CN111103551A - Method and device for calculating SOH (state of health) of battery system and battery system - Google Patents

Method and device for calculating SOH (state of health) of battery system and battery system Download PDF

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Publication number
CN111103551A
CN111103551A CN201811260327.7A CN201811260327A CN111103551A CN 111103551 A CN111103551 A CN 111103551A CN 201811260327 A CN201811260327 A CN 201811260327A CN 111103551 A CN111103551 A CN 111103551A
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soh
value
battery system
discharging
battery
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CN111103551B (en
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张春
武锡斌
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Beiqi Foton Motor Co Ltd
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Beiqi Foton Motor Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4285—Testing apparatus
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The disclosure relates to a method and a device for calculating the state of health (SOH) of a battery system and the battery system. The battery system comprises at least one battery module, and the method comprises the following steps: determining a charging capacity-based (SOH) value of the battery system, a discharging internal resistance-based (SOH) value of the battery system, and a discharging voltage-based (SOH) value of the battery system; and calculating the actual SOH value of the battery system according to the charging capacity-based SOH value of the battery system, the discharging internal resistance-based SOH value of the battery system and the discharging voltage-based SOH value of the battery system. Therefore, the accuracy of calculation of the SOH can be improved, and more accurate basis is provided for subsequent prediction of the service life of the battery and the like.

Description

Method and device for calculating SOH (state of health) of battery system and battery system
Technical Field
The disclosure relates to the field of batteries, in particular to a method and a device for calculating the state of health (SOH) of a battery system and the battery system.
Background
The SOH (state of health) of the battery is used to indicate the percentage of the current capacity of the battery to the rated capacity, and may reflect the state of health of the battery. The SOH of a battery is an important parameter for predicting the service life of the battery. At present, the SOH of the battery is often estimated by using the capacity fade and the cycle life of the battery, and the service life of the battery is predicted. However, since the updating frequency of the battery core in the battery is fast, the data collection of the battery capacity attenuation and the cycle life is not complete, and the SOH cannot be accurately estimated, so that the remaining service life of the battery cannot be accurately reflected.
Disclosure of Invention
The disclosure aims to provide a method and a device for calculating the state of health (SOH) of a battery system and the battery system, so as to improve the accuracy of estimation of the SOH of the battery system.
In order to achieve the above object, according to a first aspect of the present disclosure, there is provided a method for calculating a state of health, SOH, of a battery system including at least one battery module, the method including:
determining a charging capacity-based (SOH) value of the battery system, a discharging internal resistance-based (SOH) value of the battery system, and a discharging voltage-based (SOH) value of the battery system;
and calculating the actual SOH value of the battery system according to the charging capacity-based SOH value of the battery system, the discharging internal resistance-based SOH value of the battery system and the discharging voltage-based SOH value of the battery system.
Optionally, the determining a charge capacity based SOH value of the battery system includes:
when the battery system is in a charging mode, determining the charging capacity corresponding to the increase of each battery module from a first preset voltage to a second preset voltage;
determining an SOH value corresponding to each battery module according to the determined charging capacities and the corresponding relationship between the preset charging capacity of the battery module and the SOH value;
and determining the SOH value based on the charging capacity of the battery system according to the SOH value corresponding to each battery module.
Optionally, the determining the SOH value based on the charging capacity of the battery system according to the SOH value corresponding to each battery module includes:
sequencing the SOH values corresponding to the battery modules in a sequence from small to large to generate a sequencing queue;
determining a Kth SOH value in the sorting queue as a charging capacity-based SOH value of the battery system, wherein K is calculated by the following formula (1):
K＝[a*N](1)
wherein, N is the number of the battery modules, a is a preset coefficient, and 0< a < 1.
Optionally, the determining the discharging internal resistance-based SOH value of the battery system includes:
when the battery system is in a discharging mode, determining a first discharging power of the battery system, a module discharging power and an average discharging current of each battery module in the battery system in the process that the residual capacity SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
calculating a discharge internal resistance R of the battery system by the following formula (2):
Figure BDA0001843749850000021
wherein N is the number of battery modules, PiA module discharge power, P, for the ith said battery moduleALLThe first discharge power is set, I is the average discharge current, and t is the time variation corresponding to the process that the SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
and determining the SOH value of the battery system based on the discharging internal resistance according to the discharging internal resistance and the corresponding relation between the preset discharging internal resistance and the SOH value.
Optionally, the determining a discharging voltage SOH-based value of the battery system includes:
determining a second discharge power and a discharge capacity corresponding to the process that the SOC of the residual capacity of the battery system changes from a third preset SOC value to a fourth preset SOC value when the battery system is in a discharge mode;
determining the average discharge voltage of the battery system according to the second discharge power and the discharge capacity;
and determining the SOH value of the battery system based on the discharging voltage according to the discharging average voltage and the corresponding relation between the preset discharging voltage and the SOH value.
Optionally, the calculating an actual SOH value of the battery system according to a charging capacity SOH-based value of the battery system, a discharging internal resistance SOH-based value of the battery system, and a discharging voltage SOH-based value of the battery system includes:
determining a first weight value corresponding to the charging capacity-based SOH value, a second weight value corresponding to the discharging internal resistance-based SOH value and a third weight value corresponding to the discharging voltage-based SOH value;
the actual SOH value is calculated according to the following equation (3):
SOHpractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingFor said value of SOH based on charging capacity, SOHInternal resistance to dischargeFor said SOH value based on internal resistance to discharge, SOHDischarge voltageFor the discharging voltage-based SOH value, x is the first weight value, y is the second weight value, z is the third weight value, and x + y + z is 1.
Optionally, the method further comprises:
counting the number of times of calculation of the actual SOH value of the battery system to obtain a count value;
the first weight value x, the second weight value y, and the third weight value z are calculated by the following equations (4) to (6):
x＝x0-m*x1(4)
y＝y0+m*y1(5)
z＝z0+m*z1(6)
wherein x is0、y0、z0、x1、y1、z1Is a preset value, x0+y0+z0When x is decreased to a first critical value, y is increased to a second critical value, and z is increased to a third critical value, x, y, and z are not changed.
According to a second aspect of the present disclosure, there is provided a battery system state of health SOH calculation apparatus, the battery system including at least one battery module, the apparatus including:
a determination module for determining a charging capacity-based SOH value of the battery system, a discharging internal resistance-based SOH value of the battery system, and a discharging voltage-based SOH value of the battery system;
the calculation module is used for calculating the actual SOH value of the battery system according to the SOH value of the battery system based on the charging capacity, the SOH value of the battery system based on the discharging internal resistance and the SOH value of the battery system based on the discharging voltage.
Optionally, the determining module includes:
the first determining submodule is used for determining the charging capacity corresponding to the fact that each battery module is increased from a first preset voltage to a second preset voltage when the battery system is in a charging mode;
the second determining submodule is used for determining an SOH value corresponding to each battery module according to the determined charging capacities and the corresponding relation between the preset charging capacity of the battery module and the SOH value;
and the third determining submodule is used for determining the SOH value of the battery system based on the charging capacity according to the SOH value corresponding to each battery module.
Optionally, the third determining sub-module includes:
the sequencing submodule is used for sequencing the SOH values corresponding to the battery modules in a sequence from small to large to generate a sequencing queue;
a first calculating submodule, configured to determine a kth SOH value in the sorting queue as a charging capacity SOH-based value of the battery system, where K is calculated by the following formula (1):
K＝[a*N](1)
wherein, N is the number of the battery modules, a is a preset coefficient, and 0< a < 1.
Optionally, the determining module includes:
the fourth determining submodule is used for determining the first discharging power of the battery system, the module discharging power of each battery module in the battery system and the average discharging current in the process that the residual capacity SOC of the battery system changes from the first preset SOC value to the second preset SOC value when the battery system is in a discharging mode;
a second calculation submodule for calculating a discharge internal resistance R of the battery system by the following formula (2):
Figure BDA0001843749850000051
wherein N is the number of battery modules, PiA module discharge power, P, for the ith said battery moduleALLThe first discharge power is set, I is the average discharge current, and t is the time variation corresponding to the process that the SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
and the fifth determining submodule is used for determining the SOH value of the battery system based on the discharging internal resistance according to the discharging internal resistance and the corresponding relation between the preset discharging internal resistance and the SOH value.
Optionally, the determining module includes:
the sixth determining submodule is used for determining second discharging power and discharging capacity corresponding to the process that the residual capacity SOC of the battery system changes from a third preset SOC value to a fourth preset SOC value when the battery system is in a discharging mode;
a seventh determining submodule, configured to determine a discharging average voltage of the battery system according to the second discharging power and the discharging capacity;
and the eighth determining submodule is used for determining the SOH value of the battery system based on the discharging voltage according to the discharging average voltage and the corresponding relation between the preset discharging voltage and the SOH value.
Optionally, the calculation module comprises:
a ninth determining submodule, configured to determine a first weight value corresponding to the charging capacity-based SOH value, a second weight value corresponding to the discharging internal resistance-based SOH value, and a third weight value corresponding to the discharging voltage-based SOH value;
a third calculation submodule for calculating said actual SOH value according to the following equation (3):
SOHpractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingFor said value of SOH based on charging capacity, SOHInternal resistance to dischargeFor said SOH value based on internal resistance to discharge, SOHDischarge voltageFor the discharging voltage-based SOH value, x is the first weight value, y is the second weight value, z is the third weight value, and x + y + z is 1.
Optionally, the apparatus further includes a counting module, configured to count the number of times of calculating the actual SOH value of the battery system, so as to obtain a count value;
the ninth determining sub-module is configured to calculate the first weight value x, the second weight value y, and the third weight value z by the following equations (4) to (6):
x＝x0-m*x1(4)
y＝y0+m*y1(5)
z＝z0+m*z1(6)
wherein x is0、y0、z0、x1、y1、z1Is a preset value, x0+y0+z0M is the count value, and, when x falls to a first threshold and y rises to a second thresholdWhen the critical value and z are increased to a third critical value, x, y and z are not changed.
According to a third aspect of the present disclosure, a battery system is provided, which comprises a calculation device of the state of health SOH of the battery system provided by the second aspect of the present disclosure.
Through the technical scheme, the corresponding SOH value is determined based on the charging capacity, the discharging internal resistance and the discharging voltage, and the SOH value of the battery system is calculated by combining the SOH value based on the charging capacity, the SOH value based on the discharging internal resistance and the SOH value based on the discharging voltage, so that the accuracy of SOH calculation can be improved, and more accurate basis is provided for subsequent prediction of the service life of the battery and the like.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
fig. 1 is a flowchart of a method for calculating a state of health, SOH, of a battery system provided according to an embodiment of the present disclosure.
Fig. 2 is a flowchart of a method for calculating a state of health, SOH, of a battery system provided according to another embodiment of the present disclosure.
Fig. 3 is a flowchart of a method for calculating a state of health, SOH, of a battery system provided according to another embodiment of the present disclosure.
Fig. 4 is a flowchart of a method for calculating state of health, SOH, of a battery system provided according to another embodiment of the present disclosure.
Fig. 5 is a block diagram of a computing device of a state of health SOH of a battery system provided according to one embodiment of the present disclosure.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
Fig. 1 is a flowchart of a method for calculating a state of health, SOH, of a battery system provided according to an embodiment of the present disclosure. The battery system includes at least one battery module. As shown in fig. 1, the method may include the following steps.
In step 11, a charging-based capacity SOH value of the battery system, a discharging-based internal resistance SOH value of the battery system, and a discharging-based voltage SOH value of the battery system are determined.
In one possible embodiment, as shown in fig. 2, determining the SOH value based on the charging capacity of the battery system may include the following steps.
In step 21, when the battery system is in the charging mode, the charging capacity corresponding to the increase of each battery module from the first preset voltage to the second preset voltage is determined.
In a battery system, a corresponding management unit (e.g., a battery management unit) may be provided, which may collect, calculate, etc., various electrical parameters (e.g., current, voltage, capacitance, power, etc.) during the use of the battery for use.
For example, when the battery system is in the charging mode, the charging capacity of each battery module included in the battery system may be determined. The following description will be made with respect to individual battery modules, and the manner in which the charging capacity is determined is the same for each battery module in the battery system.
It is known that the voltage of each battery module gradually increases during the charging process of the battery system. Therefore, the current change condition of the battery module in the time period from the first preset voltage to the second preset voltage can be recorded, and the current is integrated in the time period, so that the electric quantity in the time period, namely the charging capacity corresponding to the increase of the battery module from the first preset voltage to the second preset voltage, can be obtained. Thus, the charging capacity corresponding to the increase of each battery module from the first preset voltage to the second preset voltage can be obtained.
In step 22, the SOH value corresponding to each battery module is determined according to the determined charging capacities and the corresponding relationship between the preset charging capacity of the battery module and the SOH value.
The method can be used for testing the data of the whole life cycle of the battery or the battery system made of different materials and different processes in advance to obtain the corresponding relation between the charging capacity and the SOH value of the battery module in each life cycle, and storing the corresponding relation into the corresponding battery system. The corresponding relation between the charging capacity and the SOH value of the battery module corresponding to the material and the manufacturing process of the battery system is stored in the battery system. Illustratively, the correspondence may be stored in the form of a table. Therefore, according to the charging capacity corresponding to the increase of each battery module from the first preset voltage to the second preset voltage determined in step 21, and by combining the correspondence relationship between the charging capacity of the battery module and the SOH value, the SOH value corresponding to each battery module can be determined.
In step 23, the SOH value based on the charging capacity of the battery system is determined based on the SOH value corresponding to each battery module.
After the SOH value corresponding to each battery module is determined, the SOH value based on the charging capacity of the battery system can be determined according to each SOH value.
In one embodiment, the determined SOH values may be averaged and used as the SOH value of the battery system based on the charging capacity. In this way, the SOH value based on the charge capacity of the battery system can be obtained quickly.
In another embodiment, the charge capacity-based SOH value of the battery system may be determined by:
sequencing SOH values corresponding to the battery modules in a sequence from small to large to generate a sequencing queue;
and determining the Kth SOH value in the sequencing queue as the charging capacity-based SOH value of the battery system.
Illustratively, K may be calculated by the following equation (1):
K＝[a*N](1)
wherein, N is the number of the battery modules, a is a preset coefficient, and 0< a < 1.
Since the SOH values corresponding to the battery modules are different, the SOH value corresponding to each battery module may not accurately reflect the SOH value based on the charging capacity of the entire battery system, and therefore, a preset coefficient a is introduced to control the state so as to select an optimal result. If the number N of battery modules is 10, the generated sort queue is S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10, and the preset coefficient a is 0.25, the product of a and N is rounded to obtain K being 2, and therefore, the 2 nd SOH value (i.e., S2) in the sort queue can be determined as the SOH value based on the charging capacity of the battery system.
Through the mode, the finally determined SOH value of the battery system based on the charging capacity is selected by setting the preset coefficient, so that the more accurate SOH value of the battery system based on the charging capacity can be obtained.
By the method, the charging capacity-based SOH value of the battery system can be determined quickly and accurately by utilizing the change condition of the electrical parameters in the charging mode of the battery system and the corresponding relation between the existing electrical parameters and the SOH obtained through actual test.
In one possible embodiment, as shown in fig. 3, determining the discharging internal resistance-based SOH value of the battery system may include the following steps.
In step 31, in the discharging mode of the battery system, it is determined that the first discharging power of the battery system, the module discharging power of each battery module in the battery system, and the average discharging current are generated in the process that the remaining capacity SOC of the battery system changes from the first preset SOC value to the second preset SOC value.
The SOC (state of charge) may represent a percentage of the rated capacity of the battery or the battery system. It can be directly obtained by the corresponding unit of the battery system (e.g., battery management unit). When the battery system is in the discharging mode, the SOC of the battery system is gradually reduced, so that the change condition of the relevant electrical parameters can be recorded in the process of changing the SOC of the battery system from the first preset SOC value to the second preset SOC value, so as to determine the first discharging power of the battery system, the module discharging power of each battery module and the average discharging current. For example, the first preset SOC value may be 52% and the second preset SOC value may be 48%.
For example, a current change situation in a time period in which the SOC of the battery system changes from a first preset SOC value to a second preset SOC value may be recorded, and the current may be integrated for the time period to obtain a discharge electric quantity corresponding to the time period. And simultaneously, the total output voltage of the battery system in the period of time and the output voltages of the battery modules in the battery system can be recorded. Thus, the first discharge power is the product of the discharge capacity and the total output voltage; multiplying each output voltage by the discharge electric quantity to obtain the module discharge power of each battery module; the average discharge current can be obtained by dividing the discharge electric quantity by the time variation corresponding to the time period.
In step 32, the internal discharge resistance of the battery system is calculated.
For example, the discharge internal resistance R of the battery system may be calculated by the following equation (2):
Figure BDA0001843749850000101
wherein N is the number of battery modules, PiIs the module discharge power of the ith battery module,
Figure BDA0001843749850000102
i.e. the sum of the module discharge powers, P, of the individual battery modules in the battery systemALLThe first discharge power is I, the average discharge current is I, and the time variation corresponding to the process that the SOC of the battery system changes from the first preset SOC value to the second preset SOC value is t.
In step 33, the discharging internal resistance-based SOH value of the battery system is determined according to the discharging internal resistance and the preset corresponding relationship between the discharging internal resistance and the SOH value.
The method can be used for testing the data of the whole life cycle of the battery or the battery system made of different materials and different processes in advance to obtain the corresponding relation between the discharging internal resistance and the SOH value of each life cycle, and storing the corresponding relation into the corresponding battery system. The corresponding relation between the discharging internal resistance and the SOH value corresponding to the material and the manufacturing process of the battery system is stored in the battery system. Illustratively, the correspondence may be stored in the form of a table.
The internal discharge resistance may be internal resistance corresponding to the entire battery system, or may be internal resistance corresponding to the battery module. If the corresponding relationship is the corresponding relationship between the internal discharge resistance and the SOH value of the entire battery system, then according to the internal discharge resistance calculated in step 32, in combination with the corresponding relationship, an SOH value can be directly determined, and the SOH value can be determined as the SOH value of the battery system based on the internal discharge resistance. If the corresponding relationship is the corresponding relationship between the internal resistance of the battery module and the SOH value, the discharging internal resistance is calculated in step 32, and then the discharging internal resistance is divided by the number of the battery modules included in the battery system to obtain the discharging internal resistance corresponding to a single battery module, and then the determined SOH value is taken as the SOH value based on the discharging internal resistance of the battery system by combining the corresponding relationship.
By the method, the SOH value of the battery system based on the discharging internal resistance can be determined quickly and accurately by using the change condition of the electrical parameters in the discharging mode of the battery system and the corresponding relation between the electrical parameters and the SOH obtained through the existing practical test.
In one possible embodiment, as shown in fig. 4, determining the SOH-based value of the battery system may include the following steps.
In step 41, when the battery system is in the discharging mode, a second discharging power and a discharging capacity corresponding to a process that the remaining capacity SOC of the battery system changes from the third preset SOC value to the fourth preset SOC value are determined.
As described above, when the battery system is in the discharging mode, the SOC of the battery system is gradually decreased, and therefore, the change of the relevant electrical parameter during the process of changing the SOC of the battery system from the third preset SOC value to the fourth preset SOC value can be recorded to determine the second discharging power and the discharging capacity of the battery system. For example, the first preset SOC value may be 90% and the second preset SOC value may be 40%.
For example, the current change condition in the time period from the third preset SOC value to the fourth preset SOC value of the battery system SOC may be recorded, and the current may be integrated for the time period, so as to obtain the discharge capacity corresponding to the time period. And meanwhile, the discharge voltage of the battery system in the time period can be recorded, and the discharge capacity is multiplied by the discharge voltage to obtain second discharge power of the battery system in the time period from the change of the SOC value from the third preset SOC value to the fourth preset SOC value.
In step 42, a discharge average voltage of the battery system is determined based on the second discharge power and the discharge capacity.
And dividing the second discharge power by the discharge capacity to obtain the average discharge voltage of the battery system.
In step 43, the SOH value based on the discharging voltage of the battery system is determined according to the discharging average voltage and the preset corresponding relationship between the discharging voltage and the SOH value.
The method can be used for testing the data of the whole life cycle of the battery or the battery system made of different materials and different processes in advance, so as to obtain the corresponding relation between the discharge voltage and the SOH value of each life cycle, and store the corresponding relation into the corresponding battery system. The corresponding relation between the discharging voltage and the SOH value corresponding to the material and the manufacturing process of the battery system is stored in the battery system. Illustratively, the correspondence may be stored in the form of a table.
According to the average discharging voltage in the time period from the third preset SOC value to the fourth preset SOC value of the SOC of the battery system obtained in step 42, an SOH value can be obtained by combining the correspondence between the discharging voltage and the SOH value, and the SOH value is determined as the discharging voltage-based SOH value of the battery system.
By the mode, the SOH value of the battery system based on the discharge voltage can be determined quickly and accurately by utilizing the change condition of the electrical parameters in the discharge mode of the battery system and the existing corresponding relation between the electrical parameters and the SOH obtained through practical test.
Returning to fig. 1, in step 12, an actual SOH value of the battery system is calculated based on the SOH value of the charge-based capacity of the battery system, the SOH value of the discharge-based internal resistance of the battery system, and the SOH value of the discharge-based voltage of the battery system.
In one embodiment, the SOH values based on the charging capacity SOH, the discharging internal resistance SOH and the discharging voltage SOH may be directly averaged to calculate the actual SOH value of the battery system.
In another embodiment, step 12 may include the steps of:
determining a first weight value corresponding to the charging capacity SOH value, a second weight value corresponding to the discharging internal resistance SOH value and a third weight value corresponding to the discharging voltage SOH value;
the actual SOH value of the battery system is calculated.
Since the sensitivity of the charging capacity, the discharging internal resistance and the discharging voltage to the service life of the battery system are different, and the accuracy of the SOH determined by the three may also be different, different calculation weights may be assigned to the three. The sum of the first weight value, the second weight value and the third weight value is 1. For example, the first weight value may be within a numerical range of [0.3, 0.5], the second weight value may be within a numerical range of [0.25, 0.35], and the third weight value may be within a numerical range of [0.25, 0.35 ].
In one embodiment, the first, second, and third weight values may be set to constant values. For example, the first weight value is 0.3, the second weight value is 0.35, and the third weight value is 0.35.
In one embodiment, the weight value may also be dynamically determined to improve accuracy. In this embodiment, the first weight value x, the second weight value y, and the third weight value z may be determined as follows:
counting the number of times of calculation of the actual SOH value of the battery system to obtain a count value;
calculating x, y, z by the following formulas (4) to (6):
x＝x0-m*x1(4)
y＝y0+m*y1(5)
z＝z0+m*z1(6)
wherein x is0、y0、z0、x1、y1、z1Is a preset value, x0+y0+z0When x is decreased to the first threshold value, y is increased to the second threshold value, and z is increased to the third threshold value, x, y, and z are not changed. Since the influence of the charging capacity on the SOH is reduced and the influence of the discharging voltage and the discharging internal resistance on the SOH is increased as the battery is used, the calculation weights of the charging capacity, the discharging voltage and the discharging internal resistance can be dynamically changed according to the influence. Exemplarily, x0Can be 0.5, y0Can be 0.25, z0May be 0.25, x1May be 2/3000, y1Can be 1/3000, z11/3000 may be included, and the first threshold value may be 0.3, the second threshold value may be 0.35, and the third threshold value may be 0.35.
After determining the respective corresponding calculation weights of the charging capacity, the discharging internal resistance and the discharging voltage, the actual SOH value of the battery system can be calculated.
For example, the actual SOH value, i.e., SOH, may be calculated according to the following equation (3)Practice of：
SOHPractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingBased on the value of the charging capacity SOH, SOHInternal resistance to dischargeBased on the SOH value of the internal resistance to discharge, SOHDischarge voltageBased on the SOH value of the discharge voltage.
Through the scheme, the corresponding SOH value is determined based on the charging capacity, the discharging internal resistance and the discharging voltage, and the SOH value of the battery system is calculated by combining the SOH value based on the charging capacity, the SOH value based on the discharging internal resistance and the SOH value based on the discharging voltage, so that the accuracy of SOH calculation can be improved, and more accurate basis is provided for subsequent prediction of the service life of the battery and the like.
Fig. 5 is a block diagram of a computing device of a state of health SOH of a battery system provided according to one embodiment of the present disclosure. As shown in fig. 5, the battery system includes at least one battery module, and the apparatus 50 includes:
a determination module 51 for determining a charging capacity based SOH value of the battery system, a discharging internal resistance based SOH value of the battery system, and a discharging voltage based SOH value of the battery system;
the calculation module 52 is configured to calculate an actual SOH value of the battery system according to a charging capacity SOH-based value of the battery system, a discharging internal resistance SOH-based value of the battery system, and a discharging voltage SOH-based value of the battery system.
Optionally, the determining module 51 includes:
the first determining submodule is used for determining the charging capacity corresponding to the fact that each battery module is increased from a first preset voltage to a second preset voltage when the battery system is in a charging mode;
the second determining submodule is used for determining an SOH value corresponding to each battery module according to the determined charging capacities and the corresponding relation between the preset charging capacity of the battery module and the SOH value;
and the third determining submodule is used for determining the SOH value of the battery system based on the charging capacity according to the SOH value corresponding to each battery module.
Optionally, the third determining sub-module includes:
the sequencing submodule is used for sequencing the SOH values corresponding to the battery modules in a sequence from small to large to generate a sequencing queue;
a first calculating submodule, configured to determine a kth SOH value in the sorting queue as a charging capacity SOH-based value of the battery system, where K is calculated by the following formula (1):
K＝[a*N](1)
wherein, N is the number of the battery modules, a is a preset coefficient, and 0< a < 1.
Optionally, the determining module 51 includes:
the fourth determining submodule is used for determining the first discharging power of the battery system, the module discharging power of each battery module in the battery system and the average discharging current in the process that the residual capacity SOC of the battery system changes from the first preset SOC value to the second preset SOC value when the battery system is in a discharging mode;
a second calculation submodule for calculating a discharge internal resistance R of the battery system by the following formula (2):
Figure BDA0001843749850000151
wherein N is the number of battery modules, PiA module discharge power, P, for the ith said battery moduleALLThe first discharge power is set, I is the average discharge current, and t is the time variation corresponding to the process that the SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
and the fifth determining submodule is used for determining the SOH value of the battery system based on the discharging internal resistance according to the discharging internal resistance and the corresponding relation between the preset discharging internal resistance and the SOH value.
Optionally, the determining module 51 includes:
the sixth determining submodule is used for determining second discharging power and discharging capacity corresponding to the process that the residual capacity SOC of the battery system changes from a third preset SOC value to a fourth preset SOC value when the battery system is in a discharging mode;
a seventh determining submodule, configured to determine a discharging average voltage of the battery system according to the second discharging power and the discharging capacity;
and the eighth determining submodule is used for determining the SOH value of the battery system based on the discharging voltage according to the discharging average voltage and the corresponding relation between the preset discharging voltage and the SOH value.
Optionally, the calculation module 52 includes:
a ninth determining submodule, configured to determine a first weight value corresponding to the charging capacity-based SOH value, a second weight value corresponding to the discharging internal resistance-based SOH value, and a third weight value corresponding to the discharging voltage-based SOH value;
a third calculation submodule for calculating said actual SOH value according to the following equation (3):
SOHpractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingFor said value of SOH based on charging capacity, SOHInternal resistance to dischargeFor said SOH value based on internal resistance to discharge, SOHDischarge voltageFor the discharging voltage-based SOH value, x is the first weight value, y is the second weight value, z is the third weight value, and x + y + z is 1.
Optionally, the apparatus 50 further includes a counting module, configured to count the number of times of calculating the actual SOH value of the battery system, so as to obtain a count value;
the ninth determining sub-module is configured to calculate the first weight value x, the second weight value y, and the third weight value z by the following equations (4) to (6):
x＝x0-m*x1(4)
y＝y0+m*y1(5)
z＝z0+m*z1(6)
wherein x is0、y0、z0、x1、y1、z1Is a preset value, x0+y0+z0When x is decreased to a first critical value, y is increased to a second critical value, and z is increased to a third critical value, x, y, and z are not changed.
With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.
The disclosure also provides a battery system comprising the calculation device for the state of health (SOH) of the battery system provided by any embodiment of the disclosure.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (10)

1. A method for calculating the state of health (SOH) of a battery system, wherein the battery system comprises at least one battery module, the method comprising:
determining a charging capacity-based (SOH) value of the battery system, a discharging internal resistance-based (SOH) value of the battery system, and a discharging voltage-based (SOH) value of the battery system;
and calculating the actual SOH value of the battery system according to the charging capacity-based SOH value of the battery system, the discharging internal resistance-based SOH value of the battery system and the discharging voltage-based SOH value of the battery system.
2. The method of claim 1, wherein the determining a charge capacity (SOH) based value for the battery system comprises:
when the battery system is in a charging mode, determining the charging capacity corresponding to the increase of each battery module from a first preset voltage to a second preset voltage;
determining an SOH value corresponding to each battery module according to the determined charging capacities and the corresponding relationship between the preset charging capacity of the battery module and the SOH value;
and determining the SOH value based on the charging capacity of the battery system according to the SOH value corresponding to each battery module.
3. The method according to claim 2, wherein the determining the SOH value based on the charging capacity of the battery system according to the SOH value corresponding to each battery module comprises:
sequencing the SOH values corresponding to the battery modules in a sequence from small to large to generate a sequencing queue;
determining a Kth SOH value in the sorting queue as a charging capacity-based SOH value of the battery system, wherein K is calculated by the following formula (1):
K＝[a*N](1)
wherein, N is the number of the battery modules, a is a preset coefficient, and 0< a < 1.
4. The method of claim 1, wherein the determining the SOH value of the battery system based on the discharging internal resistance comprises:
when the battery system is in a discharging mode, determining a first discharging power of the battery system, a module discharging power and an average discharging current of each battery module in the battery system in the process that the residual capacity SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
calculating a discharge internal resistance R of the battery system by the following formula (2):
Figure FDA0001843749840000021
wherein N is the number of battery modules, PiDischarging the module of the ith battery modulePower, PALLThe first discharge power is set, I is the average discharge current, and t is the time variation corresponding to the process that the SOC of the battery system changes from a first preset SOC value to a second preset SOC value;
and determining the SOH value of the battery system based on the discharging internal resistance according to the discharging internal resistance and the corresponding relation between the preset discharging internal resistance and the SOH value.
5. The method of claim 1, wherein the determining a discharge voltage (SOH) -based value for the battery system comprises:
determining a second discharge power and a discharge capacity corresponding to the process that the SOC of the residual capacity of the battery system changes from a third preset SOC value to a fourth preset SOC value when the battery system is in a discharge mode;
determining the average discharge voltage of the battery system according to the second discharge power and the discharge capacity;
and determining the SOH value of the battery system based on the discharging voltage according to the discharging average voltage and the corresponding relation between the preset discharging voltage and the SOH value.
6. The method of claim 1, wherein calculating the actual SOH value of the battery system from a charging capacity based SOH value of the battery system, a discharging internal resistance based SOH value of the battery system, and a discharging voltage based SOH value of the battery system comprises:
determining a first weight value corresponding to the charging capacity-based SOH value, a second weight value corresponding to the discharging internal resistance-based SOH value and a third weight value corresponding to the discharging voltage-based SOH value;
the actual SOH value is calculated according to the following equation (3):
SOHpractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingFor said value of SOH based on charging capacity, SOHInternal resistance to dischargeFor said SOH value based on internal resistance to discharge, SOHDischarge voltageFor the discharging voltage-based SOH value, x is the first weight value, y is the second weight value, z is the third weight value, and x + y + z is 1.
7. The method of claim 6, further comprising:
counting the number of times of calculation of the actual SOH value of the battery system to obtain a count value;
the first weight value x, the second weight value y, and the third weight value z are calculated by the following equations (4) to (6):
x＝x0-m*x1(4)
y＝y0+m*y1(5)
z＝z0+m*z1(6)
wherein x is0、y0、z0、x1、y1、z1Is a preset value, x0+y0+z0When x is decreased to a first critical value, y is increased to a second critical value, and z is increased to a third critical value, x, y, and z are not changed.
8. An apparatus for calculating state of health, SOH, of a battery system including at least one battery module, the apparatus comprising:
a determination module for determining a charging capacity-based SOH value of the battery system, a discharging internal resistance-based SOH value of the battery system, and a discharging voltage-based SOH value of the battery system;
the calculation module is used for calculating the actual SOH value of the battery system according to the SOH value of the battery system based on the charging capacity, the SOH value of the battery system based on the discharging internal resistance and the SOH value of the battery system based on the discharging voltage.
9. The apparatus of claim 8, wherein the computing module comprises:
a ninth determining submodule, configured to determine a first weight value corresponding to the charging capacity-based SOH value, a second weight value corresponding to the discharging internal resistance-based SOH value, and a third weight value corresponding to the discharging voltage-based SOH value;
a third calculation submodule for calculating said actual SOH value according to the following equation (3):
SOHpractice of＝x*SOHCapacity of charging+y*SOHInternal resistance to discharge+z*SOHDischarge voltage(3)
Wherein, SOHCapacity of chargingFor said value of SOH based on charging capacity, SOHInternal resistance to dischargeFor said SOH value based on internal resistance to discharge, SOHDischarge voltageFor the discharging voltage-based SOH value, x is the first weight value, y is the second weight value, z is the third weight value, and x + y + z is 1.
10. A battery system, characterized in that the battery system comprises a calculation device of the state of health SOH of the battery system according to claim 8 or 9.
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