Thomas E Loftus

US Patent:

53273338, Jul 5, 1994

Filed:

Nov 25, 1992

Appl. No.:

7/981638

Inventors:

Jeffrey J. Boylan - Dallas TX
Mark E. Jacobs - Dallas TX
Thomas P. Loftus - Mesquite TX
Allen F. Rozman - Richardson TX

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H02M 114
H02M 3335

US Classification:

363 21

Abstract:

A DC-DC converter utilizes a tapped transformer secondary winding as a means of achieving output voltage ripple cancellation. This ripple cancellation occurs at a specified input voltage. It operates by fixing the location of a tap on the secondary winding of the power transformer so that the output voltage ripple cancellation occurs at the specified input voltage. It also minimizes the volt seconds that must be sustained by the output filter inductor over a specified range of input voltage for the converter.

US Patent:

52745430, Dec 28, 1993

Filed:

Sep 23, 1992

Appl. No.:

7/949603

Inventors:

Thomas P. Loftus - Mesquite TX

Assignee:

AT&T Bell Laboratories - Murray Hill PA

International Classification:

H02M 7217

US Classification:

363127

Abstract:

A converter operating in a resonant mode of operation is used as an off-line switching power supply operating with a high power density. A drive arrangement and operative scheme for driving the power switching transistors limits the dissipation losses within the power switching transistors. Drive circuitry drives two power switching transistors with unequal duty cycles having conducting durations such that the sum of the conduction intervals substantially equals the combined switching period of the two power switching transistors. These conducting intervals are separated by very short dead time intervals controlled by the differing turn-on and turn-off times of the two power switching transistors. The short interval between alternate conductions of the two power switching transistors is sufficient in duration to allow zero voltage turn on of the power switching transistors but short enough in duration to minimize power loss and conducted noise. In the illustrative embodiment the dead time is at least an order of magnitude less than the time interval of the shortest duty cycle.

US Patent:

53051912, Apr 19, 1994

Filed:

Apr 20, 1992

Appl. No.:

7/871370

Inventors:

Thomas P. Loftus - Garland TX

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H02M 3335

US Classification:

363 17

Abstract:

A drive arrangement and operative scheme for the power switching transistors of a half-bridge power drives the two power switching transistors with unequal duty cycles having conducting durations such that the sum of the conduction intervals substantially equals the combined switching period of the two power switching transistors. The conducting intervals are separated by very short dead time intervals controlled by the differing turn-on and turn-off times of the two power switching transistors. The short interval between alternate conductions of the two power switching transistors is sufficient to allow zero voltage turn on of the power switching transistors but short enough to minimize power loss and conducted noise.

US Patent:

53532120, Oct 4, 1994

Filed:

Apr 20, 1992

Appl. No.:

7/871364

Inventors:

Thomas P. Loftus - Garland TX

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H02M 3335

US Classification:

363 17

Abstract:

A half bridge power converter utilizes two oppositely phased power switches operated with unequal duty cycles. A magnetic arrangement with two inductance values having a ratio equal to the ratio of the unequal duty cycles is included in the converter to compensate for the unequal duty cycles.

US Patent:

52688305, Dec 7, 1993

Filed:

Apr 20, 1992

Appl. No.:

7/871369

Inventors:

Thomas P. Loftus - Garland TX

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H02M 3335

US Classification:

363 17

Abstract:

A drive arrangement and operative scheme for the power switching transistors of a half-bridge power drives the two power switching transistors with unequal duty cycles having conducting durations such that the sum of the conduction intervals substantially equals the combined switching period of the two power switching transistors. The conducting intervals are separated by very short dead time intervals controlled by the differing turn-on and turn-off times of the two power switching transistors. The short interval between alternate conductions of the two power switching transistors is sufficient to allow zero voltage turn on of the power switching transistors but short enough to minimize power loss and conducted noise. Special biasing is provided to prevent drive signal application to power switches prior to attainment of a minimum voltage across the switch. Circuitry is provided for cancellation of output ripple currents at selected operating points of the power converter.

US Patent:

50364529, Jul 30, 1991

Filed:

Dec 28, 1989

Appl. No.:

7/458009

Inventors:

Thomas P. Loftus - Garland TX

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H02M 3335

US Classification:

363 71

Abstract:

Current sharing between paralleled power converters is attained by adjusting the error signal in the converters regulation circuit to assure that all the paralleled converters have a regulated output voltage that forces the converters to share the load equally. In particular circuitry is provided to limit the variation in output voltage that can be achieved through operation of the current sharing control.

US Patent:

20170150999, Jun 1, 2017

Filed:

Jan 6, 2016

Appl. No.:

14/989791

Inventors:

Chase D. Tipping - Dallas TX, US
Thomas Loftus - Austin TX, US

International Classification:

A61B 17/70

Abstract:

Embodiments of a bony implant extension arm breakoff tool are described. The tool may enable a surgeon to break a section of a bony segment implant extension located in a transdermal location within a patient. Other embodiments may be described and claimed.