Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With individual charging of plural batteries or cells
Reexamination Certificate
2001-07-03
2003-03-25
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With individual charging of plural batteries or cells
Reexamination Certificate
active
06538414
ABSTRACT:
TECHNICAL FIELD
This invention relates to an electrical energy storage device comprising a plurality of capacitor cells or secondary battery cells, or a plurality of other electrical energy storage cells, connected in series to each other. In particular, this invention relates to an electrical energy storage device provided with a cell energy adjustment device for performing energy allocation of the stored energy amount to bring an energy amount stored in one energy storage unit, which is a single cell or comprises a plurality of cells, to a target value, as well as a method for cell energy adjustment like this.
BACKGROUND ART
Conventionally, electrical energy storage cells are connected in series to each other to configure an energy storage device with a higher terminal voltage and a larger energy storage capacity than the single cell. However, management of the energy amounts stored in the individual cells in this device has hardly ever been performed.
In a configuration using capacitors as cells, resistances may be connected in parallel with the individual cells as disclosed in for example, Japanese Patent Application Laid-open No. 10-174283, or constant-voltage elements such as Zener diodes may be connected in parallel, whereby individual cells are charged in parallel charging or in partial parallel charging so that the cells are charged to have an equal voltage.
When there is no management of individual cells connected in series for charging and discharging, the cells in a conventional storage battery partially often reach a state of overcharge or overdischarge, so that those cells are degraded in performance or are broken. Alternatively, in use of cells such as capacitors which physically store charge, there is the possibility that the terminal voltage of a certain or some cells may exceed the cell withstand voltage, resulting in degradation or damage. As measures for avoiding this, it has been taken, for example, to lower the operation ratings of the energy storage device. Accordingly, it has been necessary to set the power density and energy density of the energy storage device below the values intrinsic to the cells.
Noting the low energy efficiency of these conventional technologies, a method has been proposed in which capacitors are connected to a plurality of coils of a transformer via a switching circuit and charged at equal voltages (cf. Japanese Patent Application Laid-open No. 8-214454).
However, in this conventional method, the voltages can be rendered equal upon charging, but thereafter it is not possible to render the voltages equal to each other during a waiting state before start of discharge or in the discharged state. Therefore it is not true that energy is always utilized effectively.
Hence, a new energy storage device is extremely promising which is provided with a cell energy adjustment device for managing the energy amounts of individual cells and performing the reallocation of energy. In an actual configuration of the energy storage device which performs the cell energy adjustment, the energy storage device comprises a plurality of cell series units connected in series to each other, each of the cell series units comprising a plurality of cells connected in series to each other, to thereby increase the overall energy amount, and is operated with adjusting the cell energy amounts.
The energy storage device actually uses diodes or other rectifying elements for transferring energy, each of which have the forward voltage approximately 0.7 V which cannot be neglected compared with the voltages, 1 V to 3 V, of capacitors or secondary battery cells. Hence a method is used in which the voltage is raised and energy is transferred to an entire cell series of a plurality of cells connected in series to each other.
Thus, in the configuration in which a plurality of cell series units, each unit comprising a plurality of capacitors or secondary battery cells connected in series to each other, are connected in series to each other, it has been necessary as described above to greatly raise the voltage in order to transfer energy to the entire of the cell series units, and therefore there have been many problems.
Hence one object of this invention is to provide an energy storage device comprising an energy adjustment device capable of preserving the energy stored in the individual cells forming a unit energy storage device, at an optimal target value, without loss caused in principle, whether during charging, discharging, or standby.
Another object of this invention is to provide an energy adjustment method capable of preserving the energy stored in the individual cells forming a unit energy storage device, at an optimal target value, without loss caused in principle, whether during charging, discharging, or standby.
DISCLOSURE OF THE INVENTION
This invention provides an energy storage device comprising a unit energy storage device comprising a plurality of capacitor cells or secondary battery cells connected in series to each other; and a device for transferring energy charged in one cell selected from the plurality of cells to the input/output terminals of the unit energy storage device from the selected one cell; the transferring device comprising a transformer having a plurality of primary coils and a secondary coil mutually magnetically coupled and electrically insulated; a switching circuit which opens and closes a connection circuit connecting between one coil among the plurality of primary coils of the transformer and the selected one cell; a circuit which connects the secondary coil of the transformer to the input/output terminals of the unit energy storage device through a rectifying circuit; and, a control circuit which, by driving the switching circuit, adjusts the energy stored in the selected one cell to a specific ratio with respect to the overall energy amount stored by the unit energy storage device; thereby the cell energy amounts being adjusted.
Further, according to this invention, a large-capacity energy storage device is obtained in which a plurality of the above-mentioned unit energy storage devices are connected in series to each other to thereby obtain a terminal voltage higher than that of a unit energy storage device, while also storing larger amounts of energy than a unit energy storage device; and which is provided with an energy storage device which transfers the energy charged in one cell selected from the plurality of cells to the input/output terminals of the unit energy storage device from the selected one cell, the cell energy adjustment device comprising a transformer having a plurality of primary coils and a secondary coil mutually magnetically coupled and electrically insulated; a switching circuit which opens and closes a connection circuit connecting one coil among the plurality of primary coils of the transformer and the selected one cell; a circuit which connects the secondary coil of the transformer to the input/output terminals of the unit energy storage device through a rectifying circuit; and a control circuit which, by driving the switching circuit, adjusts the energy stored in the selected one cell to a specific ratio with respect to the energy stored by the unit energy storage device; and wherein a relationship between the unit energy storage devices and the large-capacity energy storage device is made similar to another relationship between the energy cells and the unit energy storage device in the cell energy adjustment device, or connections of energy storage devices are further expanded to an arbitrary number of layers.
Further, according to this invention, an energy storage device having a cell energy adjustment device is obtained, characterized in that a plurality of energy storage cell series, each series comprising a single electrical energy storage cell or a plurality of electrical energy storage cells, are connected in series to each other; each of the energy cell series is provided with a device which measures the energy amount of the series, memorizes and processes the measured energy amounts; the cell en
Hasebe Akio
Ito Takahiko
Mori Kazuya
Seki Sumiko
Tsuruga Kikuo
Frishauf Holtz Goodman & Chick P.C.
Tokin Corporation
Tso Edward H.
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