CN111220922A - Battery SOC estimation method and device - Google Patents

Battery SOC estimation method and device Download PDF

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Publication number
CN111220922A
CN111220922A CN202010072537.4A CN202010072537A CN111220922A CN 111220922 A CN111220922 A CN 111220922A CN 202010072537 A CN202010072537 A CN 202010072537A CN 111220922 A CN111220922 A CN 111220922A
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soc
battery
current
electric quantity
last
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张延鹏
蒋锋
刘珂
高弘飞
邝忠诚
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Haima Motor Corp
Haima New Energy Vehicle Co Ltd
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Haima Motor Corp
Haima New Energy Vehicle Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/387—Determining ampere-hour charge capacity or SoC
    • G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables

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  • General Physics & Mathematics (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Abstract

The embodiment of the invention provides a method and a device for estimating the SOC of a battery, which relate to the field of estimating the SOC of the battery, and the method comprises the following steps: acquiring an electric quantity parameter of the battery during the power-off in the last period and standing time after the power-off in the last period, and judging whether the standing time exceeds a preset threshold value; if not, calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method; and if so, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method. When the standing time of the battery exceeds a preset threshold value, the electric quantity parameter of the battery is corrected, so that the integral accumulation error caused by long working time of the battery is reduced, the SOC calculation error caused by battery capacity attenuation is reduced, and the SOC estimation accuracy is improved.

Description

Battery SOC estimation method and device
Technical Field
The invention relates to the field of battery SOC estimation, in particular to a battery SOC estimation method and device.
Background
At present, electromotion becomes a new trend in the automobile industry. The pure electric vehicle is an industry target, but the pure electric vehicle has short endurance mileage and can only be used as a short distance due to the limitation of the characteristics of the power battery. The hybrid electric vehicle, especially plug-in hybrid power, because there are two sets of driving systems (engine and power battery), not only can charge, has reduced and discharged, have not had the restriction of the mileage of endurance moreover, has remedied the deficiency of the pure electric vehicle, is loved by the market deeply.
The power battery is used as an important power source of the plug-in hybrid electric vehicle, has the characteristics of high cost, high voltage, high danger and the like, and is very important for ensuring safe and efficient operation. The above object can be achieved by monitoring the Battery operating state in real time through a Battery Management System (BMS). The State of charge (SOC) of the battery is an important parameter for the operation of the battery, and is obtained through estimation by the BMS, and affects other important functions of the BMS, such as thermal management, charge and discharge control, equalization, fault diagnosis, and the like. Accurate SOC estimation is therefore of great importance.
The current SOC estimation method mainly comprises the following steps: the ampere-hour integration method is used for obtaining the charging and discharging electric quantity according to the electric quantity at the initial moment of the battery and the integral value of the current in the charging and discharging process of the battery; however, as the working time of the battery increases, the battery capacity fading brings large errors to the SOC calculation, so that the SOC estimation is not accurate enough.
Disclosure of Invention
In view of the above, the present invention provides a battery state of charge and a battery SOC estimation device.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, an embodiment of the present invention provides a battery state of charge estimation method, including:
acquiring an electric quantity parameter of the battery during the power-off in the last period and standing time after the power-off in the last period; the electric quantity parameter represents the state of charge of the battery; the standing time represents the duration of the battery from the power-off time of the last period to the power-on time of the current period;
judging whether the standing time exceeds a preset threshold value; if not, calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method; and if so, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method.
In an optional embodiment, the charge parameter includes an initial charge SOC0Current variable delta Ah and actual battery capacity Cp(ii) a The electric quantity parameters of the battery during the last period of power-off are respectively SOC0Last,. DELTA.Ah _ last and Cp_last；SOC0Last includes initial charge maximum SOCinimaxAnd initial minimum value of electric quantity SOCinimin；
Calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method, and the method comprises the following steps:
based on
Figure BDA0002377661010000021
Calculating the SOC of the current period;
therein, SOCestIs the SOC of the current cycle;
therein, SOCmaxAnd SOCminRespectively satisfy the following calculation formula:
Figure BDA0002377661010000031
Figure BDA0002377661010000032
wherein, the delta Ah _ current is the delta Ah variable quantity of the battery charging and discharging in the current period.
In an alternative embodiment, Δ Ah _ current satisfies the following calculation:
ΔAh_current＝μIΔt
wherein, mu is temperature coefficient, and mu is Cp_n/Cp_m，Cp_nIs the nominal capacity of the battery;
i is the current value of the current cycle, I ═ It-Ioffest(ii) a Wherein, ItIs the actual sampled value of the current of the present cycle, IoffestIs the average value of a plurality of current noise values in the initialization phase of the current period,
Figure BDA0002377661010000033
wherein, I1，I2…InA plurality of current noise values for the initialization phase of the current cycle;
Cp_mthe method comprises the steps that a map table is searched according to actual temperature, and the map table represents the corresponding relation between different temperatures of a battery and the actual capacity of the battery; Δ t is the duration of the current cycle.
In an optional embodiment, the charge parameter includes an initial charge SOC0Current variable delta Ah and actual battery capacity Cp；
The step of correcting the electric quantity parameter comprises the following steps:
acquiring the current temperature and the open-circuit voltage;
searching the corrected initial electric quantity SOC from an open-circuit voltage look-up table according to the current temperature and the open-circuit voltageocv(ii) a The open circuit voltage represents a terminal voltage of the battery in an open circuit state; the open-circuit voltage lookup table represents the corresponding relationship between the temperature, the open-circuit voltage of the battery and the initial electric quantity of the battery.
In an optional embodiment, the step of correcting the electric quantity parameter further includes:
the correction of the actual capacity of the battery satisfies the following calculation formula:
Cp＝η*Cp_est+(1-η)*Cp_last
where eta is the adaptive correction coefficient, Cp_estIs a corrected capacity value obtained according to the ampere-hour variation and the open-circuit voltage method, Cp_estThe following calculation formula is satisfied:
Cp_est＝-ΔAh_last/(SOCocv-SOCini)
therein, SOCocvIncluding a corrected maximum and a corrected minimum; SOCiniThe method comprises the steps of (1) including an initial electric quantity maximum value and an initial electric quantity minimum value;
when the battery is in a discharging state, the denominator is taken to be SOCocvMinimum value and SOC ofiniThe difference between the maximum values of; when the battery is in a charging state, the denominator is taken to be SOCocvMaximum value and SOC ofiniThe difference between the minimum values of (a).
In a second aspect, an embodiment of the present invention provides a battery SOC estimation device, including:
the acquisition module is used for acquiring the electric quantity parameter of the battery during the power-off in the last period and the standing time after the power-off in the last period; the electric quantity parameter represents the state of charge of the battery; the standing time represents the duration of the battery from the power-off time of the last period to the power-on time of the current period;
the judging module is used for judging whether the standing time exceeds a preset threshold value;
the processing module is used for calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method when the standing time does not exceed a preset threshold; and when the standing time exceeds a preset threshold value, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method.
In an optional embodiment, the charge parameter includes an initial charge SOC0Current variable delta Ah and actual battery capacity Cp(ii) a The electric quantity parameters of the battery during the last period of power-off are respectively SOC0_last,. DELTA.Ah _ last and Cp_last；SOC0_last includes initial power maximum SOCinimaxAnd initial minimum value of electric quantity SOCinimin；
The processing module is also used for processing the data based on
Figure BDA0002377661010000051
Calculating the SOC of the current period;
therein, SOCestIs the SOC of the current cycle;
therein, SOCmaxAnd SOCminRespectively satisfy the following calculation formula:
Figure BDA0002377661010000052
Figure BDA0002377661010000053
wherein, the delta Ah _ current is the delta Ah variable quantity of the battery charging and discharging in the current period.
In an alternative embodiment, the processing module is further configured to perform the processing based on
ΔAh_current＝μIΔt
Calculating delta Ah _ current;
wherein, mu is temperature coefficient, and mu is Cp_n/Cp_m，Cp_nIs the nominal capacity of the battery;
i is the current value of the current cycle, I ═ It-Ioffest(ii) a Wherein, ItIs the actual sampled value of the current of the present cycle, IoffestIs the average value of a plurality of current noise values in the initialization phase of the current period,
Figure BDA0002377661010000061
wherein, I1，I2…InA plurality of current noise values for the initialization phase of the current cycle;
Cp_mthe method comprises the steps that a map table is searched according to actual temperature, and the map table represents the corresponding relation between different temperatures of a battery and the actual capacity of the battery; Δ t is the duration of the current cycle.
In an optional embodiment, the charge parameter includes an initial charge SOC0Current variable delta Ah and actual battery capacity Cp；
The acquisition module is also used for acquiring the current temperature and the open-circuit voltage;
the processing module is also used for processing the data according toSearching the corrected initial electric quantity SOC from an open-circuit voltage look-up table by the current temperature and the open-circuit voltageocv(ii) a The open circuit voltage represents a terminal voltage of the battery in an open circuit state; the open-circuit voltage lookup table represents the corresponding relationship between the temperature, the open-circuit voltage of the battery and the initial electric quantity of the battery.
In an alternative embodiment, the processing module is further configured to perform the processing based on
Cp＝η*Cp_est+(1-η)*Cp_last
Calculating the actual capacity of the corrected battery;
where eta is the adaptive correction coefficient, Cp_estIs a corrected capacity value obtained according to the ampere-hour variation and the open-circuit voltage method, Cp_estThe following calculation formula is satisfied:
Cp_est＝-ΔAh_last/(SOCocv-SOCini)
therein, SOCocvIncluding a corrected maximum and a corrected minimum; SOCiniThe method comprises the steps of (1) including an initial electric quantity maximum value and an initial electric quantity minimum value;
when the battery is in a discharging state, the denominator is taken to be SOCocvMinimum value and SOC ofiniThe difference between the maximum values of; when the battery is in a charging state, the denominator is taken to be SOCocvMaximum value and SOC ofiniThe difference between the minimum values of (a).
The embodiment of the invention provides a method and a device for estimating the SOC of a battery, wherein the method comprises the following steps: acquiring an electric quantity parameter of the battery during the power-off in the last period and standing time after the power-off in the last period, and judging whether the standing time exceeds a preset threshold value; if not, calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method; and if so, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method. When the standing time of the battery exceeds a preset threshold value, the electric quantity parameter of the battery is corrected, so that the integral accumulation error caused by long working time of the battery is reduced, the SOC calculation error caused by battery capacity attenuation is reduced, and the SOC estimation accuracy is improved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 shows a schematic flow chart of a battery SOC estimation method according to an embodiment of the present invention.
Fig. 2 is a schematic flow chart of another battery SOC estimation method according to an embodiment of the present invention.
Fig. 3 is a functional block diagram of a battery SOC estimation apparatus according to an embodiment of the present invention.
Icon: 100-battery SOC estimation means; 110-an obtaining module; 120-a judgment module; 130-processing module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The current SOC estimation method mainly comprises the following steps:
1. discharge test method: the battery is continuously discharged at constant current, the discharge current and the discharge time are recorded, and the product of the discharge current and the discharge time is used as the discharge capacity, so that the residual capacity of the battery is calculated, and the method is the simplest estimation method;
2. an ampere-hour integration method: the current in the charging and discharging process of the battery is recorded in real time and integrated, so that the charging and discharging electric quantity is obtained. If the electric quantity of the battery at the initial moment is SOC0Then, the remaining capacity SOC at the time t is endedtComprises the following steps:
Figure BDA0002377661010000081
wherein, CpAnd I is the actual capacity of the battery, and the charge and discharge current of the battery.
3. Open circuit voltage method: and calculating the SOC by using the open-circuit voltage obtained by measurement according to the functional relation between the open-circuit voltage and the SOC.
4. A neural network method: the estimation of the SOC of the battery is completed by utilizing the strong learning capability, the generalization capability, the nonlinear mapping capability and the high parallelism of the neural network.
5. The Kalman filtering method comprises the following steps: and establishing a state equation and an observation equation according to the battery model. And (3) taking the SOC and the polarization voltage of the battery as state variables of the system, taking the working voltage as an observation variable of the system, and estimating the SOC of the battery by adopting a Kalman filtering algorithm.
The disadvantages of the current SOC estimation methods are:
1. the discharge experiment method is only suitable for test measurement with little current change, can be only feasible in an off-line state, inevitably needs to consume a large amount of time, can only be used for correcting measurement in a laboratory at present, and is not suitable for real vehicle estimation.
2. The simple ampere-hour integration method has the following problems: firstly, the initial SOC value of the battery cannot be calculated by an ampere-hour integration method; secondly, errors exist in current collection, and the accumulated error generated by integration is larger and larger as the working time of the battery is longer; thirdly, the attenuation of the battery capacity also brings large errors to the SOC calculation. Therefore, the method can maintain the estimation accuracy to some extent only if the initial value of the SOC is accurately known and the magnitude of the operating current can be accurately measured.
3. The open circuit voltage method requires the battery to stand still for a long time in a non-operating state, to reach a stable state of voltage for use, and cannot be used for on-line estimation.
4. The neural network method has to train a large amount of data in advance, the calculation amount is huge, and the selection and the accuracy of the training data directly determine the estimation accuracy of the model. In view of the software and hardware conditions of the real vehicle, the method is more suitable for the application of SOC estimation in a laboratory at the present stage, and the condition of effective application to the real vehicle is far from being achieved and is not mature.
5. The kalman filtering method needs to establish a battery model according to relevant parameters of the battery, and the estimation accuracy depends on the accuracy of the battery model. However, the battery is a highly nonlinear system, and it is very difficult to establish an accurate and general battery model.
In combination with engineering application practice, the embodiment of the invention provides an improved SOC estimation method based on ampere-hour integration; the method starts from the link that the ampere-hour integration algorithm possibly generates various errors, solves the problems of uncertain initial value of the ampere-hour integral SOC, current sensor acquisition errors and SOC estimation errors caused by capacity attenuation caused by battery aging, improves estimation accuracy, ensures stable and reliable work of the BMS, further improves the safety, reliability and high efficiency of the power battery operation, and saves cost.
The battery provided by the embodiment of the invention comprises a plurality of battery cells, each battery cell has its own SOC value due to the chemical property difference among the battery cells, the value range of the SOC value of the battery cell is 0-100, the maximum SOC value in all the battery cells is taken as the maximum SOC value of the power battery, and the minimum SOC value in all the battery cells is taken as the minimum SOC value of the battery in the same way. And estimating the optimal SOC value of the whole battery through certain operation based on the maximum value and the minimum value of the SOC of the battery. The battery SOC is stored in two parts: initial SOC amount of electricity SOC0And a current change amount Δ Ah, which is mainly a change in Δ Ah caused by current during charge and discharge.
Fig. 1 is a schematic flow chart of a method for estimating a battery SOC according to an embodiment of the present invention.
Step 101, acquiring an electric quantity parameter of the battery during power-off in the last period and standing time after power-off in the last period.
Step 102, judging whether the standing time exceeds a preset threshold value.
And 103, calculating the SOC of the current period according to the electric quantity parameters based on an ampere-hour integral method.
And step 104, correcting the electric quantity parameters, and calculating the SOC of the current period according to the corrected electric quantity parameters based on an ampere-hour integral method.
In this embodiment, first, an electric quantity parameter of the battery during the last period of power-off and the standing time after the last period of power-off are obtained, and then whether the standing time exceeds a predetermined threshold is judged; if not, acquiring the initial electric quantity SOC when the battery is powered down in the last period0_ last, current variation Δ Ah _ last, and actual battery capacity CpLast, based on ampere-hour integration method according to SOC0Last,. DELTA.Ah _ last and CpSecondly, calculating the SOC of the current period by a last; and if the standing time exceeds a preset threshold value, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integration method. When the standing time of the battery exceeds a preset threshold value, the electric quantity parameter of the battery is corrected, so that the integral accumulation error caused by long working time of the battery is reduced, the SOC calculation error caused by battery capacity attenuation is reduced, and the SOC estimation accuracy is improved.
Referring to fig. 2, a flow chart of another method for estimating the SOC of a battery according to an embodiment of the invention is shown.
It should be noted that the basic principle and the generated technical effect of the method for estimating the SOC of the battery provided by the embodiment are the same as those of the embodiment, and for the sake of brief description, no part of the embodiment is mentioned, and reference may be made to the corresponding contents in the embodiment.
Step 101, acquiring an electric quantity parameter of the battery during power-off in the last period and standing time after power-off in the last period.
Starting to supply power to the vehicle after the battery is electrified, stopping supplying power to the vehicle when the battery is powered off, and reading initial electric quantity SOC when the battery is powered off0_ last, current variation Δ Ah _ last, and actual battery capacity Cp_last。
And reading the standing time after the power-off of the last period, wherein the standing time represents the duration of the battery from the power-off of the last period to the power-on of the current period.
Step 102, judging whether the standing time exceeds a preset threshold value.
If yes, go to step 104; if not, step 103.
The predetermined threshold is set by human, and can be adjusted according to actual conditions.
If the standing time does not exceed the preset threshold, the error influence caused by the battery capacity attenuation is small and can be ignored, and the SOC of the current period is directly calculated by using an ampere-hour integration method.
If the standing time exceeds the preset threshold, the influence of errors caused by the battery capacity attenuation is large, and the electric quantity parameters need to be corrected, so that the problem that the obtained SOC value error of the battery is too large is solved.
And 103, calculating the SOC of the current period according to the electric quantity parameters based on an ampere-hour integral method.
Acquiring the electric quantity parameter SOC of the battery during the last period of power-off0Last,. DELTA.Ah _ last and Cp_last；SOC0Last includes initial charge maximum SOCinimaxAnd initial minimum value of electric quantity SOCinimin；
Then use
Figure BDA0002377661010000111
Calculating the SOC of the current period;
therein, SOCestIs the SOC of the current cycle;
therein, SOCmaxAnd SOCminRespectively satisfy the following calculation formula:
Figure BDA0002377661010000121
Figure BDA0002377661010000122
wherein, the delta Ah _ current is the delta Ah variable quantity of the battery charging and discharging in the current period.
It should be noted that the above formula has the following characteristics: (1) when the relative stable difference value is kept between the maximum value and the minimum value of the SOC of the battery, namely the SOCmax-SOCminWhen the overall battery SOC is smaller than a fixed value, the SOCestCloser to minimum SOCmin(ii) a When the whole battery pack SOC is larger, the SOC is largerestCloser to maximum SOCmax(ii) a (2) When the difference between the maximum and minimum SOC values of the battery is changed, i.e. SOCmax-SOCminWhen the difference is small, the SOC is not constantestCloser to minimum SOCmin(ii) a When the difference is larger, SOCestCloser to maximum SOCmax. The advantage of this formula is that it is easier to trigger the failsafe threshold when the battery SOC is close to the maximum or minimum to ensure the safety of the battery and avoid over-discharge or over-charge of the battery.
It should be noted that since temperature has a significant influence on the charge/discharge characteristics of the battery, the temperature factor is considered in calculating Δ Ah _ current, and Δ Ah _ current satisfies the following calculation formula:
ΔAh_current＝μIΔt
wherein, mu is temperature coefficient, and mu is Cp_n/Cp_m，Cp_nIs the nominal capacity of the battery; cp_mThe map table is obtained by looking up the map table according to the actual temperature, and the map table represents the corresponding relation between different temperatures of the battery and the actual capacity of the battery; the corresponding relation between the temperature and the actual capacity of the battery is a nonlinear relation and is also influenced by battery aging, and a map table is obtained through a large amount of test data.
I is the current value of the current cycle, I ═ It-Ioffest(ii) a Wherein, ItIs the actual sampled value of the current of the present cycle, IoffestIs the current periodThe average value of a plurality of current noise values in the initialization stage is that in the process of power-on initialization, the current is required to be 0 at the moment, but the current is not 0 due to acquisition errors, and a sampling value I of a plurality of sampling step lengths is monitored1，I2…InTaking the average value of these quantities as the deviation calibration quantity I of the currentoffest，
Figure BDA0002377661010000131
Wherein, I1，I2…InA plurality of current noise values for the initialization phase of the current cycle; the value of I is positive during discharge and negative during charge.
It should be noted that the current noise value means a value in which the current should be zero, but actually fluctuates up and down based on zero.
Δ t is the duration of the current cycle.
It should be noted that, in the initial power-on stage of each cycle, the current deviation calibration operation is required, and I of each cycle isoffestThe values are not necessarily equal, but in the same period IoffestThe value remains fixed, IoffestThe values have upper and lower limits.
And step 104, correcting the electric quantity parameters, and calculating the SOC of the current period according to the corrected electric quantity parameters based on an ampere-hour integral method.
Firstly, acquiring the current temperature and the open-circuit voltage; then, the corrected initial electric quantity SOC is searched from the open-circuit voltage look-up table according to the current temperature and the open-circuit voltageocv(ii) a The open-circuit voltage is the terminal voltage of the battery in an open-circuit state; the open-circuit voltage look-up table includes a corresponding relationship between temperature, open-circuit voltage of the battery, and initial charge of the battery.
Open circuit voltage and initial electric quantity SOCoThe temperature of the water tank is influenced by the temperature; the relation between the single function relation and the initial electric quantity can not be accurately expressed by fitting, so that the invention forms the open-circuit voltage and the initial electric quantity SOC at different temperatures through a large number of battery cell testsoLook-up table of open circuit voltage.
Since the battery capacity is affected by the use conditions such as aging and temperature, the actual battery capacity is estimated and corrected after a certain condition is reached, for example, a certain charge/discharge time, a certain ampere hour change amount, and the like.
The correction of the actual capacity of the battery satisfies the following calculation formula:
Cp＝η*Cp_est+(1-η)*Cp_last
where eta is the adaptive correction coefficient, Cp_estIs a corrected capacity value obtained according to the ampere-hour variation and the open-circuit voltage method, Cp_estThe following calculation formula is satisfied:
Cp_est＝-ΔAh_last/(SOCocv-SOCini)
therein, SOCocvIncluding a corrected maximum and a corrected minimum; SOCiniThe method comprises the steps of (1) including an initial electric quantity maximum value and an initial electric quantity minimum value;
when the battery is in a discharging state, the denominator is taken to be SOCocvMinimum value and SOC ofiniThe difference between the maximum values of;
when the battery is in a charging state, the denominator is taken to be SOCocvMaximum value and SOC ofiniThe difference between the minimum values of (a).
It should be noted that the method for calculating the SOC of the current cycle based on the ampere-hour integration in this step is the same as that in step 103, and the difference is that the initial value of the electric quantity in the formula is the initial value corrected by the open-circuit voltmeter, the Ah change amount Δ Ah of the current cycle is reset to 0 from the read Δ Ah _ last, and the estimation of the current cycle is started.
In summary, the method and apparatus for estimating the SOC of the battery provided in the embodiments of the present invention include: acquiring an electric quantity parameter of the battery during the power-off in the last period and standing time after the power-off in the last period, and judging whether the standing time exceeds a preset threshold value; if not, calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method; and if so, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method. When the standing time of the battery exceeds a preset threshold value, correcting the electric quantity parameter of the battery, reducing the integral accumulated error caused by long working time of the battery, reducing the SOC calculation error caused by the capacity attenuation of the battery, and improving the SOC estimation accuracy; thereby ensure that BMS job stabilization is reliable, and then improve power battery operation's security, reliability and high efficiency, saved the cost. Meanwhile, the influence of temperature is considered, the initial value of the SOC of the battery is corrected timely by an open-circuit voltage method, the influence of service conditions such as aging and temperature is considered, and the estimation and correction of the actual capacity of the battery can be carried out in a self-adaptive manner; the acquisition deviation of the current sensor is calibrated in the initial stage, so that the accuracy of the current for SOC estimation is improved; and the SOC of the battery is estimated by considering the chemical characteristic difference of the battery cells and the maximum value and the minimum value of the battery cell capacity, so that the safety of the battery is guaranteed to the maximum extent.
In order to perform the corresponding steps in the above-described embodiments and various possible manners, an implementation manner of the battery SOC estimation device is given below. Further, referring to fig. 3, fig. 3 is a functional block diagram of a battery SOC estimation device 100 according to an embodiment of the present invention. It should be noted that the basic principle and the technical effects of the battery SOC estimation device 100 provided in the present embodiment are the same as those of the above embodiments, and for the sake of brief description, no part of the present embodiment is mentioned, and reference may be made to the corresponding contents in the above embodiments. The battery SOC estimation device 100 includes: an obtaining module 110, a determining module 120 and a processing module 130.
It is understood that in one embodiment, step 101 is performed by the acquisition module 110.
It is understood that in one embodiment, step 102 is performed by the determination module 120.
It is understood that in one embodiment, steps 103 and 104 are performed by the processing module 130.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, the functional modules in the embodiments of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A battery SOC estimation method, characterized by comprising:
acquiring an electric quantity parameter of the battery during the power-off in the last period and standing time after the power-off in the last period; the electric quantity parameter represents the state of charge of the battery; the standing time represents the duration of the battery from the power-off time of the last period to the power-on time of the current period;
judging whether the standing time exceeds a preset threshold value; if not, calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method;
and if so, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method.
2. The method of claim 1, wherein the charge parameter comprises an initial charge SOC0Current variable delta Ah and actual battery capacity Cp(ii) a The electric quantity parameters of the battery during the last period of power-off are respectively SOC0Last,. DELTA.Ah _ last and Cp_last；SOC0Last includes initial charge maximum SOCinimaxAnd initial minimum value of electric quantity SOCinimin；
Calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method, and the method comprises the following steps:
based on
Figure FDA0002377659000000011
Calculating the SOC of the current period;
therein, SOCestIs the SOC of the current cycle;
therein, SOCmaxAnd SOCminRespectively satisfy the following calculation formula:
Figure FDA0002377659000000021
Figure FDA0002377659000000022
wherein, the delta Ah _ current is the delta Ah variable quantity of the battery charging and discharging in the current period.
3. The method of claim 2,
Δ Ah _ current satisfies the following calculation formula:
ΔAh_current＝μIΔt
wherein, mu is temperature coefficient, and mu is Cp_n/Cp_m，Cp_nIs the nominal capacity of the battery;
i is the current value of the current cycle, I ═ It-Ioffest(ii) a Wherein, ItIs the actual sampled value of the current of the present cycle, IoffestIs the average value of a plurality of current noise values in the initialization phase of the current period,
Figure FDA0002377659000000023
wherein, I1，I2...InA plurality of current noise values for the initialization phase of the current cycle;
Cp_mthe method comprises the steps that a map table is searched according to actual temperature, and the map table represents the corresponding relation between different temperatures of a battery and the actual capacity of the battery; Δ t is the duration of the current cycle.
4. The method of claim 1, wherein the charge parameter comprises an initial charge SOC0Current variable delta Ah and actual battery capacity Cp；
The step of correcting the electric quantity parameter comprises the following steps:
acquiring the current temperature and the open-circuit voltage;
supplying power from open circuit according to the current temperature and the open circuit voltageSearching the corrected initial electric quantity SOC in a look-up tableocv(ii) a The open-circuit voltage is the terminal voltage of the battery in an open-circuit state; the open-circuit voltage lookup table represents the corresponding relationship between the temperature, the open-circuit voltage of the battery and the initial electric quantity of the battery.
5. The method of claim 4, wherein the step of correcting the charge parameter further comprises:
the correction of the actual capacity of the battery satisfies the following calculation formula:
Cp＝η*Cp_est+(1-η)*Cp_last
where eta is the adaptive correction coefficient, Cp_estIs a corrected capacity value obtained according to the ampere-hour variation and the open-circuit voltage method, Cp_estThe following calculation formula is satisfied:
CP_est＝-ΔAh_last/(SOCocv-SOCini)
therein, SOCocvIncluding a corrected maximum and a corrected minimum; SOCiniThe method comprises the steps of (1) including an initial electric quantity maximum value and an initial electric quantity minimum value;
when the battery is in a discharging state, the denominator is taken to be SOCocvMinimum value and SOC ofiniThe difference between the maximum values of;
when the battery is in a charging state, the denominator is taken to be SOCocvMaximum value and SOC ofiniThe difference between the minimum values of (a).
6. A battery SOC estimation device, characterized by comprising:
the acquisition module is used for acquiring the electric quantity parameter of the battery during the power-off in the last period and the standing time after the power-off in the last period; the electric quantity parameter represents the state of charge of the battery; the standing time represents the duration of the battery from the power-off time of the last period to the power-on time of the current period;
the judging module is used for judging whether the standing time exceeds a preset threshold value;
the processing module is used for calculating the SOC of the current period according to the electric quantity parameter based on an ampere-hour integral method when the standing time does not exceed a preset threshold; and when the standing time exceeds a preset threshold value, correcting the electric quantity parameter, and calculating the SOC of the current period according to the corrected electric quantity parameter based on an ampere-hour integral method.
7. The apparatus of claim 6, wherein the charge parameter comprises an initial charge SOC0Current variable delta Ah and actual battery capacity Cp(ii) a The electric quantity parameters of the battery during the last period of power-off are respectively SOC0Last,. DELTA.Ah _ last and Cp_last；SOC0Last includes initial charge maximum SOCinimaxAnd initial minimum value of electric quantity SOCinimin；
The processing module is also used for processing the data based on
Figure FDA0002377659000000041
Calculating the SOC of the current period;
therein, SOCestIs the SOC of the current cycle;
therein, SOCmaxAnd SOCminRespectively satisfy the following calculation formula:
Figure FDA0002377659000000042
Figure FDA0002377659000000043
wherein Δ Ah _currenAnd t is the delta Ah variable quantity of the battery charging and discharging in the current period.
8. The apparatus of claim 7,
the processing module is also used for processing the data based on
ΔAh_current＝μIΔt
Calculating delta Ah _ current;
wherein, mu is temperature coefficient, and mu is Cp_n/Cp_m，Cp_nIs the nominal capacity of the battery;
i is the current value of the current cycle, I ═ It-Ioffest(ii) a Wherein, ItIs the actual sampled value of the current of the present cycle, IoffestIs the average value of a plurality of current noise values in the initialization phase of the current period,
Figure FDA0002377659000000051
wherein, I1，I2...InA plurality of current noise values for the initialization phase of the current cycle;
Cp_mthe method comprises the steps that a map table is searched according to actual temperature, and the map table represents the corresponding relation between different temperatures of a battery and the actual capacity of the battery; Δ t is the duration of the current cycle.
9. The apparatus of claim 6, wherein the charge parameter comprises an initial charge SOC0Current variable delta Ah and actual battery capacity Cp；
The acquisition module is also used for acquiring the current temperature and the open-circuit voltage;
the processing module is further configured to search the corrected initial electric quantity SOC from an open-circuit voltage look-up table according to the current temperature and the open-circuit voltageocv(ii) a The open-circuit voltage is the terminal voltage of the battery in an open-circuit state; the open-circuit voltage lookup table represents the corresponding relationship between the temperature, the open-circuit voltage of the battery and the initial electric quantity of the battery.
10. The apparatus of claim 9,
the processing module is also used for processing the data based on
Cp＝η*Cp_est+(1-η)*Cp_last
Calculating the actual capacity of the corrected battery;
where eta is the adaptive correction coefficient, Cp_estBased on the amount of ampere-hour change and open circuitCorrected capacity value, C, obtained by voltage methodp_estThe following calculation formula is satisfied:
CP_est＝-ΔAh_last/(SOCocv-SOCini)
therein, SOCocvIncluding a corrected maximum and a corrected minimum; SOCiniThe method comprises the steps of (1) including an initial electric quantity maximum value and an initial electric quantity minimum value;
when the battery is in a discharging state, the denominator is taken to be SOCocvMinimum value and SOC ofiniThe difference between the maximum values of;
when the battery is in a charging state, the denominator is taken to be SOCocvMaximum value and SOC ofiniThe difference between the minimum values of (a).
CN202010072537.4A 2020-01-21 2020-01-21 Battery SOC estimation method and device Pending CN111220922A (en)

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