Method and apparatus for generalized recursive least-squares process for battery state of charge and state of health
First Claim
1. A method for determining a voltage based state of charge (SOC) and state of health (SOH) of a battery system, comprising:
- providing a model of said battery system including an equivalent circuit having both low frequency and high frequency elements;
establishing a plurality of functional relationships including relationship of said equivalent circuit with SOC;
reducing at least part of said plurality of functional relationships into a set of time segmented recursive functional relationships, wherein a first state at a first time t can be modeled by a functional presentation of a second state at a second time t−
Δ
t that occurred before said first time t; and
computing a set of data points based upon said set of time segmented recursive functional relationships using a matrix for operation in matrix algebra.
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Abstract
A method for determining a voltage based or current based state of charge (SOC) and state of health (SOH) of a battery system is provided. The method includes: providing a model of the battery system including an equivalent circuit having both low frequency and high frequency elements; establishing a plurality of functional relationships comprising relationship of the equivalent circuit with SOC; reducing at least part of the plurality of functional relationships into a set of time segmented recursive functional relationships, wherein a state at a first time t can be modeled by a functional presentation of a state at a second time t−Δt that occurred before the first time t; and computing a set of data points based upon the set of time segmented recursive functional relationships using a matrix for operation in matrix algebra.
92 Citations
38 Claims
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1. A method for determining a voltage based state of charge (SOC) and state of health (SOH) of a battery system, comprising:
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providing a model of said battery system including an equivalent circuit having both low frequency and high frequency elements;
establishing a plurality of functional relationships including relationship of said equivalent circuit with SOC;
reducing at least part of said plurality of functional relationships into a set of time segmented recursive functional relationships, wherein a first state at a first time t can be modeled by a functional presentation of a second state at a second time t−
Δ
t that occurred before said first time t; and
computing a set of data points based upon said set of time segmented recursive functional relationships using a matrix for operation in matrix algebra. - View Dependent Claims (2, 3, 4)
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5. 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, wherein said method determines the value of all elements requiring regression, including an open circuit potential and a hysteresis voltage along with other circuit elements, so as to determine the state of the system as modeled by said equivalent circuit, said method comprising:
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providing a plurality of data points based upon determinations including measurement or prior computation, wherein said determinations include a determination of at least one of a voltage and a current of said battery system;
weighting said plurality of data points; and
computing values of said open circuit potential and a hysteresis voltage and other circuit elements based upon weighted data points using least square analysis expressed in recursive formulas, wherein only a state at a previous time is used for each computation;
thereby reducing the workload of a controller in both required memory space and number of mathematical operations.
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- 6. The method of claim 6 wherein all of said values are computed using recursive formulas wherein only a state at a previous time is used for each computation.
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10. A method for determining a state of charge (SOC) or state of health (SOH) of a battery system using a generalized regression method, comprising:
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determining a current-based SOC result based on Coulomb integration or Coulomb counting, wherein said Coulomb integration or counting includes self discharge and current efficiency computations;
determining a voltage based SOC result based on measurements or previous computations as a starting point, and using a recursive adaptive filter for extracting a plurality of parameter values, including;
providing a model of said battery system comprising an equivalent circuit having both low frequency and high frequency elements;
establishing a plurality of functional relationships comprising relationship of said equivalent circuit with SOC;
reducing at least part of said plurality of functional relationships into a set of time segmented recursive functional relationships, wherein a state at a time can be modeled by a functional presentation of a state at a time that occurred before; and
computing a set of data points based upon said set of time segmented recursive functional relationships using a matrix for operation in matrix algebra; and
combining current based SOC result and the voltage based SOC result with a weighting factor to generate said SOC of said battery system. - View Dependent Claims (11, 12, 13)
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14. A method for determining a state of charge (SOC) or state of health (SOH) of a battery system, comprising:
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performing a first step including determining a set of initial values for a plurality of parameters, coefficients, and derivatives based upon a plurality of linear functional relationships, and computing a result based upon said determining;
after execution of said first step, calculating a plurality of intermediate functions;
updating said plurality of parameters;
determining a open circuit voltage Vo that possesses a functional relationship with SOCV;
extracting SOCV by inverting the expression of Vo(SOCV);
calculating SOCC;
calculating a weight for weighting SOCC and SOCV; and
calculating SOC. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. 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) and a state of health (SOH) of said battery pack; and
a program product for computing SOC associated to said controller using least-squares analysis. - View Dependent Claims (34, 35, 36, 37, 38)
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Specification