Measurement of fuel cell impedance
First Claim
1. An apparatus for determining at least the real component of a fuel cell'"'"'s complex impedance, the apparatus comprising, a load device, connectable to the fuel cell for drawing a current from the fuel cell;
- a voltage sensing circuit connectable across the fuel cell for in use sensing direct and alternating components of a voltage across the fuel cell;
a current sensing circuit, for in use sensing direct and alternating components of a current drawn from the fuel cell by the load device, wherein the load device is configured to draw a direct current with a superimposed alternating current signal; and
an analysis device, connected to the voltage sensing circuit and the current sensing circuit for analyzing the detected direct and alternating components of the voltage and the detected direct and alternating components of the current to determine real and imaginary parts of the fuel cell impedance at different frequencies, whereby the real part of the fuel cell impedance can be determined.
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Abstract
This invention discloses a self-contained, portable, cost-effective apparatus for measuring the real and imaginary components of a fuel cell'"'"'s complex impedance at discrete frequencies. The apparatus comprises a CPU, a signal generation device, a fuel cell, a load bank, current and voltage sensing circuitry and a waveform acquisition device. The measurements can be done in real time and automated. The fuel cell'"'"'s internal resistance can be calculated thereby providing an indication of the electrical efficiency of the fuel cell.
55 Citations
20 Claims
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1. An apparatus for determining at least the real component of a fuel cell'"'"'s complex impedance, the apparatus comprising, a load device, connectable to the fuel cell for drawing a current from the fuel cell;
- a voltage sensing circuit connectable across the fuel cell for in use sensing direct and alternating components of a voltage across the fuel cell;
a current sensing circuit, for in use sensing direct and alternating components of a current drawn from the fuel cell by the load device, wherein the load device is configured to draw a direct current with a superimposed alternating current signal; and
an analysis device, connected to the voltage sensing circuit and the current sensing circuit for analyzing the detected direct and alternating components of the voltage and the detected direct and alternating components of the current to determine real and imaginary parts of the fuel cell impedance at different frequencies, whereby the real part of the fuel cell impedance can be determined. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- a voltage sensing circuit connectable across the fuel cell for in use sensing direct and alternating components of a voltage across the fuel cell;
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15. A method of determining at least a real component of a fuel cell'"'"'s complex impedance, the method comprising:
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(i) applying a load to the fuel cell so as to draw a current from the fuel cell, the current comprising a direct current component and an alternating current component;
(ii) varying the frequency of the alternating current component;
(iii) measuring the direct and alternating components of voltage across the fuel cell and direct and alternating components of the current drawn from the fuel cell;
(iv) from the measured current and the measured voltage determining the real impedance and the imaginary impedance at different frequencies; and
(v) from the real and imaginary impedances determined in the preceding step, determining the frequency at which the imaginary impedance is zero and determining the real impedance at said frequency, indicative of the total real impedance of the fuel cell. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification