DOUBLE-PULSE TECHNIQUE FOR ON-LINE DIAGNOSTICS OF ELECTROCHEMICAL SYSTEMS

• US 20140372054A1
• Filed: 06/11/2014
• Published: 12/18/2014
• Est. Priority Date: 06/14/2013
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: WANG, Shuoqin, VU, Luan D.
• Granted Patent: US 10,222,426 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

A method for dynamic characterization of an electrochemical system (such as a lithium-ion battery) is provided, comprising exciting an electrochemical system with a plurality of double-pulse sequences, each comprising a constant-current discharge pulse, a constant-current charge pulse having the same pulse width and pulse amplitude, and a zero-current period between the pulses; and calculating an impulse response, using a recursive or matrix-based method, to dynamically characterize the electrochemical system. A constant state-of-charge is maintained in the electrochemical system. Therefore the signal-to-noise ratio is high due to the repetition of the driving sequence. This method may be employed for on-line determination of the impedance spectrum of an electrochemical system, since the cycling profile can be easily integrated into charge/discharge profiles. Batteries (and other devices) can be diagnosed at high speed and with high accuracy. The double-pulse sequence is robust for fairly noisy systems.

Claims

1. A method for dynamic characterization of an electrochemical system, said method comprising:

(a) selecting an electrochemical system to be characterized at a plurality of times within a selected sampling window;

(b) exciting said system with a plurality of double-pulse sequences, wherein each of said double-pulse sequences comprises a discharge pulse having a pulse width and a pulse amplitude, a charge pulse having said pulse width and said pulse amplitude, and a zero-current period;

(c) receiving current data inputs each comprising measured current at a plurality of times associated with said double-pulse sequences;

(d) receiving voltage data inputs each comprising measured voltage at a plurality of times associated with said double-pulse sequences;

(e) calculating a plurality of current-derivative data inputs each comprising the time derivative of said measured current at said plurality of times;

(f) calculating a plurality of voltage-derivative data inputs each comprising the time derivative of said measured voltage at said plurality of times; and

(g) calculating an impulse response from said current, voltage, current-derivative, and voltage-derivative data inputs, at said plurality of times using a recursive or matrix-based technique, wherein said impulse response dynamically characterizes said electrochemical system.

2. The method of claim 1, wherein said discharge pulse is a constant-current discharge pulse and wherein said charge pulse is a constant-current charge pulse.

3. The method of claim 1, wherein each of said double-pulse sequences comprises a first zero-current period between said discharge pulse and said charge pulse, and a second zero-current period after said charge pulse.

4. The method of claim 1, wherein in step (b), said pulse width is tuned to characterize a main response time of said electrochemical system.

5. The method of claim 1, wherein in step (b), said pulse amplitude is tuned to characterize a diffusion response of said electrochemical system.

6. The method of claim 1, wherein step (g) utilizes a Kalman filtering technique.

7. The method of claim 1, wherein a finite impulse response digital filter is utilized to derive said impulse response at said plurality of times.

8. The method of claim 1, wherein an infinite impulse response digital filter is utilized to derive said impulse response at said plurality of times.

9. The method of claim 1, said method further comprising the step of estimating at least one electrochemical system state selected from the group consisting of state-of-health, state-of-charge, state-of-power, high-frequency resistance, charge-transfer resistance, and double-layer capacitance.

10. The method of claim 9, said method further comprising the step of calculating the Fourier transform of said impulse response to obtain at least one of said electrochemical system states.

11. A system for dynamically characterizing an electrochemical device, said system comprising an electrochemical device and a programmable power-supply apparatus electrically linked with said electrochemical device, wherein said programmable power-supply apparatus is programmed using non-transitory memory with executable code for executing the steps of:

(a) exciting said electrochemical system with a plurality of double-pulse sequences, wherein each of said double-pulse sequences comprises a discharge pulse having a pulse width and a pulse amplitude, a charge pulse having said pulse width and said pulse amplitude, and a zero-current period;

(b) sensing, in said computer, current data inputs each comprising measured current at a plurality of times associated with said double-pulse sequences;

(c) sensing, in said computer, voltage data inputs each comprising measured voltage at a plurality of times associated with said double-pulse sequences;

(d) calculating, in said computer, a plurality of current-derivative data inputs each comprising the time derivative of said measured current at said plurality of times;

(e) calculating, in said computer, a plurality of voltage-derivative data inputs each comprising the time derivative of said measured voltage at said plurality of times; and

(f) calculating an impulse response from said current, voltage, current-derivative, and voltage-derivative data inputs, at said plurality of times using a recursive or matrix-based method performed in said computer, wherein said impulse response characterizes the dynamics of said electrochemical system.

12. The system of claim 11, wherein said electrochemical device is selected from the group consisting of a battery, a fuel cell, an electrolytic cell, a capacitor, a supercapacitor, a pseudocapacitor, an electroplating system, and a galvanic corrosion system.

13. The system of claim 11, wherein said programmable power-supply apparatus is programmed to adjust said pulse width, to characterize a main response time of said electrochemical system.

14. The system of claim 11, wherein said programmable power-supply apparatus is programmed to adjust said pulse amplitude, to characterize a diffusion response of said electrochemical system.

15. The system of claim 11, wherein said programmable power-supply apparatus is programmed to utilize a Kalman filtering technique to execute step (f).

16. The system of claim 11, wherein said programmable power-supply apparatus is further programmed to estimate at least one electrochemical system state selected from the group consisting of state-of-charge, state-of-power, state-of-health, high-frequency resistance, charge-transfer resistance, and double-layer capacitance.

17. The system of claim 16, wherein said programmable power-supply apparatus is further programmed to calculate the Fourier transform of said impulse response to obtain at least one of said electrochemical system states.

18. A computer-readable medium containing program instructions for characterizing the dynamics of an electrochemical system, wherein execution of said program instructions by one or more processors of a computer causes said one or more processors to carry out the steps of:

(a) exciting said electrochemical system with a plurality of double-pulse sequences, wherein each of said double-pulse sequences comprises a discharge pulse having a pulse width and a pulse amplitude, a charge pulse having said pulse width and said pulse amplitude, and a zero-current period;

(b) sensing, in said computer, current data inputs each comprising measured current at a plurality of times associated with said double-pulse sequences;

(c) sensing, in said computer, voltage data inputs each comprising measured voltage at a plurality of times associated with said double-pulse sequences;

(d) calculating, in said computer, a plurality of current-derivative data inputs each comprising the time derivative of said measured current at said plurality of times;

(e) calculating, in said computer, a plurality of voltage-derivative data inputs each comprising the time derivative of said measured voltage at said plurality of times; and

(f) calculating an impulse response from said current, voltage, current-derivative, and voltage-derivative data inputs, at said plurality of times using a recursive or matrix-based method performed in said computer, wherein said impulse response characterizes the dynamics of said electrochemical system.

19. The computer-readable medium of claim 18, wherein said program instructions include instructions to adjust said pulse width, to characterize a main response time of said electrochemical system.

20. The computer-readable medium of claim 18, wherein said program instructions include instructions to adjust said pulse amplitude, to characterize a diffusion response of said electrochemical system.

21. The computer-readable medium of claim 18, wherein said program instructions include a Kalman filtering technique to execute step (f).

22. The computer-readable medium of claim 18, wherein said program instructions include a finite impulse response digital filter or an infinite impulse response digital filter to derive said impulse response at said plurality of times.

23. The computer-readable medium of claim 18, wherein said program instructions include instructions to estimate at least one electrochemical system state selected from the group consisting of state-of-charge, state-of-power, state-of-health, high-frequency resistance, charge-transfer resistance, and double-layer capacitance.

24. The computer-readable medium of claim 23, wherein said program instructions calculate the Fourier transform of said impulse response to obtain at least one of said electrochemical system states.