Massachusetts Institute of Technology

Kaman Electromagnetics Corp.

Newport News Shipbuilding and Dry Dock Company

Thomas A Keim

Peter P Mongeau

Thomas B Dade

David J Perreault

John G Kassakian

Woo Sok Chang

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.

Alternator control circuit and related techniques

The present invention provides a means to reduce holding current and driving current of EMVD's effectively and practically and to provide soft landing of a valve. The invention incorporates a nonlinear mechanical transformer as part of an EMVD system. The nonlinear mechanical transformer is designed for the spring and the inertia in the EMVD to have desirable nonlinear characteristics. With the presently disclosed invention, the holding current and driving current are reduced and soft valve landing is achieved. The nonlinear characteristics of a nonlinear mechanical transformer can be implemented in various ways. The concept of the invention can be applied not only to EMVD's but also to general reciprocating and bi-stable servomechanical systems, where smooth acceleration, soft landing, and small power consumption are desired.

Electromechanical valve drive incorporating a nonlinear mechanical transformer

A magnet carrier assembly for holding and carrying a high-energy-product permanent magnet is arranged for releasable attachment to a rotor of an axial disc or drum type rotor in an electric machine. The permanent magnet placed in a container which then receives a cover. The magnet carrier assembly includes a mounting flange at one end and a locating and mounting tab at an opposite end for attaching the assembly to the rotor. In certain applications, the rotor has recesses which have a size and shape complementary to the size and shape of the magnet carrier assembly. The recesses are circumaxially located around the radial periphery of the rotor at the poles of the rotor. In other embodiments, the magnet carrier assembly includes a key which is received in a mating groove in a rotor surface and is used to transfer to the rotor the electromagnetic shear force developed by the high-energy-product permanent magnet. The present magnet carrier assembly can be used with both axial field disc or radial field drum rotors. The present invention also contemplates a method and apparatus for removing and installing magnet carrier assemblies in electric machines.

Detachable magnet carrier for permanent magnet motor

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Boxborough, MA, United States of America

Thomas A Keim