Battery system and energy storage system including same
A battery system is disclosed. The battery system includes a plurality of battery cells, and a battery cell balancing unit, configured to adjust voltages across each of the battery cells to reduce variation among the voltages across the battery cells. The battery cell balancing unit includes a controller configured to receive a DC reference current and to generate an AC current based on the DC reference current, a transformer, a rectifier circuit including a rectifier connected to the output coil, and a switching unit including a plurality of switches, each configured to selectively connect the rectifier to one of the battery cells.
1. A battery system, comprising:
a plurality of battery cells; and
a battery cell balancing unit, configured to adjust voltages across each of the battery cells to reduce variation among the voltages across the battery cells, the battery cell balancing unit comprising:
a controller configured to receive a DC reference current and to generate an AC current based on the DC reference current,
a transformer comprising an input coil configured to receive the AC current, and an output coil coupled to the input coil,
a rectifier circuit comprising a rectifier connected to the output coil, and
a switching unit comprising a plurality of switches, each configured to selectively connect the rectifier to one of the battery cells.
2. The battery system of claim 1 , wherein the transformer comprises a plurality of output coils coupled to the input coil, and the rectifier circuit comprises a plurality of rectifiers, each connected to one of the output coils.
3. The battery system of claim 1 , wherein the transformer comprises a plurality of input coils configured to receive the AC current, and a plurality of output coils, each coupled to one of the input coils, wherein the rectifier circuit comprises a plurality of rectifiers, each connected to one of the output coils.
4. The battery system of claim 3 , wherein the input coils are serially connected.
5. The battery system of claim 4 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
6. The battery system of claim 3 , wherein the input coils are connected in parallel.
7. The battery system of claim 6 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
8. The battery system of claim 2 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
9. The battery system of claim 1 , further comprising a battery management system (BMS), configured to provide the reference current to the battery cell balancing unit.
10. The battery system of claim 9 , wherein the AC current is provided to the transformer by the controller according to a state of a switch controlled by a signal from the controller.
11. The battery system of claim 9 , wherein the reference current is a variable current.
12. The battery system of claim 1 , wherein the switching unit receives a switching control signal from a battery management system.
13. An energy storage system, comprising:
a battery system, comprising:
a plurality of battery cells, and
a battery cell balancing unit, configured to adjust voltages across each of the battery cells to reduce variation among the voltages across the battery cells, the battery cell balancing unit comprising:
a controller configured to receive a DC reference current and to generate an AC current based on the DC reference current,
a transformer comprising an input coil configured to receive the AC current, and an output coil coupled to the input coil,
a rectifier circuit comprising a rectifier connected to the output coil, and
a switching unit comprising a plurality of switches, each configured to selectively connect the rectifier to one of the battery cells; and
a power conversion system, comprising a controller, configured to charge the battery system with power from either a power generation system or a grid, and to discharge the battery system by providing power from the battery system to a load.
14. The energy storage system claim 13 , wherein the transformer comprises a plurality of output coils coupled to the input coil, and the rectifier circuit comprises a plurality of rectifiers, each connected to one of the output coils.
15. The energy storage system claim 13 , wherein the transformer comprises a plurality of input coils configured to receive the AC current, and a plurality of output coils, each coupled to one of the input coils, wherein the rectifier circuit comprises a plurality of rectifiers, each connected to one of the output coils.
16. The energy storage system claim 15 , wherein the input coils are serially connected.
17. The energy storage system claim 16 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
18. The energy storage system claim 15 , wherein the input coils are connected in parallel.
19. The energy storage system claim 18 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
20. The energy storage system claim 14 , wherein each of the rectifiers comprises:
an inductor;
first and second diodes connected to the inductor; and
a capacitor connected to the inductor.
21. The energy storage system claim 13 , further comprising a battery management system (BMS), configured to provide the reference current to the battery cell balancing unit.
22. The energy storage system claim 21 , wherein the AC current is provided to the transformer by the controller according to a state of a switch controlled by a signal from the controller.
23. The energy storage system claim 21 , wherein the reference current is a variable current.
24. The energy storage system claim 13 , wherein the switching unit receives a switching control signal from a battery management system.