Circuits and methods for determination and control of signal transition rates in electrochemical cells

• US 9,312,577 B2
• Filed: 11/09/2012
• Issued: 04/12/2016
• Est. Priority Date: 11/09/2012
• Status: Expired due to Fees

• Current Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Original Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Inventors: Jamison, David Kay
• Primary Examiner(s): Williams, Arun
• Application Number:
  US13/673,065
• Publication Number:
  US 20140132220A1
• Time in Patent Office: 1,250 Days
• Field of Search: 320/129
• US Class Current: 1/1
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A charge/discharge input is for respectively supplying charge to, or drawing charge from, an electrochemical cell. A transition modifying circuit is coupled between the charge/discharge input and a terminal of the electrochemical cell and includes at least one of an inductive constituent, a capacitive constituent and a resistive constituent selected to generate an adjusted transition rate on the terminal sufficient to reduce degradation of a charge capacity characteristic of the electrochemical cell. A method determines characteristics of the transition modifying circuit. A degradation characteristic of the electrochemical cell is analyzed relative to a transition rate of the charge/discharge input applied to the electrochemical cell. An adjusted transition rate is determined for a signal to be applied to the electrochemical cell that will reduce the degradation characteristic. At least one of an inductance, a capacitance, and a resistance is selected for the transition modifying circuit to achieve the adjusted transition rate.

Claims

1. A circuit, comprising:

one or more electrochemical cells;

a charge/discharge circuit configured to respectively generate charge pulses and discharge pulses to the one or more electrochemical cells, wherein the charge pulses and discharge pulses include a first transition rate; and

a transition modifying circuit operably coupled between the charge/discharge circuit and a terminal of the one or more electrochemical cells, the transition modifying circuit comprising at least one circuit element configured to receive and modify the charge pulses and discharge pulses to exhibit an adjusted transition rate on the terminal that is slower than the first transition rate and sufficient to reduce degradation of one or more charge capacity characteristics of the one or more electrochemical cells, wherein the first transition rate and the adjusted transition rate include rise and fall times for their respective pulses.

2. The circuit of claim 1, wherein the transition modifying circuit comprises at least one of an inductive constituent, a capacitive constituent, and a resistive constituent configured to generate the adjusted transition rate on the terminal.

3. The circuit of claim 1, wherein the transition modifying circuit comprises:

an inductor operably coupled between the charge/discharge circuit and the terminal of the one or more electrochemical cells and for supplying an inductive constituent; and

a capacitor operably coupled between the charge/discharge circuit and a ground terminal of the one or more electrochemical cells and for providing a capacitive constituent.

4. The circuit of claim 3, wherein the capacitor has a capacitance value configured to produce at least one of a transition rate of the charge/discharge circuit, the transition rate on the terminal, a measured characteristic of the one or more electrochemical cells, or a combination thereof.

5. The circuit of claim 3, wherein the inductor has an inductance value configured to produce at least one of a transition rate of the charge/discharge circuit, the transition rate on the terminal, a measured characteristic of the one or more electrochemical cells, or a combination thereof.

6. The circuit of claim 3, further comprising:

monitoring hardware operably coupled to the one or more electrochemical cells and configured to measure one or more characteristics of the one or more electrochemical cells; and

an analysis module operably coupled to the monitoring hardware and the transition modifying circuit;

wherein the capacitor comprises an element in which capacitance can be varied and the analysis module is configured to adjust the capacitance responsive to at least one of a transition rate of the charge/discharge circuit, the transition rate on the terminal, the one or more characteristics of the one or more electrochemical cells, or a combination thereof.

7. The circuit of claim 3, further comprising:

monitoring hardware operably coupled to the one or more electrochemical cells and configured to measure one or more characteristics of the one or more electrochemical cells; and

an analysis module operably coupled to the monitoring hardware and the transition modifying circuit;

wherein the inductor comprises a variable inductor and the analysis module is configured to adjust the inductance of the variable inductor responsive to at least one of a transition rate of the charge/discharge circuit, the transition rate on the terminal, the one or more characteristics of the one or more electrochemical cells, or a combination thereof.

8. A method, comprising:

supplying a charge/discharge input signal for one or more electrochemical cells, the charge/discharge input signal including charge pulses and discharge pulses having a input transition rate; and

modifying the charge/discharge input signal such that the charge pulses and discharge pulses exhibit an applied transition rate sufficient to reduce degradation of one or more charge capacity characteristics of the one or more electrochemical cells relative to degradation at the input transition rate using a transition modifying circuit coupled between a charge/discharge circuit and a terminal of the one or more electrochemical cells, wherein the input transition rate and the applied transition rate include rise and fall times for their respective pulses.

9. The method of claim 8, wherein modifying the charge/discharge input signal to exhibit an applied transition rate using a transition modifying circuit comprises using a transition modifying circuit including at least one of an inductive constituent, a capacitive constituent, and a resistive constituent to generate the applied transition rate on the terminal.

10. The method of claim 8, wherein modifying the charge/discharge input signal to have the applied transition rate comprises:

operably coupling an inductor between the charge/discharge circuit and the terminal of the one or more electrochemical cells to provide an inductive constituent; and

operably coupling a capacitor between the charge/discharge circuit and a ground terminal of the one or more electrochemical cells to provide a capacitive constituent.

11. The method of claim 10, wherein operably coupling the capacitor comprises operably coupling a capacitor configured for adjustment of the capacitive constituent responsive to at least one of the input transition rate, the applied transition rate, a measured characteristic of the one or more electrochemical cells, or a combination thereof.

12. The method of claim 10, wherein operably coupling the inductor comprises operably coupling an inductor configured for adjustment of the inductive constituent responsive to at least one of the input transition rate, the applied transition rate, a measured characteristic of the one or more electrochemical cells, or a combination thereof.

13. The method of claim 10, further comprising:

measuring one or more characteristics of the one or more electrochemical cells; and

determining the applied transition rate responsive to an analysis of the one or more characteristics;

wherein operably coupling the capacitor comprises operably coupling a variable capacitor configured for adjustment of the capacitive constituent responsive to the analysis.

14. The method of claim 10, further comprising:

measuring one or more characteristics of the one or more electrochemical cells; and

determining the applied transition rate responsive to an analysis of the one or more characteristics;

wherein operably coupling the inductor comprises operably coupling a variable inductor configured for adjustment of the inductive constituent responsive to the analysis.

15. A method of determining characteristics of a transition modifying circuit, comprising:

analyzing one or more degradation characteristics of an electrochemical cell relative to a first transition rate of a charge/discharge input signal applied to the electrochemical cell from a charge/discharge circuit;

determining, responsive to the analyzing, an adjusted transition rate for a modified signal to be applied to the electrochemical cell for reducing the one or more degradation characteristics; and

selecting at least one of an inductance, a capacitance, and a resistance of the transition modifying circuit for coupling between the electrochemical cell and the charge/discharge circuit for the modified signal to achieve the adjusted transition rate, wherein the first transition rate and the adjusted transition rate include rise and fall times for their respective pulses.

16. The method of claim 15, wherein analyzing the one or more degradation characteristics comprises measuring capacity loss of the electrochemical cell over an analysis period.

17. The method of claim 15, wherein selecting at least one of the inductance, the capacitance, and the resistance comprises:

selecting an inductor for operable coupling between the charge/discharge circuit and a positive terminal of the electrochemical cell; and

selecting a capacitor for operable coupling between the charge/discharge circuit and a negative terminal of the electrochemical cell.

18. A method of determining characteristics of a transition modifying circuit, comprising:

repeatedly applying a charge pulse and a discharge pulse over an analysis period to each of;

a first transition modifying circuit configured to receive the charge pulse and the discharge pulse and generate a first transition rate on a first signal applied to a first electrochemical cell; and

a second transition modifying circuit configured to receive the charge pulse and the discharge pulse and generate a second transition rate on a second signal applied to a second electrochemical cell, wherein the second transition rate is different from the first transition rate, and wherein the first transition rate and the second transition rate include rise and fall times for their respective pulses;

determining capacity loss of each of the first electrochemical cell and the second electrochemical cell after the analysis period;

repeating the repeatedly applying, and the determining the capacity loss, to determine a loss trend for each of the first electrochemical cell and the second electrochemical cell; and

selecting components for the transition modifying circuit responsive to the loss trend of the first electrochemical cell and the loss trend of the second electrochemical cell.

19. The method of claim 18, wherein selecting components for the transition modifying circuit comprises selecting an inductor, a capacitor, a resistor, or an operable combination thereof to achieve a desired transition rate for a signal applied to an electrochemical cell.

20. The method of claim 19, wherein selecting an inductor, a capacitor, a resistor, or an operable combination thereof comprises:

selecting an inductor for operable coupling between the charge/discharge input and a positive terminal of the electrochemical cell; and

selecting a capacitor for operable coupling between the charge/discharge input and a negative terminal of the electrochemical cell.

21. The method of claim 18, wherein the analysis period comprises about a month.

22. The method of claim 18, wherein repeating the repeatedly applying, and the determining the capacity loss to determine a loss trend, comprises repeating at least three times.