Lucent Technologies Inc.

Valery I Meleshin

Simon Fraidlin

Rais K Miftakhutdinov

Alexey V Nemchinov

Sergey M Korotkov

Victor Yakushev

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 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.

Single stage power converter and method of operation thereof

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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Moscow, Russia

Valery I Meleshin