Voltage balancing circuit for multi-cell modules

• US 20050269988A1
• Filed: 09/24/2004
• Published: 12/08/2005
• Est. Priority Date: 06/04/2004
• Status: Abandoned Application

• Current Assignee: Tesla Inc.
• Original Assignee: Maxwell Technologies Incorporated (Tesla Inc.)
• Inventors: Thrap, Guy C.
• Application Number:
  US10/948,892
• Publication Number:
  US 20050269988A1
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

An energy storage module includes a number of cells coupled in series between two end terminals, and intermediate terminal or terminals providing access to one or more junctions between individual cells of the module. Voltages of the module'"'"'s cells are balanced by an intra-module voltage balancer. Two or more such modules are connected in series. To balance voltages of the modules, inter-module voltage balancers are used. In one embodiment, an inter-module voltage balancer is connected to a junction of two modules and to intermediate terminals of the two modules. The inter-module balancer attempts to balance voltages of one or more cells of one of the two modules against one or more cells of the other module. Through operation of the intra-module balancers of each module, voltages of both modules are balanced.

Claims

1. An electric energy storage module, comprising:

a first end terminal and a second end terminal;

a plurality of energy storage cells connected in series between the first end terminal and a second end terminal to provide voltage output from the first and the second end terminals;

a holder capable of holding the plurality of energy storage cells;

an intra-module voltage balancer capable of equalizing voltages of the energy storage cells; and

at least one intermediate terminal coupled to one or more common junction of two of the energy storage cells, wherein the first end terminal, the second end terminal, and wherein the at least one intermediate terminal are externally accessible.

2. A module according to claim 1, wherein the holder comprises an enclosure surrounding and containing the plurality of energy storage cells and the intra-module voltage balancer.

3. A module according to claim 2, wherein the plurality of energy storage cells comprises a plurality of double layer capacitors.

4. A module according to claim 2, wherein each energy storage cell of the plurality of energy storage cells comprises a capacitor.

5. A module according to claim 2, wherein the plurality of energy storage cells comprises a plurality of secondary cells.

6. A module according to claim 2, wherein the intra-module voltage balancer comprises a flyback circuit.

7. A module according to claim 2, wherein the intra-module voltage balancer comprises a shunt balancer.

8. A module according to claim 2, wherein the intra-module balancer comprises an active balancer.

9. A module according to claim 1, wherein:

the at least one intermediate terminal includes one intermediate terminal coupled to a first common junction of two of the energy storage cells; and

the first common junction is in the middle of the series of the energy storage cells so that exactly a first number of energy storage cells are present between the first common junction and the first end terminal, and exactly the first number of energy storage devices are present between the first common junction and the second end terminal.

10. A module according to claim 9, wherein the first number is equal to one.

11. A module according to claim 1, wherein:

the at least one intermediate terminal includes a first intermediate terminal coupled to a first common junction of two of the energy storage cells, and a second intermediate terminal coupled to a second common junction of two of the energy storage cells; and

a first number of energy storage cells are present between the first common junction and the first end terminal, and the first number of energy storage cells are present between the second common junction and the second end terminal.

12. A module according to claim 11, wherein the first number is equal to one.

13. A module according to claim 11, wherein the first number is greater than one.

14. An energy storage apparatus, comprising:

a plurality of energy storage modules; and

one or more inter-module voltage balancer connected to the plurality of energy storage modules to equalize voltages of the modules, wherein each module of the plurality of energy storage modules comprises;

a first end terminal and a second end terminal,

a plurality of energy storage cells connected in series between the first end terminal and a second end terminal of said each module to provide voltage output from the first and the second end terminals of said each module,

a holder capable of holding the plurality of energy storage cells of said each module, an intra-module voltage balancer capable of equalizing voltages of the energy storage cells of said each module, and

at least one intermediate terminal coupled to one or more common junction of two of the energy storage cells of said each module; and

wherein the first end terminal, the second end terminal, and the at least one intermediate terminal of said each module are externally accessible and connected to the at least one inter-module voltage balancer.

15. An energy storage apparatus according to claim 14, wherein the holder of said each module comprises an enclosure surrounding and containing the plurality of energy storage cells of said each module and the intra-module voltage balancer of said each module.

16. An energy storage apparatus according to claim 15, wherein the inter-module voltage balancer directly equalizes voltages of combinations of fewer than all cells of said each module, and indirectly equalizes voltages of the modules.

17. An energy storage apparatus according to claim 15, wherein:

the at least one intermediate terminal of said each module includes one intermediate terminal coupled to a first common junction of two of the energy storage cells of said each module; and

the first common junction of said each module is in the middle of the series of the energy storage cells of said each module so that exactly a first number of energy storage cells are present between the first common junction and the first end terminal of said each module, and exactly the first number of energy storage devices are present between the first common junction and the second end terminal of said each module.

18. An energy storage apparatus according to claim 17, wherein the first number is equal to one.

19. An energy storage apparatus according to claim 17, wherein the first number is greater than one.

20. An energy storage apparatus according to claim 17, wherein the plurality of energy storage cells of said each module comprises a plurality of double layer capacitors.

21. An energy storage apparatus according to claim 15, wherein:

the at least one intermediate terminal of said each module includes a first intermediate terminal coupled to a first common junction of two of the energy storage cells of said each module, and a second intermediate terminal coupled to a second common junction of two of the energy storage cells of said each module; and

a first number of energy storage cells are present between the first common junction and the first end terminal of said each module, and the first number of energy storage cells are present between the second common junction and the second end terminal of said each module.

22. An energy storage apparatus according to claim 21, wherein the first number is equal to one.

23. An energy storage apparatus according to claim 21, wherein the first number is greater than one.

24. An energy storage apparatus according to claim 21, wherein the plurality of energy storage cells of said each module comprises a plurality of double layer capacitors.

32. An energy storage device of claim 16, wherein the inter-module balancer comprises a flyback circuit.

33. An energy storage device of claim 16, wherein the inter-module balancer comprises a shunt balancer.

34. An energy storage device of claim 16, wherein the inter-module balancer comprises an active balancer.

25. An energy storage device, comprising:

a first module comprising;

a first end terminal and a second end terminal, a first plurality of energy storage cells connected in series between the first end terminal and the second end terminal to provide voltage output from the first and the second end terminals,

a first holder capable of holding the first plurality of energy storage cells,

a first intra-module voltage balancer capable of equalizing voltages of the energy storage cells of the first plurality, and

a first intermediate terminal coupled to a common junction of two of the energy storage cells of the first plurality, wherein the first end terminal, the second end terminal, and the first intermediate terminal of the first module are externally accessible;

a second module comprising;

a third end terminal and a fourth end terminal,

a second plurality of energy storage cells connected in series between the third end terminal and the fourth end terminal to provide voltage output from the third and the fourth end terminals,

a second holder capable of holding the second plurality of energy storage cells,

a second intra-module voltage balancer capable of equalizing voltages of the energy storage cells of the second plurality, and

a second intermediate terminal coupled to a common junction of two of the energy storage cells of the second plurality, wherein the third end terminal, the fourth end terminal, and the second intermediate terminal are externally accessible; and

an inter-module voltage balancer, wherein the first module and the second module are connected in series so that the second end terminal of the first module is coupled to the third end terminal of the second module, and wherein the inter-module voltage balancer is connected to the second end terminal of the first module, the first intermediate terminal of the first module, and to the second intermediate terminal of the second module to equalize directly voltage of cells located between the first intermediate terminal and the second end terminal of the first module and voltage of cells located between the second intermediate terminal and the third end terminal of the second module.

26. The energy storage device of claim 25, wherein the first holder comprises a first enclosure surrounding and containing the first plurality of energy storage cells and the first intra-module voltage balancer, and the second holder comprises a second enclosure surrounding and containing the second plurality of energy storage cells and the second intra-module voltage balancer.

27. The energy storage device of claim 25, wherein the first plurality of cells comprises a plurality of double layer capacitors, and the second plurality of cells comprises a plurality of double layer capacitors.

28. The energy storage device of claim 25, wherein exactly one cell is located between the first intermediate terminal and the second end terminal of the first module, and exactly one cell is located between the second intermediate terminal and the third end terminal of the second module.

29. The energy storage device of claim 25, wherein exactly the same number of cells is located between the first intermediate terminal and the second end terminal of the first module as the number of cells located between the second intermediate terminal and the third end terminal of the second module.

30. The energy storage device of claim 29, wherein at least two cells are located between the first intermediate terminal and the second end terminal of the first module.

31. A method of equalizing voltages of rechargeable multi-cell modules with intra-module voltage balancers, the modules being connected in series, each module comprising a plurality of energy storage cells connected in series between a first end terminal and a second end terminal, the method comprising:

providing an inter-module voltage balancer;

connecting the inter-module voltage balancer between two adjacent modules of the plurality of modules; and

operating the inter-module voltage balancer to balance directly voltages of combinations of fewer than all cells of each module, thereby equalizing indirectly voltages of the modules.

35. A energy storage system, comprising:

a plurality of modules, each module comprising a plurality of interconnected double-layer capacitors;

one or more intra-module balancer, wherein between each double-layer capacitor there is interconnected one intra-module balancer to equalize voltages of the double-layer capacitors; and

one or more inter-module balancer, wherein between each module there is interconnected one inter-module balancer to equalize voltages appearing across the modules.

36. The energy storage system of claim 35, wherein the plurality of modules comprise an enclosure surrounding and containing the interconnected double-layer capacitors.

37. The energy storage system of claim 35, wherein the inter-module balancer equalizes voltages across one or more double-layer capacitor in one module against voltages across one or more double-layer capacitor in a second module.

38. The energy storage device of claim 37, wherein the voltages across the one or more double-layer capacitor is less than the voltages across the modules.