Hydrogenics Corporation

Norman A Freeman

Ravi B Gopal

Stéphane Massé

Pierre Rivard

Stephen Burany

St&eacute;phane Mass&eacute;

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.

System and method for measuring internal resistance of electrochemical devices

A system and method for monitoring cell voltages for a plurality of electrochemical cells connected in series forming a cell stack. The method includes dividing the cells into at least two cell groups, measuring the voltage across each cell group and estimating the minimum cell voltage for each group based on the average cell stack voltage and an estimated number of deficient cells in each group. The lowest minimum cell voltage for the entire cell stack is then determined.

Method and apparatus for monitoring fuel cell voltages

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.

System and method for measuring fuel cell voltage and high frequency resistance

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.

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Toronto, Canada

Norman A Freeman