Management device, electric storage device, electric storage system and electric apparatus for managing charging and discharging of a plurality of electric storage cells connected in series
Charging and discharging of a plurality of electric storage cells connected in series are: managed by equalizing voltages of a plurality of electric storage cells; and, without disconnecting or shifting an electrical connection between (a) the plurality of electric storage cells and (b- 1 ) a load which uses electric power of the plurality of electric storage cells or (b- 2 ) a charging device which charges the plurality of electric storage cells, (i) sending electric power of the plurality of electric storage cells to an external apparatus which is different from the load and the charging device, or (ii) receiving receives electric power supplied to the plurality of electric storage cells from the external apparatus.
1. An electric storage system comprising:
a plurality of electric storage cells connected in series to each other;
a plurality of electric storage devices, each of the plurality of electric storage devices being connected in series to each other, each of the plurality of electric storage devices includes:
a corresponding plurality of electric storage cells from among the plurality of electric storage cells; and
a management device configured to manage charging and discharging of the corresponding plurality of electric storage cells;
an electric power line electrically connectable to each of a plurality of management devices; and
a controller;
wherein
the electric power line includes a low potential bus and a high potential bus, a first electric storage device among the plurality of electric storage devices further includes:
a first terminal equipotentially connected to the low potential bus and a negative pole end of the corresponding plurality of electric storage cells; and
a second terminal equipotentially connected to the high potential bus and a positive pole end of the corresponding plurality of electric storage cells;
each of one or more other electric storage devices except for the first electric storage device, among the plurality of electric storage devices further include:
an insulated bidirectional DC-DC converter,
wherein two terminals of a primary side of the insulated bidirectional DC-DC converter are connected to a positive pole end and a negative pole end of the corresponding plurality of electric storage cells, and two terminals of a secondary side of the insulated bidirectional DC-DC converter are connected to the low potential bus and the high potential bus; and
the controller is configured to control an operation of the DC-DC converter.
2. The electric storage system according to claim 1 , wherein
the insulated bidirectional DC-DC converter provided at each of the one or more other electric storage devices is configured to (i) send electric power of the corresponding plurality of electric storage cells to an external apparatus which is different from the load and the charging device, or (ii) receive electric power supplied to the corresponding plurality of electric storage cells from the external apparatus without disconnecting or shifting an electrical connection between (a) the corresponding plurality of electric storage cells and (b- 1 ) a load which uses electric power of the corresponding plurality of electric storage cells or (b- 2 ) a charging device which charges the corresponding plurality of electric storage cells, and
the external apparatus comprises one or more electric storage cells which are arranged between (a) the corresponding plurality of electric storage cells and (b- 1 ) the load or (b- 2 ) the charging device, and are connected in series to the corresponding plurality of electric storage cells.
3. The electric storage system according to claim 1 , wherein the insulated bidirectional DC-DC converter provided at each of the one or more other electric storage devices adjusts a voltage to be sent or received.
4. The electric storage system according to claim 1 , wherein the insulated bidirectional DC-DC converter provided at each of the one or more other electric storage devices starts sending or receiving electricity in response to receiving a signal for starting sending or receiving electricity, or stops sending or receiving electricity in response to receiving a signal for stopping sending or receiving electricity.
5. The electric storage system according to claim 1 , wherein a rated voltage of the first electric storage device and a rated voltage of at least one of the one or more other electric storage devices are different from each other.
6. The electric storage system according to claim 1 , wherein a number of the corresponding plurality of electric storage cells managed by the first electric storage device and a number of the corresponding plurality of electric storage cells managed by at least one of the one or more other electric storage devices are different from each other.
7. An electric apparatus comprising:
the electric storage system according to claim 1 ; and
a load which uses electric power of the electric storage system.
8. The electric storage system according to claim 1 , wherein
the first electric storage device further includes an equalization unit which equalizes voltages of the corresponding plurality of electric storage cells, and
the one or more other electric storage devices further include an equalization unit which equalizes voltages of the corresponding plurality of electric storage cells.
9. The electric storage system according to claim 1 , wherein:
the first electric storage device is arranged on a most negative pole side.
10. The electric storage system according to claim 9 , wherein
the positive pole end and the negative pole end of the corresponding plurality of electric storage cells in the first electric storage device are physically connected to the electric power line and always electrically connected to the electric power line.
11. The electric storage system according to claim 1 , wherein
the insulated bidirectional DC-DC converter includes:
a transformer including a first coil and a second coil, a first end of the first coil being connected to the positive pole end of the corresponding plurality of electric storage cells, and a first end of the second coil being connected to the terminal connected to the high potential bus;
a first switching element, a first end of which is connected to a second end of the first coil, and a second end of which is connected to the negative pole end of the corresponding plurality of electric storage cells;
a first diode, a first end of which is connected to the second end of the first coil, and a second end of which is connected to the negative pole end of the corresponding plurality of electric storage cells, the first diode being configured to pass current in a direction from the negative pole end to the positive pole end;
a second switching element, a first end of which is connected to a second end of the second coil, and a second end of which is connected to the terminal connected to the low potential bus; and
a second diode, a first end of which is connected to the second end of the second coil, and a second end of which is connected to the terminal connected to the low potential bus, the second diode being configured to pass current in a direction from the terminal connected to the low potential bus to the terminal connected to the high potential bus.
12. The electric storage system according to claim 11 , wherein
the insulated bidirectional DC-DC converter is a flyback DC-DC converter.
13. The electric storage system according to claim 1 , wherein
the electric storage system further comprises
a control unit which controls transmission of electric power among the plurality of electric storage devices.
14. The electric storage system according to claim 13 , wherein the control unit determines, based on a voltage or State of Charge (SOC) of each of the corresponding plurality of electric storage cells included in each of the plurality of electric storage devices, (i) an electric storage device that sends electricity to the electric power line and (ii) an electric storage device that receives electricity from the electric power line, selecting from the plurality of electric storage devices; and
generates at least one of (i) an instruction to cause the insulated bidirectional DC-DC converter in the electric storage device that sends electricity to the electric power line to start an electricity sending operation, and (ii) an instruction to cause the insulated bidirectional DC-DC converter in the electric storage device that receives electricity from the electric power line to start an electricity receiving operation.
15. The electric storage system according to claim 14 , wherein:
the control unit determines, based on a voltage or State of Charge (SOC) of each of the corresponding plurality of electric storage cells included in each of the plurality of electric storage devices, at least one of (i) an electric storage device that stops the electricity sending operation and (ii) an electric storage device that stops the electricity receiving operation; and
the control unit generates at least one of (i) an instruction to cause the insulated bidirectional DC-DC converter in the electric storage device that stops the electricity sending operation to stop an electricity sending operation, and (ii) an instruction to cause the insulated bidirectional DC-DC converter in the electric storage device that stops the electricity receiving operation to stop an electricity receiving operation.
16. The electric storage system according to claim 13 , wherein
first identification information is provided to each of the plurality of electric storage cells among all of the plurality of electric storage devices, the first identification information being different from each other,
second identification information is provided to each of the plurality of electric storage cells, the second identification information being different from each other within the respective electric storage device, and
when first identification information corresponding to at least one electric storage cell is received from the controller, a corresponding one of the plurality of management devices identifies second identification information corresponding to the at least one electric storage cell based on the received first identification information.
17. The electric storage system according to claim 16 , wherein
the first identification information provided to each of the plurality of electric storage cells is (i) different from the second identification information or (ii) identical to the second identification information.
18. The electric storage system according to claim 16 , wherein
when second identification information corresponding to at least one electric storage cell is received from the controller, the controller identifies first identification information corresponding to the at least one electric storage cell based on the received second identification information.
19. The electric storage system according to claim 18 , wherein one of the plurality of management devices includes a storage unit which stores at least one of the first identification information and the second identification information.