Lucent Technologies Inc.

Other

At&t Bell Laboratories

Tyco Electronics Logistics Ag

Simon Fraidlin

Anatoliy Polikarpov

Valery I Meleshin

Rais K Miftakhutdinov

Andrey Frolov

Alexey V Nemchinov

Sergey M Korotkov

Mark E Jacobs

Allen Frank Rozman

Vijayan J Thottuvelil

James C Wadlington

William F Slack

Sergey Louzanov

Nickolay A Snetkov

Anatoly G Polikarpov

Victor Yakushev

An impedance network for passive shoot-through protection of active switches in clamp-mode topologies. In one exemplary embodiment a switch-mode converter, includes: a primary switch; an auxiliary switch coupled in series with a capacitor; and an impedance network, coupled to the primary switch and the auxiliary switch; configured to limit current during simultaneous conduction of the primary and auxiliary switches. The impedance network includes a resistor coupled in series to a diode and both in parallel with an inductor. The impedance network permits the design of a clamp-mode converter without the need for a delay between switch turn-off and turn-on of primary and auxiliary switches.

Protection circuit for active switches in clamp-mode topologies, and power converter employing the same

A switching circuit, a method of processing power and a single stage power factor corrector employing the switching circuit or the method. In one embodiment, the switching circuit includes: (1) a power switch coupled to a primary winding of a transformer; and (2) an active clamp coupled to the power switch. The active clamp includes: (2,) series-coupled first and second capacitors, coupled across the power switch and the primary winding, having opposing polarities thereacross, and (2,) a clamping switch coupled to a node between the series-coupled first and second capacitors. The clamping switch opens to allow energy stored in the first capacitor to be transferred to an output of the power converter via the second capacitor. The clamping switch further closes to allow energy stored in the second capacitor to be transferred to the output.

Switching circuit, method of operation thereof and single stage power factor corrector employing the same

A controller or a method for regulating a non-isolated power factor corrector and a power factor corrector employing the controller or the method. The power factor corrector is adapted to provide a DC output voltage at an output thereof. The power factor corrector has first and second power switches, coupled to an input thereof, that receive unrectified AC power. In one embodiment, the controller includes: (1) a sensor, coupled proximate the input, that senses a polarity of the unrectified AC power and (2) a drive circuit, coupled to the sensor, that: (2a) closes the first power switch and modulates the second power switch to regulate the DC output voltage when the polarity is negative, and (2b) closes the second power switch and modulates the first power switch to continue to regulate the DC output voltage when the polarity is positive.

Controller for a non-isolated power factor corrector and method of regulating the power factor corrector

An AC active clamp, a method of operating the same and a power factor corrector employing the AC active clamp or the method. The power factor corrector has a primary switching circuit coupled to a primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. The primary switching circuit has first and second power switches configured to receive unrectified AC power. In one embodiment, the AC active clamp includes a switching circuit having first and second clamping switches series coupled in opposition and a capacitor coupled to the switching circuit. The switching circuit and the capacitor are coupled across at least a portion of the primary winding and are configured to mitigate adverse effects of a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of the first and second power switches of the primary switching circuit.

AC active clamp for isolated power factor corrector and method of operating the same

For use with a power converter couplable to a source of electrical energy, the converter having a power switch that conducts intermittently to transfer energy from the source to an inductive element, and a freewheeling diode that alternately conducts with the power switch to transfer energy to an output of the converter, an active clamp and a method of operating the active clamp. In one embodiment, the active clamp includes: (1) an inductor, coupled in series with the freewheeling diode, and (2) a series-coupled capacitor and clamping switch, coupled in parallel with the inductor, that cooperate therewith to mitigate adverse effects of reverse recovery currents associated with the freewheeling diode and enable substantially zero voltage switching of the power and clamping switches.

Active clamp for power converter and method of operation thereof

A circuit associated with a power converter, a method of operation thereof and a power converter employing the circuit or the method. The power converter has a primary switching circuit coupled to a tapped primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. The circuit is coupled across a tapped portion of the tapped primary winding. In one embodiment, the circuit includes: (1) an inductor, configured to reduce current spikes in the primary switching circuit caused by a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of a power switch of the primary switching circuit; and (2) a diode, coupled to the inductor via the tapped portion, configured to clamp a voltage across the rectifier. The tapped portion is configured to enable energy from the inductor to be recovered within the power converter.

Circuit associated with a power converter and method of operation thereof

A boost converter, a method of converting power and a power supply incorporating the boost converter or the method. In one embodiment, the boost converter has an input couplable to a source of electrical power and includes: (1) a boost inductor coupled to the input and adapted to conduct currents bidirectionally, (2) a first controllable switch coupled to the boost inductor, (3) a second controllable switch coupled to a node between the first controllable switch and the boost inductor and (4) a controller, coupled to the first and second controllable switches, that closes the first controllable switch to provide a charging conductive path across the input to charge the boost inductor and alternately closes the second controllable switch to provide: (4,) a forward conductive path from the boost inductor to an output of the boost converter when a voltage at the node exceeds a voltage at the output to provide power to the output and (4,) a reverse conductive path from the output to the boost inductor when the voltage at the output exceeds the voltage at the node to decrease the voltage at the node and thereby decrease a switching voltage of the first controllable switch.

Boost converter, method of converting power and power supply employing the same

A secondary active clamp for a power converter, a method of actively clamping energy of the power converter and a power converter employing the clamp or the method. The power converter has a primary switching circuit coupled to a primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. In one embodiment, the clamp includes (1) an inductor coupled in series with a freewheeling diode of the rectifier and (2) a series-coupled capacitor and clamping switch coupled in parallel with the inductor. The series-coupled capacitor and clamping switch cooperate with the inductor to mitigate adverse effects of a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of a power switch of the primary switching circuit.

Active clamp for isolated power converter and method of operating thereof

A single stage power converter, a method of processing rectified AC power, and a power supply incorporating the converter or the method. In one embodiment, the converter is couplable via a rectifier to a source of AC power, has a filter capacitor and an isolation transformer with a primary winding, and includes: (1) a significant energy storage device coupled to the primary winding, (2) a first switch, coupled to the primary winding, that conducts intermittently to couple the primary winding to the rectifier to transfer a portion of rectified AC power to a magnetizing inductance of the isolation transformer and (3) a second switch, coupled between the primary winding and the significant energy storage device, that conducts alternately with the first switch, the first and second switches substantially zero-voltage switching and the converter correcting a power factor of the AC power.

Single stage power converter and method of operation thereof

The present invention relates to a power converter which uses pulse width modulated (PWM) control to provide a galvanically isolated dc output. Topologically, the converter uses a full-bridge switching scheme with a boost converter, and can be referred to as an isolated boost converter. The converter includes an ancillary circuit comprised of a switch transistor and a series connected capacitor which act as an active clamp. The converter of the present invention allows for a number of significant advantages. The converter provides zero voltage transitions in all switches, thereby preventing losses due to leakage currents in the switching transistors during switching transitions. The converter further provides a path for transformer magnetizing current flow, and also clamps the leakage inductance related to voltage spikes across the switches. These advantages allow the converter to keep stress on the active components low which makes the circuit more efficient. The circuit of the present invention has a simple structure which gives it good power density and makes it inexpensive, and is also capable of high frequency operation.

Full-bridge isolated Current Fed converter with active clamp

An isolated flyback secondary inductor converter (IFSIC) and method of operation thereof. The IFSIC has a transformer with a primary winding for receiving electrical energy from a source of electrical power and a secondary winding coupled to the primary winding. The IFSIC also has a switch for intermittently coupling the transformer to the source of electrical power. The IFSIC includes a series-coupled inductor and diode coupled in parallel with the secondary winding to provide a path for the energy from the transformer when the transistor is ON, allowing the energy to be stored in the inductor rather than in the transformer.

Isolated flyback secondary inductor convertor

An asymmetrical power converter and a method of operation thereof. According to a first aspect of the present invention, the asymmetrical converter includes (1) first and second transformers having serially-coupled primary windings and differing turns ratios; (2) a first power switch coupled to a first end of the serially-coupled primary windings; (3) a second power switch coupled to a node between the serially-coupled primary windings and (4) a capacitive element coupled to a second end of the serially-coupled primary windings to maintain a volts-second balance thereacross during alternate switching cycles of the first and second power switches. According to a second aspect of the present invention, the asymmetrical converter includes (1) first and second transformers having serially-coupled primary windings and differing turns ratios; (2) a first power switch coupled to a first end of the serially-coupled primary windings; (3) a second power switch coupled to a second end of the serially-coupled primary windings and (4) a capacitive element coupled to a node between the serially-coupled primary windings to maintain a volts-second balance thereacross during alternate switching cycles of the first and second power switches.

Asymmetrical power converter and method of operation thereof

A single stage power converter has an energy storage device and is configured to receive electrical power. The single stage power converter includes: (1) an inductor, coupled to the energy storage device, for affecting a voltage across the energy storage device, (2) an asymmetrical half-bridge power circuit coupled to the energy storage device and having first and second power switches capable of being alternately activated to conduct current from the energy storage device to an output thereof and (3) a controller for controlling activation of the first and second power switches as a function of a characteristic of the output thereby to enhance a regulation of the output.

A voltage stress (e.g., reverse voltage stress) in rectifying diodes of, for instance, an asymmetrical DC-to-DC converter is reduced by using a transformer circuit having multiple power transformers with a composite static transfer characteristic. More specifically, the static transfer characteristic is selected to be monotonic in combination with the transformer circuit including two transformers, having independent isolated cores, coupling an input to output of the converter. A primary to secondary winding ratio of each of the two transformers is selected in such a way as to achieve a reduction in reverse voltage in at least one of the rectifying diodes. The reduction in the reverse voltage and, hence, improved efficiency of the rectifier is directly translatable into an increase in a power density of the converter.

Reduced voltage stress asymmetrical DC-to-DC converter using first and

An integrated power converter and a method of operation thereof. The integrated power converter, having an energy storage device, includes: (1) a conditioning circuit coupled to the energy storage device and having a control switch for affecting a voltage across the energy storage device, (2) an asymmetrical half-bridge power circuit coupled to the energy storage device and having first and second power switches capable of being alternately activated to conduct current from the energy storage device to an output thereof and (3) a controller for controlling activation of both the control switch and the first and second power switches as a function of a characteristic of the output thereby to enhance a regulation of the output.

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Plano, TX, United States of America

Simon Fraidlin