Electricity: battery or capacitor charging or discharging – Battery or cell charging – With thermal condition detection
Reexamination Certificate
2000-09-18
2001-06-12
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
With thermal condition detection
Reexamination Certificate
active
06246217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a non-aqueous electrolytic battery module for use with an artificial satellite.
2. Description of the Related Art
An artificial satellite is usually equipped with a solar battery and a secondary battery. The solar battery supplies power to the artificial satellite during a solstice season (i.e., a period in which the solar battery is exposed to sunlight). During the solstice season, the secondary battery is charged by the solar battery. During an eclipse season (i.e., a period in which sunlight is blocked by the earth and the solar battery is not exposed to sunlight), the secondary battery supplies power to the artificial satellite.
A secondary battery provided in an artificial satellite is required to maintain stable charge/discharge cycles for over fifteen years. A nickel-hydrogen battery, for example, has conventionally been used as such a secondary battery. During a solstice season, i.e., a season during about 138 days in which the solar battery is always exposed to sunlight, the secondary battery is maintained in a fully charged state or a highly charged state by means of a float charging operation. During an eclipse season, i.e., a season during about 45 days in which the solar battery is eclipsed by the earth once a day, the secondary battery is discharged to supply power for the artificial satellite.
Recently, an attempt has been made to use a lithium battery including lithium-ion battery as a secondary battery to be provided in an artificial satellite. A lithium battery is deteriorated faster than is a nickel-hydrogen battery, when the batteries are maintained at high temperature. Further, the lithium battery is deteriorated much more than the nickel-hydrogen battery, when the batteries are maintained at a highly charged state. For these reasons, in a case where a lithium battery is maintained in the same managed temperature state or manage charged state as that in which a conventional nickel-hydrogen battery is maintained, the lithium battery is deteriorated faster than is the nickel-hydrogen battery. As a result, the discharging capacity of the lithium battery is diminished, and hence the lithium battery encounters difficulty in maintaining a stable charge/discharge characteristic.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a non-aqueous electrolyte battery for an artificial satellite which can exhibit a stable charge/discharge characteristic over a long period of time.
According to a first aspect of the present invention, a non-aqueous electrolyte battery module comprises: a non-aqueous electrolyte battery to be provided in an artificial satellite; temperature measuring means for measuring the temperature of the non-aqueous electrolyte battery; heating/cooling means for heating or cooling the non-aqueous electrolyte battery; and battery temperature control means for controlling the heating/cooling means on the basis of the temperature measured by the temperature measuring means; wherein when the satellite is in a solstice season, a managed temperature of the non-aqueous electrolyte battery is controlled to be equal to or lower than a managed temperature of the non-aqueous electrolyte battery achieved when the satellite is in an eclipse season. That is, when the satellite is in the eclipse season, the managed temperature of the non-aqueous electrolyte battery is higher than the managed temperature of the non-aqueous electrolyte battery which is in the solstice season. Since the solstice season (about 138 days) is considerably longer than the eclipse season, the time during which the battery is maintained at a high temperature can be significantly shortened, thus preventing deterioration of the battery.
According to a second aspect of the present invention, in the first aspect, it is preferable that the managed temperature of the non-aqueous electrolyte battery is set to 10° C. to 35° C. when the satellite is in a eclipse season, and the managed temperature of the non-aqueous electrolyte battery is set to −30° C. to 10° C. when the satellite is in a solstice season.
According to the present invention, the battery is set so as to achieve the managed temperature set for the eclipse season or the managed temperature set for the solstice season, as soon as possible. The temperature of the battery is controlled so as to fall within the managed temperature ranges. At the time of transition from the eclipse season to the solstice season or vice versa, a lag naturally can arise in the change of temperature of an actual battery. Even in a case where the temperature of the battery temporarily exceeds the managed temperature range as a result of a rapid discharge operation, it goes without saying that such a case falls within the scope of the invention.
According to a third aspect of the present invention, in the first or second aspect, it is preferable that the non-aqueous electrolyte battery further comprises: charge/discharge condition detecting means for detecting the charge/discharged state of the non-aqueous electrolyte battery; charging/discharging means for charging and discharging the non-aqueous electrolyte battery; and charging/discharging control means for controlling the charging/discharging means on the basis of the charge/discharged state of the non-aqueous electrolyte battery detected by the charge/discharge condition detecting means; wherein when the satellite is located at the start of the eclipse season, a managed charged state of the non-aqueous electrolyte battery is controlled so as to be set a value of 50% or more, and when the satellite is in the solstice season, the charging/discharging control means controls the managed charged state of the non-aqueous electrolyte battery so as to be set a value of 75% or less. As a result, the power supply capability of the battery is ensured during the shadow period, and there can be prevented deterioration of the battery, which would otherwise be caused when the battery is placed in a highly-charged state for a long period of time during the solstice season.
According to a fourth aspect of the present invention, in the third aspect, it is preferable that when the satellite is in a solstice season, the managed charged state of the non-aqueous electrolyte battery is controlled so as to be a value of 75% or less by means of intermittent charging/discharging operations.
According to the present invention, the battery is set so as to achieve the managed temperature set for the eclipse season or the temperature set for the solstice season, as soon as possible. The temperature of the battery is controlled so as to fall within the managed temperature ranges. At the time of transition from the eclipse season to the solstice season or vice versa, a lag naturally can arise in the change of temperature of an actual battery. Even in a case where the managed charged state temporarily exceeds the charged state of the battery for any reason, it goes without saying that such a case falls within the scope of the invention.
When an artificial satellite is in a shadow period, a non-aqueous electrolyte battery provided in the satellite is set so as to supply power to equipment provided in the satellite. Therefore, there is a necessity for avoiding an increase in the internal resistance of the battery at a low temperature and to avoid an increase in self-discharge rate at a high temperature. During the solstice season, the battery is held at a lower temperature in order to prevent deterioration of the battery, which would otherwise be caused at high temperature. Further, during the eclipse season, freezing of the non-aqueous electrolyte battery must be prevented. To these ends, in the first aspect of the present invention, the managed temperature of the non-aqueous electrolyte battery during the eclipse season is set so as to become equal to or greater than that achieved during the solstice season. Consequently, when the satellite is in the solstice season, the managed temperature of the non-aqueous electrolyte
Imamura Nobutaka
Inoue Takefumi
Miyanaga Naozumi
Yoshida Hiroaki
Japan Storage Battery Co., Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tso Edward H.
LandOfFree
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