Method and apparatus for managing energy in plural energy storage units

• US 7,615,966 B2
• Filed: 05/28/2002
• Issued: 11/10/2009
• Est. Priority Date: 05/25/2001
• Status: Expired due to Term

• Current Assignee: Texas Instruments Northern Virginia, Inc. (Texas Instruments, Inc.)
• Original Assignee: Texas Instruments Northern Virginia, Inc. (Texas Instruments, Inc.)
• Inventors: Houldsworth, John, Stirk, Gary L.
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Muralidar; Richard V
• Application Number:
  US10/478,757
• Publication Number:
  US 20050024015A1
• Time in Patent Office: 2,723 Days
• Field of Search: 320/119, 320/118, 320/116, 320/132
• US Class Current: 320/132
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A system for managing energy stored in a plurality of series connected energy storage units has a plurality of energy storage unit controllers, each controller being associated with one of the plurality of energy storage units, a balancing circuit between two of the energy storage units, the balancing circuit being controlled by at least one of the energy storage unit controllers, a serial electrical interface between the energy storage unit controllers for providing voltage isolated bi-directional communication, and a central controller in electrical communication with the energy storage unit controllers. A method for managing charge in a plurality of series connected energy storage units forming an energy storage device includes monitoring a current supplied to the energy storage device, determining at least one of a charging rate and a capacity of a first energy storage unit and a second energy storage unit in the energy storage device, and diverting current from the first energy storage unit to the second energy storage unit in response to the steps of monitoring and determining.

Claims

1. A system for managing energy stored in a plurality of series connected energy storage units, the system comprising:

a plurality of energy storage unit controllers, each controller being associated with one of the plurality of energy storage units;

a current pump circuit to transfer energy between each individual one of the energy storage units and another individual one of the energy storage units, the current pump circuit being controlled by at least one of the energy storage unit controllers;

a central controller in electrical communication with the energy storage unit controllers, the central controller having a measuring function and a charge movement function separate from the measuring function whereby energy storage unit imbalance can be anticipated before it occurs; and

a serial electrical interface between the energy storage unit controllers for providing voltage isolated bi-directional communication to control the energy storage unit controllers to transfer energy between the energy storage units, the serial electrical interface being configured to connect the central controller to a first communication port of a first energy storage unit controller and to connect a second communication port of the first energy storage unit controller to a first communication port of a second energy storage unit controller.

2. The system of claim 1, wherein the energy storage unit comprises two or more storage cells and wherein the energy storage unit controller monitors a parameter of the associated energy storage unit selected from the group consisting of voltage, temperature, and current.

3. The system of claim 1, wherein the current pump circuit includes a reactive element and at least one switch, the switch being controlled by at least one of the energy storage unit controllers.

4. The system of claim 1, wherein a voltage monitored by any one energy storage unit controller is no more than 5 V.

5. The system of claim 1, wherein the communications are digital communications.

6. The system of claim 1, comprising a current sense resistor in series with the energy storage units and wherein the central controller monitors a current in the current sense resistor.

7. The system of claim 1, comprising a disconnect switch in series with the energy storage units and wherein the disconnect switch is operatively interfaced to the central controller.

8. The system of claim 1, wherein the storage unit controllers can be a separate integrated circuit, a discrete component, or a hybrid of an integrated circuit and a discrete component.

9. The system of claim 1, wherein the integrated circuit can be in a multi-chip module.

10. The system of claim 1, wherein the serial electrical interface provides bi-directional, two way alternate, using bit asynchronous transfer, byte synchronous logical ring with contra flow.

21. The system of claim 1 wherein the measuring function is determined by an energy storage unit voltage or weighted excursion thereof and a proportion of load current scaled according to a learned capacity delta.

22. The system of claim 21 wherein the current pump circuit is operated at a single rate and charge movement is controlled by time-proportioning.

23. The system of claim 1 further comprising a control loop monitoring a polarity of current supplied to or diverted from an energy storage unit with which it is associated for a given weighted voltage of the energy storage unit and a load current.

11. A system for managing energy stored in plural series connected energy storage units comprising:

first means for monitoring voltage across a first energy storage unit;

second means for separately monitoring voltage across a second energy storage unit;

means for transferring charge between each individual one of the first and second energy storage units and another individual one of the first and second energy storage units by exchanging energy between the first and second energy storage units in response to the first and second monitoring means during at least one of charging and discharging of the first and second energy storage units, the charge transferring means including a reactive equalization circuit;

means for controlling the first and second means for monitoring voltage wherein the means for controlling is a central controller having a measuring function and a charge movement function separate from the measuring function whereby energy storage unit imbalance can be anticipated before it occurs; and

means for voltage isolated bi-directional communications between the first and second monitoring means to control the first and second monitoring means to transfer energy between the first and second energy storage units, the communications means connecting the controlling means to a first communication port of the first monitoring means and connecting a second communication port of the first monitoring means to a first communication port of the second monitoring means.

12. The system of claim 11, wherein the first monitoring means monitors a temperature of the first energy storage unit.

13. The system of claim 11, wherein the second monitoring means monitors a temperature of the second energy storage unit.

14. The system of claim 11, wherein the charge transferring means includes an inductor to store energy from one energy storage unit for transfer to the other energy storage unit, at least one switch and a diode connected across each switch in the reactive equalization circuit.

15. The system of claim 11, comprising means for monitoring current in the plural series connected energy storage units.

16. The system of claim 11, wherein the communications are digital communications.

17. The system of claim 11, comprising a disconnect switch in series with the energy storage units.

18. The system of claim 11, wherein each of the first and second monitoring means is a dedicated controller.

24. The system of claim 11 wherein the measuring function is determined by an energy storage unit voltage or weighted excursion thereof and a proportion of load current scaled according to a learned capacity delta.

25. The system of claim 24 wherein the charge transferring means comprises a current pump circuit operated at a single rate and charge movement is controlled by time-proportioning.

26. The system of claim 11 further comprising control loop means monitoring a polarity of current supplied to or diverted from an energy storage unit with which it is associated for a given weighted voltage of the energy storage unit and a load current.

19. A method for managing charge in a plurality of series connected energy storage units forming an energy storage device, the method comprising:

measuring in a central controller a current supplied to the energy storage device;

determining in the central controller at least one of a charging rate and a capacity of a first energy storage unit and a second energy storage unit in the energy storage device, the central controller having the measuring function and a charge movement function separate from the measuring function whereby energy storage unit imbalance can be anticipated before it occurs; and

transferring energy from each individual one of the first and second energy storage units to another individual one of the first and second energy storage units in response to the steps of measuring and determining.

20. The method of claim 19, wherein the storage unit balancing current compensates for an impedance of the storage unit.

27. The method of claim 19 wherein the measuring is determined by an energy storage unit voltage or weighted excursion thereof and a proportion of load current scaled according to a learned capacity delta.

28. The method of claim 19 further comprising measuring by a control loop a polarity of current supplied to or diverted from an energy storage unit with which it is associated for a given weighted voltage of the energy storage unit and a load current.