Energy storage cell impedance measuring apparatus, methods and related systems

Patent metadata

Field	Value
Publication number	US-9851414-B2
Application number	US-201514789959-A
Country	US
Kind code	B2
Filing date	Jul 1, 2015
Priority date	Dec 21, 2004
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

Energy storage cell impedance testing devices, circuits, and related methods are disclosed. An energy storage cell impedance measuring device includes a sum of sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell. A method includes applying an SOS signal comprising a sum of sinusoidal current signals to the energy storage cell with the SOS current excitation circuit, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies. The method also includes measuring an electrical signal at a positive terminal and a negative terminal of the energy storage cell, and computing an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.

First claim

What is claimed is:

1. An energy storage cell impedance measuring device, comprising:
a sum-of-sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell, the SOS current excitation circuit configured to apply an SOS signal through the energy storage cell, the SOS signal including a sum of a plurality of sinusoidal current signals, each of the plurality of sinusoidal current signals oscillating at a different one of a plurality of different frequencies; and
control circuitry configured to operably couple to the SOS current excitation circuit, the positive terminal, and the negative terminal, the control circuitry comprising:
an SOS control module configured to cause the SOS current excitation circuit to produce the SOS signal;
at least one signal measuring module configured to measure electrical signals on the positive terminal and the negative terminal of the energy storage cell; and
an impedance computation module configured to use the electrical signals measured by the at least one signal measuring module to compute an impedance of the energy storage cell for each frequency of the SOS signal.

2. The energy storage cell impedance measuring device of claim 1 , wherein the plurality of different frequencies include integer harmonic frequencies of a lowest frequency of the plurality of different frequencies.

3. The energy storage cell impedance measuring device of claim 2 , wherein the plurality of sinusoidal current signals of the SOS signals include alternating sine and cosine current signals for each successive frequency of the plurality of different frequencies.

4. The energy storage cell impedance measuring device of claim 1 , further comprising a high voltage buffer operably coupled between the SOS current excitation circuit and the energy storage cell, the high voltage buffer configured to isolate at least one signal line of the SOS current excitation circuit carrying at least a portion of the SOS signal from a direct current voltage potential difference between the positive terminal and the negative terminal.

5. The energy storage cell impedance measuring device of claim 4 , wherein the high voltage buffer includes a high voltage blocking capacitor operably coupled between at least one of the differential current sources and at least one of the positive terminal and the negative terminal of the energy storage cell.

6. The energy storage cell impedance measuring device of claim 1 , wherein the differential current sources include a push current source configured to push current into the energy storage cell, and a pull current source configured to pull current from the energy storage cell.

7. The energy storage cell impedance measuring device of claim 6 , wherein the push current source is configured to provide at least substantially a same current as the pull current source.

8. The energy storage cell impedance measuring device of claim 1 , wherein the differential current sources are configured to provide the SOS signal through an energy storage cell having a direct current voltage potential output of greater than about sixty (60) volts direct current.

9. The energy storage cell impedance measuring device of claim 1 , wherein the differential current sources are configured to provide the SOS signal through an energy storage cell having a direct current voltage potential output of at least about three hundred (300) volts direct current.

10. A method of measuring impedance of an energy storage cell, the method comprising:
applying, with a sum-of-sinusoids (SOS) current excitation circuit of an impedance measuring device including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell, an SOS signal to the energy storage cell, the SOS signal comprising a sum of sinusoidal current signals, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies;
measuring an electrical signal at the positive terminal and the negative terminal of the energy storage cell with at least one signal measuring module of the impedance measuring device coupled to the positive terminal and the negative terminal; and
computing, with an impedance computation module of the impedance measuring device, an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.

11. The method of claim 10 , wherein measuring an electrical signal at the positive terminal and the negative terminal with the at least one measuring module comprises:
measuring a voltage potential response to the SOS signal across the positive terminal and the negative terminal of the energy storage cell; and
measuring a current response to the SOS signal through the energy storage cell.

12. The method of claim 11 , wherein computing, with an impedance computation module, the impedance of the energy storage cell at each of the plurality of different frequencies comprises dividing a portion of the measured voltage potential response that corresponds to each of the plurality of different frequencies by a portion of the measured current response that corresponds to a same one of the plurality of different frequencies.

13. The method of claim 12 , wherein computing, with an impedance computation module, the impedance of the energy storage cell comprises calculating the impedance of the energy storage cell without calibrating control circuitry configured to compute the impedance of the energy storage cell.

14. The method of claim 10 , further comprising calibrating, using a single shunt of known resistance, control circuitry configured to compute the impedance of the energy storage cell.

15. The method of claim 14 , wherein calibrating the control circuitry comprises:
applying, with the SOS current excitation circuit, a first SOS signal having a first magnitude to the single shunt;
measuring a response of the single shunt to the first SOS signal with the at least one signal measuring module;
applying, with the SOS current excitation circuit, a first orthogonal SOS signal having the first magnitude to the single shunt; and
measuring a response of the single shunt to the first orthogonal SOS signal with the at least one signal measuring module.

16. The method of claim 15 , wherein calibrating the control circuitry further comprises:
applying, with the SOS current excitation circuit, a second SOS signal having a second magnitude, different from the first, to the single shunt;
measuring a response of the single shunt to the second SOS signal with the at least one signal measuring module;
applying, with the SOS current excitation circuit, a second orthogonal SOS signal having the second magnitude to the single shunt; and
measuring a response of the single shunt to the second orthogonal SOS signal with the at least one signal measuring module.

17. The method of claim 10 , wherein applying the SOS signal comprises applying, with the SOS current excitation circuit, the SOS signal for a single period of a lowest frequency of the plurality of different frequencies.

18. An energy storage cell impedance measuring circuit, comprising:
differential current sources, including:
a push current source configured to operably couple to a positive terminal of an energy storage cell;
a pull current source configured to opera

Assignees

• Battelle Energy Alliance Llc

Inventors

• Morrison John L
• Morrison William H
• Christophersen Jon P

Classifications

• G01R31/3662 Primary

  Physics · mapped topic

• G01R31/3606

  Physics · mapped topic

• G01R31/3842

  combining voltage and current measurements · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title

• G01R31/389 Primary

  Measuring internal impedance, internal conductance or related variables · CPC title