CN107329091B - Method, device and system for measuring internal temperature of battery - Google Patents
Method, device and system for measuring internal temperature of battery Download PDFInfo
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- CN107329091B CN107329091B CN201710570753.XA CN201710570753A CN107329091B CN 107329091 B CN107329091 B CN 107329091B CN 201710570753 A CN201710570753 A CN 201710570753A CN 107329091 B CN107329091 B CN 107329091B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
Abstract
The embodiment of the invention provides a method, a device and a system for measuring the internal temperature of a battery, wherein the method comprises the following steps: determining a target Nyquist curve of a battery in the working process of the battery; determining a target intersection point of the target Nyquist curve and a real axis, and determining the frequency of the target intersection point; determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency; therefore, the temperature inside the battery can be directly determined according to the frequency corresponding to the intersection point of the target Nyquist curve and the real axis, and the accuracy of measuring the temperature inside the battery is improved.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a method, a device and a system for measuring the internal temperature of a battery.
Background
With the continuous development of economy, the non-renewable resources are continuously reduced, and the environment is inevitably polluted; therefore, renewable resources, secondary energy and the like can be applied to various fields to achieve the purposes of energy conservation and environmental protection; for example, secondary energy electric energy is applied to the field of automobiles such as new energy automobiles, wherein the new energy automobiles use batteries, storage batteries and the like as the driving force of the automobiles; the battery management system is generally adopted to monitor the battery state of the new energy automobile so as to ensure the driving safety of the new energy automobile, for example, the internal temperature of the battery is monitored.
Generally, when measuring the internal temperature of a battery, one or more couples are used to collect the surface temperature of the battery, and then the internal temperature of the battery is measured; the accuracy of the temperature of the battery measured by the method is not high because a certain temperature difference exists between the surface and the interior of the battery.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a method for measuring the internal temperature of a battery so as to improve the accuracy of measuring the internal temperature of the battery.
Correspondingly, the embodiment of the invention also provides a device and a system for measuring the internal temperature of the battery, which are used for ensuring the realization and the application of the method.
In order to solve the above problems, the present invention discloses a method for measuring the internal temperature of a battery, which specifically comprises: determining a target Nyquist curve of a battery in the working process of the battery; determining a target intersection point of the target Nyquist curve and a real axis, and determining the frequency of the target intersection point; and determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency.
The invention discloses a device for measuring the internal temperature of a battery, which specifically comprises: the curve determining module is used for determining a target Nyquist curve of the battery in the working process of the battery; the frequency determination module is used for determining a target intersection point of the target Nyquist curve and the real axis and determining the frequency of the target intersection point; and the temperature determining module is used for determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency.
The invention discloses a temperature measuring system which comprises a battery and a device for measuring the internal temperature of the battery in the embodiment of the invention.
A readable storage medium on which a battery internal temperature measurement program is stored, which when executed by a processor implements the battery internal temperature measurement program method of an embodiment of the present invention.
Compared with the prior art, the embodiment of the invention has the following advantages:
the method and the device can acquire the preset linear relation between the internal temperature and the frequency of the battery in advance, then determine the target Nyquist curve of the battery in the working process of the battery, and then determine the frequency corresponding to the target intersection point according to the target intersection point of the target Nyquist curve and a real axis; determining the temperature corresponding to the frequency corresponding to the target intersection point, namely the temperature inside the battery according to the preset linear relation; therefore, the temperature inside the battery can be directly determined according to the frequency corresponding to the intersection point of the target Nyquist curve and the real axis, and the accuracy of measuring the temperature inside the battery is improved.
Drawings
FIG. 1 is a schematic representation of the Nyquist curve for a battery of the present invention;
FIG. 2 is a flow chart illustrating the steps of one embodiment of a method for measuring the internal temperature of a battery according to the present invention;
FIG. 3 is a flow chart of steps in another embodiment of a method of measuring the internal temperature of a battery of the present invention;
FIG. 4 is a schematic diagram of a test system for determining a predetermined linear relationship according to the present invention;
FIG. 5 is a block diagram of an embodiment of the device for measuring the internal temperature of a battery according to the present invention;
FIG. 6 is a block diagram of another embodiment of the device for measuring the internal temperature of a battery according to the present invention;
FIG. 7 is a block diagram of a temperature measurement system according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
For convenience of description of the following embodiments, the nyquist curve is described. Generally, the characteristics of an electrochemical system can be analyzed by its corresponding electrochemical impedance spectrum; the battery in the embodiment of the invention can be equivalent to an electrochemical system, so that the electrochemical impedance spectrum of the battery can be obtained firstly, and then the temperature of the battery can be analyzed through the electrochemical impedance spectrum of the battery. Alternating currents with different frequencies can pass through the battery, so that voltage drop at two ends of the battery is obtained, and impedance of the battery is further determined; the impedance of the battery is a function of frequency, and a corresponding Nyquist curve can be determined according to a real part and an imaginary part of the impedance corresponding to each frequency. As shown in fig. 1, a diagram of a nyquist curve of a battery is shown, in which the horizontal axis of a coordinate system is a real axis, the vertical axis is an imaginary axis, the horizontal axis corresponding to a certain point on the curve is a real impedance component coefficient, the vertical axis is an imaginary impedance component coefficient, and each point on the nyquist curve corresponds to a frequency. The nyquist curves corresponding to the different states of the battery all have intersections with the real axis, as shown by point a in fig. 1, where the intersections of the different nyquist curves with the real axis are different.
One of the core ideas of the embodiment of the invention is that the preset linear relation between the temperature and the frequency is determined in advance through testing batteries with different internal temperatures; and further determining the frequency corresponding to the target intersection point of the target Nyquist curve in the working process of the battery, and determining the temperature corresponding to the frequency of the target intersection point, namely the internal temperature of the battery according to a preset linear relation.
Referring to fig. 2, a flowchart illustrating steps of an embodiment of a method for measuring a temperature inside a battery according to the present invention is shown, which may specifically include the following steps:
Step 202, determining a target intersection point of the target Nyquist curve and the real axis, and determining the frequency of the target intersection point.
And 203, determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency.
In the embodiment of the present invention, the factors affecting the electrochemical characteristics of the battery include various factors, wherein the internal temperature of the battery is a factor affecting the electrochemical characteristics of the battery, that is, when the internal temperature of the battery changes, the electrochemical characteristics of the battery also change; when the electrochemical characteristics of the battery change, the internal impedance of the battery also changes, and correspondingly, the nyquist curve of the battery is also different, and the intersection point of the nyquist curve and the real axis is also different. Generally, the internal temperature of the battery is in a certain range (e.g., -40 degrees +60 degrees), the internal temperature of the battery, and the frequency of the intersection point of the nyquist curve of the battery and the real axis are in a linear relationship, so that the preset linear relationship between the internal temperature of the battery and the frequency, such as T ═ T, can be predetermined in the embodiment of the present invention0+k(f-f0) Wherein T is the internal temperature of the battery, T0Is the ambient temperature of the battery, f0For the battery at T0Frequency, T, of intersection of Nyquist curve and real axis at temperature0And f0And f, determining the frequency of the intersection point of the Nyquist curve corresponding to the battery at the T temperature and the real axis when the battery is at the T temperature, and further determining the internal temperature of the battery according to the preset linear relation in the working process of the battery.
In the working process of the battery, alternating currents with different frequencies can pass through the battery, the internal impedance of the battery is determined according to the voltage drop of the battery and the current passing through the battery, and then the target Nyquist curve of the battery is determined according to the internal impedance of the battery; and the target Nyquist curve is a Nyquist curve corresponding to the current state of the battery. After the target nyquist curve is acquired, a target intersection point of the target nyquist curve and the real axis is determined, and then the frequency of the target intersection point is determined, for example, the frequencies corresponding to two coordinate points near the target intersection point can be determined, the two coordinate points can be two points with opposite vertical coordinate signs, and then the frequency of the target intersection point is determined according to the frequencies corresponding to the two coordinate points and the impedance corresponding to the two coordinate points. And then determining the temperature corresponding to the frequency of the target intersection point according to a preset linear relation, wherein the temperature is the temperature in the battery. For example, the preset linear relationship is T ═ T0+k(f-f0) If the frequency f of the target intersection point is determined to be f1, the current battery internal temperature T is T0+k(f1-f0). In addition, in the working process of the battery, the target Nyquist curve of the battery can be determined according to a preset period, and then the temperature in the battery can be determined in time so as to improve the safety; the preset period may be set as required, and may be, for example, a time for determining the internal temperature of the battery, or a fixed time period, such as 5 minutes.
The method and the device can acquire the preset linear relation between the internal temperature and the frequency of the battery in advance, then determine the target Nyquist curve of the battery in the working process of the battery, and then determine the frequency corresponding to the target intersection point according to the target intersection point of the target Nyquist curve and a real axis; determining the temperature corresponding to the frequency corresponding to the target intersection point, namely the temperature inside the battery according to the preset linear relation; therefore, the temperature inside the battery can be directly determined according to the frequency corresponding to the intersection point of the target Nyquist curve and the real axis, and the accuracy of measuring the temperature inside the battery is improved.
In another embodiment of the present invention, the battery may be tested in advance when the internal temperature of the battery is in different states to determine the preset linear relationship.
Referring to fig. 3, a flow chart showing steps of another embodiment of the method for measuring the internal temperature of the battery according to the present invention is shown, and specifically, the method may include the following steps:
step 301, testing the battery when the inside of the battery is at different temperatures in advance, and determining the relationship between the temperature inside the battery and the frequency.
In the embodiment of the present invention, before the battery is in the working state, the battery may be tested in advance when the battery is at different temperatures, and the relationship between the internal temperature of the battery and the frequency is determined, that is, the preset linear relationship is determined, specifically, as follows:
and a substep S11 of respectively determining the test Nyquist curves corresponding to different temperatures.
The battery can be tested when the battery is at different temperatures, and after the battery is tested at each temperature, the test Nyquist curve corresponding to the temperature is determined, so that the test Nyquist curves corresponding to different temperatures are obtained. As shown in fig. 4, a schematic structural diagram of a test system for determining a preset linear relationship according to the present invention is shown, the test system includes a battery, an incubator for adjusting a temperature of the battery, wherein the adjusted temperature corresponds to a range of-40 degrees +60 degrees, and a test unit for determining the preset linear relationship, i.e., performing sub-step S1-step S3. When testing is carried out, the battery can be placed in the incubator, the testing module is connected with two ends of the battery, then the incubator is adjusted to the temperature to be tested, and after the battery is placed in the incubator for a long time, the temperature inside the battery can be basically consistent with the surface temperature of the battery; at the moment, the testing unit can be adopted to provide alternating current for the battery, measure the voltage drop of the two ends of the battery and calculate the internal impedance of the battery according to the current flowing through the battery and the voltage drop of the two ends of the battery; and determining the corresponding test Nyquist curve of the battery at the temperature. Therefore, the corresponding Nyquist curve for testing when the internal temperature of the battery is at various different temperatures is obtained according to the method. The method for specifically determining the test nyquist curve is similar to the method for subsequently determining the target nyquist curve, and the method for determining the target nyquist curve is explained in detail subsequently.
And a substep S12, respectively determining the test intersection point of each test Nyquist curve and the real axis, and determining the frequency of the test intersection point, wherein the frequency of the test intersection point corresponds to the temperature.
And a substep S13, determining the relation between the battery temperature and the frequency according to the frequency of the test intersection and the temperature corresponding to the frequency of the test intersection.
Determining the test intersection point of the Nyquist curve and the real axis and the frequency of each test intersection point for each test Nyquist curve; in the embodiment of the invention, each temperature corresponds to one test nyquist curve, so that the frequency of the test intersection point corresponds to the temperature. The frequency of the test intersection point is similar to the method for determining the frequency of the target intersection point, and the method for determining the target nyquist curve is explained in detail later. In the embodiment of the present invention, a plurality of sets of data can be obtained, where each set of data consists of temperature and a cutoff frequency corresponding to the temperature, for example: (f1, T1), (f2, T2), (f3, T3), (f4, T4), (f5, T5), (f6, T6). The frequency of the battery internal temperature and the test intersection point is in a linear relation, wherein one expression of the linear relation is T-T0+k(f-f0) Thus, the slope k can be calculated from any two sets of data. In another embodiment of the present invention, in order to reduce the error, a plurality of slope values may be calculated, and an average value of the plurality of slopes is determined as the slope k of the linear relationship correspondence expression. For example, k1 ═ T2-T1)/(f2-f1, k2 ═ T4-T3)/(f4-f3, and k2 ═ T6-T5)/(f6-f5 are calculated, and thus, k ═ k1+ k2+ k3)/3 can be obtained. The embodiment of the invention can take the environmental temperature corresponding to the environment where the battery is positioned as T0Testing the Nyquist curve at the environment temperatureThe intercept frequency of the line is determined as f0(ii) a The method for testing the internal temperature of the battery can be applied to a plurality of different scenes, and the corresponding environmental temperatures of the different application scenes can be different, so that the environmental temperature of the battery which can be possibly positioned can be determined, and then the incubator is adopted to simulate different environmental temperatures T0Determining the intercept frequency f corresponding to each environmental temperature0(ii) a Furthermore, expressions corresponding to the preset linear relations can be determined, and in practical application, the corresponding preset linear relations can be determined according to application scenes. For example, when the method for measuring the internal temperature of the battery is applied to a new energy automobile, the environmental temperature can be divided into 3 types: t10＝0、T2020, and T3032; the corresponding intercept frequencies are f1 respectively0、f20、f30If the current season is winter, the corresponding expression of the corresponding preset linear relation is as follows: T-T10+k(f-f10) If the device is in spring or autumn, the expression corresponding to the preset linear relationship is as follows: T-T20+k(f-f20) If the summer season is in summer, the corresponding expression of the corresponding preset linear relation is as follows: T-T30+k(f-f30)。
Step 302, in the working process of the battery, the target Nyquist curve is determined.
In the embodiment of the invention, the temperature in the battery can be measured in the working process of the battery so as to ensure the use safety. After the preset linear relation is obtained, the temperature in the battery can be determined according to the frequency of the target intersection point; therefore, in the working process of the battery, the target nyquist curve of the battery and the frequency of the target intersection point can be determined, and then the current internal temperature of the battery is determined according to the frequency of the target intersection point, which is specifically as follows:
and a substep S21 of inputting alternating currents with different frequencies to the battery in sequence and respectively obtaining battery voltages corresponding to the currents with different frequencies.
Alternating currents with different frequencies can be sequentially input into the battery, so that the alternating currents flow through the battery, wherein the frequency of the current can be configured according to requirements, and in order to obtain an accurate target Nyquist curve, the frequency range of the current can be 100mHz-10 kHz; the duration of the current at each frequency is the inverse of its frequency, e.g. 1Hz for 1 second. When the current of each frequency flows through the battery, the voltage drop at two ends of the battery within the duration time of the current of the frequency is recorded, and the voltage corresponding to the current of the frequency flowing through the battery can be obtained, wherein the current and the voltage are functions of the frequency.
And a substep S22 of calculating the impedance corresponding to each frequency according to the voltage and the current.
After the voltage corresponding to each frequency current is determined, according to the current and the voltage of each frequency, the impedance corresponding to the frequency can be determined, i.e. the ratio of the voltage to the current is determined, such as z (f) u (f)/i (f), i.e. the impedance is also a function of the frequency, wherein u (f) is the voltage, and i (f) is the current. After substituting the function expression corresponding to the voltage and the current into the calculation, the obtained specific expression of the impedance, namely the complex function expression of the impedance, can be written as: z (f) ═ a (f) + jb (f), where a (f) is the real part expression of impedance, b (f) is the imaginary part expression of impedance, and when the frequency is determined, the corresponding impedance can be uniquely determined accordingly, i.e. the real part of impedance corresponds to one value and the imaginary part of impedance corresponds to one value. Thus, for each frequency, a corresponding impedance may be determined, and thus the impedance for each frequency.
And a substep S23 of determining the target Nyquist curve according to the impedance corresponding to each frequency.
Therefore, impedance corresponding to a plurality of frequencies can be obtained, and a target Nyquist curve can be determined according to the value of an imaginary part and the value of a real part of the impedance corresponding to each frequency, wherein each frequency corresponds to one point on the target Nyquist curve.
After the target nyquist curve is determined, a target intersection point of the target nyquist curve and a real axis can be determined, and the frequency of the target intersection point is determined, specifically as follows:
and 303, determining a real part value of the impedance corresponding to the target intersection point, and determining two reference points meeting a preset condition according to the real part value.
And 305, determining the frequency corresponding to the target intersection point according to the frequency and the imaginary part value corresponding to each reference point.
In the embodiment of the present invention, each frequency corresponds to a point on the target nyquist curve, but in a few cases, a point of a certain frequency on the target nyquist curve is the target intersection point, and therefore, the frequency corresponding to the target intersection point needs to be calculated. The real part value of the impedance corresponding to the target intersection point on the target nyquist curve can be determined, and two reference points meeting a preset condition are determined according to the real part value of the impedance, wherein the preset condition is that the signs of the imaginary parts of the impedances of the two reference points are opposite, and the imaginary parts of the impedances of the two reference points are close to zero. Specifically, in order to select two reference points meeting the preset condition, two points a1 and B1 which are located on two sides of the target intersection point and have different imaginary part values of impedance may be selected; then, it can be determined that a1 corresponds to frequency fA1 and B1 corresponds to frequency fB 1; in order to select two points where the imaginary values of the two impedances are nearest to zero, a dichotomy may be continuously used to determine a point between the two selected points, and specifically, a frequency value fC1 may be calculated by dichotomy for fA1 and fB 1. Then, determining an impedance C1 corresponding to fC1 by inputting alternating current with the frequency of fC1 into the battery, and if the imaginary part of the impedance C1 is the same as the imaginary part of the impedance A1 in sign, determining a frequency by calculating fA1 and fC1 by using a dichotomy; if the signs of the impedance imaginary part coefficient of C1 and the impedance imaginary part coefficient of B1 are the same, determining a frequency by calculating fB1 and fC1 by adopting a dichotomy; and determining two points with the impedance imaginary part coefficient closest to zero according to the method, and determining the two points as reference points.
In the embodiment of the present invention, the length of the curve between the two reference points is very short, and the target intersection point is also located on the curve, and the following equation can be obtained according to the limit theorem and the definition of the derivative:
wherein, fm1 and fm2 are the frequencies of two reference points, respectively, B (fm1) and B (fm2) are the imaginary values of two reference point impedances, respectively, fm1 is the frequency of the target intersection point to be solved, and B (fm0) is the value of the imaginary part of the target intersection point impedance. Therefore, the frequency fm0 at which the target intersection is calculated:
and step 306, determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation.
After the frequency of the target intersection point is calculated, the temperature inside the battery can be determined according to the preset linear relation, namely the frequency of the target intersection point is substituted into an expression corresponding to the preset linear relation for calculation, and the temperature inside the battery is obtained.
The method includes the steps that the battery is tested when the interior of the battery is at different temperatures in advance, test Nyquist curves corresponding to the different temperatures are determined respectively, test intersection points of the test Nyquist curves and a real axis are determined respectively, and the frequency of the test intersection points is determined, wherein the frequency of the test intersection points corresponds to the temperature; determining the relation between the battery temperature and the frequency according to the frequency of the test intersection point and the temperature corresponding to the frequency of the test intersection point; and then in the battery working process, the internal temperature of the battery can be directly determined according to the preset linear relation, and the efficiency of determining the internal temperature of the battery is improved. The preset linear relation is the relation between the internal temperature of the battery and the frequency, so that the internal temperature of the battery can be directly determined according to the frequency of the intersection point of the target Nyquist curve and the real axis, the accuracy and precision of determining the internal temperature of the battery are improved, and the safety is improved.
It should be noted that, for simplicity of description, the method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the illustrated order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments of the present invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.
Referring to fig. 5, a block diagram of a structure of an embodiment of a device for measuring temperature inside a battery according to the present invention is shown, and specifically, the device may include the following modules: a curve determination module 501, a frequency determination module 502, and a temperature determination module 503, wherein,
a curve determining module 501, configured to determine a target nyquist curve of a battery during operation of the battery;
a frequency determining module 502, configured to determine a target intersection point of the target nyquist curve and the real axis, and determine a frequency of the target intersection point;
a temperature determining module 503, configured to determine the temperature inside the battery according to the frequency of the target intersection point and a preset linear relationship, where the preset linear relationship is a relationship between the temperature inside the battery and the frequency.
Referring to fig. 6, there is shown a block diagram of the structure of an embodiment of the apparatus for measuring the internal temperature of a battery according to the present invention;
in another embodiment of the present invention, the apparatus further includes a relationship determination module 504, which is used to test the battery in advance when the battery is at different temperatures, and determine the relationship between the internal temperature of the battery and the frequency.
Optionally, the relationship determining module 504 is specifically configured to determine the nyquist curves corresponding to different temperatures respectively; respectively determining test intersection points of each test Nyquist curve and a real axis, and determining the frequency of the test intersection points, wherein the frequency of the test intersection points corresponds to the temperature; and determining the relation between the battery temperature and the frequency according to the frequency of the test intersection point and the temperature corresponding to the frequency of the test intersection point.
Optionally, the curve determining module 501 is specifically configured to sequentially input alternating currents with different frequencies to the battery, and respectively obtain battery voltages corresponding to the currents with different frequencies; calculating impedance corresponding to each frequency according to the voltage and the current; determining the target Nyquist curve according to the impedance corresponding to each frequency; wherein the current, voltage and impedance are functions of frequency.
Optionally, the frequency determining module 502 is specifically configured to determine a real part value of the impedance corresponding to the target intersection point, and determine two reference points meeting a preset condition according to the real part value; determining the imaginary part values of the frequency and the impedance corresponding to each reference point; and determining the frequency corresponding to the target intersection point according to the frequency and the imaginary part value corresponding to each reference point.
The method and the device can acquire the preset linear relation between the internal temperature and the frequency of the battery in advance, then determine the target Nyquist curve of the battery in the working process of the battery, and then determine the frequency corresponding to the target intersection point according to the target intersection point of the target Nyquist curve and a real axis; determining the temperature corresponding to the frequency corresponding to the target intersection point, namely the temperature inside the battery according to the preset linear relation; therefore, the temperature inside the battery can be directly determined according to the frequency corresponding to the intersection point of the target Nyquist curve and the real axis, and the accuracy of measuring the temperature inside the battery is improved.
For the device embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
Referring to fig. 7, a block diagram of a temperature measurement system according to an embodiment of the present invention is shown, specifically as follows: the temperature measuring system includes a battery 71 and the above-described battery internal temperature measuring device 72, wherein the battery internal temperature measuring device 72 includes: a curve determination module 721, a frequency determination module 722, and a temperature determination module 723.
Optionally, the above battery internal temperature measuring device 72 further includes: a temperature determination module 724.
In one example of the present invention, the temperature measuring system may be applied to a new energy vehicle, wherein the battery 71 may be a battery of the new energy vehicle; one of the battery internal temperature measuring devices 72 may be provided for each battery of the new energy vehicle, or one of the battery internal temperature measuring devices 72 may be provided for a plurality of batteries of the new energy vehicle.
The method and the device can acquire the preset linear relation between the internal temperature and the frequency of the battery in advance, then determine the target Nyquist curve of the battery in the working process of the battery, and then determine the frequency corresponding to the target intersection point according to the target intersection point of the target Nyquist curve and a real axis; determining the temperature corresponding to the frequency corresponding to the target intersection point, namely the temperature inside the battery according to the preset linear relation; therefore, the temperature inside the battery can be directly determined according to the frequency corresponding to the intersection point of the target Nyquist curve and the real axis, and the accuracy of measuring the temperature inside the battery is improved. In addition, the embodiment of the invention does not need a temperature sensor, thereby saving the cost and saving the wiring space.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The method for measuring the internal temperature of the battery, the device for measuring the internal temperature of the battery and the system for measuring the internal temperature of the battery provided by the invention are described in detail, specific examples are applied in the description to explain the principle and the implementation mode of the invention, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (12)
1. A method for measuring a temperature inside a battery, comprising:
determining a target Nyquist curve of a battery in the working process of the battery;
determining a target intersection point of the target Nyquist curve and a real axis, and determining the frequency of the target intersection point, wherein the frequency of the target intersection point is determined according to the frequency and the impedance of two points which are positioned at two sides of the target intersection point and have different imaginary part values of impedance;
and determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency.
2. The method of claim 1, wherein the step of determining the frequency of the target intersection comprises:
determining a real part value of the impedance corresponding to the target intersection point, and determining two reference points which meet a preset condition and are positioned at two sides of the target intersection point according to the real part value, wherein the preset condition is that signs of imaginary part values of the impedance of the two reference points are opposite;
determining the imaginary part values of the frequency and the impedance corresponding to each reference point;
and determining the frequency corresponding to the target intersection point according to the frequency and the imaginary part value corresponding to each reference point.
3. The method of claim 1, wherein the step of determining a target nyquist curve includes:
sequentially inputting alternating currents with different frequencies to the battery, and respectively obtaining battery voltages corresponding to the currents with different frequencies;
calculating impedance corresponding to each frequency according to the voltage and the current;
determining the target Nyquist curve according to the impedance corresponding to each frequency;
wherein the current, voltage and impedance are functions of frequency.
4. The method of claim 1, further comprising:
the battery is tested in advance when the interior of the battery is at different temperatures, and the relationship between the internal temperature of the battery and the frequency is determined.
5. The method of claim 4, wherein the step of determining the battery internal temperature versus frequency comprises:
respectively determining test Nyquist curves corresponding to different temperatures;
respectively determining test intersection points of each test Nyquist curve and a real axis, and determining the frequency of the test intersection points, wherein the frequency of the test intersection points corresponds to the temperature;
and determining the relation between the battery temperature and the frequency according to the frequency of the test intersection point and the temperature corresponding to the frequency of the test intersection point.
6. A battery internal temperature measuring device, comprising:
the curve determining module is used for determining a target Nyquist curve of the battery in the working process of the battery;
the frequency determination module is used for determining a target intersection point of the target Nyquist curve and a real axis and determining the frequency of the target intersection point, wherein the frequency of the target intersection point is determined according to the frequency and the impedance of two points which are positioned at two sides of the target intersection point and have different imaginary part values of the impedance;
and the temperature determining module is used for determining the temperature inside the battery according to the frequency of the target intersection point and a preset linear relation, wherein the preset linear relation is the relation between the temperature inside the battery and the frequency.
7. The apparatus of claim 6,
the frequency determination module is specifically configured to determine a real part value of the impedance corresponding to the target intersection point, and determine two reference points that satisfy a preset condition and are located on two sides of the target intersection point according to the real part value; determining the imaginary part values of the frequency and the impedance corresponding to each reference point; and determining the frequency corresponding to the target intersection point according to the frequency and the imaginary part value corresponding to each reference point, wherein the preset condition is that the signs of the imaginary part values of the impedances of the two reference points are opposite.
8. The apparatus of claim 6,
the curve determining module is specifically used for sequentially inputting alternating currents with different frequencies to the battery and respectively acquiring battery voltages corresponding to the currents with different frequencies; calculating impedance corresponding to each frequency according to the voltage and the current; determining the target Nyquist curve according to the impedance corresponding to each frequency; wherein the current, voltage and impedance are functions of frequency.
9. The apparatus of claim 6, further comprising:
and the relation determining module is used for testing the battery when the inside of the battery is at different temperatures in advance and determining the relation between the temperature inside the battery and the frequency.
10. The apparatus of claim 9,
the relation determining module is specifically used for respectively determining the corresponding test Nyquist curves of different temperatures; respectively determining test intersection points of each test Nyquist curve and a real axis, and determining the frequency of the test intersection points, wherein the frequency of the test intersection points corresponds to the temperature; and determining the relation between the battery temperature and the frequency according to the frequency of the test intersection point and the temperature corresponding to the frequency of the test intersection point.
11. A temperature measurement system, comprising: a battery and a battery internal temperature measuring device as claimed in claims 6-10 above.
12. A readable storage medium, characterized in that the readable storage medium has stored thereon a battery internal temperature measurement program which, when executed by a processor, implements the steps of the battery internal temperature measurement program method according to any one of claims 1 to 5.
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