State of charge method and apparatus
First Claim
1. A method for determining a state of charge (SOC) of a battery system based upon an equivalent circuit of said battery system using least square regression comprising:
- determining an open circuit potential and resistance of said equivalent circuit;
providing a plurality of data points based upon determinations including measurement or prior computation;
weighting said plurality of data points; and
computing values of said resistance and open-circuit potential based upon weighted data points using least square analysis expressed in recursive formulas to determine the SOC.
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Abstract
A method for determining state of charge (SOC) of a battery system based upon an equivalent circuit of the battery system. A potential and resistance of the equivalent circuit are computed. The method uses a least squares regression means, and includes: providing a plurality of data points as a starting point based upon determinations including measurement or prior computation, wherein the determinations include a determination of a voltage of the battery system; weighting the plurality of data points; and computing values of the resistance and potential based upon weighted data points using recursive formulas, wherein only a state at a previous time is reflected respectively.
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Citations
21 Claims
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1. A method for determining a state of charge (SOC) of a battery system based upon an equivalent circuit of said battery system using least square regression comprising:
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determining an open circuit potential and resistance of said equivalent circuit;
providing a plurality of data points based upon determinations including measurement or prior computation;
weighting said plurality of data points; and
computing values of said resistance and open-circuit potential based upon weighted data points using least square analysis expressed in recursive formulas to determine the SOC. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining a state of charge (SOC) in a battery system based on determining values of a resistance R and an open circuit voltage Voc, respectively, comprising:
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creating at least two data points based upon measurement or prior computation;
establishing a linear relationship using said resistance R and said open circuit voltage Voc;
applying least square analysis upon said linear relationship;
formulating a recursive relationship, wherein a first state at a backward time increment solely determines a current state after said backward time increment, said recursive relationship being the summation of said first state manifested in a recast summation derived from integrals, and a data point at current time. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
determining a first set of intermediate functions;
assigning initial values to said first set of intermediate functions;
establishing a recursive relationship of said set of intermediate functions; and
computing values of said resistance R and said open circuit voltage Voc based upon said first set of intermediate functions.
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9. The method of claim 7, wherein said first set of intermediate functions includes:
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10. The method of claim 7, wherein said initial values include:
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Sw|1=Υ
1SI|1=Υ
1I1SII|1=Υ
1I12SV|1=Υ
1V1SIv|1=Υ
1I1V1.
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11. The method of claim 7, wherein said recursive relationship includes:
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12. The method of claim 7, including applying a skewness test before said method is performed.
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13. The method of claim 12, wherein said skewness test includes the steps of:
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defining a second set of intermediate functions, wherein each of said second set of intermediate functions is expressed in a recursive form based on an immediate prior state in time;
assigning initial values to said second set of intermediate function;
applying said skewness test based upon said second set of intermediate functions; and
determining a result of said skewness test.
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14. The method of claim 13, wherein said second set of intermediate functions includes:
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15. The method of claim 7 including computing a recursive power expression based on said data points.
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16. The method of claim 15, wherein said power expression is a max discharge and charge power of said battery system.
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17. The method of claim 16, wherein said power expression is:
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18. A vehicle powertrain control system, comprising:
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a battery pack;
a power inverter coupled to said battery pack;
a controller controlling said power inverter, said controller monitoring a state of charge (SOC) of said battery pack; and
a program product for computing a resistance and an open circuit voltage both being functionally related to said SOC, said program product being associated to said controller. - View Dependent Claims (19, 20, 21)
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Specification