Battery fuel gauging system
View Patent ↗The present disclosure discloses a battery fuel gauging system, which includes a battery voltage collecting module and a microprocessor module. An input terminal of the battery voltage collecting module is configured to collect a terminal voltage of the battery. The microprocessor module is configured to receive the terminal voltage and estimate the remaining charge in the battery. The microprocessor module estimates an open-circuit voltage of the battery according to the terminal voltage of the battery and a built-in battery model, and further calculates the battery's remaining charge based on SOC-OCV relations of a typical lithium-ion battery. The present disclosure is capable of maintaining the precision of the battery fuel gauging system and can set the battery fuel gauging system inside or outside of the battery.
1. A battery fuel gauging system, comprising:
a battery comprising a terminal voltage, an open-circuit voltage and a built-in battery model;
a battery voltage collecting module comprising an input terminal and an output terminal, the input terminal being connected to the battery and configured to collect the terminal voltage of the battery, wherein the battery voltage collecting module works intermittently;
a microprocessor module, being connected to the output terminal of the battery voltage collecting module and configured to receive the terminal voltage of the battery and estimate remaining charge in the battery;
wherein, the microprocessor module estimates the open-circuit voltage of the battery according to the terminal voltage of the battery in conjunction with the built-in battery model, and further calculates the battery's remaining charge based on SOC-OCV(state of charge-open-circuit voltage) relations of a typical lithium-ion battery, the built-in battery model is described by the following equation set:
V
o
(
t
)
=
V
ocv
(
t
)
-
I
1
(
t
)
*
R
1
-
I
2
(
t
)
*
R
2
(
1
)
I
2
(
t
)
*
R
2
=
V
C
1
(
t
)
(
2
)
∫
0
t
I
2
-
I
1
C
1
dt
=
V
C
1
(
t
)
(
3
)
SOC
(
t
)
=
SOC
(
0
)
-
∫
0
t
I
1
(
t
)
dt
(
4
)
wherein, V o (t) represents the terminal voltage of the battery, V ocv (t) represents the open-circuit voltage of the battery, R 1 represents an equivalent ohmic resistance of the battery, R 2 represents an equivalent polarization differential resistance, I 1 (t) represents charge current or discharge current of the battery, and I 2 (t) represents the current flowing through the equivalent polarization differential resistance R 2 , SOC(t) is the present remaining charge in the battery, and SOC(0) is initial charge amount of the battery, C 1 represents a responding speed of the polarization voltage differential to current excitation and is decided by the intrinsic characteristics of the battery, the present open-circuit voltage of the battery is calculated according to the built-in battery model in conjunction with the presently collected terminal voltage of the battery, and the present open-circuit voltage of the battery is further utilized to calculate the remaining charge in the battery according to the SOC-OCV relations of the typical lithium-ion battery.
2. The battery fuel gauging system according to claim 1 , wherein a relational table correlating the open-circuit voltage of the battery and the remaining charge is established according to characteristics of the battery, and the open-circuit voltage is calculated according to the terminal voltage of the battery, and further the corresponding remaining charge is obtained by looking up the table, when the open-circuit voltage of the battery is amidst a plurality of discrete data points, linear interpolation is utilized to calculate the remaining charge in the battery.
3. The battery fuel gauging system according to claim 1 , wherein relational data correlating the open-circuit voltage of the battery and the remaining charge is established according to characteristics of the battery, and a relational polynomial set correlating the open-circuit voltage of the battery and the remaining charge is retained, further the open-circuit voltage of the battery is calculated according to the terminal voltage of the battery, and finally the open-circuit voltage is substituted into the polynomial set correlating the open-circuit voltage of the battery and the remaining charge.
4. A battery fuel gauging system, comprising:
a battery comprising a terminal voltage, an open-circuit voltage and a built-in battery model;
a battery voltage collecting module comprising an input terminal and an output terminal, wherein the input terminal of the battery voltage collecting module is connected to the battery and configured to collect the terminal voltage of the battery;
a microprocessor module, being connected to the output terminal of the battery voltage collecting module and configured to receive the terminal voltage of the battery and estimate remaining charge in the battery;
wherein the microprocessor module estimates the open-circuit voltage of the battery according to the terminal voltage of the battery and the built-in battery model, and further calculates the battery's remaining charge based on SOC-OCV relations of a typical lithium-ion battery;
wherein the battery voltage collecting module comprises a voltage sampling unit and an analog-to-digital conversion unit.
5. The battery fuel gauging system according to claim 4 , wherein the voltage sampling unit is a switched capacitor circuit or a high input resistance amplifier.
6. The battery fuel gauging system according to claim 4 , wherein the voltage sampling unit comprises at its front end a low pass filter.
7. The battery fuel gauging system according to claim 4 , wherein the battery voltage collecting module works intermittently.
8. The battery fuel gauging system according to claim 4 , wherein the microprocessor module is a digital signal processor (DSP).
9. The battery fuel gauging system according to claim 4 , wherein the microprocessor module is a programmable device programmed with certain algorithms.
10. The battery fuel gauging system according to claim 4 , wherein the built-in battery model is described by the following equation set:
V
o
(
t
)
=
V
ocv
(
t
)
-
I
1
(
t
)
*
R
1
-
I
2
(
t
)
*
R
2
(
1
)
I
2
(
t
)
*
R
2
=
V
C
1
(
t
)
(
2
)
∫
0
t
I
2
-
I
1
C
1
dt
=
V
C
1
(
t
)
(
3
)
SOC
(
t
)
=
SOC
(
0
)
-
∫
0
t
I
1
(
t
)
dt
(
4
)
wherein, V o (t) represents the terminal voltage of the battery, V ocv (t) represents the open-circuit voltage of the battery, R 1 represents an equivalent ohmic resistance of the battery, R 2 represents an equivalent polarization differential resistance, I 1 (t) represents charge current or discharge current of the battery, and I 2 (t) represents the current flowing through the equivalent polarization differential resistance R 2 , SOC(t) is the present remaining charge in the battery, and SOC(0) is initial charge amount of the battery, C 1 represents a responding speed of the polarization voltage differential to current excitation and is decided by the intrinsic characteristics of the battery, the present open-circuit voltage of the battery is calculated according to the built-in battery model in conjunction with the presently collected terminal voltage of the battery, and the current open-circuit voltage of the battery is further utilized to calculate the remaining charge in the battery according to the SOC-OCV relations of the typical lithium-ion battery.
11. The battery fuel gauging system according to claim 10 , wherein a relational table correlating the open-circuit voltage of the battery and the remaining charge is established according to characteristics of the battery, and the open-circuit voltage is calculated according to the terminal voltage of the battery, and further the corresponding remaining charge is obtained by looking up the table, when the open-circuit voltage of the battery is amidst a plurality of discrete data points, linear interpolation is utilized to calculate the remaining charge in the battery.
12. The battery fuel gauging system according to claim 10 , wherein relational data correlating the open-circuit voltage of the battery and the remaining charge is established according to characteristics of the battery, and a relational polynomial set correlating the open-circuit voltage of the battery and the remaining charge is retained, further the open-circuit voltage of the battery is calculated according to the terminal voltage of the battery, and finally the open-circuit voltage is substituted into the polynomial set correlating the open-circuit voltage of the battery and the remaining charge.
13. A battery fuel gauging method, wherein the battery comprises a terminal voltage V o (t), an open-circuit voltage V ocv (t) and a built-in battery model, comprising:
establishing SOC-OCV (state of charge-open-circuit voltage) relations of a typical lithium-ion battery, wherein the SOC-OCV relations are the relations between the open-circuit voltage V ocv (t) of the battery and present remaining charge SOC(t) in the battery;
establishing the built-in battery model of the battery, the built-in battery model of the battery being described by the following equation set:
V
o
(
t
)
=
V
ocv
(
t
)
-
I
1
(
t
)
*
R
1
-
I
2
(
t
)
*
R
2
(
1
)
I
2
(
t
)
*
R
2
=
V
C
1
(
t
)
(
2
)
∫
0
t
I
2
-
I
1
C
1
dt
=
V
C
1
(
t
)
(
3
)
SOC
(
t
)
=
SOC
(
0
)
-
∫
0
t
I
1
(
t
)
dt
(
4
)
wherein, V o (t) represents the terminal voltage of the battery, V ocv (t) represents the open-circuit voltage of the battery, R 1 represents an equivalent ohmic resistance of the battery, R 2 represents an equivalent polarization differential resistance, I 1 (t) represents charge current or discharge current of the battery, and I 2 (t) represents the current flowing through the equivalent polarization differential resistance R 2 , SOC(t) is the present remaining charge in the battery, and SOC(0) is initial charge amount of the battery, C 1 represents a responding speed of the
polarization voltage differential to current excitation and is decided by the intrinsic characteristics of the battery, equation (4) is an SOC characteristic equation of the battery, with which the SOC characteristic of the battery at every time point is in accordance;
estimating the charge current or discharge current I 1 (t) of the battery at a present time point depending on the SOC characteristic of the battery at a previous sampling time point;
calculating the current I 2 (t) flowing through the polarization differential resistance R 2 according to equations (2) and (3) with the present charge current or discharge current I 1 (t) of the battery;
calculating the present open-circuit voltage V ocv (t) of the battery according to equation (1) together with the present charge current or discharge current Ii(t) of the battery, the present current I 2 (t) flowing through the polarization differential resistance R 2 , and a presently collected terminal voltage V o (t) of the battery; and
estimating the remaining charge in the battery, according to the SOC-OCV relations of the typical battery model with the present open-circuit voltage of the battery.
14. The battery fuel gauging method according to claim 13 , wherein the step of estimating the remaining charge in the battery according to the SOC-OCV relations of the typical battery model with the present open-circuit voltage of the battery comprises the following steps:
establishing a relational table correlating the open-circuit voltage of the battery and the remaining charge in the battery;
looking up the table to obtain the present remaining charge in the battery corresponding to the present open-circuit voltage of the battery;
when the present open-circuit voltage of the battery is amidst a plurality of discrete data points, utilizing linear interpolation to calculate the present remaining charge in the battery.
15. The battery fuel gauging method according to claim 13 , wherein the step of estimating the remaining charge in the battery according to the SOC-OCV relations of the typical battery model with the present open-circuit voltage of the battery comprises the following steps:
establishing relational data correlating the open-circuit voltage of the battery and the remaining charge in the battery according to the characteristics of the battery;
establishing a relational polynomial set with regard to the open-circuit voltage of the battery and the remaining charge in the battery;
substituting the present open-circuit voltage of the battery into the polynomial set to calculate the present remaining charge in the battery.
16. The battery fuel gauging method according to claim 13 , further comprising:
providing a battery voltage collecting module comprising an input terminal and an output terminal, and a microprocessor module;
connecting the input terminal of the battery voltage collecting module to the battery to collect the terminal voltage of the battery;
connecting the microprocessor module to the output terminal of the battery voltage collecting module to receive the terminal voltage of the battery and estimate the remaining charge in the battery;
wherein the microprocessor module estimates the open-circuit voltage of the battery according to the terminal voltage of the battery and the built-in battery model, and further calculates the battery's remaining charge based on the SOC-OCV relations of the typical lithium-ion battery.
17. The battery fuel gauging method according to claim 16 , wherein the battery voltage collecting module works intermittently.
18. The battery fuel gauging method according to claim 16 , wherein the battery collecting module comprises a voltage sampling unit and an analog-to-digital conversion unit.
19. The battery fuel gauging method according to claim 16 , wherein the microprocessor module is a digital signal processor (DSP) or a programmable device programmed with certain algorithms.