Available input-output power estimating device for secondary battery

• US 20050275407A1
• Filed: 06/10/2005
• Published: 12/15/2005
• Est. Priority Date: 06/11/2004
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nakamura, Hideo, Yumoto, Daijiro
• Granted Patent: US 7,486,079 B2
• Time in Patent Office: Days
• US Class Current: 324/426
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

An available input-output power estimating device for a secondary battery includes a parameter estimating section substituting a measured current value I and a measured voltage value V into an adaptive digital filter using an equivalent circuit model of the secondary battery for thereby collectively estimating values of parameters in the equivalent circuit model, an open circuit voltage calculator substituting I, V, and the estimated parameter values into the equivalent circuit model for calculating an open circuit voltage {circumflex over (V)}₀, an available input power estimating section estimating an available input power P_in of the secondary battery using components (â_n,{circumflex over (b)}_n), associated with a direct term in the equivalent circuit model, in the estimated parameters, the open circuit voltage estimate value {circumflex over (V)}₀ and an upper limit voltage V_max of the terminal voltage, and an available output power estimating section estimating an available output power P_out for the secondary battery using (â_n,{circumflex over (b)}_n), {circumflex over (V)}₀ and a lower limit voltage {circumflex over (V)}_min of the terminal voltage.

Claims

1. An available input-output power estimating device for a secondary battery, comprising:

a current detector measuring a value I of a current of the secondary battery;

a voltage detector measuring a value V of a terminal voltage of the secondary battery;

a parameter estimating section substituting the measured current value I and the measured voltage value V into an adaptive digital filter using a battery model represented by an equation (a) for thereby collectively estimating a value of a parameter vector, as a parameter vector estimate value, in the equation (a);

an open circuit voltage calculator substituting the measured current value I, the measured voltage value V, and the parameter estimate value into the equation (a) for thereby calculating a value {circumflex over (V)}₀, as an open circuit voltage estimate value, of an open circuit voltage;

an available input power estimating section substituting a set of components (â

_n, {circumflex over (b)}_n), which is associated with a direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and an upper limit voltage V_max, which is predetermined, of the terminal voltage V into an equation (b) for thereby estimating an available input power Pin of the secondary battery; and

an available output power estimating section substituting the one set of components (â

_n, {circumflex over (b)}_n), which is associated with the direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and a lower limit voltage V_min, which is predetermined, of the terminal voltage V into an equation (c) for thereby estimating an available output power P_out of the secondary battery;

wherein

the equations (a), (b), and (c) are described, respectively, as

$\begin{array}{cc}V=\frac{B<br><br>\left(s\right)}{A<br><br>\left(s\right)}<br><br>I+\frac{1}{C<br><br>\left(s\right)}<br><br>V_0,& \left(a\right)\\ P_{\mathrm{in}}=\frac{V_{\max }-{\hat{V}}_0}{{\hat{b}}_n}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\hat{a}}_n<br><br>V_{\max },& \left(b\right)\\ \mathrm{and}& \text{\hspace{1em}<br><br>}\\ P_{\mathrm{out}}=\frac{{\hat{V}}_0-V_{\min }}{{\hat{b}}_n}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\hat{a}}_n<br><br>V_{\min }& \left(c\right)\end{array}$

where A(s) , B(s) , and C(s) represent polynomials of a Laplace operator s, respectively, as follows;

$\begin{array}{cc}A<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>a_k<br><br>s^k,B<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>b_k<br><br>s^k,\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>C<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>c_k<br><br>s^k& \left(d\right)\end{array}$

where the first order coefficients a₁, b₁, and c₁ of the polynomials take non-zero values, respectively.

2. The available input-output power estimating device for the secondary battery according to claim 1, wherein:

the set of components (â

_n, {circumflex over (b)}_n) of the parameter vector estimate value is filtered with a lowpass function.

3. The available input-output power estimating device for the secondary battery according to claim 1, wherein:

in case of A(s)=K(T₂s+1) , B(s)=T₁s+1, and C(s)=T₃s+1 in the equation (a), components {circumflex over (T)}₁ and {circumflex over (K)}{circumflex over (T)}₂ of the parameter vector estimate value are filtered with a lowpass transfer function G(s) and then, in place of the equation (b) and the equation (c), an equation (e) and an equation (f) are used, wherein the equations (e) and (f) are described, respectively, as

$\begin{array}{cc}{P}_{\mathrm{in}}=\left(V_{\max }-{\hat{V}}_0\right)<br><br>G<br><br>\left(s\right)<br><br>\left\{\frac{{\hat{T}}_1}{\hat{K}<br><br>{\hat{T}}_2}\right\}<br><br>V_{\max },<br><br>\mathrm{and}& \left(e\right)\\ {\hat{P}}_{\mathrm{out}}=\left({\hat{V}}_0-V_{\min }\right)<br><br>G<br><br>\left(s\right)<br><br>\left\{\frac{{\hat{T}}_1}{\hat{K}<br><br>{\hat{T}}_2}\right\}<br><br>V_{\min }& \left(f\right)\end{array}$

where T₁, T₂, and T₃ are time constants, respectively;

K is an internal resistance of the secondary battery.

4. The available input-output power estimating device for the secondary battery according to claim 1, wherein:

in case of A(s)=K(T₂s+1) , B(s)=T₁+1 , and C(s)=T₃s+1 in the equation (d), a filter treatment is executed on a ratio

$\frac{{\hat{T}}_1}{{\hat{T}}_1}$

calculated from the parameter vector estimate value is filtered with a lowpass transfer function G(s) and then, in place of the equation (b) and the equation (c), an equation (g) and an equation (h) are used, wherein the equations (g) and (h) are described as

$\begin{array}{cc}{P}_{\mathrm{in}}=\frac{V_{\max }-{\hat{V}}_0}{\hat{K}}<br><br>G<br><br>\left(s\right)<br><br>\left\{\frac{{\hat{T}}_1}{{\hat{T}}_2}\right\}<br><br>V_{\max },<br><br>\mathrm{and}& \left(g\right)\\ P_{\mathrm{out}}=\frac{{\hat{V}}_0-V_{\min }}{\hat{K}}<br><br>G<br><br>\left(s\right)<br><br>\left\{\frac{{\hat{T}}_1}{{\hat{T}}_2}\right\}·<br><br>V_{\min },& \left(h\right)\end{array}$

where T₁, T₂ , and T₃ are time constants, respectively;

K is an internal resistance of the secondary battery.

5. An available input-output power estimating device for a secondary battery, comprising:

a current detecting means measuring a value I of a current of the secondary battery;

a voltage detecting means measuring a value V of a terminal voltage of the secondary battery;

a parameter estimating means substituting the measured current value I and the measured voltage value V into an adaptive digital filter using a battery model represented by an equation (a) for thereby collectively estimating a value of a parameter vector, as a parameter vector estimate value, in the equation (a);

an open circuit voltage calculating means substituting the measured current value I, the measured voltage value V, and the parameter estimate value into the equation (a) for thereby calculating a value {circumflex over (V)}₀, as an open circuit voltage estimate value, of an open circuit voltage;

an available input power estimating means substituting a set of components (â

_n, {circumflex over (b)}_n), which is associated with a direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and an upper limit voltage V_max, which is predetermined, of the terminal voltage V into an equation (b) for thereby estimating an available input power P_in of the secondary battery; and

an available output power estimating means substituting the one set of components (â

_n, {circumflex over (b)}_n), which is associated with the direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and a lower limit voltage V_min, which is predetermined, of the terminal voltage V into an equation (c) for thereby estimating an available output power P_out of the secondary battery;

wherein

the equations (a) , (b), and (c) are described, respectively, as

$\begin{array}{cc}V=\frac{B<br><br>\left(s\right)}{A<br><br>\left(s\right)}<br><br>I+\frac{1}{C<br><br>\left(s\right)}<br><br>V_0,& \left(a\right)\\ P_{\mathrm{in}}=\frac{V_{\max }-{\hat{V}}_0}{{\hat{b}}_n}<br><br>{\hat{a}}_n<br><br>V_{\max },<br><br>\mathrm{and}& \left(b\right)\\ P_{\mathrm{out}}=\frac{{\hat{V}}_0-V_{\min }}{{\hat{b}}_n}<br><br>{\hat{a}}_n<br><br>V_{\min }& \left(c\right)\end{array}$

where A(s) , B(s) , and C(s) represent polynomials of a Laplace operator s, respectively, as follows;

$\begin{array}{cc}A<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>a_k<br><br>s^k,B<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>b_k<br><br>s^k,\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>C<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>c_k<br><br>s^k& \left(d\right)\end{array}$

where the first order coefficients a₁, b₁, and c₁ of the polynomials take non-zero values, respectively.

6. An estimating method of an available input-output power for a secondary battery, comprising:

measuring a value I of a current of the secondary battery;

measuring a value V of a terminal voltage of the secondary battery;

substituting the measured current value I and the measured voltage value V into an adaptive digital filter using a battery model represented by an equation (a) for thereby collectively estimating a value of a parameter vector, as a parameter vector estimate value, in the equation (a);

substituting the measured current value I , the measured voltage value V, and the parameter estimate value into the equation (a) for thereby calculating a value {circumflex over (V)}₀, as an open circuit voltage estimate value, of an open circuit voltage;

substituting a set of components (â

_n, {circumflex over (b)}_n), which is associated with a direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and an upper limit voltage V_max, which is predetermined, of the terminal voltage V into an equation (b) for thereby estimating an available input power P_in of the secondary battery; and

substituting the one set of components (â

_n, {circumflex over (b)}_n), which is associated with the direct term in the equation (a), of the parameter vector estimate value, the open circuit voltage estimate value {circumflex over (V)}₀, and a lower limit voltage V_min, which is predetermined, of the terminal voltage V into an equation (c) for thereby estimating an available output power P_out of the secondary battery;

wherein the equations (a), (b), and (c) are described, respectively, as

$\begin{array}{cc}V=\frac{B<br><br>\left(s\right)}{A<br><br>\left(s\right)}<br><br>I+\frac{1}{C<br><br>\left(s\right)}<br><br>V_0,& \left(a\right)\\ P_{\mathrm{in}}=\frac{V_{\max }-{\hat{V}}_0}{{\hat{b}}_n}<br><br>{\hat{a}}_n<br><br>V_{\max },<br><br>\mathrm{and}& \left(b\right)\\ P_{\mathrm{out}}=\frac{{\hat{V}}_0-V_{\min }}{{\hat{b}}_n}<br><br>{\hat{a}}_n<br><br>V_{\min }& \left(c\right)\end{array}$

where A(s), B(s), and C(s) represent polynomials of a Laplace operator s, respectively, as follows;

$\begin{array}{cc}A<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>a_k<br><br>s^k,B<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>b_k<br><br>s^k,\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>C<br><br>\left(s\right)=\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>c_k<br><br>s^k& \left(d\right)\end{array}$

where the first order coefficients a₁, b₁, and c₁ , of the polynomials take non-zero values, respectively.