Energy storage device with assembly of energy storage cells and balancing circuit

• US 8,288,991 B2
• Filed: 04/07/2008
• Issued: 10/16/2012
• Est. Priority Date: 04/18/2007
• Status: Active Grant

• Current Assignee: Valeo Equipements Electriques Moteur (Valeo SE)
• Original Assignee: Valeo Equipements Electriques Moteur (Valeo SE)
• Inventors: Sardat, Pierre, Matt, Jean-Claude, Doffin, Hugues, Dessirier, Bruno
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US12/596,376
• Publication Number:
  US 20100090649A1
• Time in Patent Office: 1,653 Days
• Field of Search: 320/107, 320/116, 320/117, 320/118, 320/119
• US Class Current: 320/118
• CPC Class Codes: B60L 2260/46 by self learning
• CPC Class Codes: B60L 3/06 Limiting the traction current under mechanical overload conditions
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The invention relates to an energy storage device, particularly for an automobile, that comprises: an assembly (2) of serially-connected energy storage cells; a balancing circuit adapted for balancing the cells during the discharge thereof by enabling the flow of one or more balancing currents in one or more cells of the assembly (2); optionally a diagnosis system (61) for providing at least one piece of information associated with at least one cell in the assembly; wherein the balancing circuit (10; 41) is adapted for controlling the balancing current(s) based at least on external information independent from the energy-storage cell assembly and/or information associated with at least one of the cells and provided by the optional diagnosis system.

Claims

1. An energy storage device, in particular for a motor vehicle, comprising:

an assembly (2) of energy storage cells (Ci) connected in series;

a balancing circuit connected between the storage cells configured to enable the cells (Ci) to be balanced while they being discharged, by circulating at least one balancing current in at least one of the cells of the assembly (2); and

a diagnostic system (61) configured to enable the delivery of at least one piece of information associated with at least one of the cells of the assembly;

the balancing circuit being configured to control at least one of the balancing current or the duration of balancing (Dr3) at least depending on an external piece of information independent of the assembly of energy storage cells or of the external piece of information associated with at least one of the cells, delivered by the diagnostic system.

2. The device according to claim 1, wherein the diagnostic system is configured to deliver information including temperature information associated with at least one of the cells, voltage information associated with one of the cells, voltage information associated with several cells of the assembly, voltage information at the terminals of the assembly itself.

3. The device according to claim 2, wherein the balancing circuit is configured to allow the intensity of the balancing current to be varied from 0 Amperes to a maximum predetermined value.

4. The device according to claim 3, wherein the balancing circuit (10;

41) is maintained in operation while the temperature associated with at least one of the cells is above a threshold equal to about 40°

C.

5. The device according claim 4, wherein the diagnostic system (61) is configured to control at least one of the starting and the interruption of the balancing circuit.

6. The device according to claim 1, wherein the external piece of information is selected from one of:

voltage information for a battery powering the vehicle'"'"'s onboard network, information issued by a battery management system (BMS), information for activation of the balancing circuit, wherein such information is issued by an engine control system and information linked to an onboard network power supply by detection of an ignition key in position +APC.

7. The device according to claim 6, wherein the balancing circuit is configured so as to be able to function in two modes, a first mode in which the balancing of the energy storage cells is accompanied by one or more low balancing currents, when the vehicle is stationary, and a second mode in which the balancing of the cells is accompanied by one or more strong balancing currents, when the vehicle is moving.

8. The device according to claim 7, wherein the balancing circuit switches from the first mode to the second mode once the voltage at the terminals of a battery of the vehicle or at the terminals of the assembly of cells exceeds a predetermined threshold equal to 12 to 13 Volts.

9. The device according to claim 1, further comprising an oscillator (62) configured to control at least one of the starting and the interruption of the balancing circuit intermittently via the diagnostic system (61).

10. The device according to claim 9, wherein the oscillator (62) is configured to control the starting and the interruption of the diagnostic system (61).

11. The device according to claim 9, wherein the fact that the oscillator directly controls the balancing circuit.

12. The device according to claim 9, wherein the balancing circuit is configured to function for a predetermined period after being started by the oscillator (62), then, depending on the circumstances, to switch itself off after this predetermined period.

13. The device according to claim 1, wherein the balancing circuit comprises one or more transformers of the flyback type.

14. The device according to claim 1, wherein the balancing circuit is configured to allow an intensity of the balancing current or currents to be varied depending on the state of ageing of the cell or cells, the ageing is determined by at least one of the following pieces of information:

a value of the internal resistance of the energy storage cell or cells (ESR or Equivalent Series Resistance), a capacitance value of the energy storage cell or cells, the state of charge of one or more cells (SOC), the state of energy of one or more cells (SOE).

15. The device according to claim 1, wherein the balancing is realized intermittently;

and wherein the duration (Dr3) of at least one of a balancing phase and the duration (Dr4) between two successive triggerings of the balancing are linked to the state of ageing of the cell or of the cells Ci, the ageing being determined by at least one of the following pieces of information;

a value of the internal resistance of the energy storage cell or cells (ESR or Equivalent Series Resistance), a capacitance value of the energy storage cell or cells, the state of charge of one or more cells (SOC), the state of energy of one or more cells (SOE).

16. The device according to claim 1, wherein the balancing is realized intermittently;

and wherein the duration (Dr2) between two signals for the reactivation of balancing is selected depending on the state of ageing of the cell or of the cells, the ageing being determined by at least one of the following pieces of information;

a value of the internal resistance of the energy storage cell or cells (ESR or Equivalent Series Resistance), a capacitance value of the energy storage cell or cells, the state of charge of one or more cells (SOC), the state of energy of one or more cells (SOE).

17. The device according to claim 1, wherein the diagnostic system is configured to deliver end-of-life information for the energy storage cell or cells, the information is in the form of a warning signal, as a function of at least one of the frequency of activation of the balancing circuit and the intensity of the balancing current or currents.

18. An energy storage device, in particular for a motor vehicle, comprising:

an assembly (2) of energy storage cells (Ci) connected in series;

a balancing circuit connected to the cells configured to enable balancing of the cells (Ci) while they are being discharged; and

an oscillator (62) configured to enable at least one of an intermittent triggering and a stoppage of the balancing circuit.

19. A method for balancing during a discharge, when the motor vehicle is stationary or running, of an energy storage device associated with the motor vehicle comprising an assembly (2) of energy storage cells connected in series, the method comprising the following steps:

enabling a balancing of the cells (Ci) while they are being discharged, by circulating one or more balancing currents in one or more cells of the assembly (2); and

controlling the balancing current or currents, in particular to provoke the triggering of the balancing, at least depending on an external piece of information independent of the assembly of energy storage cells and/or information associated with at least one of the cells.

20. The method according to claim 19, wherein the optimization of the ratios (Dr1/Dr2), where Dr1 is a duration of a balancing activation signal and Dr2 is a duration between two signals for reactivation of a balancing phase, and (Dr3/Dr4), where Dr3 is a duration of the balancing phase and Dr4 is a duration between successive triggerings of a balancing phase, and of the intensity (Ip) is selected so as, firstly, to minimize the auto-discharge of the assembly of cells (Ci) in order to optimize the rate of availability of the assembly of cells (Ci) depending on the service profile and its state of ageing, and secondly, to have an image of the state of health of the assembly of cells (Ci) which can be utilized in a strategy for predicting the end of life of the assembly of cells (Ci).

21. An energy storage device (1′

), in particular for a motor vehicle, comprising;

an assembly (2) of energy storage cells (Ci) connected in series; and

a balancing circuit (10′

) connected to the cells configured to enable, in a first phase (Ph1), a discharge and a balancing of the cells (Ci) up to at least a low predetermined threshold (Einf) of voltage at the terminals of the energy storage cells and, in a second phase (Ph2) which follows the first phase, an accelerated discharge of the cells below the low predetermined threshold.

22. The device according to claim 21, wherein the balancing circuit is configured so that at the end of the second phase (Ph2), the voltage at the terminals of each of the cells (Ci) is essentially zero.

23. The device according to claim 22, wherein the balancing circuit (10′

) is configured so that the duration of the first phase (Ph1) is greater than that of the second phase (Ph2) at least 10 times to at least 100 times greater.

24. The device according to claim 23, wherein the balancing circuit (10′

) ceases the forced balancing of the cells at the end of the first phase.

25. An energy storage device comprising:

an assembly (2) of energy storage cells (Ci) connected in series; and

a balancing circuit (10;

41) connected to the energy storage cells configured to enable the drawing of energy from at least one of said cells and the distribution of the energy is thus drawn to at least one other of said cells;

the balancing circuit (10) being configured to allow, during one phase of discharge of the energy storage device, the charging voltage of at least one of the cells to be increased only with the energy drawn from at least one of the energy storage cells of the device;

the balancing circuit (10) being also configured to enable symmetrical discharge of the cells (Ci) to a voltage at least 3 times weaker than the maximum serviceable voltage of the cells at least 10 times weaker to at least 20 times weaker.

26. The device according to claim 25, wherein the balancing circuit (10) is configured so that it can be permanently connected to a power supply network of a motor vehicle.