David J Perreault

US Patent:

6912142, Jun 28, 2005

Filed:

Oct 22, 2001

Appl. No.:

10/086069

Inventors:

Thomas A. Keim - Boxborough MA, US
David J. Perreault - Brookline MA, US

Assignee:

Massachusetts Institute of Technology - Cambridge MA

International Classification:

H02M005/42

US Classification:

363 89

Abstract:

An alternator system having an alternating current (ac) voltage source includes a switched-mode rectifier (SMR) coupled to the ac voltage source and having an output port coupled to an output of the alternator system, and a controller coupled to said switched-mode rectifier so as to provide a controlled pulse sequence synchronized with an angular rotor position of the (ac) voltage source to activate and deactivate the switched-mode rectifier. The controller further includes a PWM generator having a first input to receive a total duty ratio signal synchronized with an angular rotor position of the (ac) voltage source. The switched mode rectifiers are controlled to increase power output levels at lower speeds near idle. The controller combines improved idle speed power output levels with load matching improvements from PWM control for more efficient operation when compared to circuits using conventional control or PWM load matching control alone.

US Patent:

20020089866, Jul 11, 2002

Filed:

Oct 22, 2001

Appl. No.:

10/080819

Inventors:

Thomas Keim - Boxborough MA, US
David Perreault - Brookline MA, US

International Classification:

H02M005/42

US Classification:

363/089000

Abstract:

An alternator system having an alternating current (ac) voltage source includes a switched-mode rectifier (SMR) coupled to the ac voltage source and having an output port coupled to an output of the alternator system, and a controller coupled to said switched-mode rectifier so as to provide a controlled pulse sequence synchronized with an angular rotor position of the (ac) voltage source to activate and deactivate the switched-mode rectifier. The controller further includes a PWM generator having a first input to receive a total duty ratio signal synchronized with an angular rotor position of the (ac) voltage source. The switched mode rectifiers are controlled to increase power output levels at lower speeds near idle. The controller combines improved idle speed power output levels with load matching improvements from PWM control for more efficient operation when compared to circuits using conventional control or PWM load matching control alone.

US Patent:

48072583, Feb 21, 1989

Filed:

Nov 17, 1987

Appl. No.:

7/121654

Inventors:

Richard W. Sieber - Attleboro MA
David A. Perreault - Reading MA
Arnold Paige - Natick MA

Assignee:

GTE Laboratories Incorporated - Waltham MA

International Classification:

H04L 700

US Classification:

375108

Abstract:

In a digital communication system including a central PABX subsystem coupled by a transmission line to a remote telephone subsystem, a method for establishing synchronization between the PABX and the telephone. The data format includes a message transmitted from the PABX to the telephone during the first half of a frame and a response transmitted from the telephone to the PABX during the second half of the frame. The synchronization method includes the steps of recognizing that synchronization has been lost, discontinuing transmission of responses by placing the line driver in a high impedance state while continuing transmission of messages, and detecting a valid message on the transmission line. The valid message is detected by finding in sequence, a message stop bit, the stop bit remaining on the line for one half frame and a message start bit. When a valid message is detected, transmission of responses is resumed.