Electric energy storage device with cell energy control, and method of controlling cell energy

• US 6,538,414 B1
• Filed: 07/03/2001
• Issued: 03/25/2003
• Est. Priority Date: 11/05/1999
• Status: Expired due to Fees

• Current Assignee: NEC Tokin Corporation (Yageo Corporation)
• Original Assignee: Tokin Corporation (Yageo Corporation)
• Inventors: Hasebe, Akio, Mori, Kazuya, Tsuruga, Kikuo, Seki, Sumiko, Ito, Takahiko
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/869,737
• Time in Patent Office: 630 Days
• Field of Search: 320/116, 320/117, 320/118, 320/119, 320/122
• US Class Current: 320/119
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

An energy adjusting device is provided which transfers energy charged in an arbitrary cell to the input/output terminals of a unit energy storage device. The energy adjusting device includes a transformer having a plurality of primary coils and a secondary coil mutually coupled magnetically but electrically insulated, switching circuits which open and close the circuits of the primary coils of the transformer connected to the arbitrary cell, a circuit connecting the secondary coil of the transformer via a rectifying circuit to the input/output terminals of the unit energy storage device, and a control circuit which, by operating the switching circuits, adjusts the amount of energy stored in the cells to a specific ratio with respect to the amount of energy stored by the unit energy storage device.

Claims

1. An energy storage device comprising a unit energy storage device having a plurality of capacitor cells or secondary battery cells connected in series to each other;

and a cell energy adjusting device which transfers energy charged in one cell selected from said plurality of cells to input/output terminals of said unit energy storage device from the selected one cell, said cell energy adjusting device comprising;

a transformer having a plurality of primary coils and a secondary coil electrically insulated and mutually coupled magnetically;

a switching circuit which opens and closes a connection circuit connecting between said selected one cell and one coil among said plurality of primary coils;

a circuit connecting the secondary coil of said transformer to the input/output terminals of said unit energy storage device through a rectifying circuit; and

,

a control circuit which, by driving said switching circuit, adjusts the energy amount stored in said selected one cell to a specific ratio with respect to the overall energy amount stored by said unit energy storage device.

2. The energy storage device according to claim 1, wherein said plurality of cells are classified to form at least one cell group;

said transformer is provided with a number of transformers corresponding to said at least one cell group constituting said unit energy storage device; and

each of said transformers has a plurality of said primary coils which are connected respectively to the cells in each of said at least one cell group via said switching circuits, and said secondary coil, which is connected to the input/output terminals of said unit energy storage device through said rectifying circuit.

3. The energy storage device according to claim 2, wherein each of said respective transformers is provided with a third coil.

4. The energy storage device according to claim 1, wherein said transformer has a plurality of primary coils which are connected to corresponding ones of said plurality of cells via respective switching circuits, respectively, said secondary coil being connected to the input/output terminals of the unit energy storage device.

5. The energy storage device according to claim 4, wherein said transformer is further provided with at least one third coil.

6. The energy storage device according to claim 1, wherein a switching circuit is connected in series to the secondary coil of said transformer connected through said rectifying circuit to the input/output terminals of said unit energy storage device, or a switching function is added to the rectifying circuit connected in series to the secondary coil of said transformer, so that the connection between the input/output terminals of the unit energy storage device and the secondary coil of said transformer can thereby be temporarily interrupted.

7. The energy storage device according to claim 6, further comprising a circuit for supplying, through capacitors, control signals to the switching circuits connected to respective cells, based on either of a potential connected to the input/output terminals of said unit energy storage device or another potential of said selected one cell.

8. The energy storage device according to claim 1, further comprising a circuit adapted to detect an open terminal voltage of the secondary coil of said transformer connected to the unit energy storage device in synchronization with operation to control the switching circuit connected to said selected one cell, and to define the amount of energy stored in said selected one cell.

9. The energy storage device according to claim 1, further comprising energy normalization control means which comprises at least one of a control circuit and software for controlling the switching circuit connected to said selected one cell to partially transfer the energy stored in said selected one cell to the input/output terminals of said unit energy storage device to thereby control normalization of the energy amount stored in said selected one cell, when the energy amount stored in said selected one cell is defined as excessive with respect to the energy amount stored by said unit energy storage device.

10. The energy storage device according to claim 1, further comprising energy allocation means which comprises at least one of a circuit and software for determining a ratio of energy amount to be stored in each of the cells with respect to the energy amount stored by the unit energy storage device.

11. The energy storage device according to claim 1, which further comprises:

energy allocation means comprising at least one of a circuit and software for determining a ratio of energy amount to be stored in each of the cells in said unit energy storage device with respect to the energy amount stored by said unit energy storage device, when charging and discharging of the unit energy storage device are performed repeatedly, the unit energy storage device is left standing in a state in which an arbitrary amount of energy is stored, or the unit energy storage device is repeatedly left and charged/discharged; and

a function for learning the appropriate amount to be stored in each of the cells from at least one of characteristics of each cell including an initial state thereof, and prediction of charging/discharging of the unit energy storage device.

12. A large-capacity energy storage device comprising a plurality of unit energy storage devices connected in series to each other, each of the unit energy storage devices comprising a plurality of capacitor cells or secondary battery cells connected in series to each other, said large capacity energy storage device having a higher terminal voltage than each of the unit energy storage devices while storing a larger amount of energy than each of the unit energy storage devices, and said large-capacity energy storage device including a cell energy amount adjusting device which is a device to transfer energy charged in one selected cell to the input/output terminals of one said unit energy storage device from the one selected cell, and which comprises a transformer having a plurality of primary coils electrically insulated and mutually magnetically coupled and a secondary coil;

a switching circuit to open and close a connection circuit connecting between said one selected cell and one of said primary coils of said transformer;

a circuit connecting the secondary coil of said transformer to the input/output terminals of the one said unit energy storage device through a rectifying circuit; and

a control circuit for driving said switching circuit to adjust the amount of energy stored in each of the cells to a specific ratio with respect to the energy amount stored by the one said unit energy storage device; and

wherein

a relationship between said unit energy storage devices and the large-capacity energy storage device is made similar to another relationship between said energy cells and the one said unit energy storage device, or connections of said unit energy storage devices are further expanded to a prescribed number of layers.

13. An energy storage device comprising a plurality of unit energy storage devices connected to each other, each having a single electrical energy storage cell or a plurality of electrical energy storage cells;

wherein

each of said unit energy storage devices has a cell energy adjustment device which measures the amount of energy of the unit, memorizes and processes said measured amount of energy, and controls operation of switching circuits, to transfer energy charged in a selected one unit energy storage device via a transformer;

a plurality of coils are provided corresponding to each of said unit energy storage devices;

transformers are provided corresponding to respective unit energy storage devices;

a circuit is configured connecting transformer coils, switching circuits, and rectifying circuits; and

energy is directly transferred from the selected one unit energy storage device to another unit energy storage device.

14. The energy storage device according to claim 13, wherein said electrical energy storage cells are either capacitor cells or secondary battery cells.

15. The energy storage device according to claim 13, wherein the plurality of unit energy storage devices are connected in series to each other;

and each of the unit energy storage devices includes a mechanism similar to that in the energy storage device so that energy is transferred directly from the one selected unit energy storage device to a different one of the unit energy storage devices within the energy storage device, or to another energy storage device.

16. The energy storage device according to claim 13, wherein the connection of the unit energy storage devices is further extended to form a layered structure having a prescribed number of layers, and energy is directly transferred from one of the unit energy storage devices having a small amount of accumulated energy to unit energy storage devices having an equal level of accumulated energy, or to unit energy storage devices having a same or higher level of accumulated energy.

17. The energy storage device according to claim 13, wherein a relationship between said energy storage device and said unit energy storage devices is configured similar to another relationship between each of said unit energy storage devices and said capacitor cells or secondary battery cells;

and wherein the energy of a selected capacitor cell or secondary battery cell is transferred to another of the cells or to another of the energy storage devices.

18. A cell energy adjustment method in which a plurality of energy storage devices each comprising a single electrical energy storage cell or a plurality of electrical energy storage cells, are connected in series to each other;

a device for measuring the energy amounts of respective energy storage devices to memorize and process the measured results is provided; and

energy charged in a selected one of the energy storage devices is transferred through a transformer by operating switching circuits controlled by the device;

wherein transformers are provided corresponding to the respective energy storage devices, coils of said transformers are connected to the switching circuits and rectifying circuits, and energy is transferred directly from any one of the energy storage devices to another one of the energy storage devices.

19. The cell energy adjustment method according to claim 18, wherein said electrical energy storage cells comprise a plurality of capacitor cells or secondary battery cells.

20. The cell energy adjustment method according to claim 18, wherein each of said energy storage devices comprises a plurality of unit energy storage devices;

and each of said unit energy storage devices has mechanism similar to that in the energy storage device so that energy is transferred directly from one selected unit energy storage device to another of the unit energy storage devices within the same energy storage device, or to another energy storage device.

21. The cell energy adjustment method according to claim 18, wherein connection of the energy storage devices is further extended to form a layered structure having a prescribed number of layers, and energy is directly transferred from one of the storage devices having a small amount of accumulated energy to storage devices having an equal level of accumulated energy, or to storage devices having an equal or greater level of accumulated energy.

22. The cell energy adjustment method according to claim 18, wherein a relationship between said energy storage devices and said unit energy storage devices is configured similar to another relationship between said unit energy storage device and said capacitor cells or secondary battery cells, and wherein the energy of one selected capacitor cell or secondary battery cell is transferred to another of the cells or to another of the energy storage devices.

23. An electrical energy storage device comprising a plurality of unit energy storage devices connected in series to each other each having a single electrical energy storage cell or a plurality of electrical energy storage cells, and comprising a cell energy adjustment device;

wherein

said cell energy adjustment device is provided with a device to measure the energy amounts of each of the unit energy storage devices, to memorize and process said measured energy amount, and to control operation of switching circuits, to transfer, via a transformer, energy charged in any one of the unit energy storage devices; and

a plurality of coils are provided corresponding to each of said unit energy storage devices;

transformers are provided corresponding to respective energy storage devices;

a circuit is configured connecting the transformer coils, switching circuits, and rectifying circuits; and

energy is transferred directly from a selected one unit energy storage device to another unit energy storage device.

24. An energy storage device comprising a plurality of energy storage cells connected in series to each other and a cell energy adjustment device to adjust the energy amount of each of the cells;

wherein

said energy adjustment device comprises first switching circuits connected in series to said energy storage cells, and a first transformer comprising a plurality of coils connecting said first switching circuits to said series of the energy storage cells; and

each of said first switching circuits comprises a first FET and either one of a diode connected in series to and in a direction opposed to a first parasitic diode of said first FET or a second FET having a second parasitic diode in a direction opposed to said first parasitic diode of said first FET.

25. An energy storage device comprising a plurality of first energy storage devices connected in series to each other, and an energy adjustment device which adjusts the energy amounts of said first energy storage devices;

wherein

said energy adjustment device comprises first switching circuits connected in series with said first energy storage devices, and a first transformer comprising a plurality of coils connecting said first switching circuits to said first energy storage devices; and

each of said first switching circuits comprises a first FET, and either one of a diode connected in series to and in a direction opposed to a first parasitic diode of said first FET or a second FET having a second parasitic diode in a direction opposed to said first parasitic diode of said first FET.

26. The energy storage device according to claim 25, wherein

each of said first energy storage devices comprises a plurality of second energy storage devices; and second switching circuits connected in series to said respective second energy storage devices;

each of said switching circuits is connected in series to each of said second energy storage devices and one of the coils of a second transformer comprising a plurality of coils; and

,

each of said second switching circuits comprises a third FET and either one of a diode connected in series to and in a direction opposed to a third parasitic diode of said third FET or a fourth FET having a fourth parasitic diode in a direction opposed to said third parasitic diode of said third FET.

27. The energy storage device according to claim 26, wherein each of said second energy storage devices comprises a single capacitor or a single secondary battery.

28. The energy storage device according to claim 26, wherein each of said second energy storage devices comprises a plurality of capacitors or a plurality of secondary batteries, connected in series to each other.

29. A cell energy adjustment device for adjusting the energy amount of each of cells in a plurality of first energy storage devices, wherein a first switching circuit is formed by a FET and Schottky barrier diode connected in parallel to each other, said first switching circuit is connected in series to one of said first energy storage devices and to one coil of a first transformer comprising a plurality of coils, and a plurality of first energy storage devices connected to coils of said first transformer are connected in series to each other.

30. The cell energy adjustment device according to claim 29, wherein each of said first energy storage devices comprises a single capacitor cell or a single secondary battery cell.

31. The cell energy adjustment device according to claim 29, wherein each of said first energy storage devices comprises a plurality of second energy storage devices;

each of said second energy storage devices is connected, together with a second switching circuit comprising a FET and a Schottky barrier diode connected in parallel to each other, to one coil of a second transformer comprising a plurality of coils, and a plurality of said second energy storage devices connected to said second transformer coils are connected in series to each other.

32. The cell energy adjustment device according to claim 31, wherein each of said second energy storage devices comprises a plurality of capacitor cells or a plurality of secondary battery cells, connected in series to each other.

33. The cell energy adjustment device according to claim 31, wherein each of said second energy storage devices comprises a single capacitor cell or a single secondary battery cell.