a latch, coupled to the charge reservoir, that activates when the voltage reaches a threshold to couple the charge reservoir to the power supply control circuit and initiate operation thereof.

Low trickle current startup bias circuit and method of operation thereof

For use with a boost converter having a boost inductor couplable to a source of electrical power, a rectifier coupled to the boost inductor and a boost switch coupled across the rectifier, the boost converter operable in discontinuous mode, a circuit for, and method of, providing a reduced output voltage from the boost converter. In one embodiment, the circuit includes an autotransformer, coupled across an output of the boost converter, having an intermediate tap that provides a reduced output voltage at the output.

Boost converter having reduced output voltage and method of operation

An active circuit for delivering three phase AC input power received from a three phase rectifier to a boost converter and a method of operating the same. In one embodiment, the active circuit includes a phase selection switching circuit, coupled to the rectifier, that selects an inner phase of the three phase AC input power. The active circuit also includes a switching network, coupled to the phase selection switching circuit and the rectifier, that controls a current waveshape of the inner phase and a current waveshape of at least one other phase, thereby to reduce harmonics associated with three phase AC input current.

Phase selection circuit for three phase power converter and method of

For use in a boost converter having a boost inductor coupled between an input and an output of the boost converter and an output capacitor coupled between rails of the output, an energy storage circuit for, and method of, extending a holdup time of the boost converter. In one embodiment, the energy storage circuit includes: (1) a holdup capacitor coupled to a first rail of the input, (2) a holdup switch, coupled to a second rail of the input and the holdup capacitor, capable of closing during a holdup mode to allow the holdup capacitor to discharge current into the input and (3) a voltage stabilizing circuit, coupled between the holdup capacitor and the output capacitor, that: (3a) when the boost converter is in a normal mode, provides a substantially impeded path for charge current to flow from the output capacitor to charge the holdup capacitor, and (3b) when the boost converter is in an initial phase of the holdup mode, provides a substantially unimpeded path for holdup current to flow from the holdup capacitor to the output capacitor prior to the closing of the holdup switch.

Boost converter having extended holdup time and method of operation

A power supply and method of operation thereof. In one embodiment, the power supply includes: (1) a primary side power switch, (2) an isolation transformer having a primary winding coupled to the primary side power switch, the primary side power switch conducting intermittently to transfer current from an input of the power supply to the isolation transformer, (3) a secondary side power switch, coupled to a secondary winding of the isolation transformer, that is operable to conduct within a conduction period of the primary side power switch to transfer current from the isolation transformer to an output of the power supply, a portion of the current being contained within the power supply during a nonconduction period of the secondary side power switch and (4) a capacitor, coupled to the secondary side power switch, that, circulates the portion toward the output during the nonconduction period.

Power supply employing circulating capacitor and method of operation

For use with a boost converter having first, second and third input inductors, a switching network, method of reducing input current total harmonic distortion (THD) associated with the boost converter, and boost converter employing the switching network and method. In one embodiment, the switching network includes first and second switches coupled between corresponding rails of the boost converter. The switching network also includes first, second and third L-C resonant networks wye-coupled to a node located between the first and second switches and coupled to the first, second and third input inductors, respectively. The first and second switches and the first, second and third L-C resonant networks cooperate to create resonant voltages across, and induce phase currents through, the first, second and third input inductors to reduce input current THD associated with the boost converter.

Growing community of inventors

Plano, TX, United States of America

Yimin Jiang