Reduced stack voltage circuitry for energy storage system diagnostics

Patent metadata

Field	Value
Publication number	US-10895604-B2
Application number	US-201615744470-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Jul 17, 2015
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

Systems and methods to provide a low voltage interface coupleable between an energy storage device or a DC power source (e.g., fuel cell stack, battery) and one or more AC signal diagnostic systems. The low voltage interface reduces a voltage of the DC power source and supplies the reduced voltage to the one or more AC signal diagnostic systems without affecting the results of the measurements obtained by the one or more AC signal diagnostic systems. Such functionality provides a safer method for performing advanced analysis (e.g., EIS, frequency analysis) while utilizing lower cost and/or smaller components.

First claim

The invention claimed is:

1. A low voltage interface which in use couples a direct current (DC) power source to an alternating current (AC) signal diagnostic system, the DC power source comprises a positive node, the AC signal diagnostic system comprises a diagnostic signal output node which applies an AC signal to the DC power source, the AC signal diagnostic system further comprises a measurement input node, the low voltage interface comprising:
an interface input node electrically coupleable to the positive node of the DC power source;
a first interface output node electrically coupleable to the measurement input node of the AC signal diagnostic system; and
a voltage-reduction circuit electrically coupled to the interface input node and the first interface output node, the voltage-reduction circuit:
receives an input voltage from the DC power source via the interface input node, the input voltage comprising a DC component and an AC component;
reduces the DC component of the input voltage without substantially affecting a magnitude or phase of the AC component of the input voltage, or reduces the DC component of the input voltage with a constant amplification or a constant phase shift of the AC component of the input voltage, which provides a measurement voltage including, a reduced DC component; and
provides the measurement voltage to the measurement input node of the AC signal diagnostic system via the first interface output node.

2. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises a DC voltage source electrically coupled in series between the interface input node and the first interface output node, and maintains a zero or constant phase between the interface input node and the first interface output node.

3. The low voltage interface of claim 1 wherein the voltage-reduction circuit reduces the DC component of the input voltage without substantially affecting the magnitude or phase of the AC component of the input voltage, or reduces the DC component of the input voltage with a constant amplification or phase shift of the AC component of the input voltage, for AC signals having a frequency between 0.01 Hz and 5000 Hz.

4. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises at least one resistor electrically coupled in series with a biasing current source.

5. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises at least one Zener diode electrically coupled in series with a biasing current source.

6. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises a V BE multiplier circuit electrically coupled in series with a biasing current source.

7. The low voltage interface of claim 6 wherein the biasing current source provides a zero- or constant-phase current response with respect to the output voltage.

8. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises one of at least one resistor electrically coupled in series with a biasing current source, at least one Zener diode electrically coupled in series with a biasing current source, and a V BE multiplier circuit electrically coupled in series with a biasing current source, the biasing current source having an input impedance which is at least 10 times greater than the impedance of the at least one resistor, or the at least one Zener diode, or the V BE multiplier circuit.

9. The low voltage interface of claim 1 wherein the voltage-reduction circuit reduces the DC component of the input voltage to a voltage of less than 60 volts.

10. The low voltage interface of claim 1 wherein the first interface output node is electrically coupleable to at least one of a load of the AC signal diagnostic system or a system load driven by the DC power source.

11. The low voltage interface of claim 1 wherein the voltage-reduction circuit comprises:
a second interface output node electrically coupleable to the diagnostic signal output node of the AC signal diagnostic system, wherein the voltage-reduction circuit:
reduces the DC component of the input voltage without substantially affecting the phase of the AC component of the input voltage, or reduces the DC component of the input voltage with a constant phase shift of the AC component of the input voltage, or reduces the DC component of the input voltage without substantially affecting the magnitude of the AC component of the diagnostic signal output node, which provides a reduced voltage; and
provides the reduced voltage to the diagnostic signal output node of the AC signal diagnostic system via the second interface output node.

12. The low voltage interface of claim 11 wherein the voltage-reduction circuit comprises at least one resistor electrically coupled in series between the interface input node and the second interface output node.

13. The low voltage interface of claim 11 wherein the voltage-reduction circuit comprises at least one Zener diode electrically coupled in series between the interface input node and the second interface output node.

14. The low voltage interface of claim 11 wherein the voltage-reduction circuit comprises at least one of a controlled voltage source or a constant-voltage load bank electrically coupled in series between the interface input node and the second interface output node.

15. The low voltage interface of claim 14 wherein reducing the DC component of the input voltage comprises applying the input voltage to a circuit that has a current source with a zero- or constant-phase current response with respect to the output voltage.

16. The low voltage interface of claim 14 wherein the voltage-reduction circuit comprises a controlled voltage source with at least one of active phase compensation or passive phase compensation.

17. A direct current (DC) power system, comprising:
a DC power source comprising a positive node;
alternating current (AC) signal diagnostic system comprising a diagnostic signal output node which applies an AC signal to the DC power source, the AC signal diagnostic system further comprising a measurement input node; and
a low voltage interface comprising:
an interface input node electrically coupled to the positive node of the DC power source;
a first interface output node electrically coupled to the measurement input node of the AC signal diagnostic system; and
a voltage-reduction circuit electrically coupled to the interface input node and the first interface output node, the voltage-reduction circuit:
receives an input voltage from the DC power source via the interface input node, the input voltage comprising a DC component and an AC component;
reduces the DC component of the input voltage without substantially affecting a magnitude or phase of the AC component of the input voltage, or reduces the DC component of the input voltage with a constant amplification or constant phase shift of the AC component of the input voltage, which provides a measurement voltage including a reduced DC component; and
provides the measurement voltage to the measurement input node of the AC signal diagnostic system via the first interface output node.

18. The DC power system of claim 17 wherein the DC power source comprises a fuel cell stack.

19. The DC power system of claim 17 wherein the AC signal diagnostic system comprises an electrochemical impedance spectroscopy (EIS) system.

20. A method, comprising:
receiving an input voltage at an interface input node of a low voltage interface electrically coupl

Assignees

• Ballard Power Systems
• Univ Fraser Simon

Inventors

• Devaal Jacob W
• Homayouni Hooman
• Golnaraghi Farid

Classifications

• G01R31/3835

  involving only voltage measurements · CPC title

• G01R31/389 Primary

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

• Y02E60/50

  Fuel cells · CPC title

• G01N27/416

  Systems (G01N27/27 takes precedence) · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title