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Bypass apparatus and method for series connected energy storage devices

United States Patent

April 4, 2000
View the Complete Patent at the US Patent & Trademark Office
A bypass apparatus and method for series connected energy storage devices. Each of the energy storage devices coupled to a common series connection has an associated bypass unit connected thereto in parallel. A current bypass unit includes a sensor which is coupled in parallel with an associated energy storage device or cell and senses an energy parameter indicative of an energy state of the cell, such as cell voltage. A bypass switch is coupled in parallel with the energy storage cell and operable between a non-activated state and an activated state. The bypass switch, when in the non-activated state, is substantially non-conductive with respect to current passing through the energy storage cell and, when in the activated state, provides a bypass current path for passing current to the series connection so as to bypass the associated cell. A controller controls activation of the bypass switch in response to the voltage of the cell deviating from a pre-established voltage setpoint. The controller may be included within the bypass unit or be disposed on a control platform external to the bypass unit. The bypass switch may, when activated, establish a permanent or a temporary bypass current path.
Rouillard; Jean (Saint-Luc, CA), Comte; Christophe (Montreal, CA), Daigle; Dominik (St-Hyacinthe, CA)
3M Innovative Properties Company (St. Paul, MN), Hydro-Quebec Corporation (Montreal, CA)
08/ 900,325
July 25, 1997
GOVERNMENT LICENSE RIGHTS The Government of the United States of America has rights in this invention pursuant to Cooperative Agreement No. DE-FC02-91CE50336 awarded by the U.S. Department of Energy.