CN111722134B - Method and device for measuring direct current impedance of battery, charging system and terminal equipment - Google Patents

Method and device for measuring direct current impedance of battery, charging system and terminal equipment Download PDF

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CN111722134B
CN111722134B CN201910204613.XA CN201910204613A CN111722134B CN 111722134 B CN111722134 B CN 111722134B CN 201910204613 A CN201910204613 A CN 201910204613A CN 111722134 B CN111722134 B CN 111722134B
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charging
voltage
constant current
current charging
battery
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CN111722134A (en
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张加亮
谢红斌
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Guangdong Oppo Mobile Telecommunications Corp Ltd
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Guangdong Oppo Mobile Telecommunications Corp 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]
    • G01R31/389—Measuring internal impedance, internal conductance or related variables

Abstract

The application provides a method for measuring direct current impedance of a battery, which comprises the following steps: determining a difference value between the size of a first voltage interval in a first constant current charging stage and the size of a second voltage interval in a second constant current charging stage, wherein the charging of the battery in the first voltage interval and the charging in the second voltage interval correspond to the same first charging temperature and/or first charging duration, and the charging currents of the first constant current charging stage and the second constant current charging stage are the same; and determining the variation of the direct current impedance of the battery between the first constant current charging stage and the second constant current charging stage based on the difference and the charging current. The method for measuring the direct current impedance of the battery can more accurately determine the variable quantity of the direct current impedance and further accurately know the charging information in the battery process.

Description

Method and device for measuring direct current impedance of battery, charging system and terminal equipment
Technical Field
The present invention relates to the field of charging, and more particularly, to a method and apparatus for measuring a dc impedance of a battery, a charging system, and a terminal device.
Background
The dc impedance is a very important parameter of the battery during charging and discharging processes, and mainly includes the real resistance and polarization impedance of the battery during operation. The uncertainty of the polarization impedance is determined by the factors such as the charging temperature, depth of discharge (DoD), State of Charge (SoC), and the Charge/discharge rate. This, in turn, has large fluctuations during each use and therefore has been difficult to test accurately. However, if the direct current impedance of the battery can be accurately known, the battery information of the battery in the charging and discharging process can be more clearly mastered so as to ensure the safety of the battery in the charging and discharging process.
In the prior art, most of the methods for testing the direct current impedance are to charge a battery for a period of time, and then calculate the equivalent resistance by using the voltage difference after the voltage is kept stable by suspending the charging operation. However, this method cannot know the information of the battery during the charging process and the aging condition of the battery.
Therefore, it is desirable to provide an effective impedance measurement scheme to obtain battery information during battery charging.
Disclosure of Invention
The application provides a method and a device for measuring direct current impedance of a battery, which can effectively measure the variation of the impedance, so that battery information in the charging process of the battery can be known more accurately.
In a first aspect, a method for measuring dc impedance of a battery, the battery being charged in a segmented constant current mode, the method comprising: determining a difference value between a first voltage interval in a first constant current charging stage and a second voltage interval in a second constant current charging stage, wherein the first voltage interval is a difference value between an ending value and a starting value of the first voltage interval, the second voltage interval is a difference value between an ending value and a starting value of the second voltage interval, the battery adopts the same first charging temperature and/or first charging time length when the first voltage interval is charged and when the second voltage interval is charged, and the charging current of the first constant current charging stage is the same as that of the second constant current charging stage; and determining the variation of the direct current impedance of the battery between the first constant current charging stage and the second constant current charging stage based on the difference and the charging current.
In a second aspect, there is provided a device for measuring dc impedance of a battery, the battery being charged in a segmented constant current mode, the device comprising: the first determining unit is used for determining the difference value between the size of a first voltage interval in a first constant current charging stage and the size of a second voltage interval in a second constant current charging stage, wherein the size of the first voltage interval is the difference value between the ending value and the starting value of the first voltage interval, the size of the second voltage interval is the difference value between the ending value and the starting value of the second voltage interval, the battery adopts the same first charging temperature and/or first charging time length when charging in the first voltage interval and when charging in the second voltage interval, and the charging current of the first constant current charging stage is the same as that of the second constant current charging stage; and the second determining unit is used for determining the variation of the direct current impedance of the battery between the first constant current charging stage and the second constant current charging stage based on the difference and the charging current.
In a third aspect, there is provided a device for measuring dc impedance of a battery, the battery being charged in a segmented constant current mode, the device comprising: at least one circuit configured to perform the method of the first aspect.
In a fourth aspect, a device for measuring dc impedance of a battery, the battery being charged in a segmented constant current mode, is provided, the device comprising a processor and a memory, wherein the memory is configured to store program code, and the processor is configured to call the program code for performing the method of the first aspect.
In a fifth aspect, there is provided a charging system comprising the measuring device of the third or fourth aspect and a battery.
In a sixth aspect, there is provided a terminal device comprising the measuring apparatus of the third or fourth aspect and a battery.
In the embodiment of the present application, the battery is charged in a segmented constant current mode, and in different charging processes, a constant current charging stage with the same charging current exists, and then, the variation of the dc impedance between the constant current charging stages with the same charging current can be determined based on the difference between the voltage increase amounts (i.e. the first voltage interval and the second voltage interval) of the constant current charging stage with the same charging current in different charging processes, that is, the present application can determine the variation of the dc impedance in the constant current charging stage in the charging process, so that it can be avoided that a long charging time needs to be suspended when determining the dc impedance of the battery, and the charging time lengths and/or the charging temperatures corresponding to the first voltage interval and the second voltage interval are the same, so as to avoid the influence of the charging time lengths and/or the charging temperatures on determining the variation of the dc impedance, therefore, the variable quantity of the direct current impedance can be more accurately determined, and the charging information in the battery process can be further accurately known.
Drawings
Fig. 1 is a schematic diagram of a segmented constant current charging mode provided by an embodiment of the present application;
fig. 2 is another schematic diagram of a segmented constant current charging mode provided by an embodiment of the present application;
fig. 3 is a schematic flowchart of a method for measuring dc impedance of a battery according to an embodiment of the present application;
fig. 4 is another schematic flow chart of a method for measuring the dc impedance of a battery according to an embodiment of the present disclosure;
FIG. 5 is a further schematic flow chart of a method for measuring DC impedance of a battery according to an embodiment of the present disclosure;
fig. 6 is a further schematic flow chart of a method for measuring dc impedance of a battery according to an embodiment of the present application;
fig. 7 is a schematic block diagram of a device for measuring dc impedance of a battery according to an embodiment of the present application;
fig. 8 is another schematic block diagram of a device for measuring the dc impedance of a battery provided in an embodiment of the present application;
fig. 9 is a schematic block diagram of a charging system of an embodiment of the present application;
fig. 10 is a schematic block diagram of a terminal device according to an embodiment of the present application.
Detailed Description
The technical solution in the present application will be described below with reference to the accompanying drawings. It should be understood that the specific examples in this specification are provided solely to assist those skilled in the art in better understanding the embodiments of the present application and are not intended to limit the scope of the embodiments of the present application.
For a clearer understanding of the present application, the operation principle of the rechargeable battery will be described below, so as to facilitate the subsequent understanding of the impedance variation. However, it should be understood that the following description is only for better understanding of the present application and should not be taken as limiting the present application in particular.
Taking a lithium ion battery as an example, the lithium ion battery mainly depends on the movement of lithium ions between a positive electrode and a negative electrode to work, when the battery is charged, the positive electrode of the battery generates the lithium ions, the generated lithium ions move to the negative electrode through electrolyte, the negative electrode is provided with a plurality of micropores, and the lithium ions reaching the negative electrode are embedded into the micropores. Along with the charging, a layer of film is formed on the surface of the battery cathode, lithium ions are difficult to enter the film in the process of entering micropores, the macro shows that the charging is slower and slower, and the direct current impedance is larger and larger. Similarly, in a lithium ion battery after many times of charge and discharge, the internal resistance of the battery increases due to oxidation, resulting in an increasing dc resistance. The direct current impedance of the battery can reflect battery information of the battery in the charging and discharging process so as to ensure the safety of the battery in the charging and discharging process.
The charging of the battery in the embodiment of the present application may be charging in a segmented constant current mode, the segmented constant current mode may include a plurality of constant current charging stages, and the charging current in any one of the constant current charging stages may be constant.
In a primary charging process (wherein a primary charging process may be understood as from the start of charging to full charge of the battery), the current of a preceding constant current charging phase may be greater than or equal to the current of a subsequent constant current charging phase. The current of the plurality of constant current charging stages can be uniformly decreased or non-uniformly decreased. The charging time lengths of the currents in the constant current charging phases can be the same or different. The voltage increment amounts of different constant current charging stages may be the same or different.
In the segmented constant-current charging mode, each constant-current charging stage can be switched to the next charging stage when a specific voltage, a specific temperature or a specific charging time is reached, and each charging process can be stopped when the specific voltage, the specific charging time or the specific charging temperature is reached.
Optionally, in the embodiment of the present application, in the charging in the segmented constant current mode, the charging processes of different times may be the same in at least one of the following aspects, and may also be different in at least one of the following aspects:
the number of the constant current charging stages, the voltage increase amount of the constant current charging stages in the same sequence (for example, the mth constant current charging stage in the charging process), the current magnitude of the constant current charging stages in the same sequence, the maximum charging time length of the constant current charging stages in the same sequence, the maximum temperature tolerable for the constant current charging stages in the same sequence, and the like.
Fig. 1 and 2 show schematic diagrams of segmented constant current charging modes of different embodiments, respectively.
In the segmented constant current charging mode as shown in fig. 1, switching is performed to reach a certain voltage, and as shown in fig. 1, in the first constant current charging phase, the battery is charged with a constant current of 2A, and switching is performed to the next current when the charging voltage reaches 4.2V. For example, the current is switched to 1.5A when the charging voltage reaches 4.2V, at which time the battery is charged with a constant current of 1.5A for the second constant current charging phase, the current is switched when the charging voltage reaches 4.4V, and so on until the battery is fully charged.
In the segmented constant current charging mode shown in fig. 2, the switching is performed at the same time interval, and as shown in fig. 2, in the first constant current charging phase, the battery is charged with a constant current of 4A from 0 to t1, and when the charging time period reaches t1, the current is switched to the second constant current charging phase. For example, when the charging time period reaches 1 minute, the current is switched to 2A, at which time for the second constant current charging phase, the battery is charged with a constant current of 2A, and the charging time period is the same as the time period of the first constant current charging phase, and so on until the battery is fully charged.
As the battery is cyclically charged and discharged, the dc impedance of the battery changes under the same charging scenario (e.g., the same charging current, the same charging temperature, and the same charging duration). Therefore, in the embodiment of the present application, based on the voltage difference between the size of the first voltage interval of the first constant current charging stage and the size of the second voltage interval of the second constant current charging stage in the charging process of the battery (the size of the first voltage interval of the first constant current charging stage is the difference between the ending value and the starting value of the first voltage interval, and the size of the second voltage interval of the second constant current charging stage is the difference between the ending value and the starting value of the second voltage interval), the change of the dc impedance can be obtained according to the voltage difference and the current, and the change of the dc impedance can be the change of the impedance of the specific charging stage, so that the change of the impedance can be determined based on each stage, and the impedance can be measured and the impedance difference can be measured without waiting until the charging is finished.
As the battery is cyclically charged and discharged, the dc impedance of the battery changes even under the same charging scenario (e.g., the same charging current, the same charging temperature, and the same charging time duration), and therefore, the following solution is provided in the embodiments of the present application, and the amount of change in dc impedance caused by the change can be determined.
The following describes in detail a method for measuring dc impedance of a battery according to an embodiment of the present application with reference to fig. 3. The battery may be a lithium ion battery or a zinc ion battery, which is not limited in the present application.
The method for measuring the direct-current impedance of the battery provided by the embodiment of the application can be used in a test stage, is convenient for setting the switching current of the battery produced in the same batch, and can also be used in practical application, wherein the current is switched when a certain parameter in the battery reaches a certain value, and the method is not limited in the application.
As shown in fig. 3, the method 300 for measuring the dc impedance of the battery according to the embodiment of the present application may include steps S310 to S320.
S310, determining a difference value between a first voltage interval in a first constant current charging stage and a second voltage interval in a second constant current charging stage, wherein the first voltage interval is a difference value between an ending value and a starting value of the first voltage interval, the second voltage interval is a difference value between an ending value and a starting value of the second voltage interval, charging of the battery in the first voltage interval and charging in the second voltage interval correspond to the same first charging temperature and/or first charging time length, and charging currents of the first constant current charging stage and the second constant current charging stage are the same.
The first constant current charging stage mentioned in the embodiment of the present application may be any constant current charging stage or a specific constant current charging stage in the nth charging process, and the second constant current charging stage may be any constant current charging stage or a specific constant current charging stage in the (n + k) th charging process. The above-mentioned difference between the first voltage interval in the first constant current charging phase and the second voltage interval in the second constant current charging phase for the interval size may be understood as: a difference between a voltage increase represented by the first voltage interval and a voltage increase represented by the second voltage interval; the voltage interval size can be understood as a difference between an end value and a start value of the voltage interval, the first voltage interval size is a difference between an end value and a start value of the first voltage interval, and the second voltage interval size is a difference between an end value and a start value of the second voltage interval.
In this embodiment of the present application, determining the variation of the dc impedance may be completed in a charging process, or may also be performed after the charging is completed, which is not specifically limited in this application.
The first charging temperature mentioned in the embodiment of the present application may be a temperature interval, and the charging temperatures in the first voltage interval and the second voltage interval are the same, which may mean that the initial charging temperature and the termination charging temperature are the same; it may also mean that one of the initial charging temperature and the terminal charging temperature is the same. Alternatively, the first charging temperature may be a temperature value, for example, may refer to an average temperature during charging, for example, the average charging temperatures of the first voltage interval and the second voltage interval are the same.
It should be understood that the first constant current charging phase and the second constant current charging phase may be considered to be the same charging phase of two different charging processes, considering that the charging current of the first constant current charging phase is the same as that of the second constant current charging phase.
It should also be understood that the first and second ones of the first constant current charging phase and the second constant current charging phase in the embodiments of the present application are merely for distinguishing the two, and the order in which they are located in the charging process should not be limited.
The order of the first constant current charging stage in the constant current charging stage included in the nth charging process may be the same as the order of the second constant current charging stage in the constant current charging stage included in the n + k charging process.
For example, the first constant current charging stage and the second constant current charging stage are respectively the first constant current charging stage in the nth charging process and the n + k charging process.
For example, in the first charging process, the battery is charged with a constant current of 2A in the first constant current charging stage, the voltage is increased from 3.4V to 4.2V after charging for 2 minutes, in the second charging process, similarly, the battery is charged with a current of 2A in the second constant current charging stage for 2 minutes, at this time, the voltage may be increased from 3.4 to 4.4V, and then, for this battery, the voltage difference corresponding to the first constant current charging stage is (that is, the size of the voltage interval or the voltage increase amount) 0.8V, and the voltage difference corresponding to the second constant current charging stage is 1V (that is, the size of the voltage interval or the voltage increase amount), and in the two constant current charging processes, the voltage differences corresponding to the same constant current charging stage charging for 2 minutes with the same current of 2A are different. It should be understood that the above values for time, current and voltage are merely illustrative and are not intended to be limiting.
For example, for the same battery, in the first charging process, the battery is charged with a constant current of 2A in the first constant current charging stage, when the voltage rises from 3.4V to 4.2V, at this time, the temperature of the battery is 20 degrees, in the second charging process, the battery is still charged with a current of 2A in the first constant current charging stage, when the temperature of the battery reaches 20 degrees, the voltage may rise from 3.4V to 4.4V, then for the battery, the voltage difference corresponding to the first constant current charging stage is 0.8V, and the voltage difference corresponding to the second constant current charging stage is 1V, and in the two constant current charging processes, the voltage difference corresponding to the same constant current charging stage with the same current of 2A when the same temperature is reached is different. It should be understood that the above values for temperature, current and voltage are merely illustrative and are not intended to be limiting.
Optionally, in the first constant current charging stage and the second constant current charging stage, the battery may be charged with the same initial voltage and the same current, and the charging time is the same, and the voltage difference corresponding to the battery in the first constant current charging stage and the second constant current charging stage is calculated by using the measured voltage.
It can be understood that after the battery is charged and discharged for many times, the dc impedance of the battery changes correspondingly and changes nonlinearly, and if the starting voltage of the first voltage interval in the first constant current charging stage and the starting voltage of the second voltage interval in the second constant current charging stage are different, the battery is charged with the same current and the charging time is the same, the calculated variation of the dc impedance may have an error, and the measurement accuracy is not accurate with the measured accuracy of the same starting voltage.
In some embodiments, n is less than or equal to a preset value.
Specifically, n is less than or equal to a preset value, which can be empirically obtained, and within this preset value, the impedance of the battery does not change greatly, for example, in the previous 50 charging processes, the impedance of the battery may change slightly, for example, 0.1 ohm, and even if we charge the battery in the same charging manner, the battery will not be damaged greatly. The same charging mode means that within the range that n is less than or equal to a preset value, the charging mode is the same every time, and each constant current charging stage in different charging processes is the same without considering the influence of temperature and time on the battery.
And S320, determining the variable quantity of the direct current impedance of the battery between the first constant current stage and the second constant current stage based on the voltage difference and the charging current. Specifically, when the difference between voltages in the same constant current charging stage in different charging processes and the charging current in the charging process in the same stage can be obtained, the variation of the dc impedance in the two charging processes can be calculated based on the difference between the voltages and the charging current.
For example, if the battery is charged with 2A current for the same time, the voltage difference corresponding to the first constant current charging stage is 0.8V, and the voltage difference corresponding to the second constant current charging stage is 1V, in the two constant current charging processes, it can be determined that the variation of the dc impedance between the first constant current charging stage and the second constant current charging stage is 0.1 ohm.
In this process, the charging time is the same for charging the battery with the same current, and the voltage difference of the next time is larger than that of the previous time, so that the dc impedance of the battery is increased for the same charging time in the same constant current charging stage.
According to the method for measuring the direct current impedance of the battery, the battery is charged for multiple times by using the same constant current in stages, the aging condition of the battery after multiple charging and discharging can be further known by comparing the variable quantity of each section of direct current impedance after multiple charging, and therefore the switching of the current is determined to ensure the safety of the battery in the charging process.
Optionally, in some embodiments, as shown in fig. 4, after S320, the method 300 may further include step S330.
S330, determining the direct current impedance of the second constant current charging stage based on the direct current impedance of the first constant current charging stage and the variable quantity of the direct current impedance between the first constant current charging stage and the second constant current charging stage.
Specifically, the dc impedance of the second constant current charging phase can be determined by knowing the dc impedance of the first constant current charging phase and the amount of change in the dc impedance of the constant current phase. For example, if the dc impedance of the first constant current charging stage in the first charging process is 5 ohms, and the variation of the second constant current charging stage with respect to the dc impedance of the first constant current charging stage is 0.5 ohms, the dc impedance of the second constant current charging stage is 5.5 ohms.
Optionally, in some embodiments, a voltage starting value of the first voltage interval is the same as a voltage starting value of the second voltage interval; or, the end-of-voltage value of the first voltage interval is the same as the end-of-voltage value of the second voltage interval, the following conditions mentioned above can be achieved: the minimum charging voltage of the first constant current charging stage is the same as the minimum charging voltage of the second constant current charging stage, the minimum charging voltage of the first constant current charging stage is assumed to be equal to the voltage starting value of the first voltage interval, and the minimum charging voltage of the second constant current charging stage is assumed to be equal to the voltage starting value of the second voltage interval; or, the maximum charging voltage of the first constant current charging stage is the same as the maximum charging voltage of the second constant current charging stage, assuming that the maximum charging voltage of the first constant current charging stage is equal to the voltage end value of the first voltage interval, and assuming that the maximum charging voltage of the second constant current charging stage is equal to the voltage end value of the second voltage interval.
Optionally, in some embodiments, at least one of the following relationships may be satisfied:
the voltage start value of the first voltage interval may be equal to or greater than the minimum charging voltage of the first constant current charging phase, the voltage end value of the first voltage interval may be less than or equal to the maximum charging voltage of the first constant current charging phase, the voltage start value of the second voltage interval may be equal to or greater than the minimum charging voltage of the second constant current charging phase, and the voltage end value of the second voltage interval may be less than or equal to the maximum charging voltage of the second constant current charging phase.
Alternatively, if the minimum charging voltage of the first constant current charging stage and the minimum charging voltage of the second constant current charging stage are different, the larger of the two minimum charging voltages may be selected as the voltage starting value of the first voltage interval and the second voltage interval, and then the first voltage interval and the second voltage interval may be determined according to the first charging duration and/or the first charging temperature, respectively, starting with the starting value.
Or, if the maximum charging voltage of the first constant current charging stage and the maximum charging voltage of the second constant current charging stage are different, selecting a small one from the two maximum charging voltages as the voltage end value of the first voltage interval and the second voltage interval, and then starting with the end value, and advancing according to the first charging duration and/or the first charging temperature to respectively determine the first voltage interval and the second voltage interval.
It can be understood that in some constant current charging stages, the minimum charging voltage of the first constant current charging stage is the same as the minimum charging voltage of the second constant current charging stage, for example, for a battery that has been completely discharged twice, the minimum charging voltage of the first constant current charging stage and the minimum charging voltage of the second constant current charging stage are both 0V, and if the battery is charged with the same current and the charging time is guaranteed to be the same, the calculated impedance variation of the direct current in this case may be more effective, so as to facilitate understanding of the aging condition of the battery during charging and discharging, where it is assumed that the minimum charging voltage of the first constant current charging stage is equal to the starting voltage of the first voltage interval, and the minimum charging voltage of the second constant current charging stage is equal to the starting voltage of the second voltage interval.
For example, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, the voltage rises from 3.4V to 4.2V after charging for 2 minutes, in the second charging process, similarly, the second constant current charging stage still charges the battery with a current of 2A for a period of 2 minutes, at which the voltage may rise from 3.4V to 4.4V, and the voltage difference corresponding to charging the battery with the same current for 2 minutes is 0.2V. It should be understood that the above values for time, current and voltage are merely illustrative and are not intended to be limiting.
In some constant current charging phases, the minimum charging voltage of the first constant current charging phase is the same as the minimum charging voltage of the second constant current charging phase, e.g., for the two charging and discharging processes, the final voltage of the last segment is the same, and may be 5V, at this time, if the battery is charged with the same current and the charging time is ensured to be the same, even if the starting voltages of the first constant-current charging stage and the second constant-current charging stage are different, since the ending voltages of the first constant-current charging stage and the second constant-current charging stage are the same, the amount of change in the calculated dc impedance is also valid in this case, assuming that the maximum charging voltage of the first constant current charging phase is equal to the end voltage of the first voltage interval, and assuming that the maximum charging voltage of the second constant current charging phase is equal to the end voltage of the second voltage interval.
It can be understood that, since the starting voltages of the first constant-current charging phase and the second constant-current charging phase are the same, the variation of the dc impedance can be directly calculated by using the ratio of the voltage difference between the two charging operations to the charging current. The dc impedance of the first constant current charging stage in the first charging process may be calculated first, then the dc impedance of the second constant current stage in the second charging process may be calculated, and the variation of the dc impedance of the second constant current stage relative to the dc impedance of the first constant current charging stage may be determined by using the calculated dc impedances of the two times.
Optionally, in some embodiments, the voltage start value of the first voltage interval is a minimum charging voltage of the first constant current charging phase, the voltage start value of the second voltage interval is a minimum charging voltage of the second constant current charging phase, the voltage end value of the first voltage interval is smaller than a maximum charging voltage of the first constant current charging phase, and the voltage end value of the second voltage interval is a maximum charging voltage of the second constant current charging phase.
It can be understood that, for the same battery, as the number of charging and discharging times of the battery increases, the dc impedance increases accordingly, and if the battery is charged with the same current in two charging processes and the charging time is the same, the voltage reached by the next charging is larger than the voltage reached by the previous charging.
That is, for the same battery, if the same current is used to charge the battery in two charging processes to reach the same voltage, the time for reaching the voltage at the next time is reduced compared with the time for reaching the voltage at the previous time.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, the voltage rises from 3.4V to 4.2V after 2 minutes of charging, and in the second charging process, likewise, the second constant current charging stage still charges the battery with a current of 2A, and may reach a voltage of 4.2V after 1.5 minutes of charging, at which time the current should be switched to the next current, because if the battery is further charged with a current of 2A for 2 minutes, it may be possible to charge the battery to its cut-off voltage or even to exceed its cut-off voltage in a very short time, which may seriously impair the performance or life of the battery.
It can be understood that the voltage end value of the second voltage interval may not be the maximum charging voltage of the second constant current charging stage, and the variation of the dc impedance may also be measured without reaching the maximum charging voltage.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, the voltage rises from 3.4V to 4.2V after charging for 2 minutes, and in the second charging process, the second constant current charging stage also charges the battery with a current of 2A, and may reach a voltage of 3.9V after charging for 1 minute, and then the variation of the dc impedance of the battery within 1 minute may be calculated.
It should be understood that the values of time, voltage and current are only used as examples, and the application is not limited thereto.
Optionally, in some embodiments, as shown in fig. 5, before S320, the method 300 may further include steps S311-S312.
S311, determining the charging time length when the battery reaches the maximum charging voltage of the second constant current charging stage in the second constant current charging stage as the first charging time length.
In order to more accurately measure the impedance variation in a plurality of charging processes, it should be ensured that the battery is the impedance variation measured at the same current and the same time, and therefore, the charging period of the maximum charging voltage reached in the subsequent constant current charging stage should be determined as the first charging period.
It should be understood that the former and latter are relative concepts intended to indicate the amount of change in the impedance of the battery over a plurality of charges and discharges, for example, the former may be the first and the latter may be the second, 100 th; the previous time may be 50 th time, and the next time may be 51 th time or 200 th time, which is not limited in this application, as long as the next time is charged after the previous time with respect to the previous time, the embodiment of the present application may be applied.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, the voltage rises from 3.4V to 4.2V after charging for 2 minutes, and in the second charging process, similarly, the first constant current charging stage still charges the battery with a current of 2A, and may reach a voltage of 4.2V after charging for 1.5 minutes, and at this time, the current is switched to the next current, so that 1.5 minutes should be determined as the first charging time period.
That is to say, in the above process, the currents used before 1.5 minutes are all the same, the voltage difference is determined by using the corresponding voltage of the same constant current charging stage in the two charging processes in 1.5 minutes, and the variation of the dc impedance is determined according to the ratio of the voltage difference to the current, so that the determined variation of the dc impedance is relatively accurate.
S312, determine the voltage reached by the first charging duration of the battery during the first constant current charging phase as the voltage end value of the first voltage interval.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, the voltage rises from 3.4V to 4.2V after charging for 2 minutes, in the second charging process, similarly, the second constant current charging stage still charges the battery with a current of 2A, the voltage of 4.2V may be reached after charging for 1.5 minutes, and the battery is switched to the next current to continue charging, at this time, since the end voltage of the first constant current charging stage has been reached, 1.5 minutes is determined as the first charging duration, and correspondingly, the voltage corresponding to 1.5 minutes in the first constant current charging stage in the first charging process may be determined as the voltage end value of the first voltage interval.
It will be understood that the end of voltage value of the first voltage interval is determined not only to find a reference value for switching the current, but also to better compare the voltages of the batteries of the same constant current charging phase of the different charging processes, so that on the one hand it is avoided that the voltages exceed the cut-off voltage due to an excessive charging current, and on the other hand it is possible to compare the variation of the dc impedance of the same battery in the different charging processes without exceeding the cut-off voltage.
Optionally, in some embodiments, the charging duration and the voltage reached by the battery are monitored and recorded in real time during the first constant current charging phase.
Specifically, for the same battery, in the first constant current charging stage, the first constant current charging stage charges the battery with a constant current of 2A, after charging for 2 minutes, the voltage rises from 3.4 to 4.2V, in the second charging process, similarly, the second constant current charging stage still charges the battery with a current of 2A, and may reach a voltage of 4.2V after charging for 1.5 minutes, and switch to the next current to continue charging the battery, since the charging currents are the same within 1.5 minutes in the first constant current charging stage, the voltage corresponding to charging for 1.5 minutes in the first charging process can be searched, and the amount of change in the dc impedance of the battery in the two charging processes is calculated by using the same charging time.
It can be understood that, taking the above-mentioned process as an example, in the first constant current charging stage and the second constant current charging, the charging duration is the same current for charging the battery within 1.5 minutes, so according to the requirement, the charging duration and the corresponding voltage of the two charging processes can also be monitored in real time, and thus the variation of the dc impedance at any time within 1.5 minutes of the charging duration of the two charging processes can be determined.
For example, the amount of change in dc impedance of 0.5 minute or 1 minute may be determined, and the charging voltage corresponding to charging for 0.5 minute or 1 minute may be monitored in the first constant-current charging stage, or the first constant-current charging stage may be monitored in real time, and the monitored content may be recorded, which facilitates subsequent searching.
The specific monitoring method may be electronic monitoring, such as real-time monitoring of time and voltage, or video shooting, and recording according to the content of video monitoring, or manual recording.
Optionally, in some embodiments, the voltage start value of the first voltage interval is a minimum charging voltage of the first constant current charging phase, the voltage start value of the second voltage interval is a minimum charging voltage of the second constant current charging phase, the voltage end value of the first voltage interval is a maximum charging voltage of the first constant current charging phase, and the voltage end value of the second voltage interval is a maximum charging voltage of the second constant current charging phase.
It can be understood that, as the battery is charged and discharged for a plurality of times, the dc impedance increases, and if the battery is charged with the same current in the first constant current charging stage and the second constant current charging stage and reaches the same temperature, the voltage reached in the subsequent constant current charging stage is relatively lower than the voltage reached in the previous constant current charging stage. However, in practice, when a certain temperature is reached, the current should be switched to be smaller so as to avoid damage to the battery caused by continuously charging the battery with the current before switching.
For the same battery, in the first charging process, the battery is charged by constant current of 2A in the first constant current charging stage, when the voltage rises from 3.4V to 4.2V, the temperature of the battery is 20 ℃, the initial voltage value of the first voltage interval is 3.4V, and the final voltage value is 4.2V; in the second charging process, the battery is still charged with the current of 2A in the second constant current charging stage, when the temperature of the battery reaches 20 ℃, the voltage may be 4.0V, the voltage of 4.2V corresponding to the current temperature in the first charging is not yet reached, the voltage start value of the second voltage interval is 0V, and the voltage end value is 4.0V, since the temperature has reached the end temperature of the first constant current charging stage, the current should be switched to the next current, for example, to 1A, otherwise if the battery is further charged with the current of 2A, the temperature of the battery may sharply rise in a short time, which may seriously damage the performance or the service life of the battery.
Optionally, in some embodiments, as shown in fig. 6, before S320, the method 300 may further include steps S313 to S314.
And S313, determining the charging temperature at which the battery reaches the maximum charging voltage in the first constant current charging stage as the first charging temperature.
Specifically, taking temperature as an example, in order to more accurately measure the variation of impedance in the same constant current charging stage in a plurality of charging processes, it should be ensured that the battery has the variation of impedance measured at the same current and at the same temperature, and since the voltage reached in the subsequent constant current charging stage is relatively lower than the voltage reached in the previous constant current charging stage when the battery is charged at the same current and at the same temperature, the charging temperature of the voltage reached in the previous constant current charging stage should be determined as the first charging temperature.
It should be understood that the former and latter are relative concepts intended to indicate the amount of change in the impedance of the battery over a plurality of charges and discharges, for example, the former may be the first and the latter may be the second, 100 th; the previous time may be 50 th time, and the next time may be 51 th time or 200 th time, which is not limited in this application, as long as the next time is charged after the previous time with respect to the previous time, the embodiment of the present application may be applied.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, when the voltage rises from 3.4V to 4.2V, the temperature of the battery is 20 degrees, in the second charging process, the second constant current charging stage still charges the battery with a current of 2A, when the temperature of the battery reaches 20 degrees, the current is switched to the next current, the voltage may be 4.0V at this time, and the voltage of 4.2V corresponding to the current temperature of the first constant current charging stage has not been reached, so 20 degrees should be determined as the first charging temperature.
That is, in the two charging processes, the first constant current charging stage and the second constant current charging stage charge the battery with the same current 2A before 20 degrees, the voltage difference is determined by using the corresponding voltage when the temperature of the first constant current charging stage and the second constant current charging stage is 20 degrees in the two charging processes, and the variation of the direct current impedance is determined according to the ratio of the voltage difference to the current, so that the determined variation of the direct current impedance is relatively accurate.
And S314, determining the voltage reached when the battery is charged to reach the first charging temperature in the second charging stage process as the voltage ending value of the second voltage interval and the maximum charging voltage of the second constant current charging stage.
For example, for the same battery, in the first charging process, the first constant current charging stage charges the battery with a constant current of 2A, when the voltage rises from 3.4V to 4.2V, the temperature of the battery is 20 degrees, in the second charging process, similarly, the second constant current charging stage still charges the battery with a current of 2A, when the temperature of the battery reaches 20 degrees, the current is switched to the next current, the voltage may be 4.0V at this time, and the voltage corresponding to the temperature of the second charging process reaching 20 degrees is the voltage end value of the second voltage interval and the maximum charging voltage of the second constant current charging stage.
It can be understood that, taking the above-mentioned process as an example, the current with the temperature within 20 degrees is used for charging the battery with the same current 2A, so that the variation of the dc impedance of any temperature with the temperature within 20 degrees in the same constant current charging process in two charging processes, for example, the variation of the dc impedance at the temperature of 10 degrees, may also be determined.
The specific monitoring method may be electronic monitoring, such as real-time monitoring of temperature and voltage, or video shooting, and recording according to the content of video monitoring, or manual recording, which is not limited in this application, and the embodiment of the present application can be applied as long as the voltage corresponding to any temperature can be measured.
It should be understood that in the above S314, the voltage reached by the battery when the battery is charged to reach the first charging temperature during the second charging phase may also be determined as the voltage end value of the second voltage interval, and the second constant current charging phase may continue to be charged until the voltage end value of the second constant current charging phase is equal to the voltage end value of the first constant current charging phase.
Optionally, in some embodiments, the first constant current charging phase is a first constant current charging phase in an nth charging process, and the second constant current charging phase is a first constant current charging phase in an n + k charging process.
In this implementation, for the schemes defined in S313 and S314, since the starting voltage of the first constant current charging phase is the same in the two charging processes, but since the ending voltage of the first constant current charging phase is different at the same charging temperature, it may cause that the subsequent constant charging phases in the same order are not aligned in the two charging processes, and it is not favorable to obtain the first charging interval and the second charging interval where the above-mentioned starting voltage values are aligned, and then only the dc impedance change value or the dc impedance corresponding to the first constant current charging phase may be calculated.
It is understood that the nth charge may be the 1 st charge, and the (n + k) th charge may be the 2 nd charge, or the 3 rd charge, the 500 th charge; or the nth charging may be the 20 th charging, and the n + k charging may be the 21 st charging, or may be the 400 th or 500 th charging, which is not limited in this application, and the embodiments of the present application may be applied as long as the voltage values in the charging processes of different times can be measured.
According to the method, the direct current impedance information of the battery after discharging for multiple times can be further known by comparing the direct current impedance variable quantity in any two charging processes.
The method embodiment of the present application is described in detail above with reference to fig. 1 to 6, and the apparatus embodiment of the present application is described below with reference to fig. 7 to 10, where the apparatus embodiment and the method embodiment correspond to each other, so that the non-detailed portions can refer to the foregoing method embodiments, and the apparatus can implement any possible implementation manner in the above method side.
Fig. 7 and 8 illustrate a device 400 for measuring dc impedance of a battery according to an embodiment of the present disclosure, where the battery is charged in a segmented constant current mode, and as shown in fig. 7 and 8, the device 400 for measuring dc impedance of a battery according to an embodiment of the present disclosure may include a first determining unit 410 and a second determining unit 420.
A first determining unit 410, configured to determine a difference between a size of a first voltage interval in a first constant current charging phase and a size of a second voltage interval in a second constant current charging phase, where the size of the first voltage interval is a difference between an end value and a start value of the first voltage interval, the size of the second voltage interval is a difference between an end value and a start value of the second voltage interval, the battery employs the same first charging temperature and/or first charging duration when charging in the first voltage interval and when charging in the second voltage interval, and charging currents of the first constant current charging phase and the second constant current charging phase are the same;
a second determining unit 420, configured to determine, based on the difference and the charging current, a variation of the dc impedance of the battery between the first constant current charging phase and the second constant current charging phase.
Optionally, in this embodiment of the application, as shown in fig. 8, the measurement apparatus further includes a third determination unit 430.
A third determining unit 430, configured to determine the dc impedance of the second constant-current charging phase based on the dc impedance of the first constant-current charging phase and the variation of the dc impedance.
Optionally, in an embodiment of the present application, a minimum charging voltage of the first constant current charging stage is the same as a minimum charging voltage of the second constant current charging stage; and/or the maximum charging voltage of the first constant current charging stage is the same as the maximum charging voltage of the second constant current charging stage.
Optionally, in this embodiment of the application, a voltage starting value of the first voltage interval is a minimum charging voltage of the first constant current charging stage, and a voltage starting value of the second voltage interval is a minimum charging voltage of the second constant current charging stage; the voltage end value of the first voltage interval is smaller than the maximum charging voltage of the first constant current charging stage, and the voltage end value of the second voltage interval is the maximum charging voltage of the second constant current charging stage.
Optionally, in this embodiment of the application, as shown in fig. 8, the measurement apparatus further includes a fourth determination unit 440, configured to:
determining the charging time length when the battery reaches the maximum charging voltage of the second constant current charging stage in the second constant current charging stage as the first charging time length;
and determining the voltage reached by the first charging time period during the first constant current charging stage process of the battery as the voltage termination value of the first voltage interval.
Optionally, in this embodiment of the present application, as shown in fig. 8, the measurement apparatus further includes a monitoring recording unit 450, configured to:
and in the first constant current charging stage, monitoring and recording the charging time length and the reached voltage of the battery in real time.
Optionally, in this embodiment of the application, a voltage starting value of the first voltage interval is a minimum charging voltage of the first constant current charging stage, and a voltage starting value of the second voltage interval is a minimum charging voltage of the second constant current charging stage; the voltage end value of the first voltage interval is the maximum charging voltage of the first constant current charging stage, and the voltage end value of the second voltage interval is the maximum charging voltage of the second constant current charging stage.
Optionally, in this embodiment of the application, as shown in fig. 8, the measurement apparatus further includes a fifth determination unit 460, configured to:
determining a charging temperature at which the battery reaches the maximum charging voltage in the first constant current charging phase as the first charging temperature;
and determining the voltage reached by the battery when the battery is charged to reach the first charging temperature in the second constant current charging stage as the voltage termination value of the second voltage interval and the maximum charging voltage of the second constant current charging stage.
Optionally, in this embodiment of the application, the first constant current charging stage is a first constant current charging stage in an nth charging process, and the second constant current charging stage is a first constant current charging stage in an n + k charging process.
Optionally, in this embodiment of the application, as shown in fig. 8, the measurement apparatus further includes a sixth determining unit 470, configured to:
and determining the ratio of the voltage interval charged in the first constant current charging stage to the charging current in the first constant current charging stage as the direct current impedance of the first constant current charging stage.
Optionally, in an embodiment of the present application, the first constant current charging stage is a constant current charging stage in an nth charging process, and the second constant current charging stage is a constant current charging stage in an n + k charging process, where n is an integer greater than or equal to 1, and k is an integer greater than or equal to 1.
Optionally, in this embodiment of the present application, n is less than or equal to a preset value.
Optionally, in this embodiment, n is equal to 1.
Optionally, the measurement apparatus 400 may be implemented by hardware, in this case, the measurement apparatus 400 includes at least one circuit, and the at least one circuit may implement the functions of the above units, and may be specifically configured to perform the method 300.
Alternatively, the measurement apparatus 400 may be implemented by a processor and a memory, the memory is used for storing program codes, and the processor is used for calling the program codes to implement the functions of the above units, and in particular, may be used for executing the method 300.
Fig. 9 is a schematic block diagram of a charging system 500 according to an embodiment of the present application. The charging system includes a measurement device 510 and a battery 520.
The measurement apparatus 510 may be used to implement the method 300, and may implement the functions implemented by the apparatus 400, which are not described herein again for brevity.
Fig. 10 is a schematic block diagram of a terminal device 600 according to an embodiment of the present application. The terminal device 600 includes a measuring means 610 and a battery 620.
The measurement apparatus 610 may be used to implement the method 300, and may implement the functions implemented by the apparatus 400, which are not described herein again for brevity.
In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware or any other combination. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a Digital Video Disk (DVD)), or a semiconductor medium (e.g., a Solid State Disk (SSD)), among others.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (30)

1. A method for measuring dc impedance of a battery, wherein the battery is charged in a segmented constant current mode, the method comprising:
in the process of charging the battery, determining a difference value between the size of a first voltage interval in a first constant current charging stage and the size of a second voltage interval in a second constant current charging stage, wherein the size of the first voltage interval is the difference value between the ending value and the starting value of the first voltage interval, the size of the second voltage interval is the difference value between the ending value and the starting value of the second voltage interval, the charging of the battery in the first voltage interval and the charging in the second voltage interval correspond to the same first charging temperature and/or first charging time length, and the charging currents of the first constant current charging stage and the second constant current charging stage are the same;
and determining the variation of the direct current impedance of the battery between the first constant current charging stage and the second constant current charging stage based on the difference value between the size of a first voltage interval in the first constant current charging stage and the size of a second voltage interval in the second constant current charging stage and the charging current.
2. The measurement method according to claim 1, characterized in that the method further comprises:
and determining the direct current impedance of the second constant current charging stage based on the direct current impedance of the first constant current charging stage and the variable quantity of the direct current impedance.
3. Method according to claim 1 or 2, characterized in that the voltage starting value of the first voltage interval is the same as the voltage starting value of the second voltage interval; or the like, or, alternatively,
the voltage end value of the first voltage interval is the same as the voltage end value of the second voltage interval.
4. The measurement method according to claim 1, wherein the voltage start value of the first voltage interval is the minimum charging voltage of the first constant current charging phase, and the voltage start value of the second voltage interval is the minimum charging voltage of the second constant current charging phase;
the voltage end value of the first voltage interval is smaller than the maximum charging voltage of the first constant current charging stage, and the voltage end value of the second voltage interval is the maximum charging voltage of the second constant current charging stage.
5. The measurement method according to claim 4, characterized in that the method further comprises:
determining the charging time length when the battery reaches the maximum charging voltage of the second constant current charging stage in the second constant current charging stage as the first charging time length;
and determining the voltage reached by the first charging time period during the first constant current charging stage process of the battery as the voltage termination value of the first voltage interval.
6. The measurement method according to claim 5, characterized in that the method further comprises:
and in the first constant current charging stage, monitoring and recording the charging time length and the reached voltage of the battery in real time.
7. The method according to claim 1, wherein a voltage start value of the first voltage interval is a minimum charging voltage of the first constant current charging phase, a voltage start value of the second voltage interval is a minimum charging voltage of the second constant current charging phase, a voltage end value of the first voltage interval is a maximum charging voltage of the first constant current charging phase, and a voltage end value of the second voltage interval is a maximum charging voltage of the second constant current charging phase.
8. The measurement method according to claim 7, characterized in that the method further comprises:
determining a charging temperature at which the battery reaches the maximum charging voltage in the first constant current charging phase as the first charging temperature;
and determining the voltage reached by the battery when the battery is charged to reach the first charging temperature in the second constant current charging stage as the voltage termination value of the second voltage interval and the maximum charging voltage of the second constant current charging stage.
9. The method of claim 8, wherein the first constant current charging phase is a first constant current charging phase in an nth charging process, and wherein the second constant current charging phase is a first constant current charging phase in an n + k charging process.
10. The measurement method according to claim 1, characterized in that the method further comprises:
and determining the ratio of the voltage interval charged in the first constant current charging stage to the charging current in the first constant current charging stage as the direct current impedance of the first constant current charging stage.
11. The measurement method according to claim 1, wherein the first constant current charging stage is a constant current charging stage in an nth charging process, and the second constant current charging stage is a constant current charging stage in an n + k charging process, where n is an integer greater than or equal to 1, and k is an integer greater than or equal to 1.
12. The measurement method according to claim 11, wherein n is less than or equal to a preset value.
13. The measurement method according to claim 11 or 12, characterized in that said n is equal to 1.
14. A device for measuring the dc impedance of a battery, wherein the battery is charged in a segmented constant current mode, the device comprising:
the first determining unit is used for determining the difference value between the size of a first voltage interval in a first constant current charging stage and the size of a second voltage interval in a second constant current charging stage, wherein the size of the first voltage interval is the difference value between the ending value and the starting value of the first voltage interval, the size of the second voltage interval is the difference value between the ending value and the starting value of the second voltage interval, the same first charging temperature and/or first charging time length are adopted when the battery is charged in the first voltage interval and when the battery is charged in the second voltage interval, and the charging currents of the first constant current charging stage and the second constant current charging stage are the same;
and the second determining unit is used for determining the variation of the direct current impedance of the battery between the first constant current charging stage and the second constant current charging stage based on the difference value between the size of the first voltage interval in the first constant current charging stage and the size of the second voltage interval in the second constant current charging stage and the charging current.
15. The measurement device of claim 14, further comprising:
and the third determining unit is used for determining the direct current impedance of the second constant current charging stage based on the direct current impedance of the first constant current charging stage and the variation of the direct current impedance.
16. A measuring device according to claim 14 or 15, wherein the minimum charging voltage of the first constant current charging phase is the same as the minimum charging voltage of the second constant current charging phase; and/or the maximum charging voltage of the first constant current charging stage is the same as the maximum charging voltage of the second constant current charging stage.
17. The measurement device according to claim 14, wherein the voltage start value of the first voltage interval is the minimum charging voltage of the first constant current charging phase and the voltage start value of the second voltage interval is the minimum charging voltage of the second constant current charging phase;
the voltage end value of the first voltage interval is smaller than the maximum charging voltage of the first constant current charging stage, and the voltage end value of the second voltage interval is the maximum charging voltage of the second constant current charging stage.
18. The measurement device according to claim 17, further comprising a fourth determination unit configured to:
determining the charging time length when the battery reaches the maximum charging voltage of the second constant current charging stage in the second constant current charging stage as the first charging time length;
and determining the voltage reached by the first charging time period during the first constant current charging stage process of the battery as the voltage termination value of the first voltage interval.
19. The measurement device of claim 18, further comprising a monitoring and recording unit configured to:
and in the first constant current charging stage, monitoring and recording the charging time length and the reached voltage of the battery in real time.
20. The measurement device according to claim 14, wherein the voltage start value of the first voltage interval is the minimum charging voltage of the first constant current charging phase and the voltage start value of the second voltage interval is the minimum charging voltage of the second constant current charging phase;
the voltage end value of the first voltage interval is the maximum charging voltage of the first constant current charging stage, and the voltage end value of the second voltage interval is the maximum charging voltage of the second constant current charging stage.
21. The measurement device according to claim 20, further comprising a fifth determination unit configured to:
determining a charging temperature at which the battery reaches the maximum charging voltage in the first constant current charging phase as the first charging temperature;
and determining the voltage reached by the battery when the battery is charged to reach the first charging temperature in the second constant current charging stage as the voltage termination value of the second voltage interval and the maximum charging voltage of the second constant current charging stage.
22. The measurement device of claim 21, wherein the first constant current charging phase is a first constant current charging phase in an nth charging process, and wherein the second constant current charging phase is a first constant current charging phase in an n + k charging process.
23. The measurement device according to claim 14, characterized in that the measurement device further comprises a sixth determination unit for:
and determining the ratio of the voltage interval charged in the first constant current charging stage to the charging current in the first constant current charging stage as the direct current impedance of the first constant current charging stage.
24. The measurement device according to claim 14, wherein the first constant current charging phase is a constant current charging phase in an nth charging process, and the second constant current charging phase is a constant current charging phase in an n + k charging process, where n is an integer greater than or equal to 1, and k is an integer greater than or equal to 1.
25. The measurement device of claim 24, wherein n is less than or equal to a preset value.
26. A measuring device according to claim 24 or 25, characterized in that said n is equal to 1.
27. A device for measuring the dc impedance of a battery, wherein the battery is charged in a segmented constant current mode, the device comprising:
at least one circuit for performing the method of any one of claims 1 to 13.
28. A device for measuring the dc impedance of a battery, wherein the battery is charged in a segmented constant current mode, the device comprising a processor and a memory, wherein the memory is configured to store program code, and wherein the processor is configured to invoke the program code to perform the method according to any one of claims 1 to 13.
29. A charging system comprising the measurement device according to claim 27 or 28 and the battery.
30. A terminal device, characterized in that it comprises a measuring device according to claim 27 or 28 and said battery.
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