System and method for measuring internal resistance of electrochemical devices
First Claim
1. An electrochemical system comprising a plurality of cells;
- a current supply/draw means for superimposing modulated current values through the plurality of cells, wherein the current supply/draw means comprises a modulator, wherein the modulator comprises a control device and a modulated current generator, wherein the control device is operable to control the modulated current generator to superimpose the modulated current values in burst time periods for high frequency resistance measurement, with a rest time periods between the burst time periods of no superimposition of modulated current values;
an external load connected to the plurality of cells in parallel with the current supply/draw means for drawing a DC current from the plurality of cells wherein the DC current is drawn from the plurality of cells during both the rest time period and the burst time periods;
a measuring device including a plurality of inputs connected across the plurality of cells to generate signals indicative of voltage and current characteristics of the plurality of cells; and
,a controller for controlling at least one system operating condition based on to the voltage and current characteristics received from the measuring device, the controller being connected to the measuring device.
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Abstract
A method and system are provided for measuring impedance and voltage characteristics of individual cells of multi-cell electrochemical devices, for example a battery or a fuel cell stack. The electrochemical system comprises a plurality of cells; a measuring device including a plurality of inputs connected across the plurality of cells to generate voltage and current signals indicative of voltage and current characteristics of the plurality of cells; a current supply/draw means for superimposing modulated current values through the plurality of cells; and a controller for controlling at least one system operating condition based on the voltage and current characteristics received from the measuring device, the controller being connected to the measuring device. The method comprises (a) superimposing modulated current values across a plurality of cells of the electrochemical device; (b) drawing current from the plurality of cells to generate voltage and current signals indicative of voltage and current characteristics of the plurality of cells; and, (c) controlling the at least one system operating condition based on the voltage and current characteristics of the plurality of cells, wherein the at least one system operating condition comprises at least one of temperature, humidity and reactant flow rates, within the electrochemical system.
56 Citations
26 Claims
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1. An electrochemical system comprising a plurality of cells;
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a current supply/draw means for superimposing modulated current values through the plurality of cells, wherein the current supply/draw means comprises a modulator, wherein the modulator comprises a control device and a modulated current generator, wherein the control device is operable to control the modulated current generator to superimpose the modulated current values in burst time periods for high frequency resistance measurement, with a rest time periods between the burst time periods of no superimposition of modulated current values; an external load connected to the plurality of cells in parallel with the current supply/draw means for drawing a DC current from the plurality of cells wherein the DC current is drawn from the plurality of cells during both the rest time period and the burst time periods; a measuring device including a plurality of inputs connected across the plurality of cells to generate signals indicative of voltage and current characteristics of the plurality of cells; and
,a controller for controlling at least one system operating condition based on to the voltage and current characteristics received from the measuring device, the controller being connected to the measuring device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling at least one system operating condition of a multi-cell electrochemical system, the method comprising:
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(a) superimposing modulated current values from a current supply/draw means across a plurality of cells of the electrochemical device in burst time periods for high frequency resistance measurement, with a rest time periods between the burst time periods of no superimposition of modulated current values; (b) drawing current from the plurality of cells to generate voltage and current signals indicative of voltage and current characteristics of the plurality of cells; and
,(C) controlling the at least one system operating condition based on the voltage and current characteristics of the plurality of cells; and
,(d) connecting an external load to the plurality of cells in parallel with the current supply/draw means, wherein the external load draws a DC current from the plurality of cells during both the rest time period and the burst time periods. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. An electrochemical system comprising a plurality of cells;
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a measuring device including a plurality of inputs connected across the plurality of cells to generate voltage and current signals indicative of voltage and current characteristics of the plurality of cells, wherein the measuring device provides a plurality of primary channels for the voltage and current signals, there being one channel for the voltage across each cell, and wherein the measuring device includes a splitter for separating out at least the DC components of the voltages across the individual cells from the primary channels, the splitter having first channels as outputs for the DC components; a current supply/draw means comprising a modulator for superimposing modulated current values through the plurality of cells; an external load connected to the plurality of cells in parallel with the current supply/draw means for drawing a DC current from the plurality of cells wherein the DC current is drawn from the plurality of cells during both the rest time period and the burst time periods; and a controller for controlling at least one system operating condition based on the voltage and current characteristics received from the measuring device the controller being connected to the measuring device. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification