| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hybrid system using a nickel hydride battery as a power storage unit in which overdischarge and overcharge of the nickel hydride battery are prevented and battery capacity can be used efficiently by estimating the charging state (SOC) of the nickel hydride battery accurately regardless of the SOC or the magnitude of charge/discharge current, and overcharge is prevented by regulating the charging current at the time of charging the nickel hydride battery. SOLUTION: When the SOC of a nickel hydride battery 27 being operated by a system controller 1 falls within a constant voltage SOC range where the nickel hydride battery 27 exhibits constant voltage characteristics, the SOC is estimated based on the integrated value of charge/discharge current of the nickel hydride battery 27. When the SOC is lower than the constant voltage SOC range, the SOC is estimated based on the inclination of preset discharge voltage characteristics D of the nickel hydride battery 27 and then discharge end thereof is determined. COPYRIGHT: (C)2005,JPO&NCIPI
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