CN114019396A - Battery pack impedance detection method and device - Google Patents
Battery pack impedance detection method and device Download PDFInfo
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- CN114019396A CN114019396A CN202010692035.1A CN202010692035A CN114019396A CN 114019396 A CN114019396 A CN 114019396A CN 202010692035 A CN202010692035 A CN 202010692035A CN 114019396 A CN114019396 A CN 114019396A
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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
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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]
- G01R31/3644—Constructional arrangements
- G01R31/3648—Constructional arrangements comprising digital calculation means, e.g. for performing an algorithm
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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]
- G01R31/392—Determining battery ageing or deterioration, e.g. state of health
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Abstract
The embodiment of the application discloses a battery pack impedance detection method and device, and specifically relates to the step of injecting an alternating current signal into a negative electrode of a battery pack when the battery pack is in a static state, so that a voltage signal of each battery cell under the action of the alternating current signal is acquired. And determining a first resistance of the battery cell according to the injected alternating current signal and the voltage signal corresponding to the battery cell aiming at any battery cell. And when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the battery cell in the dynamic state, and determining the second resistance of the battery cell according to the dynamic voltage, the dynamic current and the static voltage. And then, filtering and fusing the first resistor and the second resistor, and obtaining the accurate resistance value of the battery cell through filtering iteration. Namely, the real-time performance is high when the battery pack is in a dynamic state; and when the device is static, the reliability is high. And carrying out filtering iteration on two calculation results obtained by calculation in two states at the same time, thereby obtaining an accurate electric core resistance value and providing accurate calculation data for calculating the residual quantity and the health degree of the battery.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a battery pack impedance detection method and device.
Background
With the development of new energy vehicles, the requirements on battery packs and battery management systems are higher and higher, and particularly the accuracy and safety of battery management are higher and higher. The existing scheme of the battery pack is realized in a mode that a plurality of strings of battery cells are connected in series to form the battery pack, and the inconsistency of the resistance of the battery cells inevitably exists. Moreover, as the service time is prolonged, the inconsistency is increased, and the deviation of the electric quantity and the health degree estimation of the battery pack is increased, so that the improper control strategy of the Battery Management System (BMS) is caused, and the service life of the battery pack is shortened or the estimation of the endurance mileage is inaccurate. Therefore, it is necessary to obtain the cell resistance so as to make an accurate estimation of the electric quantity and the health degree according to the cell resistance.
Disclosure of Invention
In view of this, embodiments of the present disclosure provide a method and an apparatus for detecting an impedance of a battery pack, so as to achieve more reasonable and effective processing of a network request.
In order to solve the above problem, the technical solution provided by the embodiment of the present application is as follows:
in a first aspect of an embodiment of the present application, a method for detecting impedance of a battery pack is provided, where the battery pack includes a plurality of battery cells, and the method includes:
inputting an alternating current signal to the battery pack when the battery pack is in a static state; the battery pack is in a static state, and the current of the battery pack is smaller than a first preset threshold value;
for any one of the battery cells, acquiring a voltage signal of the battery cell, and determining a first resistance of the battery cell according to the voltage signal and the alternating current signal;
when the battery pack is in a dynamic state, acquiring dynamic voltage and dynamic current of the battery core; the battery pack is in a dynamic state, and the current of the battery pack is greater than a second preset threshold value;
determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and a static voltage, wherein the static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state;
and performing filtering iteration on the first resistor and the second resistor until filtering convergence to obtain the resistance of the battery core.
In one possible implementation, the determining a first resistance according to the voltage signal and the ac signal includes:
determining a phase difference according to the voltage signal and the alternating current signal;
and determining a first resistance of the battery cell according to the modulus of the voltage signal and the phase difference.
In one possible implementation manner, the determining the second resistance of the battery cell according to the dynamic voltage, the dynamic current, and the static voltage includes:
subtracting the static voltage from the dynamic voltage to obtain a first voltage;
dividing the first voltage by the dynamic current to obtain a second resistance of the cell.
In one possible implementation manner, the battery pack includes at least two battery modules, each battery module includes a plurality of battery cells, and the method further includes:
when the alternating current signal is input into the battery pack, acquiring a voltage signal of any high-voltage connection point, and determining a third impedance according to the voltage signal and the alternating current signal; the high-voltage connecting points comprise one or more of connecting points among modules, connecting points among the modules and the high-voltage relay or connecting points among the high-voltage relay and the output terminal;
when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the high-voltage connection point;
determining a fourth impedance of the high voltage connection point from the dynamic voltage, the dynamic current, and a static voltage; the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in a static state;
and performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
In one possible implementation, the method further includes:
and when the resistance of any one high-voltage connection point is greater than a third preset threshold value, early warning is carried out.
In one possible implementation, the filtering iteration is performed using a complementary filter or a kalman filter.
In a second aspect of embodiments of the present application, there is provided a battery pack impedance detection apparatus, the apparatus including:
the input unit is used for inputting an alternating current signal to the battery pack when the battery pack is in a static state; the battery pack is in a static state, and the current of the battery pack is smaller than a first preset threshold value;
the first acquisition unit is used for acquiring a voltage signal of the battery cell aiming at any battery cell;
a first determination unit, configured to determine a first resistance of the battery cell according to the voltage signal and the alternating current signal;
the second acquisition unit is used for acquiring the dynamic voltage and the dynamic current of the battery cell when the battery pack is in a dynamic state; the battery pack is in a dynamic state, and the current of the battery pack is greater than a second preset threshold value;
a second determining unit, configured to determine a second resistance of the battery cell according to the dynamic voltage, the dynamic current, and a static voltage, where the static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state;
and the first iteration unit is used for carrying out filtering iteration on the first resistor and the second resistor until filtering convergence to obtain the resistor of the battery cell.
In a possible implementation manner, the first determining unit includes:
the first determining subunit is used for determining a phase difference according to the voltage signal and the alternating current signal;
and the second determining subunit is used for determining the first resistance of the battery cell according to the modulus of the voltage signal and the phase difference.
In a possible implementation manner, the second determining unit includes:
the first obtaining subunit is used for subtracting the static voltage from the dynamic voltage to obtain a first voltage;
and the second obtaining subunit is configured to divide the first voltage by the dynamic current to obtain a second resistance of the battery cell.
In a possible implementation manner, the battery pack includes at least two battery modules, each battery module includes a plurality of battery cells, and the apparatus further includes:
a third obtaining unit, configured to obtain a voltage signal of the high-voltage connection point for any one of the high-voltage connection points when the ac signal is input to the battery pack;
a third determining unit for determining a third impedance according to the voltage signal and the alternating current signal; the high-voltage connecting points comprise one or more of connecting points among modules, connecting points among the modules and the high-voltage relay or connecting points among the high-voltage relay and the output terminal;
the fourth acquisition unit is used for acquiring the dynamic voltage and the dynamic current of the high-voltage connection point when the battery pack is in a dynamic state;
a fourth determining unit, configured to determine a fourth impedance of the high-voltage connection point according to the dynamic voltage, the dynamic current, and the static voltage; the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in a static state;
and the second iteration unit is used for performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
In one possible implementation, the apparatus further includes:
and the early warning unit is used for early warning when the resistance of any one high-voltage connection point is greater than a third preset threshold value.
In one possible implementation, the filtering iteration is performed using a complementary filter or a kalman filter.
Therefore, the embodiment of the application has the following beneficial effects:
according to the embodiment of the application, firstly, when the battery pack is in a static state, the alternating current signal is injected into the negative electrode of the battery pack, so that the voltage signal of each battery cell under the action of the alternating current signal is obtained. And determining a first resistance of the battery cell according to the injected alternating current signal and the voltage signal corresponding to the battery cell aiming at any battery cell. And then, when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the battery cell in the dynamic state, and determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and the static voltage. And then, filtering and fusing the first resistor and the second resistor, and obtaining the accurate resistance value of the battery cell through filtering iteration. Namely, the real-time performance is high when the battery pack is in a dynamic state; and when the device is static, the reliability is high. And carrying out filtering iteration on two calculation results obtained by calculation in two states at the same time, thereby obtaining an accurate electric core resistance value and providing accurate calculation data for subsequent calculation of the residual quantity and the health degree of the battery.
Drawings
Fig. 1a is a schematic diagram of a battery pack according to an embodiment of the present disclosure;
fig. 1b is a schematic diagram of another battery pack structure provided in the embodiment of the present application;
fig. 2 is a flowchart of a method for detecting an impedance of a battery pack according to an embodiment of the present disclosure;
fig. 3 is a flowchart of another method for detecting impedance of a battery pack according to an embodiment of the present disclosure;
fig. 4 is a structural diagram of a battery pack impedance detection apparatus according to an embodiment of the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the drawings are described in detail below.
The inventors found in studies on conventional BMS products that the conventional BMS products did not calculate the internal cell resistance. In this case, the estimated battery pack life and the mileage deviation are large, which causes an inappropriate BMS control strategy.
In addition, the reliability of the high voltage copper tab connection within the battery pack gradually decreases with increasing life. The existing monitoring means only carries out monitoring and judgment according to a temperature sensor of a module lug, and protection is adopted when the temperature is over-temperature. However, this solution does not monitor the reliability of the high voltage connections inside the battery pack by a hundred percent, and when these unreliable connections fail and the BMS does not monitor them, the external output of the battery pack is likely to be abnormally interrupted, resulting in an accident of the vehicle in motion.
Based on this, the embodiment of the application provides a battery pack impedance detection method, when a battery pack is in different states, the resistances of an electric core in two different states are respectively obtained, and then the two resistances are subjected to filtering calculation, so that a relatively accurate resistance is obtained. Specifically, when the battery pack is in a static state, an alternating current signal is input to a negative electrode of the battery pack, and a voltage signal of the battery cell after the alternating current signal is injected is acquired. And determining a first resistance of the battery cell according to the voltage signal of the battery cell and the original alternating current signal. And then, when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of each battery cell in the state, and determining the second resistance of each battery cell according to the dynamic voltage, the dynamic current and the static voltage of each battery cell in a static state. And finally, performing filtering iteration on the first resistor and the second resistor until filtering convergence so as to obtain the resistance of the battery cell.
In addition, for the impedance of the high-voltage connection point of the battery pack, similarly, when the battery pack is in a static state and an alternating current signal is injected, a voltage signal of the high-voltage connection point at the moment is obtained, and a third impedance is determined according to the voltage signal and the alternating current signal. And when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the high-voltage connection point. And determining the fourth impedance of the high-voltage connecting point according to the dynamic voltage, the dynamic current and the static voltage of the high-voltage connecting point in a static state. And finally, performing filtering iteration on the third impedance and the fourth impedance until filtering convergence so as to obtain the impedance of the high-voltage connection point, and then performing early warning to realize safety monitoring when the impedance of the high-voltage connection point is greater than a threshold value.
For the convenience of understanding of the present application, referring to the schematic structure of the battery pack shown in fig. 1a, the battery pack may include a plurality of battery modules as shown in fig. 1 a. Wherein, R0 is the effective resistance between the battery cathode sampling point and the module 1, R1-Rk-1 is the effective resistance between the modules, and Rk is the effective resistance between the battery anode sampling point and the module k. Each battery module may include a plurality of cells, as shown in fig. 1b, where a cn sampling point is a negative sampling point of an nth cell, and a cn +1 sampling point is a positive sampling point of the nth cell.
In specific implementation, when the battery pack is in a static state, an alternating current signal is input to the negative electrode of the battery pack, and a voltage signal of a corresponding battery cell is acquired from each sampling point, so that the first resistance of each battery cell is determined according to the voltage signal and the alternating current signal. And when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the corresponding battery cell from each sampling point, and acquiring the second resistance of the battery cell according to the dynamic voltage and the dynamic current of the battery cell and the static voltage of the battery cell. And performing filtering iteration by using the first resistor and the second resistor, thereby obtaining the resistance of the battery cell.
It should be noted that, for each cell of the battery pack, the resistance value of the cell may be determined by using the above description.
Referring to fig. 2, which is a flowchart of a method for detecting impedance of a battery pack provided in an embodiment of the present application, where the battery pack includes a plurality of battery cells, as shown in fig. 2, the method may include:
s201: when the battery pack is in a static state, an alternating current signal is input into the battery pack.
In this embodiment, when the battery pack is in a static state, an ac signal is input to the battery pack, so that the ac signal is used to determine the resistance of the battery cell in the static state. The static state of the battery pack means that the current of the battery pack is smaller than a first preset threshold, and the first preset threshold can be set according to the actual application condition, for example, the first preset threshold is 5A.
In specific implementation, the current of the battery pack may be sampled first, and whether the sampled current is smaller than a first preset threshold is determined, if so, it is indicated that the battery pack is in a static state, and then an alternating current signal is injected into the battery pack.
S202: and acquiring a voltage signal of the battery cell aiming at any battery cell, and determining a first resistance of the battery cell according to the voltage signal and the alternating current signal.
After the alternating current signal is injected into the battery pack, the voltage signal of each battery cell is obtained, and the first resistance of each battery cell is determined according to the voltage signal of each battery cell and the injected alternating current signal.
In a specific implementation, the present embodiment provides a specific implementation of determining a first resistance, where the determining the first resistance according to the voltage signal and the ac signal includes: determining a phase difference according to the voltage signal and the alternating current signal; and determining a first resistance of the battery cell according to the modulus value of the voltage signal and the phase difference.
That is, a phase change of the ac signal across the cell is determined based on the input ac signal and the output voltage signal, and the first resistance of the cell is determined based on a modulus of the voltage signal and the phase change, e.g., with a phase difference of
If the modulus value corresponding to the voltage signal is | Z |, the first resistance of the cell is
In practical application, in order to reduce interference of other interference signals, after the voltage signal is acquired, fourier transform is performed, and then a signal component of a specific frequency (frequency of an alternating current signal) is extracted, so that the first resistance of the battery cell is calculated according to a modulus of the voltage signal of the specific frequency.
Specifically, as shown in fig. 1b, the first resistance of each cell may be obtained by calculation using formula (1):
wherein R iscnIs the first resistance of the nth cell,
is the effective value of the voltage at two ends of the cell n, and I is the current value of the injected AC signal
S203: and when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the battery core.
In this embodiment, when the battery pack is in a dynamic state, the dynamic voltage and the dynamic current of each battery cell in the state are acquired. The dynamic voltage may be a voltage of the battery pack during charging and discharging, and the dynamic current may be a current of the battery pack during charging and discharging. The battery pack is in a dynamic state, which means that the current of the battery pack is greater than a second preset threshold, and the second preset threshold may be determined according to an actual application condition, for example, the second preset threshold is 80A.
In practical application, the battery pack may be sampled first, and whether the sampled current is greater than a second preset threshold is determined, and if so, it is determined that the battery pack is in a dynamic state.
S204: and determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and the static voltage.
And after the dynamic voltage and the dynamic current of the battery cell in the dynamic state are obtained, determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and the voltage corresponding to the battery cell in the static state. The static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state.
In a possible implementation manner, a specific implementation manner is provided for determining the second resistance, where determining the second resistance of the battery cell according to the dynamic voltage, the dynamic current, and the static voltage includes: subtracting the static voltage from the dynamic voltage to obtain a first voltage; and dividing the first voltage by the dynamic current to obtain a second resistance of the cell. For example, the static voltage V of a certain cell in a static state0With a dynamic current I and a dynamic voltage V1Then, the resistance R of the cell is (V)1-V0) And I. Wherein, V0Is a step currentVoltage, V, occurring immediately before1I is the voltage at which the step current occurs and I is the step current.
S205: and performing filtering iteration on the first resistor and the second resistor until filtering convergence to obtain the resistance of the battery core.
After the first resistance and the second resistance which are respectively corresponding to the static state and the dynamic state of the battery cell are obtained, filtering iteration is carried out on the first resistance and the second resistance until the resistance of the battery cell is obtained after filtering convergence, so that the battery residual capacity and the battery health degree of the battery pack are estimated according to the resistance of each battery cell, and more accurate estimation of the endurance mileage is provided. In particular, filtering iterations may be performed using a complementary filter and a kalman filter. Namely, the first resistor and the second resistor are used as input parameters of the filter, and the covariance of the resistors obtained by the filter according to the estimation of the first resistor and the second resistor meets the preset condition.
As can be seen from the above description, in the present embodiment, first, when the battery pack is in a static state, an alternating current signal is injected into the negative electrode of the battery pack, so as to obtain a voltage signal of each battery cell under the action of the alternating current signal. And determining a first resistance of the battery cell according to the injected alternating current signal and the voltage signal corresponding to the battery cell aiming at any battery cell. And then, when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the battery cell in the dynamic state, and determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and the static voltage. And then, filtering and fusing the first resistor and the second resistor, and obtaining the accurate resistance value of the battery cell through filtering iteration. Namely, the real-time performance is high when the battery pack is in a dynamic state; and when the device is static, the reliability is high. And carrying out filtering iteration on two calculation results obtained by calculation in two states at the same time, thereby obtaining an accurate electric core resistance value and providing accurate calculation data for subsequent calculation of the residual quantity and the health degree of the battery.
Based on the method example, the impedance of the high-voltage connection point of the battery pack can be detected, so that after the impedance of the high-voltage connection point is obtained, early warning is carried out according to the impedance of the high-voltage connection point, and the purpose of safety monitoring is achieved. The detection of the impedance of the high voltage connection point will be explained below.
Referring to fig. 3, which is a flowchart of another method for detecting impedance of a battery pack provided in an embodiment of the present application, where the battery pack includes at least two battery modules, each battery module includes a plurality of battery cells, and the method may include:
s301: when an alternating current signal is input into the battery pack, a voltage signal of a high-voltage connection point is obtained for any high-voltage connection point, and a third impedance is determined according to the voltage signal and the alternating current signal.
The high-voltage connection point comprises one or more of an inter-module connection point, a connection point between the module and the high-voltage relay or a connection point between the high-voltage relay and the output terminal. The high voltage relay may include a main negative relay and a main positive relay, among others.
During specific implementation, when the high-voltage connection point is a connection point between the negative electrode of the first battery cell and the main negative relay, the third impedance is determined according to the voltage signal and the alternating current signal of the high-voltage connection point:
wherein R is0Is the impedance between the negative pole of the first cell and the voltage of the main negative relay,
the effective value of the voltage of the negative electrode of the first battery cell and the main negative relay is shown, and I is the current value of the alternating current signal.
When the high-voltage connection point is a connection point between two adjacent modules, wherein the third impedance is determined according to the voltage signal of the high-voltage connection point and the alternating current signal as follows:
wherein R isk-1Is a third impedance between the k-1 th battery module and the k-th battery module,
is the effective voltage value between the kth-1 battery module and the kth battery module, and I is the current value of the alternating current signal.
When the high-voltage connection point is the connection point between the main positive relay and the highest cell positive pole in the kth battery module, wherein, the third impedance is determined according to the voltage signal and the alternating current signal of the high-voltage connection point:
wherein R iskIs the third impedance between the main positive relay and the highest cell positive pole in the kth battery module,
the effective voltage value of the highest electric core anode in the main positive relay and the kth battery module is provided, and I is the current value of the alternating current signal.
In specific implementation, the impedance at the two ends of the main and negative relays can be determined according to the effective voltage values at the two ends of the main and negative relays and the current value of the alternating current signal; the impedance across the main positive relay can be determined by the effective value of the voltage across the main positive relay and the current value of the alternating current signal.
S302: and when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the high-voltage connection point.
S303: and determining the fourth impedance of the high-voltage connecting point according to the dynamic voltage, the dynamic current and the static voltage.
In particular implementations, R ═ V (V) can be used1-V0) And I. Wherein, V0The voltage immediately before the occurrence of the step current, i.e. the quiescent voltage, V1Is the voltage at which the step current occurs, i.e. the dynamic voltage, I is the step current. And the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in the static state.
S304: and performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
Specifically, filtering iterations may be performed using a complementary filter or kalman filter to obtain the impedance of the high voltage connection point, which may be seen in S205.
Based on the foregoing method embodiment, an embodiment of the present application provides a battery pack impedance detection apparatus, see fig. 4, which is a schematic structural diagram of the battery pack impedance detection apparatus provided in the embodiment of the present application, and the apparatus includes:
an input unit 401, configured to input an ac signal to the battery pack when the battery pack is in a static state; the battery pack is in a static state, and the current of the battery pack is smaller than a first preset threshold value;
a first obtaining unit 402, configured to obtain, for any one of the battery cells, a voltage signal of the battery cell;
a first determining unit 403, configured to determine a first resistance of the battery cell according to the voltage signal and the alternating current signal;
a second obtaining unit 404, configured to obtain a dynamic voltage and a dynamic current of the battery cell when the battery pack is in a dynamic state; the battery pack is in a dynamic state, and the current of the battery pack is greater than a second preset threshold value;
a second determining unit 405, configured to determine a second resistance of the battery cell according to the dynamic voltage, the dynamic current, and a static voltage, where the static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state;
a first iteration unit 406, configured to perform filtering iteration on the first resistance and the second resistance until filtering convergence obtains the resistance of the battery cell.
In a possible implementation manner, the first determining unit includes:
the first determining subunit is used for determining a phase difference according to the voltage signal and the alternating current signal;
and the second determining subunit is used for determining the first resistance of the battery cell according to the modulus of the voltage signal and the phase difference.
In a possible implementation manner, the second determining unit includes:
the first obtaining subunit is used for subtracting the static voltage from the dynamic voltage to obtain a first voltage;
and the second obtaining subunit is configured to divide the first voltage by the dynamic current to obtain a second resistance of the battery cell.
In a possible implementation manner, the battery pack includes at least two battery modules, each battery module includes a plurality of battery cells, and the apparatus further includes:
a third obtaining unit, configured to obtain a voltage signal of the high-voltage connection point for any one of the high-voltage connection points when the ac signal is input to the battery pack;
a third determining unit for determining a third impedance according to the voltage signal and the alternating current signal; the high-voltage connecting points comprise one or more of connecting points among modules, connecting points among the modules and the high-voltage relay or connecting points among the high-voltage relay and the output terminal;
the fourth acquisition unit is used for acquiring the dynamic voltage and the dynamic current of the high-voltage connection point when the battery pack is in a dynamic state;
a fourth determining unit, configured to determine a fourth impedance of the high-voltage connection point according to the dynamic voltage, the dynamic current, and the static voltage; the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in a static state;
and the second iteration unit is used for performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
In one possible implementation, the apparatus further includes:
and the early warning unit is used for early warning when the resistance of any one high-voltage connection point is greater than a third preset threshold value.
In one possible implementation, the filtering iteration is performed using a complementary filter or a kalman filter.
It should be noted that, implementation of each unit in this embodiment may refer to the above method embodiment, and this embodiment is not described herein again.
According to the above, when the battery pack is in a static state, the alternating current signal is injected into the negative electrode of the battery pack, so that the voltage signal of each battery cell under the action of the alternating current signal is acquired. And determining a first resistance of the battery cell according to the injected alternating current signal and the voltage signal corresponding to the battery cell aiming at any battery cell. And then, when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the battery cell in the dynamic state, and determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and the static voltage. And then, filtering and fusing the first resistor and the second resistor, and obtaining the accurate resistance value of the battery cell through filtering iteration. Namely, the real-time performance is high when the battery pack is in a dynamic state; and when the device is static, the reliability is high. And carrying out filtering iteration on two calculation results obtained by calculation in two states at the same time, thereby obtaining an accurate electric core resistance value and providing accurate calculation data for subsequent calculation of the residual quantity and the health degree of the battery.
It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the system or the device disclosed by the embodiment, the description is simple because the system or the device corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
It is further 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 apparatus 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 apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (12)
1. A method for detecting impedance of a battery pack, wherein the battery pack comprises a plurality of battery cells, the method comprising:
inputting an alternating current signal to the battery pack when the battery pack is in a static state; the battery pack is in a static state, and the current of the battery pack is smaller than a first preset threshold value;
for any one of the battery cells, acquiring a voltage signal of the battery cell, and determining a first resistance of the battery cell according to the voltage signal and the alternating current signal;
when the battery pack is in a dynamic state, acquiring dynamic voltage and dynamic current of the battery core; the battery pack is in a dynamic state, and the current of the battery pack is greater than a second preset threshold value;
determining a second resistance of the battery cell according to the dynamic voltage, the dynamic current and a static voltage, wherein the static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state;
and performing filtering iteration on the first resistor and the second resistor until filtering convergence to obtain the resistance of the battery core.
2. The method of claim 1, wherein determining a first resistance from the voltage signal and the ac signal comprises:
determining a phase difference according to the voltage signal and the alternating current signal;
and determining a first resistance of the battery cell according to the modulus of the voltage signal and the phase difference.
3. The method of claim 1, wherein determining the second resistance of the cell from the dynamic voltage, the dynamic current, and the static voltage comprises:
subtracting the static voltage from the dynamic voltage to obtain a first voltage;
dividing the first voltage by the dynamic current to obtain a second resistance of the cell.
4. The method of claim 1, wherein the battery pack comprises at least two battery modules, wherein the battery modules comprise a plurality of cells, and wherein the method further comprises:
when the alternating current signal is input into the battery pack, acquiring a voltage signal of any high-voltage connection point, and determining a third impedance according to the voltage signal and the alternating current signal; the high-voltage connecting points comprise one or more of connecting points among modules, connecting points among the modules and the high-voltage relay or connecting points among the high-voltage relay and the output terminal;
when the battery pack is in a dynamic state, acquiring the dynamic voltage and the dynamic current of the high-voltage connection point;
determining a fourth impedance of the high voltage connection point from the dynamic voltage, the dynamic current, and a static voltage; the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in a static state;
and performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
5. The method of claim 4, further comprising:
and when the resistance of any one high-voltage connection point is greater than a third preset threshold value, early warning is carried out.
6. The method according to any of claims 1-5, characterized in that the filtering iteration is performed with a complementary filter or Kalman filter.
7. A battery pack impedance detection apparatus, the apparatus comprising:
the input unit is used for inputting an alternating current signal to the battery pack when the battery pack is in a static state; the battery pack is in a static state, and the current of the battery pack is smaller than a first preset threshold value;
the first acquisition unit is used for acquiring a voltage signal of the battery cell aiming at any battery cell;
a first determination unit, configured to determine a first resistance of the battery cell according to the voltage signal and the alternating current signal;
the second acquisition unit is used for acquiring the dynamic voltage and the dynamic current of the battery cell when the battery pack is in a dynamic state; the battery pack is in a dynamic state, and the current of the battery pack is greater than a second preset threshold value;
a second determining unit, configured to determine a second resistance of the battery cell according to the dynamic voltage, the dynamic current, and a static voltage, where the static voltage is a voltage corresponding to the battery cell when the battery pack is in a static state;
and the first iteration unit is used for carrying out filtering iteration on the first resistor and the second resistor until filtering convergence to obtain the resistor of the battery cell.
8. The apparatus of claim 7, wherein the first determining unit comprises:
the first determining subunit is used for determining a phase difference according to the voltage signal and the alternating current signal;
and the second determining subunit is used for determining the first resistance of the battery cell according to the modulus of the voltage signal and the phase difference.
9. The apparatus of claim 7, wherein the second determining unit comprises:
the first obtaining subunit is used for subtracting the static voltage from the dynamic voltage to obtain a first voltage;
and the second obtaining subunit is configured to divide the first voltage by the dynamic current to obtain a second resistance of the battery cell.
10. The apparatus of claim 7, wherein the battery pack comprises at least two battery modules, each battery module comprising a plurality of cells, and the apparatus further comprises:
a third obtaining unit, configured to obtain a voltage signal of the high-voltage connection point for any one of the high-voltage connection points when the ac signal is input to the battery pack;
a third determining unit for determining a third impedance according to the voltage signal and the alternating current signal; the high-voltage connecting points comprise one or more of connecting points among modules, connecting points among the modules and the high-voltage relay or connecting points among the high-voltage relay and the output terminal;
the fourth acquisition unit is used for acquiring the dynamic voltage and the dynamic current of the high-voltage connection point when the battery pack is in a dynamic state;
a fourth determining unit, configured to determine a fourth impedance of the high-voltage connection point according to the dynamic voltage, the dynamic current, and the static voltage; the static voltage is the voltage corresponding to the high-voltage connecting point when the battery pack is in a static state;
and the second iteration unit is used for performing filtering iteration on the third impedance and the fourth impedance until filtering convergence to obtain the impedance of the high-voltage connecting point.
11. The apparatus of claim 10, further comprising:
and the early warning unit is used for early warning when the resistance of any one high-voltage connection point is greater than a third preset threshold value.
12. The apparatus according to any of claims 7-11, characterized in that the filtering iteration is performed with a complementary filter or a kalman filter.
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| CN202010692035.1A CN114019396A (en) | 2020-07-17 | 2020-07-17 | Battery pack impedance detection method and device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117805642A (en) * | 2024-02-29 | 2024-04-02 | 双一力(宁波)电池有限公司 | Voltage acquisition method and device for battery cell, processor and storage medium |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117805642A (en) * | 2024-02-29 | 2024-04-02 | 双一力(宁波)电池有限公司 | Voltage acquisition method and device for battery cell, processor and storage medium |
| CN117805642B (en) * | 2024-02-29 | 2024-05-28 | 双一力(宁波)电池有限公司 | Voltage acquisition method and device for battery cell, processor and storage medium |
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