CN107024666B - Apparatus for estimating battery SOC - Google Patents

Abstract

The invention relates to the technical field of battery management, and discloses a device for estimating battery SOC. The device includes a processor, and the processor is configured to: determine whether the battery enters the discharge end; in the case of judging that the battery enters the discharge end , the SOC value of the battery is estimated according to the detected current I of the battery, the voltage V of the battery, and the pre-stored correspondence between the voltage V, current I and the SOC value of the battery at different rates. The accuracy of the SOC value estimated by the device is greatly improved, which provides a basis for users to accurately judge the cruising range of the electric vehicle.

Description

Apparatus for estimating battery SOC

technical field

The present invention relates to the technical field of battery management, and in particular, to an apparatus for estimating battery SOC.

Background technique

Lithium batteries are widely used in electric vehicles, energy storage, and backup power because of their high energy density and good environmental performance. State-of-Charge (SOC) is one of the key parameters of lithium batteries. SOC reflects the remaining power of the battery pack and is a direct parameter for users to evaluate the current electric vehicle cruising range and the remaining working time of the backup power supply.

At present, the battery management system (Battery Management System, BMS) mainly uses the ampere-hour integration method to estimate the SOC of the battery pack, and supplements it with the open circuit voltage at rest for correction. However, this method has certain defects, mainly in that when the lithium battery is at the end of discharge, if there is a large error in the SOC, the user will misjudge the cruising range of the electric vehicle, and the lithium battery will terminate the discharge in advance, causing the electric vehicle to be in the middle of the road. Serious consequences such as "squatting".

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device for estimating battery SOC, which estimates battery SOC based on the corresponding relationship between battery voltage V, current I and SOC value under different magnifications, thereby improving the accuracy of SOC estimation.

To achieve the above objects, embodiments of the present invention provide an apparatus for estimating battery SOC, the apparatus including a processor configured to:

Determine whether the battery has entered the end of discharge;

In the case of judging that the battery has entered the end of discharge, the SOC value of the battery is estimated according to the detected current and voltage of the battery and the pre-stored correspondence between the voltage, current and SOC value of the battery at different rates.

Preferably, the processor is configured to:

comparing the estimated battery SOC value with a threshold;

If the estimated SOC value is less than the threshold, it is judged that the battery enters the end of discharge.

Preferably, the threshold is 15%.

Preferably, the processor is configured to:

In the case of judging that the battery has entered the end of discharge, according to the corresponding relationship between the voltage, current and SOC value of the battery under different magnifications, determine a plurality of current values corresponding to the current voltage value V ₁ under different magnifications in the corresponding relationship;

Two current values I ₁ and I ₂ adjacent to the detected current current value I _x of the battery are determined from the plurality of current values, wherein the current current value I _x is located between the two current values I ₁ and I ₂ ;

The SOC value of the battery is estimated according to formula (1):

which is

Among them, SOC _x is the estimated SOC value of the battery, I _x is the detected current current value, I ₁ and I ₂ are the two current values that are adjacent to I _x in the current value corresponding to the current voltage V ₁ in the corresponding relationship, respectively. SOC ₁ and SOC ₂ are the SOC values corresponding to I ₁ and I ₂ , respectively.

Preferably, the device further includes:

Voltage sensor, used to detect the voltage of the battery;

Current sensor, used to detect the current of the battery.

An apparatus for estimating a battery state-of-charge SOC includes a processor configured to:

Determine the charge and discharge status of the battery;

In the case of judging that the battery is in a charging state, determine whether the battery has entered the charging end;

In the case of judging that the battery has entered the charging end, the SOC value of the battery is estimated according to the detected current of the battery, the voltage of the battery, and the pre-stored first correspondence between the voltage, current and the SOC value of the battery at different rates;

In the case of judging that the battery is in a discharge state, judge whether the battery has entered the end of discharge;

In the case of judging that the battery has entered the end of discharge, the SOC value of the battery is estimated according to the detected battery current, the battery voltage, and the pre-stored second correspondence between the battery voltage, current and SOC value at different rates.

Preferably, judging whether the battery enters the end of charging comprises: comparing the estimated SOC value with a first threshold, and if the estimated SCO value is greater than the first threshold, judging that the battery enters the end of charging;

Determining whether the battery has entered the end of discharge includes comparing the estimated SOC value with a second threshold, and if the estimated SCO value is less than the second threshold, judging that the battery has entered the end of discharge.

Preferably, the first threshold is 85% and the second threshold is 15%.

Preferably, the processor is configured to:

In the case of judging that the battery has entered the end of charging/discharging, according to the first/second correspondence between the voltage, current and SOC value of the battery at different rates, determine the first/second correspondence at different rates in the first/second correspondence a plurality of current values corresponding to the current voltage value V ₁ ;

Two current values I ₁ and I ₂ adjacent to the detected current current value I _x of the battery are determined from the plurality of current values, wherein the current current value I _x is located between the two current values I ₁ and I ₂ ;

The SOC value of the battery is estimated according to formula (1):

which is

Wherein, SOC _x is the estimated SOC value of the battery, I _x is the detected current value, and I ₁ and I ₂ are the current values corresponding to the current voltage V ₁ in the first/second correspondence, respectively. The two current values adjacent to I _x , SOC ₁ and SOC ₂ , are the SOC values corresponding to I ₁ and I ₂ , respectively.

Preferably, the first correspondence is the charging curves of the battery at different rates, and the second correspondence is the discharge curves of the batteries at different rates.

Through the above technical solution, the battery SOC estimation is realized, and the accuracy of the SOC estimation is improved.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached image:

FIG. 1 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention;

2 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention;

3 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention;

4 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention;

5 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention;

6 is a schematic block diagram of an apparatus for estimating battery SOC according to an embodiment of the present invention;

Figure 7 shows the charging curves of lithium batteries at different rates;

Figure 8 shows the end-of-charge curves of lithium batteries at different rates;

Figure 9 shows the discharge curves of lithium batteries at different rates; and

Figure 10 shows the discharge end curves of lithium batteries at different rates.

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

As used in this application, the term "end of charge" refers to a stage in the charging process of a battery near the completion of charging, and the term "end of discharge" refers to a stage in the process of discharging a battery near the completion of discharge.

FIG. 1 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention. As shown in FIG. 1 , in an embodiment of the present invention, a method for estimating battery SOC is provided, and the method may include:

In step S11, it is judged whether the battery has entered the charging end;

In step S12, in the case of judging that the battery has entered the charging end, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored voltage V, current I and SOC value of the battery at different rates The corresponding relationship of , estimate the SOC value of the battery.

The battery may be, for example, a lithium battery.

The above-mentioned corresponding relationship can be, for example, the charging curves of the battery under different magnifications (as shown in FIG. 7 ). The charging profile may be predetermined and stored. For example, the charging profile can be stored in the memory of the BMS. Methods of determining this charging profile may be known to those skilled in the art.

The voltage of the battery can be detected, for example, using a voltage sensor. The current of the battery can be detected, for example, using a current sensor. Alternatively, the voltage and current of the battery may be detected, for example, by a battery management system (Battery Management System, BMS).

Determining whether the battery has entered the end of charging in step S11 may include comparing the estimated battery SOC value with a threshold, and if the estimated SOC value is greater than the threshold, judging that the battery has entered the end of charging. The SOC value can be estimated using, for example, the ampere-hour integration method. In an embodiment of the present invention, the threshold may be, for example, 85%, but those skilled in the art can understand that the threshold may be any other suitable value.

FIG. 2 is a flowchart of a method for estimating battery SOC according to an embodiment of the present invention. As shown in FIG. 2, in an embodiment of the present invention, a method for estimating battery SOC is provided, and the method may include:

In step S21, the voltage V of the battery and the current I of the battery are detected;

In step S22, the SOC value of the battery is estimated; for example, the ampere-hour integration method can be used to estimate the SOC value of the battery;

In step S23, it is judged whether the battery has entered the charging end;

In step S24, in the case of judging that the battery has entered the charging end, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored voltage V, current I and SOC value of the battery at different rates The corresponding relationship of , estimate the SOC value of the battery.

In the embodiment shown with reference to FIG. 2 , steps S23 and S24 may be the same as or similar to steps S11 and S12 in the embodiment shown with reference to FIG. 1 .

In an embodiment of the present invention, the estimated current SOC value of the battery in the above step S12 or step S24 may include:

Determine a plurality of current values corresponding to the current voltage value under different magnifications in the above-mentioned corresponding relationship. For example, in an embodiment of the present invention, a plurality of current values corresponding to the current voltage value of the battery on the charging curve of the battery under different magnifications can be determined;

Two current values adjacent (eg, closest) to the detected current current value of the battery are determined from the plurality of current values, wherein the current current value lies between the two current values. Figure 7 shows the charging curves of lithium batteries at different rates. Although the figure shows the charging curve of a lithium battery, those skilled in the art will understand that other types of batteries are also applicable. As shown in FIG. 8 , the current voltage value of the battery is V ₁ , the current current value is I _x , and the two current values adjacent to the current current value in the battery charging curves of different rates are I ₁ and I ₂ , which are the same as I ₁ . The SOC values corresponding to I ₂ are SOC ₁ and SOC ₂ , respectively.

The SOC value of the battery is estimated according to formula (1):

which is

Among them, SOC _x is the estimated SOC value of the battery, I _x is the detected current value, and I ₁ and I ₂ are the current values corresponding to the current voltage V ₁ in the corresponding relationship (such as the charging curve) and I respectively. The two adjacent current values of _x , SOC ₁ and SOC ₂ are the SOC values corresponding to I ₁ and I ₂ respectively.

Through the above method, the SOC value of the battery can be corrected at the end of battery charging, thereby improving the SOC estimation accuracy.

3 is a flowchart of a method for estimating a battery end-of-discharge SOC according to an embodiment of the present invention. As shown in FIG. 3 , in an embodiment of the present invention, a method for estimating the SOC at the end of discharge of a battery is provided, and the method may include:

In step S31, it is judged whether the battery has entered the discharge end;

In step S32, in the case of judging that the battery has entered the end of discharge, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored voltage V, current I and SOC value of the battery at different rates The corresponding relationship of , estimate the SOC value at the end of the discharge of the battery.

The battery may be, for example, a lithium battery.

The above-mentioned corresponding relationship can be, for example, the discharge curves of the battery at different rates (as shown in FIG. 9 ). The discharge curve may be predetermined and stored. For example, the discharge curve can be stored in the memory of the BMS. Methods of determining this discharge curve may be known to those skilled in the art.

The voltage of the battery can be detected, for example, using a voltage sensor. The current of the battery can be detected, for example, using a current sensor. Alternatively, the voltage and current of the battery may be detected, for example, by a battery management system (Battery Management System, BMS).

The method of judging whether the battery has entered the end of discharge in step S31 may include comparing the estimated battery SOC value with a threshold, and if the estimated SOC value is less than the threshold, judging that the battery has entered the end of discharge. The SOC value can be estimated using, for example, the ampere-hour integration method. In an embodiment of the present invention, the threshold may be, for example, 15%, but those skilled in the art can understand that the threshold may be any other suitable value.

4 is a flowchart of a method for estimating a battery end-of-discharge SOC according to an embodiment of the present invention. As shown in FIG. 4 , in an embodiment of the present invention, a method for estimating the SOC at the end of discharge of a battery is provided, and the method may include:

In step S41, the voltage V of the battery and the current I of the battery are detected;

In step S42, the SOC value of the battery is estimated; for example, the ampere-hour integration method can be used to estimate the SOC value of the battery;

In step S43, it is judged whether the battery has entered the discharge end;

In step S44, in the case of judging that the battery has entered the end of discharge, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored voltage V, current I and SOC value of the battery at different rates The corresponding relationship of , estimate the SOC value of the battery.

In the embodiment shown in FIG. 4 , steps S43 and S44 may be the same as or similar to steps S31 and S32 in the embodiment shown in FIG. 3 .

In an embodiment of the present invention, the estimated current SOC value of the battery in the above step S32 or step S44 may include:

Determine a plurality of current values corresponding to the current voltage value under different magnifications in the above-mentioned corresponding relationship. For example, in an embodiment of the present invention, a plurality of current values corresponding to the current voltage value of the battery on the discharge curve of the battery at different rates can be determined;

Two current values adjacent (eg, closest) to the detected current current value of the battery are determined from the plurality of current values, wherein the current current value lies between the two current values. Figure 9 shows the discharge curves of lithium batteries at different rates. Figure 10 shows the discharge end curves of lithium batteries at different rates. Although the figure shows the discharge curve of a lithium battery, those skilled in the art will understand that other types of batteries are also applicable. As shown in FIG. 10 , the current voltage value of the battery is V ₁ , the current current value is I _x , and the two current values adjacent to the current current value in the battery discharge curves of different rates are I ₁ and I ₂ , which are the same as I ₁ . The SOC values corresponding to I ₂ are SOC ₁ and SOC ₂ , respectively.

The SOC value of the battery is estimated according to formula (3):

which is

Among them, SOC _x is the estimated SOC value of the battery, I _x is the detected current current value, I ₁ and I ₂ are the current values corresponding to the current voltage V ₁ in the corresponding relationship (for example, the discharge curve) and I The two adjacent current values of _x , SOC ₁ and SOC ₂ are the SOC values corresponding to I ₁ and I ₂ respectively.

Through the above method, the SOC value of the battery can be corrected at the end of the battery discharge, thereby improving the SOC estimation accuracy.

FIG. 5 is a flowchart of a method for estimating the end-of-charge/discharge SOC of a battery according to an embodiment of the present invention. As shown in FIG. 5 , in an embodiment of the present invention, a method for estimating battery SOC is provided, and the method may include:

In step S51, determine the charging and discharging state of the battery;

In step S52, when it is judged that the battery is in a charged state, the SOC value at the end of the battery charge is estimated according to the method shown in FIG. 1 or FIG. 2; in step S53, when it is judged that the battery is in a discharged state, according to FIG. 3 Or the method shown in Figure 4 estimates the SOC value at the end of battery discharge.

If it is determined that the battery is neither in a charged state nor in a discharged state, the method ends.

6 is a schematic block diagram of an apparatus for estimating battery SOC according to an embodiment of the present invention. The apparatus may be used to perform the method for estimating battery SOC in the above-described embodiments. Specifically, as shown in FIG. 6 , the apparatus for estimating the battery SOC includes a processor 10 .

In one embodiment of the present invention, the processor 10 may be configured to:

Determine whether the battery has entered the charging end;

In the case of judging that the battery has entered the end of charging, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored correspondence between the voltage V, current I and SOC value of the battery at different rates, estimate The SOC value of the battery.

In an embodiment of the present invention, the device may further include a voltage sensor 20 for detecting the voltage of the battery; and a current sensor 30 for detecting the current of the battery. The processor 10 is also used to estimate the SOC value of the battery. For example, the processor 10 may estimate the SOC value of the battery using, for example, an ampere-hour integration method before determining that the battery is entering the end of charge.

In addition, the apparatus may further comprise a memory 40 configured to store the above-mentioned correspondence. This correspondence may be, for example, the above-mentioned charging curve.

In another embodiment of the present invention, the processor 10 may be configured to:

Determine whether the battery has entered the end of discharge;

In the case of judging that the battery has entered the end of discharge, according to the detected current I of the battery, the voltage V of the battery, and the pre-stored correspondence between the voltage V, current I and SOC value of the battery at different rates, estimate The SOC value of the battery at the end of discharge.

In one embodiment of the present invention, the processor 10 may also be configured to estimate the SOC value of the battery using, for example, an ampere-hour integration method before judging that the battery has entered the end of discharge.

In this embodiment, the memory 40 may be configured to store the above-mentioned correspondence. This correspondence is, for example, the above-described discharge curve.

In yet another embodiment of the present invention, the processor 10 may be configured to:

Determine the charge and discharge status of the battery;

In the case of judging that the battery is in a charged state, the above-mentioned steps for estimating the battery SOC in the charging process can be performed;

When it is determined that the battery is in a discharged state, the above-mentioned steps for estimating the SOC of the battery during the discharging process may be performed.

In addition, the processor 10 may also be configured to perform no operation if it is determined that the battery is neither in a charged state nor in a discharged state.

In an alternative or additional embodiment of the present invention, the apparatus may further include a display 50 configured to display the SOC value of the battery.

In one embodiment of the invention, the device may be a BMS.

In one embodiment of the present invention, a computer-readable storage medium is provided, and instructions are stored on the storage medium, and the instructions, when executed by a processor, cause the processor to execute any of the operations shown in FIGS. 1 to 5 . Method for estimating battery SOC.

The accuracy of the SOC value estimated by the above method has been greatly improved, ensuring that the SOC is maintained within a reasonable range, preventing damage to the battery due to overcharge, reducing battery life, and preventing users from driving a car that is mistakenly thought to be fully charged. , resulting in serious consequences such as the car "squatting" halfway.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, These simple modifications all belong to the protection scope of the present invention. In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner under the condition of no contradiction. In order to avoid unnecessary repetition, the present invention has The combination method will not be specified otherwise.

In addition, the various embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims (8)

1. An apparatus for estimating a state of charge, SOC, of a battery, the apparatus comprising a processor configured to:

judging whether the battery enters a discharging tail end or not;

under the condition that the battery enters the discharging end, estimating and correcting the SOC value of the battery according to the detected current of the battery, the voltage of the battery and the pre-stored corresponding relation between the voltage, the current and the SOC value of the battery under different multiplying powers so as to improve the estimation precision of the SOC value of the discharging end of the battery;

wherein estimating and correcting the SOC value of the battery specifically includes:

under the condition that the battery enters the discharging end, determining the voltage value V and the current voltage value V under different multiplying powers in the corresponding relation according to the corresponding relation among the voltage, the current and the SOC value of the battery under different multiplying powers₁A corresponding plurality of current values;

determining and detecting a present current value I of the battery from a plurality of current values_xTwo adjacent current values I₁And I₂Wherein the current value I_xAt these two current values I₁And I₂To (c) to (d);

estimating the SOC value of the battery according to equation (1):

namely, it is

Therein, SOC_xTo estimate the SOC value of the battery, I_xFor the detected current value, I₁And I₂Respectively corresponding to the current voltage V₁Corresponding current value of I_xTwo adjacent current values, SOC₁And SOC₂Are respectively represented by₁And I₂The corresponding SOC value.

2. The apparatus of claim 1, wherein the processor is configured to:

comparing the estimated battery SOC value with a threshold value;

and if the estimated SOC value is less than the threshold value, judging that the battery enters the discharging end.

3. The apparatus of claim 2, wherein the threshold is 15%.

4. The apparatus of claim 1, further comprising:

a voltage sensor for detecting a voltage of the battery;

and the current sensor is used for detecting the current of the battery.

5. An apparatus for estimating a state of charge, SOC, of a battery, the apparatus comprising a processor configured to:

judging the charge and discharge state of the battery;

under the condition of judging that the battery is in a charging state, judging whether the battery enters a charging tail end or not;

under the condition that the battery enters the charging end, estimating and correcting the SOC value of the battery according to the detected current of the battery, the voltage of the battery and the prestored first corresponding relation between the voltage, the current and the SOC value of the battery under different multiplying powers so as to improve the estimation precision of the SOC value of the charging end of the battery;

under the condition of judging that the battery is in a discharging state, judging whether the battery enters a discharging tail end or not;

under the condition that the battery enters the discharging end, estimating and correcting the SOC value of the battery according to the detected current of the battery, the voltage of the battery and the pre-stored second corresponding relation between the voltage, the current and the SOC value of the battery under different multiplying powers so as to improve the estimation precision of the SOC value of the discharging end of the battery;

wherein estimating and correcting the SOC value of the battery specifically includes:

under the condition that the battery enters the charging/discharging end, determining the current voltage value V at different multiplying powers in the first/second corresponding relation according to the first/second corresponding relation of the voltage, the current and the SOC value of the battery at different multiplying powers₁A corresponding plurality of current values;

determining and detecting a present current value I of the battery from a plurality of current values_xTwo adjacent current values I₁And I₂Wherein the current value I_xAt these two current values I₁And I₂To (c) to (d);

estimating the SOC value of the battery according to equation (1):

namely, it is

Therein, SOC_xTo estimate the SOC value of the battery, I_xFor the detected current value, I₁And I₂Respectively, the current voltage V in the first/second corresponding relationship₁Corresponding current value of I_xTwo adjacent current values, SOC₁And SOC₂Are respectively represented by₁And I₂The corresponding SOC value.

6. The apparatus of claim 5,

determining whether the battery enters the charging terminal includes: comparing the estimated SOC value with a first threshold value, and if the estimated SCO value is larger than the first threshold value, judging that the battery enters a charging tail end;

determining whether the battery enters the discharge end includes: and comparing the estimated SOC value with a second threshold value, and if the estimated SCO value is smaller than the second threshold value, judging that the battery enters the discharging tail end.

7. The apparatus of claim 6, wherein the first threshold is 85% and the second threshold is 15%.

8. The apparatus of claim 6, wherein the first corresponding relationship is a charge curve of the battery at different rates, and the second corresponding relationship is a discharge curve of the battery at different rates.

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