Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells
Reexamination Certificate
2000-01-18
2001-10-02
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
Reexamination Certificate
active
06297616
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a charge and discharge system for electric power storage equipment, and a method of manufacturing the electric power storage equipment using the same.
In the manufacture of a lithium-ion secondary battery or nickel-metal hydride secondary battery, and the like, a charging treatment or a charging-discharging treatment of a unit battery is performed in order to inspect the secondary battery after assembling, or to activate chemical reactions, and so on. Conventionally, when a defective battery was found in the charging-discharging test of the batteries after assembling, it was necessary to select the defective battery individually. Therefore, the charging-discharging operation is performed on each battery individually by providing an independent charge and discharge power source for each battery.
In particular, a lithium ion secondary battery requires not only constant current charging, but also constant voltage charging during a charging operation. Therefore, an individual electric power source system for charging, which makes it possible to set the charging current and the charging voltage individually for respective batteries, is used.
On the other hand, when the battery is to be used for electric vehicles or batteries for electric power storage, a set of batteries is formed by connecting a plurality of unit batteries in series. The set of unit batteries connected in series is charged by applying a voltage at both end terminals, and voltage is discharged from both end terminals for taking out electric power. In a case when the set of batteries is charged or discharged under a condition wherein the batteries are connected in series, the same charging current flows through all the respective batteries. Therefore, if the capacity of one of the respective batteries differs somewhat from the other batteries, a variation in the voltage of the individual battery is generated.
Particularly, a lithium-ion secondary battery requires that the battery voltage be maintained at a value lower than a designated voltage during the charging operation. Therefore, a charge and discharge system, wherein a set of batteries connected in multi-series is charged or discharge, is well-known, as disclosed in JP-A-8-88944 (1996). In order to suppress the variation in the individual batteries connected in series, an electric power source is provided to the respective batteries for correction.
However, in the case when an individual unit battery is charged or discharged by a respective charge and discharge electric power source, a number of charge and discharge electric power supplies, which is proportional in number to the number of the unit batteries being charged or discharged simultaneously, are required. Particularly, the charge and discharge apparatus for activation treatment or inspection of the secondary batteries after assembling requires several hours for a series of charging-discharging operations. Therefore, in order to improve production efficiency, it is necessary to charge or discharge a large number of unit batteries simultaneously using a large number of charge and discharge electric power supplies. Therefore, a problem is generated in that a large number of the electric power supplies are required, in spite of the need only for charging or discharging a large number of unit batteries with a similar current and voltage pattern.
In accordance with the charge and discharge system, wherein plural unit batteries are connected in series for composing a set of batteries, and wherein the charging or discharging of the set of plural batteries is carried out simultaneously using an electric power source for the simultaneous charging or discharging, circuits for bypassing defective batteries which are detected during the charging or discharging operations are required for every one of the batteries. In order to charge or discharge the batteries so that the voltage of respective batteries becomes uniform by compensating a variation in voltage caused by variation in the capacity of a particular battery, a respective charge and discharge electric power source is required for each respective battery. In particular, for a lithium-ion secondary battery, it is necessary to perform charging or discharging while measuring the voltage of the respective battery precisely. In a condition under which each of the unit batteries is connected in series, the voltage of the respective battery must be detected by a differential voltage, and a problem arises in that the circuit for detecting the voltage becomes complex.
In a case when a plurality of batteries connected in parallel are charged or discharged, the charging current or discharging current does not become uniform, and so each of the batteries can not be charged fully. Furthermore, additional circuits for detecting a failed battery and separating the failed battery become necessary.
SUMMARY OF THE INVENTION
The present invention has been achieved in consideration of the above problems.
The charge and discharge apparatus for electric power storage means relating to the present invention comprises an AC power source; a transformer comprising a primary winding connected to the AC power source, and plural secondary windings; and plural electric power converters comprising plural AC sides connected to plural secondary windings, and plural DC sides for connection to plural electric power storage means.
In accordance with the present invention, the plural electric power storage means can be charged simultaneously from the AC power source, or plural electric power storage mea ns can be discharged simultaneously to the AC power source, because the electric power storage means is connected to plural secondary windings of the trans former, which is connected to the AC power source.
The charge and discharge apparatus of the electric power storage means according to the present invention comprises an apparatus having a charging function, an apparatus having a discharging function, and an apparatus having a charging and discharging function. As the AC power source, various apparatus which can output AC power are usable. However, an apparatus which comprises an electric power converter connected to a transformer is desirable. In this case, charging or discharging plural electric power storage means can be controlled simultaneously as an unit by controlling the electric power converter so that the current flowing through the primary winding becomes a current reference. As the electric power storage means, there are secondary batteries, a battery set wherein plural unit secondary batteries are connected in series, electrical double layer capacitors, condensers, fuel cells, and so on.
In accordance with the charge and discharge apparatus of the electric power storage means according to the present invention, a motor driving system can be composed by providing an AC power source to the electric power converter, and furthermore, providing a motor, and an inverter for driving the motor, to which the electric power is supplied from the electric power converter. In accordance with the charge and discharge apparatus of the electric power storage means according to the present invention, an electric power storage means can be composed by connecting the AC power source to an electric power system.
A method of manufacturing the electric power storage means according to the present invention comprises the steps of: assembling main bodies of plural electric power storage means; connecting one of the assembled plural electric power storage means to respective of the DC side of the plural electric power converter in the charge and discharge apparatus of the electric power storage means according to the present invention; and performing initial charging, or initial discharging, or aging treatment with the plural electric power storage means by the charge and discharge apparatus of the electric power storage means according to the present invention.
In accordance with the present invention, it becomes possible to perform initial
Emori Akihiko
Kubo Kenji
Miyazaki Hideki
Nomura Takahiro
Tokunaga Norikazu
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Tso Edward H.
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