CN113514772A - Battery direct-current internal resistance online test method and battery management system - Google Patents
Battery direct-current internal resistance online test method and battery management system Download PDFInfo
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- 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
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- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- G—PHYSICS
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- G01R31/005—Testing of electric installations on transport means
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- 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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- 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
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- G—PHYSICS
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- 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]
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Abstract
The invention provides a method for testing the direct current internal resistance of a battery on line, which is realized in a battery system consisting of a plurality of batteries and comprises the following steps that a battery management system detects the stable state of the internal resistance of each battery; the battery management system generates corresponding control pulses when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate multiple voltage drops; the battery management system collects the voltage and current before and after each voltage drop of each battery and calculates the direct current internal resistance of each battery. The invention can overcome the problems of the prior battery direct current internal resistance on-line measurement and has better robustness and reliability.
Description
Technical Field
The invention relates to the technical field of storage battery management, in particular to a method for testing direct current internal resistance of a battery on line and a battery management system.
Background
Along with the increase of cycle number, the internal resistance value of electric automobile power battery can increase gradually, and discharge capacity constantly attenuates, and calorific capacity constantly increases, and then leads to the resistance difference between each battery of group battery constantly to increase, finally leads to the group battery to become invalid. The main reasons for failure are increased resistance and further degradation of non-uniformity, which makes the battery more susceptible to overcharge and overdischarge.
The internal resistance of the battery is an important factor influencing the safety performance and the power performance of the battery, and has important influence on the use of the battery in the whole life cycle. The internal resistance change conditions of different stages in the life cycle of the battery are generally obtained by an offline pulse test, and the method mainly tests the pulse capability of the battery, can obtain the direct current internal resistance value of the battery, and further obtain the discharge pulse and feedback pulse capability under different pulse time and discharge depth (DOD) states. For example, the specification of performance test of high-power nickel metal hydride (lithium ion) power storage batteries for HEVs in the 863 project of the ministry of science and technology of china, the test method of output density and input density of airtight nickel-metal hydride batteries for hybrid electric vehicles in the JEVS D7132003 of japan, and the test manual of power batteries for power-assisted hybrid electric vehicles in the FreedomCAR project of usa have specific test methods of direct current internal resistance of power batteries. However, the off-line direct current internal resistance testing methods have the following disadvantages: (1) the internal resistance test by using the currents with different multiplying power series and the single current has certain difference; (2) there is some difference in internal resistance values measured using different pulse durations.
In order to overcome the defects of the off-line direct current internal resistance testing method, most scholars use a least square method R-Q curve fitting method to test the direct current internal resistance of the battery, but the method relies on an empirical data model, and a large number of cyclic tests need to be carried out in a laboratory to fit an internal resistance curve with higher precision, so the method belongs to an off-line model, and has the defects of poor universality, low robustness, poor reliability, incapability of carrying out on-line measurement and real-time update according to the actual condition of the battery and the like. Therefore, further learners carry out online battery internal resistance testing by capturing special working conditions and utilizing voltage to change along with current, but the method is highly dependent on capturing the special working conditions, cannot reflect the dynamic change characteristics of internal resistance in real time, cannot control the internal resistance measuring time, and is poor in real-time performance.
Therefore, an online test method for the direct current internal resistance of the battery is needed, which can overcome the problems existing in the online measurement of the direct current internal resistance of the battery and has better robustness and reliability.
Disclosure of Invention
The technical problem to be solved by the embodiments of the present invention is to provide an online Battery dc internal resistance testing method and a Battery management system, which are used for directly measuring the Battery dc internal resistance online based on the structural characteristics of pulse current generated by an All-weather Battery (All-around-Battery, ACB) and the characteristics of fast charging step reduction, so as to overcome the problems existing in the existing online Battery dc internal resistance measurement, and have better robustness and reliability.
In order to solve the above technical problem, an embodiment of the present invention provides an online test method for dc internal resistance of a battery, which is implemented in a battery system including a plurality of batteries, and is characterized in that the method includes the following steps:
the battery management system detects the stable internal resistance state of each battery;
the battery management system generates corresponding control pulses when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate multiple voltage drops;
the battery management system collects the voltage and the current of each battery before and after each voltage drop, and calculates the direct current internal resistance of each battery according to the collected voltage and current of each battery before and after each voltage drop.
The battery is an all-weather battery, and each all-weather battery comprises a battery body, a switch and a heating sheet.
The battery management system is used for detecting the internal resistance stable state of each all-weather battery based on the real-time acquisition of the related information of the battery body in each all-weather battery, which is quickly charged when a switch is switched off and enters the quick charging initial stage.
The related information of the battery body entering the fast charging initial stage in each all-weather battery comprises the SOC, the temperature, the charging current duration, the charging current magnitude, the equilibrium state and the fault state of the battery body in each all-weather battery.
The step of detecting the stable internal resistance state of each all-weather battery specifically comprises the following steps:
if the battery body in the current all-weather battery is detected to simultaneously meet the condition that the SOC is within a preset SOC range, the temperature is within a preset temperature range, the charging current duration is greater than a preset time threshold, the charging current variation value is smaller than a preset limit value in the charging current duration, the varied charging current is greater than a preset current threshold, the balance is not started and no fault exists, and the internal resistance of the current all-weather battery is determined to be in a stable state; otherwise, determining that the internal resistance of the current all-weather battery is not in a stable state.
Wherein the preset SOC range is [ 40%, 60% ]; the preset temperature range is [25 ℃,40 ℃; the charging current duration is 60s, the preset limit value is 5A, and the preset current threshold value is 0.8C; wherein, C is 100A.
The battery management system controls the switch connected with each all-weather battery with stable internal resistance to be closed, and generates control pulse when the corresponding battery body and the heating sheet are electrically connected and conducted so as to realize that the battery body in each all-weather battery can generate multiple voltage drops.
The battery management system collects the voltage and current of each battery before and after each voltage drop, and calculates the direct current internal resistance of each battery according to the collected voltage and current of each battery before and after each voltage drop, wherein the specific steps comprise:
according to the formula
Calculating to obtain the direct current internal resistance of each battery when each voltage drop occurs; wherein, DCRiSetting i as 1-n for the direct current internal resistance of the ith voltage drop of the current battery; n is the total voltage drop times of the current battery; vb (b) ofiThe voltage of the current battery before the ith voltage drop is obtained; va (Va)iThe voltage of the current battery after the ith voltage drop is obtained; ibiThe current of the current battery before the ith voltage drop is obtained; iaiThe current is the current of the current battery after the ith voltage drop;
according to the formula
Calculating to obtain the direct current internal resistance of each battery; and the DCR is the direct current internal resistance of the current battery.
The voltage drop n generated by each battery for multiple times is continuous for 3 times, so that the batteries generate pulse discharge current for 3 times continuously, and the pulse discharge current is more than or equal to 0.8C and the pulse discharge current duration is more than or equal to 10 s; wherein, C is 100A.
The embodiment of the invention also provides a battery management system, which is realized in a battery system consisting of a plurality of batteries and comprises a battery internal resistance detection unit, a battery voltage control drop unit and a battery direct current internal resistance calculation unit; wherein the content of the first and second substances,
the battery internal resistance detection unit is used for detecting the internal resistance stable state of each battery;
the battery voltage drop control unit is used for generating corresponding control pulses when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate voltage drop for multiple times;
the battery direct current internal resistance calculation unit is used for collecting the voltage and the current of each battery before and after each voltage drop, and calculating the direct current internal resistance of each battery according to the collected voltage and current of each battery before and after each voltage drop.
The embodiment of the invention has the following beneficial effects:
the method directly measures the direct current internal resistance of the Battery on line based on the voltage drop characteristic of the stable state of the internal resistance of the Battery, particularly directly measures the direct current internal resistance of the Battery on line based on the structural characteristic of pulse current generated by an All-weather Battery (ACB) and the characteristic of rapid charging step reduction, can overcome the problems existing in the existing online measurement of the direct current internal resistance of the Battery, and has better robustness and reliability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive exercise.
Fig. 1 is a flowchart of an online testing method for dc internal resistance of a battery according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating that the method for online testing the direct current internal resistance of the battery according to the embodiment of the present invention is applied to an all-weather battery;
FIG. 3 is a diagram of the application scenario of FIG. 2;
fig. 4 is a schematic structural diagram of a battery management system according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, in an embodiment of the present invention, an on-line testing method for dc internal resistance of a battery is provided, which is implemented in a battery system composed of a plurality of batteries, and the method includes the following steps:
step S1, the battery management system detects the stable state of the internal resistance of each battery;
step S2, the battery management system generates corresponding control pulse when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate voltage drop for many times;
step S3, the battery management system collects the voltage and current before and after each voltage drop of each battery, and calculates the direct current internal resistance of each battery according to the collected voltage and current before and after each voltage drop of each battery
In step S1, the battery management system detects the internal resistance steady state of each battery according to the relevant information such as SOC, temperature, charging current duration, charging current magnitude, equilibrium state, and fault state of each battery collected in real time. For example, if the battery management system detects that the current battery simultaneously satisfies that the SOC is within a preset SOC range (e.g., [ 40%, 60%), the temperature is within a preset temperature range (e.g., [25 ℃,40 ℃), the charging current duration is greater than a preset time threshold (e.g., 60s), the charging current variation value is less than a preset limit (e.g., 5A) within the charging current duration (e.g., 60s), the varied charging current is greater than a preset current threshold (e.g., 0.8C, C is 100A), the equalization is not started, and no fault exists, it is determined that the internal resistance of the current battery is in a stable state; on the contrary, it is determined that the internal resistance of the current battery is not in the stable state, that is, if the battery management system detects that the current battery meets the condition that the SOC exceeds the preset SOC range (e.g., > 60% or < 40%), the temperature exceeds the preset temperature range (e.g., >40 ℃ or <25 ℃), the charging current duration is less than or equal to the preset time threshold (e.g., <60s), or the charging current variation value is greater than or equal to the preset limit (e.g., >5A) within the charging current duration (e.g., >60 s), and the varied charging current is less than or equal to the preset current threshold (e.g., 0.6C <0.8C), and at least one of balanced opening and fault exists, it is determined that the internal resistance of the current battery is not in the stable state.
In step S2, the battery management system generates a corresponding control pulse when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate multiple voltage drops. For example, each battery generates pulse discharge current for 3 times continuously, and the pulse discharge current is greater than or equal to 0.8C and the pulse discharge current duration is greater than or equal to 10 s; wherein, C is 100A.
In step S3, the direct current internal resistance of each battery at each voltage drop is calculated according to the formula (1);
wherein, DCRiIs a current batteryThe direct current internal resistance of the ith voltage drop, i is 1-n; n is 3, which is the total voltage drop times of the current battery; vb (b) ofiThe voltage of the current battery before the ith voltage drop is obtained; va (Va)iThe voltage of the current battery after the ith voltage drop is obtained; ibiThe current of the current battery before the ith voltage drop is obtained; iaiThe current is the current of the current battery after the ith voltage drop;
according to a formula (2), calculating to obtain the direct current internal resistance DCR of each battery;
in the embodiment of the invention, the structural characteristic that All-weather Battery (ACB) technology can generate pulse current can be considered, and in combination with the characteristics of a charging stable state and large charging current in a quick charging initial stage, the Battery management system generates control pulses in an internal resistance stable state according to a quick charging system to switch a switch of the ACB Battery, so that the Battery generates pulse discharging current, and the internal resistance of the Battery is directly calculated by capturing voltage drop generated by the Battery.
As shown in fig. 2, taking an all-weather battery (as shown in fig. 3) formed by connecting a battery body, a switch and a heating plate in series as an example, the specific steps of further analyzing the on-line testing method for the direct current internal resistance of the battery in the embodiment of the present invention are as follows:
step S10, the battery management system collects the relevant information of the battery body in each all-weather battery that is charged quickly when the switch is off and enters the quick charge initial stage in real time, and detects the internal resistance stable state of each all-weather battery according to the relevant information of each battery that is collected in real time and enters the quick charge initial stage;
step S20, the battery management system generates corresponding control pulses when detecting that the internal resistance of each all-weather battery is in a stable state, and the control pulses are used for controlling the switch connected with each all-weather battery with the internal resistance in the stable state to be closed to realize the electric connection and conduction of the corresponding heating plate, so that the battery body in each all-weather battery with the electric connection and conduction can generate multiple voltage drops;
and step S30, the battery management system collects the voltage and current before and after each voltage drop of the battery body in each all-weather battery, and calculates the direct current internal resistance of the battery body in each all-weather battery according to the collected voltage and current before and after each voltage drop of the battery body in each all-weather battery.
In step S10, a quick charge control program is preset on the battery management system, and after the battery system is connected to the charging pile, each all-weather battery in the battery system is quickly charged through the quick charge control program. At the moment, the switch of each all-weather battery is in an off state, so that the battery management system can acquire related information of the battery body in each all-weather battery, which is charged quickly when the switch is off and enters the quick charge initial stage, in real time. The related information of the battery body entering the fast charging initial stage in each all-weather battery comprises the SOC, the temperature, the charging current duration, the charging current magnitude, the equilibrium state and the fault state of the battery body in each all-weather battery.
Secondly, the battery management system detects the internal resistance stable state of each all-weather battery according to the relevant information of entering the fast charging initial stage of the battery body in each all-weather battery collected in real time, and the method specifically comprises the following steps:
if the battery management system detects that the battery body in the current all-weather battery simultaneously meets the condition that the SOC is within a preset SOC range (such as [ 40%, 60%), the temperature is within a preset temperature range (such as [25 ℃,40 ℃), the charging current duration is longer than a preset time threshold (such as 60s), the charging current variation value is smaller than a preset limit value (such as 5A) in the charging current duration (such as 60s), the varied charging current is larger than a preset current threshold (such as 0.8C, C is 100A), and the internal resistance of the current battery is determined to be in a stable state if the battery management system detects that the battery body in the current all-weather battery simultaneously meets the condition that the SOC is within the preset SOC range (such as [ 40%, 60 ℃), the charging current duration is longer than a preset time threshold, the charging current variation value is smaller than a preset limit value (such as 5A), the varied charging current is larger than the preset current threshold, and the equalized without any fault; otherwise, it is determined that the internal resistance of the current all-weather battery is not in a stable state, that is, if the battery management system detects that the current battery meets the condition that the SOC exceeds a preset SOC range (e.g., > 60% or < 40%), the temperature exceeds a preset temperature range (e.g., >40 ℃ or <25 ℃), the charging current duration is less than or equal to a preset time threshold (e.g., <60s), or the charging current variation value is greater than or equal to a preset limit (e.g., >5A) within the charging current duration (e.g., 60s), and the varied charging current is less than or equal to a preset current threshold (e.g., 0.6C <0.8C), and the internal resistance of the current all-weather battery is not in a stable state if the internal resistance is uniformly opened and has a fault.
It should be noted that the direct current internal resistance of the battery shows nonlinear change along with the temperature and the SOC state, the internal resistance of the battery has large change at the upper and lower limits of the SOC and the upper and lower limits of the temperature range, and the accuracy of online measurement of the internal resistance is poor, so that the stable state interval of the internal resistance of the battery can be calibrated through experiments, and the stable interval is selected for online internal resistance estimation, so that the accuracy can be improved.
It is understood that the battery dc internal resistance identification steady state determination condition may be evaluated according to conditions of voltage, current, temperature charging time, and the like, and the combination is not limited to the above-mentioned combination of conditions.
In step S20, the battery management system generates a corresponding control pulse when detecting that the internal resistance of each all-weather battery is in a stable state, so as to control the switch connected to each all-weather battery with the internal resistance in the stable state to be closed to electrically connect and conduct the corresponding heating sheet, so that the battery body in each all-weather battery that is electrically connected and conducted can generate multiple voltage drops. In one embodiment, the voltage drop n is continuous for 3 times, so that the battery body in the all-weather battery continuously generates the pulse discharge current for 3 times, and the pulse discharge current is greater than or equal to 0.8C and the pulse discharge current duration is greater than or equal to 10 s; wherein, C is 100A.
It should be noted that the magnitude of the battery pulse discharge current and the duration of the pulse discharge current directly affect the estimation accuracy of the internal resistance of the battery, so that the appropriate magnitude and duration of the pulse current can be designed according to the actual battery characteristics.
In step S30, the dc internal resistance of each time the voltage of the battery body is dropped in each all-weather battery can be calculated according to the formula (1) in step S3; and calculating the direct current internal resistance of the battery body in each all-weather battery according to the formula (2) in the step S3.
It should be noted that, in the embodiments of the present invention, the structural feature of the all-weather battery ACB technology is utilized to generate the pulse current, and in combination with the characteristics of the stable charging state and the large charging current at the initial stage of the battery fast charging, the control pulse is generated in the stable internal resistance state of the battery to switch the switch of the ACB battery, so that the battery generates the pulse discharging current, and the internal resistance of the battery is directly calculated by capturing the voltage drop generated by the battery.
Fig. 3 is an application scenario diagram of the method for online testing the dc internal resistance of the battery according to the embodiment of the present invention. In fig. 2, U1 to U3 are all battery bodies, S1 to S3 are all switches, and R1 to R3 are all heating plates;
after the battery management system determines that the all-weather batteries are in the stable internal resistance state, the battery management system generates control pulses to switch corresponding switches S1-S3 of the ACB batteries to form voltage drop, so that the battery bodies in all-weather batteries continuously generate pulse discharge current for 3 times. The pulse current is not less than 0.8C and the pulse duration is not less than 10 s.
The battery management system captures the pulse voltage drop generated by the voltage of the battery body for 3 times continuously, calculates the direct current internal resistances DCR1, DCR2 and DCR3 when the voltage of each battery body is dropped for 3 times, and finally calculates the average value DCR of the direct current internal resistances DCR of each battery body for 3 times, namely (DCR1+ DCR2+ DCR 3)/3.
As shown in fig. 4, in an embodiment of the present invention, a battery management system is provided, which is implemented in a battery system composed of a plurality of batteries, and includes a battery internal resistance detection unit 110, a control battery voltage drop unit 120, and a battery direct current internal resistance calculation unit 130; wherein the content of the first and second substances,
the battery internal resistance detection unit 110 is configured to detect an internal resistance stable state of each battery;
the battery voltage drop control unit 120 is configured to generate a corresponding control pulse when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate multiple voltage drops;
the battery dc internal resistance calculation unit 130 is configured to collect voltage and current before and after each voltage drop of each battery, and calculate dc internal resistance of each battery according to the collected voltage and current before and after each voltage drop of each battery.
The battery is an all-weather battery, and each all-weather battery comprises a battery body, a switch and a heating sheet.
The battery management system is used for detecting the internal resistance stable state of each all-weather battery based on the real-time acquisition of the related information of the battery body in each all-weather battery, which is quickly charged when a switch is switched off and enters the quick charging initial stage.
The related information of the battery body entering the fast charging initial stage in each all-weather battery comprises the SOC, the temperature, the charging current duration, the charging current magnitude, the equilibrium state and the fault state of the battery body in each all-weather battery.
The embodiment of the invention has the following beneficial effects:
the method directly measures the direct current internal resistance of the Battery on line based on the voltage drop characteristic of the stable state of the internal resistance of the Battery, particularly directly measures the direct current internal resistance of the Battery on line based on the structural characteristic of pulse current generated by an All-weather Battery (ACB) and the characteristic of rapid charging step reduction, can overcome the problems existing in the existing online measurement of the direct current internal resistance of the Battery, and has better robustness and reliability.
It should be noted that, in the foregoing system embodiment, each included system unit is only divided according to functional logic, but is not limited to the above division as long as the corresponding function can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.
It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by relevant hardware instructed by a program, and the program may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.
Claims (10)
1. An on-line testing method for direct current internal resistance of a battery, which is realized in a battery system composed of a plurality of batteries, is characterized by comprising the following steps:
the battery management system detects the stable internal resistance state of each battery;
the battery management system generates corresponding control pulses when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate multiple voltage drops;
the battery management system collects the voltage and the current of each battery before and after each voltage drop, and calculates the direct current internal resistance of each battery according to the collected voltage and current of each battery before and after each voltage drop.
2. The method for on-line testing of DC internal resistance of battery as claimed in claim 1, wherein said batteries are all-weather batteries, and each all-weather battery comprises a battery body, a switch and a heating plate.
3. The method for on-line testing the direct current internal resistance of the battery as claimed in claim 2, wherein the battery management system is used for detecting the stable state of the internal resistance of each all-weather battery based on the real-time collection of the related information of the battery body in each all-weather battery, which is rapidly charged when the switch is turned off and enters the rapid charging initial stage.
4. The method for on-line testing of DC internal resistance of battery as claimed in claim 3, wherein the information related to the entering of the battery body into the fast-charging initial stage in each all-weather battery includes SOC, temperature, charging current duration, charging current magnitude, equalization state and fault state of the battery body in each all-weather battery.
5. The method for on-line testing of the direct current internal resistance of the battery according to claim 4, wherein the step of detecting the stable state of the internal resistance of each all-weather battery specifically comprises the steps of:
if the battery body in the current all-weather battery is detected to simultaneously meet the condition that the SOC is within a preset SOC range, the temperature is within a preset temperature range, the charging current duration is greater than a preset time threshold, the charging current variation value is smaller than a preset limit value in the charging current duration, the varied charging current is greater than a preset current threshold, the balance is not started and no fault exists, and the internal resistance of the current all-weather battery is determined to be in a stable state; otherwise, determining that the internal resistance of the current all-weather battery is not in a stable state.
6. The on-line test method for the direct current internal resistance of the battery according to claim 5, wherein the preset SOC range is [ 40%, 60% ]; the preset temperature range is [25 ℃,40 ℃; the charging current duration is 60s, the preset limit value is 5A, and the preset current threshold value is 0.8C; wherein, C is 100A.
7. The method for on-line testing of direct current internal resistance of battery as claimed in claim 3, wherein the battery management system is based on controlling the switch connected to each all-weather battery with the internal resistance in a stable state to be closed, so as to generate the control pulse when the corresponding battery body and the heating plate are electrically connected and conducted, thereby realizing that the battery body can generate multiple voltage drops in each all-weather battery.
8. The battery direct-current internal resistance online test method according to claim 1, wherein the battery management system collects the voltage and current before and after each voltage drop of each battery, and calculates the direct-current internal resistance of each battery according to the collected voltage and current before and after each voltage drop of each battery, the specific steps comprising:
according to the formula
Calculating to obtain the direct current internal resistance of each battery when each voltage drop occurs; wherein, DCRiSetting i as 1-n for the direct current internal resistance of the ith voltage drop of the current battery; n is the total voltage drop times of the current battery; vbiThe voltage of the current battery before the ith voltage drop is obtained; va (Va)iThe voltage of the current battery after the ith voltage drop is obtained; ibiThe current of the current battery before the ith voltage drop is obtained; iaiThe current is the current of the current battery after the ith voltage drop;
according to the formula
Calculating to obtain the direct current internal resistance of each battery; and the DCR is the direct current internal resistance of the current battery.
9. The method for on-line testing the direct current internal resistance of the battery according to claim 8, wherein the voltage drop n generated by each battery is 3 times in succession, so that the battery generates the pulse discharge current 3 times in succession, and the pulse discharge current is greater than or equal to 0.8C and the pulse discharge current duration is greater than or equal to 10 s; wherein, C is 100A.
10. A battery management system is realized in a battery system composed of a plurality of batteries and is characterized by comprising a battery internal resistance detection unit, a battery voltage control drop unit and a battery direct current internal resistance calculation unit; wherein the content of the first and second substances,
the battery internal resistance detection unit is used for detecting the internal resistance stable state of each battery;
the battery voltage drop control unit is used for generating corresponding control pulses when detecting that the internal resistance of each battery is in a stable state, so that each battery can generate voltage drop for multiple times;
the battery direct current internal resistance calculation unit is used for collecting the voltage and the current of each battery before and after each voltage drop, and calculating the direct current internal resistance of each battery according to the collected voltage and current of each battery before and after each voltage drop.
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