Fuel cell voltage monitoring system and the method thereof
First Claim
1. A system for monitoring at least one cell voltage of an electrochemical device for a plurality of cells connected in series, the system comprising:
- a plurality of differential amplifiers, each differential amplifier having two inputs and one output, wherein the inputs are each connected, in use, to the plurality of cells;
a switching network having a plurality of inputs and one output, the inputs of the switching network connected to the outputs of the differential amplifiers;
an analog to digital converter having an input connected to the output of the switching network and adapted to provide digital values indicative of the voltages measured by the plurality of differential amplifiers; and
, a controller connected to the switching network and the analog to digital converter to control the operation of the switching network and the analog to digital converter, wherein the controller is further adapted to receive the digital values from the output of the analog to digital converter.
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Abstract
This invention discloses a system and method for monitoring the voltage of a fuel cell in a fuel cell stack. The system comprises a plurality of differential amplifiers, a switching network, an analog to digital converter and a controller. The system may further include a remote PC. Each differential amplifier has a high common-mode rejection ratio. The differential amplifiers are connected to terminals in the fuel cell stack at which the voltage is to be measured. An output of a single differential amplifier is chosen by the switching network, under the direction of the controller, and converted to digital values by the analog to digital converter. The digital values are used by the controller to calculate the cell voltage of the fuel cell. The controller also controls the analog to digital converter. The invention further comprises a calibration method and apparatus which are used to calibrate the measurement system before performing voltage measurements on the fuel cell stack. This invention allows the cell voltage of a fuel cell with almost any common-mode voltage to be measured using readily available differential amplifiers.
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Citations
30 Claims
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1. A system for monitoring at least one cell voltage of an electrochemical device for a plurality of cells connected in series, the system comprising:
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a plurality of differential amplifiers, each differential amplifier having two inputs and one output, wherein the inputs are each connected, in use, to the plurality of cells;
a switching network having a plurality of inputs and one output, the inputs of the switching network connected to the outputs of the differential amplifiers;
an analog to digital converter having an input connected to the output of the switching network and adapted to provide digital values indicative of the voltages measured by the plurality of differential amplifiers; and
,a controller connected to the switching network and the analog to digital converter to control the operation of the switching network and the analog to digital converter, wherein the controller is further adapted to receive the digital values from the output of the analog to digital converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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13. A method for monitoring cell voltages for a plurality of electrochemical cells connected in series and having output terminals, the method comprising the steps of:
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(a) connecting the voltage from two terminals of the plurality of cells connected in series to the inputs of a differential amplifier having two inputs and one output;
(b) rejecting the common-mode voltage from the voltages at the two terminals, in the differential amplifier, to give the voltage differential between the two terminals; and
,(c) converting the voltage differential from analog to digital values.
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Specification