Self-diagnosis system for an energy storage device
First Claim
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1. A self-diagnosis system for an energy storage device, the energy storage device including a plurality of electrochemical cells forming a cell string, said system comprising:
- a. a current source providing a constant current;
b. a cell selector switch operative to select a particular one of the electrochemical cells within the cell string;
c. a voltage measurement means for measuring an initial voltage and a second voltage of said particular cell;
d. a processing unit coupled to said voltage measurement means, said processing unit operative to calculate an internal resistance of said particular cell on a basis of the constant current value and the initial and second voltages;
e. said electronic self-diagnosis system capable to determine a state of health of said energy storage device on the basis of the internal resistance of each cell of said cell string.
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Abstract
A self-diagnosis system for an energy storage device, the latter including a plurality of electrochemical cells connected in series or parallel to form a cell string. The self-diagnosis system correlates a state of health of the battery based on the internal resistance value of each electrochemical cell of the energy storage device and determines a corresponding battery initial capacity which enables the self-diagnosis system to evaluate the exact capacity of the battery at any given time.
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Citations
20 Claims
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1. A self-diagnosis system for an energy storage device, the energy storage device including a plurality of electrochemical cells forming a cell string, said system comprising:
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a. a current source providing a constant current;
b. a cell selector switch operative to select a particular one of the electrochemical cells within the cell string;
c. a voltage measurement means for measuring an initial voltage and a second voltage of said particular cell;
d. a processing unit coupled to said voltage measurement means, said processing unit operative to calculate an internal resistance of said particular cell on a basis of the constant current value and the initial and second voltages;
e. said electronic self-diagnosis system capable to determine a state of health of said energy storage device on the basis of the internal resistance of each cell of said cell string. - View Dependent Claims (2)
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3. An energy storage device comprising a housing, a plurality of electrochemical cells each having a positive electrode, a negative electrode and an electrolyte separator therebetween;
- said plurality of electrochemical cells connected in series or parallel to form a cell string within said housing; and
an electronic self-diagnosis system comprising a processing unit, a current source, a voltage measurement means, a cell selector switch adapted to select a single electrochemical cell within said cell string;
said electronic self-diagnosis system measuring an internal resistance of each cell of said cell string, one cell at a time, to determine a state of health of said energy storage device;
wherein said cell selector switch selects a first cell of said cell string, said voltage measurement means measures an initial voltage and a second voltage of said selected cell, said current source provides a constant current;
the constant current value, the initial and second voltage measurement being processed by said processing unit wherein said processing unit calculates the internal resistance of said selected cell using Ohmn'"'"'s law, said processing unit further comprising a memory for storing electrochemical cell'"'"'s capacity fade as a function of its internal resistance, said processing unit correlating the highest calculated internal resistance of said cell string to a corresponding state of health value stored in said memory to define an overall state of health of said energy storage device. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- said plurality of electrochemical cells connected in series or parallel to form a cell string within said housing; and
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16. An energy storage device comprising a housing, a plurality of electrochemical cells each having a positive electrode, a negative electrode and an electrolyte separator therebetween;
- said plurality of electrochemical cells connected in series or parallel to form a cell string within said housing; and
an electronic self-diagnosis system;
said electronic self-diagnosis system correlating a measured internal resistance of said cell string to a state of health value representative of a capacity fade of said cell string;
said electronic self-diagnosis system selecting an initial capacity of said energy storage device corresponding to said state of health value;
said electronic self-diagnosis system monitoring a state of charge of said energy storage device by measuring, energy flowing in or out of said energy storage device and adding or subtracting said energy to determine an exact battery capacity. - View Dependent Claims (17, 18, 19)
- said plurality of electrochemical cells connected in series or parallel to form a cell string within said housing; and
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20. A method for determining a state of health of an energy storage device, the energy storage device including a plurality of electrochemical cells forming a cell string, the energy storage device characterized by a state of health value representative of a capacity fade of the cell string, said method comprising:
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a correlating a measured internal resistance of the cell string to the state of health value;
b. selecting an initial capacity of the energy storage device corresponding to the, state of health value c. monitoring a state of charge of the energy storage device by measuring energy flowing in or out of said energy storage device and adding or subtracting the energy to determine an exact battery capacity.
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Specification