Apparatus and method for estimating charge rate of secondary cell

• US 7,098,625 B2
• Filed: 10/30/2003
• Issued: 08/29/2006
• Est. Priority Date: 11/25/2002
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nakamura, Hideo, Yumoto, Daijiro
• Primary Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US10/695,800
• Publication Number:
  US 20040100227A1
• Time in Patent Office: 1,034 Days
• Field of Search: 320/132, 324126-130
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

In charge rate estimating apparatus and method for a secondary cell, a current flowing through the secondary cell is measured, a voltage across terminals of the secondary cell is measured, an adaptive digital filtering is carried out using a cell model in a continuous time series shown in an equation (1), all of parameters at one time are estimated, the parameters corresponding to an open-circuit voltage which is an offset term of the equation (1) and coefficients of A(s), B(s), and C(s) which are transient terms, and, the charge rate is estimated from a relationship between a previously derived open-circuit voltage V₀ and the charge rate SOC using the open-circuit voltage V₀,

$\begin{array}{cc}V=\frac{B\left(s\right)}{A\left(s\right)}·I+\frac{1}{C\left(s\right)}·V_0,& \left(1\right)\end{array}$

• • wherein s denotes a Laplace transform operator, A(s), B(s), and C(s) denote poly-nominal functions of s.

Claims

1. A charge rate estimating apparatus for a secondary cell, comprising:

a current detecting section capable of measuring a current flowing through the secondary cell;

a terminal voltage detecting section capable of measuring a voltage across terminals of the secondary cell;

a parameter estimating section that calculates an adaptive digital filtering using a cell model in a continuous time series shown in an equation (1) and estimates all parameters at one time, the parameters corresponding to an open-circuit voltage V₀ which is an offset term of the equation (1) and coefficients of A(s), B(s), and C(s), which are transient terms; and

a charge rate estimating section that estimates the charge rate from a previously derived relationship between an open-circuit voltage and a charge rate of the secondary cell and the open-circuit voltage V₀,

3. A charge rate estimating apparatus for a secondary cell as claimed in claim 1, wherein the cell model is calculated from an equation (6),

4. A charge rate estimating apparatus for a secondary cell as claimed in claim 3, wherein

5. A charge rate estimating apparatus for a secondary cell as claimed in claim 4, wherein a=T₁·

T₃, b=T₁+T₃, c=K·

T₂·

T₃, d=K·

(T₂+T₃), e=K+A·

T₁, f=A - - - (11).

6. A charge rate estimating apparatus for a secondary cell as claimed in claim 5, wherein a stable low pass filter G₁(s) is introduced into both sides of the equation (10) to derive the following equation:

7. A charge rate estimating apparatus for a secondary cell as claimed in claim 6, wherein actually measurable currents I and terminal voltages V which are processed by means of a low pass filter are as follows:

8. A charge rate estimating apparatus for a secondary cell as claimed in claim 7, wherein, using the equation (13), the equation of (12) is rewritten and rearranged as follows:

9. A charge rate estimating apparatus for a Secondary cell as claimed in claim 8, wherein a parameter estimating algorithm with the equation (16) as a prerequisite is defined as follows:

2. A charge rate estimating apparatus for a secondary cell, comprising:

a current detecting section capable of measuring a current flowing through the secondary cell;

a terminal voltage detecting section capable of measuring a voltage across terminals of the secondary cell;

a parameter estimating section that calculates an adaptive digital filtering using a cell model in a continuous time series shown in an equation (1) and estimates all parameters at one time, the parameters corresponding to an open-circuit voltage V₀, which is an offset term of the equation (1), and coefficients of A(s), B(s), and C(s), which are transient terms; and

a charge rate estimating section that estimates the charge rate from a previously derived relationship between an open-circuit voltage and a charge rate of the secondary cell and the open-circuit voltage V₀,

13. A charge rate estimating apparatus for a secondary cell as claimed in claim 2, wherein the cell model is calculated from an equation (6),

10. A charge rate estimating method for a secondary cell, comprising:

measuring a current flowing through the secondary cell;

measuring a voltage across terminals of the secondary cell;

calculating an adaptive digital filtering to provide an adaptive digital filter calculation using a cell model in a continuous time series shown in an equation (1);

estimating all parameters at one time, the parameters corresponding to an open-circuit voltage V₀, which is an offset term of the equation (1), and coefficients of A(s), B(s), and C(s), which are transient terms; and

estimating the charge rate from a previously derived relationship between an open-circuit voltage and a charge rate of the secondary cell and the open-circuit voltage V₀,

12. A charge rate estimating method for a secondary cell as claimed in claim 10, wherein the cell model is calculated from an equation (6),

11. A charge rate estimating method for a secondary cell, comprising:

measuring a current flowing through the secondary cell;

measuring a voltage across terminals of the secondary cell;

calculating an adaptive digital filtering to provide an adaptive digital filter calculation using a cell model in a continuous time series shown in an equation (1);

estimating all parameters at one time, the parameters corresponding to an open-circuit voltage V₀, which is an offset term of the equation (1), and coefficients of A(s), B(s), and C(s), which are transient terms; and

estimating the charge rate from a previously derived relationship between an open-circuit voltage and a charge rate of the secondary cell and the open-circuit voltage V₀,

15. A charge rate estimating method for a secondary cell as claimed in claim 11, wherein the cell model is calculated from an equation (6),

14. A charge rate estimating apparatus for a secondary cell, comprising:

a current detecting section capable of measuring a current flowing through the secondary cell;

a terminal voltage detecting section capable of measuring a voltage across terminals of the secondary cell;

a parameter estimating section that calculates an adaptive digital filtering using a cell model in a continuous time series shown in an equation (1) estimates all of parameters at one time, the parameters corresponding to an open-circuit voltage V₀ which is an offset term of the equation (1) and coefficients of A(s), B(s), and C(s) which are transient terms; and

a charge rate estimating section that estimates the charge rate from a previously derived relationship between an open-circuit voltage and a charge rate of the secondary cell, and the open-circuit voltage V₀,