Best Power Technology, Inc.

Pensar Corporation

Robert F Bourke

David L Layden

Richard V Baxter, Jr

Terrance D Paul

Richard I Cook

David R Ellingson

Two or more gated type power switches, particularly mosfets, are disclosed in a protection circuit which protects the other power switches should one of them short to its respective gate. The circuit includes elements for sensing the occurrence of the failure, for carrying or diverting excess current from the gates, and increasing the impedance of the gates to minimize any damage. The circuit prevents the failure of one mosfet in a drain to gate short mode from destroying or damaging the other parallel mosfets. The invention results in easier analysis and repair of any damage should a breakdown occur, and for the first time makes practical the use of many mosfets in parallel for power switching applications.

Gated parallel power switching devices protection circuit

A method and apparatus are disclosed for use with a battery powered inverter for powering a load through a ferroresonant transformer. The current flow through the inverter-ferroresorant transformer is sensed and is utilized to modulate the inverter's pulse width at a point, after a peak voltage but before saturation begins, when the slope of the inverter-ferroresonant transformer current with respect to time is at or near zero. A maximum current limiting feature can be provided in the method and apparatus of the present invention.

Method and apparatus for modulating inverter pulse width

Growing community of inventors

Fairchild, WI, United States of America

Robert F Bourke