System and method for measuring fuel cell voltage and high frequency resistance
First Claim
1. An apparatus for measuring impedance and voltage characteristics of cells of a multi-cell electrochemical device, the apparatus comprising:
- a voltage measuring means including a plurality of inputs for connection across a plurality of measuring points between cells of the electrochemical device, to generate voltage signals indicative of the measured voltages, the voltage measuring means providing a plurality of primary channels for the measured voltages, there being one channel for the voltage across adjacent measuring points; and
wherein the voltage measuring means includes a channel splitter for separating out components of the measured voltages across adjacent measuring points from the primary channels, the channel splitter having first channels for providing DC components of the measured voltages and second channels for providing AC components of the measured voltages;
a load, connectable in series with the electrochemical device, and adapted to draw a DC current with a superimposed AC perturbation current; and
a controller connected to and controlling the voltage measuring means and the load, for controlling the characteristics of the load and for receiving the voltage signals from the voltage measuring means, wherein the controller is adapted to control the load to provide desired DC and AC load current characteristics.
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Abstract
A method and apparatus are provided for measuring impedance and voltage characteristics of cells of multi-cell electrochemical devices, for example a battery or a fuel cell stack. Voltages are measured across individual cells, or groups of cells. At the same time, a load is connected in series with the electrochemical device. Both the device for measuring the voltages and the load are controlled together, preferably by means of a controller, which can include some form of microprocessor. This enables the load to be controlled to provide a desired combination of DC and AC current characteristics. By setting appropriate DC and AC current characteristics, desired characteristics of the impedance of individual cells can be measured.
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Citations
16 Claims
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1. An apparatus for measuring impedance and voltage characteristics of cells of a multi-cell electrochemical device, the apparatus comprising:
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a voltage measuring means including a plurality of inputs for connection across a plurality of measuring points between cells of the electrochemical device, to generate voltage signals indicative of the measured voltages, the voltage measuring means providing a plurality of primary channels for the measured voltages, there being one channel for the voltage across adjacent measuring points; and
wherein the voltage measuring means includes a channel splitter for separating out components of the measured voltages across adjacent measuring points from the primary channels, the channel splitter having first channels for providing DC components of the measured voltages and second channels for providing AC components of the measured voltages;
a load, connectable in series with the electrochemical device, and adapted to draw a DC current with a superimposed AC perturbation current; and
a controller connected to and controlling the voltage measuring means and the load, for controlling the characteristics of the load and for receiving the voltage signals from the voltage measuring means, wherein the controller is adapted to control the load to provide desired DC and AC load current characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of monitoring the voltage and impedance characteristics of cells of a multi-cell electrochemical device, the method comprising:
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(i) providing a load connected in series with the electrochemical device;
(ii) controlling the load to provide desired current characteristics, comprising a desired combination of a DC current and a superimposed AC current perturbation, according to a series of set load conditions;
(iii) measuring the voltage across a plurality of measuring points between cells of the electrochemical device by providing a plurality of primary channels, there being one channel for the voltage across adjacent measuring points, and separating out components of the measured voltages across adjacent measuring points from the primary channels by providing at least one first channel for obtaining DC components of the measured voltage and at least one second channel for obtaining AC components of the measured voltages; and
,(iv) recording at least some of the measured voltages. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification