General Electric Company

Khai D Ngo

Alexander J Yerman

Robert Louis Steigerwald

Richard J Charles

Bantval J Baliga

William Anders Peterson

Charles S Korman

Hsueh-Rong Chang

John P Walden

A high-frequency transformer is constructed from a flexible circuit comprising a primary conductive film winding and one or more secondary conductive film windings disposed on a single dielectric membrane. The flexible circuit is folded to form a stack of primary winding layers interleaved with secondary winding layers and then inserted into a mangetic cup core. The flexible circuit is preferably patterned photolithographically.

Method of fabricating a high-frequency transformer

A conductive film magnetic component such as an inductor or transformer includes a conductive film winding having a generally serpentine configuration when disposed in a plane. This film is folded to form a stack of layers with each 'layer' comprising part of a winding turn and with successive 'layers' connected at the folds via the continuous conductive film. The conductive film may be self-supporting and coated with a dielectric layer or may be disposed on a dielectric membrane. The film and membrane are preferably patterned photolithographically.

Method of making conductive film magnetic components

A dual-permeability magnetic core structure is provided for use in small, high-frequency inductors and transformers. The dual-permeability core encloses a winding window containing planar windings and comprises high-permeability and low-permeability sections positioned to produce a highly uniform, or uniformly varying, magnetic field on the winding surfaces. The dual-permeability core products low winding losses and a low AC-to-DC resistance ratio. Fabrication of the dual-permeability core involves a method of controlling the permeability of a magnetic material and a methd of combining structures of two different permeability values.

Dual-permeability core structure for use in high-frequency magnetic

Conductive film magnetic components

A pseudo-resonant DC link for coupling direct current from a DC source to an inverter includes a plurality of switches which are controlled so as to minimize switching loss in the DC link and in the inverter. The DC link includes a capacitor and an inductor coupled through controllable switches in a manner that momentarily reduces to zero the input voltage to the inverter each time that a switch in the inverter is commutated. The controllable switches in the DC link function to allow the capacitor to resonate through the inductor and then be recharged at the end of a commutation interval. The controllable switches in the DC link are timed to that switching generally occurs under conditions of zero current.

Switching converter with pseudo-resonant DC link

A high-frequency transformer is constructed from a flexible circuit comprising a primary conductive film winding and one or more secondary conductive film windings disposed on a single dielectric membrane. The flexible circuit is folded to form a stack of primary winding layers interleaved with secondary winding layers and then inserted into a magnetic cup core. The flexible circuit is preferably patterned photolithographically.

High-frequency transformer

A multilayer capacitor comprises stacked, spaced-apart electrodes of sheet form, dielectric layers between the electrodes, and first and second groups of spaced-apart conductive vias extending transversely of the sheet-form electrodes and through aligned holes in the dielectric layers. Alternate electrodes are instantaneously positive, and the remaining electrodes are instantaneously negative. Each via of the first group is electrically connected to the positive electrodes and passes insulatingly through the negative electrodes. Similarly, each via of the second group is electrically connected to the negative electrodes and passes insulatingly through the positive electrodes. Each via has, in the plane of the electrodes, a cross-sectional form in the shape of an elongated rib of greater length than width. The elongated ribs of the first group are disposed in a first plurality of rows with their lengths in spaced-apart, aligned relationship, and the ribs of the second group are disposed in a second plurality of rows with their lengths in spaced-apart, aligned relationship. The first plurality of rows is disposed substantially orthogonally with respect to the second plurality of rows.

Multilayer capacitor suitable for substrate integration and

A dual-permeability magnetic core structure is provided for use in small, high-frequency inductors and transformers. The dual-permeability corer encloses a winding window containing planar windings and comprises high-permeability and low-permeability sections positioned to produce a highly uniform, or uniformly varying, magnetic field on the winding surfaces. The dual-permeability core produces low winding losses and a low AC-to-DC resistance ratio. Fabrication of the dual-permeability core involves a method of controlling the permeability of a magnetic material and a method of combining structures of two different permeability values.

A control circuit for a full bridge switching converter including power FET switching devices. The control circuit including a gate driver with a voltage sensor circuit which senses the precise instant to gate the power FET on in order to achieve substantially lossless switching by the converter.

Gate driver for a full-bridge lossless switching device

A synchronous rectifier is able to operate at higher frequencies and provides an output having lower noise than prior art FET synchronous rectifier system by using field effect switching devices which contain only one conductivity type of semiconductor material and connecting a high speed, low charge storage diode in parallel. Schottky diodes are preferred whereby there is no junction diode in the structure. Conventional FETs may be used when paralleled with a Schottky diode which prevents the FET's parasitic internal diode from becoming conductive.

Low noise, high frequency synchronous rectifier

A power conversion system for converting polyphase AC power at a first frequency and voltage to AC power at a second frequency and voltage includes an input rectifier circuit and an output inverter circuit coupled by a DC link or interface comprising solid state devices. The interface includes a reversely-poled diodes connected between selected terminals of the rectifier and inverter circuits for carrying current in a forward direction. Controllable switches interconnect the same terminals for carrying current in a reverse direction to the inverter circuit. A controller responds to instantaneous current at the inverter terminals and to instantaneous input line voltages for selectively energizing the interface switches.

AC-AC converter using switches in a DC link

A full bridge integrable dc-to-dc converter is described which includes four FET switching devices wherein the parasitic capacitors of the switching devices exchange energy with the leakage and magnetizing inductances of the converter transformer. Since energy is exchanged between the passive components of the circuit, the switching is accomplished in a substantially lossless manner. Energy not transmitted to the load is returned to the source rather than being dissipated in the active devices of the converter. Further, single frequency operation is accomplished over a broad range of output conditions by phase shifting the converter legs relative to one another.

Full-bridge lossless switching converter

The leakage inductance of the isolation transformer of a single-ended DC-to-DC converter resonates with a resonant capacitor connected in series with the transformer secondary to provide substantially zero current in the switching transistor during turn-on and turn-off. The overall transistor current stress is low since it is bounded by the sum of average input current and average output current. These factors allow the converter to be operated at high frequencies for improved performance.

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Gainesville, FL, United States of America

Khai D Ngo