Assessing a parameter of cells in the batteries of uninterruptable power supplies
First Claim
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1. A method of measuring the electrical efficacy of a plurality of groups of one or more battery cells while in use in an uninterruptable power supply, the method comprising:
- measuring, using simultaneous electrical connections across each group of cells, an a.c. component of a voltage across each group of cells, the a.c. component arising from a ripple current in said plurality of groups of one or more cells while in use; and
determining the electrical efficacy of each group of cells on the basis of the measured a.c. voltage components.
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Abstract
A method and apparatus for measuring the electrical efficacy of one or more battery cells for use in an uninterruptable power supply are disclosed. The efficacy is determined by making use of the ripple current which flows in the battery cells when in use in the uninterruptable power supply. Simultaneous measurement, for example, of the ripple current and a corresponding voltage component enables the internal impedance of a battery cell to be determined, the impedance acting as an indicator of electrical efficacy.
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Citations
19 Claims
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1. A method of measuring the electrical efficacy of a plurality of groups of one or more battery cells while in use in an uninterruptable power supply, the method comprising:
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measuring, using simultaneous electrical connections across each group of cells, an a.c. component of a voltage across each group of cells, the a.c. component arising from a ripple current in said plurality of groups of one or more cells while in use; and
determining the electrical efficacy of each group of cells on the basis of the measured a.c. voltage components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
measuring electrical signals representative of one of the voltage level across each group of cells and the current level through the plurality of groups of cells; and
frequency filtering the each-measured electrical signal to extract the measured a.c. component arising from the ripple current.
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8. The method of claim 7, in which the steps of filtering includes isolating a band of frequencies from each measured electrical signals.
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9. The method of claim 7, in which the step of filtering includes isolating a band of frequencies including those frequencies which include at least one harmonic frequency of an a.c. main frequency.
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10. The method of claim 9, including isolating a band of frequencies around 900 Hz.
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11. The method of claim 9, including isolating a band of frequencies around 1080 Hz.
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12. An apparatus for measuring the electrical efficacy of a plurality of groups of one or more battery cells while in use in an uninterruptable power supply, the apparatus comprising:
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simultaneous electrical connections across each group of cells;
voltage measuring means connected to said simultaneous electrical connections and arranged to thereby measure an a.c. component of a voltage across each group of cells, the a.c. voltage component arising from a ripple current in said plurality of groups of one or more battery cells while in use, the electrical efficacy of each group of cells being determined on the basis of the measured a.c. voltage components. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification