Lucent Technologies Inc.

Ericsson Gmbh

Synqor, Inc.

At+t Corp.

At&t Bell Laboratories

At&t Ipm Corp.

Richard W Farrington

Mark E Jacobs

William Hart

Martin F Schlecht

Vijayan J Thottuvelil

William P Gardiner

Hengchun Mao

Rui Liu

Jun Zhang

Claes Svardsjo

William P Wilkinson

Abram P Dancy

Leif E LaWhite

Robert J Murphy, Jr

A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.

Intermediate bus architecture with a quasi-regulated bus converter

In a power converter, the duty cycle of a primary winding circuit causes near continuous flow of power through the primary and secondary winding circuits during normal operation. By providing no regulation during normal operation, a very efficient circuit is obtained with a synchronous rectifier in the secondary operating at all times. However, during certain conditions such as start up or a short-circuit, the duty cycle of the primary may be reduced to cause freewheeling periods. A normally non-regulating isolation stage may be followed by plural non-isolating regulation stages. To simplify the gate drive, the synchronous rectifiers may be allowed to turn off for a portion of the cycle when the duty cycle is reduced. A filter inductance of the secondary winding circuit is sufficient to minimize ripple during normal operation, but allows large ripple when the duty cycle is reduced. By accepting large ripple during other than normal operation, a smaller filter inductance can be used.

Power converter with isolated and regulated stages

In a power converter, the duty cycle of a primary winding circuit causes near continuous flow of power through the primary and secondary winding circuits during normal operation. By providing no regulation during normal operation, a very efficient circuit is obtained with a synchronous rectifier in the secondary operating at all times. However, during certain conditions such as start up or a short-circuit, the duty cycle of the primary may be reduced to cause freewheeling periods. To simplify the gate drive, the synchronous rectifiers may be allowed to turn off during the freewheeling periods, resulting in large ripple. A filter inductance of the secondary winding circuit reduces that ripple, and is sufficient to minimize ripple during normal operation, but still allows large ripple during the freewheeling periods. By accepting large ripple during other than normal operation, a smaller filter inductance can be used.

Power converter with output inductance

Half-bridge isolation stage topologies are provided in power converters, dividing an input voltage between capacitors. Primary transformer windings are periodically switched across respective capacitors. In current-fed implementations, the current flow through the primary windings is constrained as by an inductive element. In some implementations, a capacitor, primary winding and switch are connected in series in different orders in each of plural legs across the input. Current feed circuitry includes a current constraining component connecting nodes within each of respective legs. The switches of the isolation stage may be turned on with a fixed duty cycle, and a secondary circuit may comprise synchronous rectifiers.

Half-bridge isolation stage topologies

The present invention provides a method for preventing a fault condition in a DC-DC converter ( ) having a first secondary winding (Ns ) coupled to a first synchronous rectifier (SQ ) and a second secondary winding (Ns ) coupled to a second synchronous rectifier (SQ ). The first synchronous rectifier (SQ ) is turned on based on a voltage across the first secondary winding (Ns ) and is turned off based on a first driver signal. The second synchronous rectifier (SQ ) is turned on based on a voltage across the second secondary winding (Ns ) and is turned off based on a second driver signal. The present invention also provides a DC-DC converter ( ) wherein a first control circuit is coupled to and controls the first synchronous rectifier (SQ ) pursuant to the method described above, and a second control circuit is coupled to and controls the second synchronous rectifier (SQ ) pursuant to the method described above.

Method of connecting synchronous rectifier modules in parallel without output voltage faults

An inductor configuration (,) comprising a three-legged inductor core (,) with a first leg (,), second leg (,), and third leg (,) integrally extending from a base (,). The first leg (,) and second leg (,) are predisposed and spaced about a first surface (,) of the base (,) to form a first channel area (,). The second leg (,) also forms, along with the third leg (,), a second channel area (,) separated from the first channel area (,) by the second leg (,). The inductor also comprises an inductor winding (,) arranged about the inductor core (,) to provide relatively equal magnetic flux through the first leg (,), second leg (,), and third leg (,) when current flows through the inductor winding (,). The inductor configuration may be used as an input or output inductor for a synchronous rectifier circuit (,).

Split inductor with fractional turn of each winding and PCB including same

A self-driven synchronous rectifier circuit having synchronous rectifiers with floating gates for a power converter or signal transformer. The circuit comprises a transformer (,) having a secondary winding with a first and second terminal, a first synchronous rectifier (SQ,) coupled to the first transformer secondary winding first terminal and having a control terminal floating relative to ground and a first drive circuit coupled to the first synchronous rectifier floating control terminal and controlling the first synchronous rectifier. A first control signal is coupled to the first drive circuit, where the first control signal controls the first drive circuit as a function of a polarity reversal of a voltage across the first transformer (,). A second synchronous rectifier (SQ,) is coupled to the first transformer secondary winding second terminal and has a control terminal floating relative to ground. A second drive circuit is coupled to the second synchronous rectifier floating control terminal and controls the second synchronous rectifier. A second control signal is coupled to the second drive circuit, where the second control signal controls the second drive circuit as a function of a polarity reversal of a voltage across the first transformer (,).

General self-driven synchronous rectification scheme for synchronous rectifiers having a floating gate

A current sharing circuit scheme comprising first and second power modules (,) each including an input side (,) and an output side (,), the power modules (,) coupled to each other via respective input sides (,), each of the output sides (,) including a positive terminal and a negative terminal. The circuit scheme also comprises first and second circuit output voltage terminals (,) and first and second set point controls (,) coupled to the negative terminal of each of the output sides (,). First and second initial set point controls (,) are included providing current signal paths between corresponding first and second set point controls (,) and the first output voltage terminal (,). The first and second set point controls (,) and the first and second initial set point controls (,) are configured to allow current sharing through said first and second circuit output voltage terminals (,) when a current signal is applied to said input side (,) of said first and second power modules(,).

Simplified current share circuit

An asymmetrical half-bridge power converter and a method of manufacturing the same. In one embodiment, the asymmetrical half-bridge power converter includes: (1) first and second power switches configured to be controlled by complementary drive signals having nominal first and second duty cycles of D and 1-D, respectively and (2) first and second capacitors, having intrinsic capacitance values proportional to 1-D and D, respectively, and intrinsic equivalent series resistance (ESR) values proportional to D and 1-D, respectively, configured to reduce input ripple current associated with the asymmetrical half-bridge power converter.

Asymmetrical half-bridge power converter having reduced input ripple and method of manufacturing the same

A self-driven synchronous rectifier circuit (,) for a DC&mdash;DC power converter. The circuit comprises a primary transformer (,), a first synchronous rectifier (SQ,) coupled to the primary transformer (,), a second synchronous rectifier (SQ,) coupled to the primary transformer (,), an external drive circuit (,). The circuit (,) also comprises a plurality of switches (SQ,, SQ,) controllably coupled to second synchronous rectifier (SQ,). The external drive circuit (,) provides turn-off signaling for both synchronous rectifiers (SQ,, SQ,) Turn-on signaling provided for first synchronous rectifier (SQ,) by the primary transformer (,) turn-on signaling for second synchronous rectifier (SQ,) is provided by the external drive circuit (,).

Externally-driven scheme for synchronous rectification

An externally-driven synchronous rectifier circuit (,) comprises first and second synchronous rectifiers (SQ,, SQ,), and first and second synchronous rectifier recovery switches (SQ,, SQ,), and a pair of resonant inductors (LR,LR,). The resonant inductors (LR,LR,) store the energy normally loss during charging and discharging the input capacitance of the first and second synchronous rectifiers (SQ,SQ,). The recovery switches (SQ,SQ,) transfer the stored energy from the at least one inductor (L,) to the output terminal (Vout) creating a more energy efficient circuit (,).

Resonant gate drive for synchronous rectifiers

A push-pull converter for converting an input voltage to a selectable output voltage is disclosed. The push-pull converter includes a pair of primary switches and a pair of primary windings of a transformer. The voltage stress across the primary switches is regulated by means of a clamp capacitor. The clamp capacitor clamps the voltage of the primary switches during the reset of the primary windings of the transformer. An alternate embodiment is also disclosed in which the voltage stress across the primary switches is regulated by means of two clamp capacitors. The clamp capacitor clamps the voltage of the primary switches during the reset of the primary windings of the transformer. The clamp capacitors extend the transformer reset period to include the lagging dead time for the corresponding switches, as well as the complementary powering stage. Current in the output section during the dead times is permitted by means of an additional diode, therein.

Push-pull power converter circuit

In a power converter having a power switch, a rectifier and a snubber circuit having an auxiliary switch that moderates reverse recovery currents associated with the rectifier, a driver for the auxiliary switch, a method of driving the auxiliary switch and a power converter employing the driver and method. In one embodiment, the driver includes a first driver switch, coupled between the power switch and the auxiliary switch, that allows the auxiliary switch to turn on concurrently with the power switch. The driver also includes a second driver switch, coupled between the auxiliary switch and an output of the power converter, that prevents a voltage of the auxiliary switch from rising above an output voltage of the power converter to assist the auxiliary switch in turning off.

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Heath, TX, United States of America

Richard W Farrington