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Circulating current battery heater

United States Patent

July 10, 2001
View the Complete Patent at the US Patent & Trademark Office
National Renewable Energy Laboratory - Visit the NREL Technology Transfer Website
A circuit for heating energy storage devices such as batteries is provided. The circuit includes a pair of switches connected in a half-bridge configuration. Unidirectional current conduction devices are connected in parallel with each switch. A series resonant element for storing energy is connected from the energy storage device to the pair of switches. An energy storage device for intermediate storage of energy is connected in a loop with the series resonant element and one of the switches. The energy storage device which is being heated is connected in a loop with the series resonant element and the other switch. Energy from the heated energy storage device is transferred to the switched network and then recirculated back to the battery. The flow of energy through the battery causes internal power dissipation due to electrical to chemical conversion inefficiencies. The dissipated power causes the internal temperature of the battery to increase. Higher internal temperatures expand the cold temperature operating range and energy capacity utilization of the battery. As disclosed, either fixed frequency or variable frequency modulation schemes may be used to control the network.
Ashtiani; Cyrus N. (West Bloomfield, MI), Stuart; Thomas A. (Toledo, OH)
DaimlerChrysler Corporation (Auburn Hills, MI), University of Toledo (Toledo, OH)
09/ 400,779
September 22, 1999
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under NREL subcontract number ZAN-6-16334-01, prime contract number DE-AC36-83CH10093 issued by the Department of Energy. The government has certain rights in this invention.