Battery management system

Abstract

The invention discloses a battery management system, and the system comprises a signal processing module which is connected with a battery pack, and is used for changing the power or potential of an excitation signal when the impedance test is carried out on the battery pack, and applying the changed excitation signal to the battery pack. By adopting the battery management system, the excitation signal is loaded to the two ends of the battery pack to form alternating current disturbance to realize impedance test of the battery pack, and the excitation signal causes small battery voltage disturbance, so that the problem that the voltage of the battery pack is sharply increased is avoided, and the fault probability of the battery management system is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery management system technology, and in particular to a battery management system. Background Technology

[0002] In related technologies, the low-power excitation signal is coupled to the battery pack by using the characteristic of capacitors to block DC and pass AC. This requires designing capacitors with large capacitance values ​​and resistors to form a passive high-pass filter circuit to filter out DC signals. However, this increases the impedance of the entire circuit, causing the voltage of the excitation signal to increase sharply, which increases the probability of battery management system failure. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to provide a battery management system in which an excitation signal is applied to both ends of a battery pack to create an AC disturbance for impedance testing of the battery pack. The excitation signal causes minimal voltage disturbance in the battery, thereby avoiding a sharp increase in battery pack voltage and reducing the probability of battery management system failure.

[0004] To address the aforementioned problems, a first aspect of the present invention provides a battery management system, comprising: a signal processing module connected to a battery pack, configured to change the power or potential of an excitation signal when performing impedance testing on the battery pack, and to apply the changed excitation signal to the battery pack.

[0005] According to an embodiment of the battery management system of the present invention, when performing impedance testing on a battery pack, the power or potential of the excitation signal is changed by a signal processing module so that the excitation signal provided by the excitation signal source can be applied to both ends of the battery pack to form an AC disturbance, thereby enabling impedance testing of the battery pack through the excitation signal. Therefore, compared to the prior art method of coupling a low-power excitation signal to the battery pack using the DC-blocking and AC-passing characteristics of a capacitor, the battery management system of this application increases the power of the excitation signal through a signal processing module, so that the excitation signal provided by the excitation signal source can be applied to both ends of the battery pack to form an AC disturbance to achieve impedance testing of the battery pack. Since the excitation signal causes minimal disturbance to the battery voltage, a sharp increase in battery pack voltage is avoided, reducing the probability of battery management system failure.

[0006] In some embodiments, the signal processing module includes: a signal generation unit for generating an initial excitation signal; a digital-to-analog conversion unit, the first end of which is connected to the signal generation unit, for performing digital-to-analog conversion on the initial excitation signal to output a converted excitation signal; and a signal coupling unit, the first end of which is connected to the second end of the digital-to-analog conversion unit, the second end of which is connected to the battery pack, the signal coupling unit being used to change the potential of the excitation signal through transformer isolation and apply the changed excitation signal to the battery pack, or to change the power of the excitation signal by superimposing the battery pack voltage with the excitation signal and apply the changed excitation signal to the battery pack.

[0007] In some embodiments, the signal coupling unit includes: a first current conversion unit, a first terminal of which is connected to a second terminal of a digital-to-analog conversion unit, and the second terminal of which is grounded, for converting the excitation signal into a current signal; a transformer, a first terminal of which is connected to a third terminal of the first current conversion unit, a first terminal of which is connected to the battery pack, and the second terminals of both the primary and secondary sides of which are grounded, for changing the potential of the current signal and applying the changed current signal to the battery pack; a first signal suppression unit, a first terminal of which is connected to a third terminal of the primary side of the transformer, and the second terminal of which is grounded, for filtering the current signal; and a second signal suppression unit, a first terminal of which is connected to a third terminal of the secondary side of the transformer, and the second terminal of which is grounded, for filtering the changed current signal.

[0008] In some embodiments, the signal coupling unit includes: an addition unit, a first terminal of which is connected to a second terminal of the digital-to-analog converter, and a second terminal of which is connected to the battery pack, for adding the battery pack voltage and the excitation signal to output a superimposed excitation signal; and a second current conversion unit, a first terminal of which is connected to a third terminal of the addition unit, a second terminal of which is connected to the battery pack, and a third terminal of which is grounded, for converting the superimposed excitation signal into a current signal and applying the current signal to the battery pack.

[0009] In some embodiments, the system further includes: a battery signal processing module connected to the battery pack, the battery signal processing module being configured to generate a battery pack response signal under the action of the excitation signal; and a data processing module connected to the battery signal processing module, the data processing module being configured to determine the impedance information of the battery pack based on the battery pack response signal and the calibration resistor signal.

[0010] In some embodiments, the system further includes a storage module connected to the data processing module for storing calibration resistance signals and providing the calibration resistance signals to the data processing module when performing impedance testing on the battery pack.

[0011] In some embodiments, the battery pack is connected in series with a calibration resistor, and the battery management system further includes a resistance signal processing module, which is connected to the calibration resistor, the signal coupling unit, and the data processing module, for calculating the voltage difference across the calibration resistor and providing the voltage difference as the calibration resistor signal to the data processing module.

[0012] In some embodiments, the first end of the calibration resistor is connected to the second end of the signal coupling unit, and the second end of the calibration resistor is connected to the positive terminal of the battery pack; the resistor signal processing module includes: a first resistor, the first end of which is connected to the first end of the calibration resistor; a second resistor, the first end of which is connected to the second end of the calibration resistor and the battery pack; a first operational amplifier, the non-inverting input of which is connected to the second end of the first resistor, the inverting input of which is connected to the second end of the second resistor, and the output of which is connected to the data processing module; a third resistor, the first end of which is connected to the inverting input of which is connected to the first operational amplifier, and the second end of which is connected to the output of which is connected to the data processing module; and a fourth resistor, the first end of which is connected to the non-inverting input of which is connected to the first operational amplifier and the second end of the first resistor, and the second end of which is grounded.

[0013] In some embodiments, the first end of the calibration resistor is connected to the second end of the signal coupling unit, and the second end of the calibration resistor is connected to the positive terminal of the battery pack; the resistance signal processing module includes: a differential operation unit, the first end of which is connected to the first end of the calibration resistor, the second end of which is connected to the second end of the calibration resistor and the battery pack, and the third end of which is grounded, for calculating the voltage difference across the calibration resistor to use the voltage difference as the calibration resistor signal; and a first filtering unit, the first end of which is connected to the fourth end of the differential operation unit, the second end of which is grounded, and the third end of which is connected to the data processing module, for filtering the calibration resistor signal and providing it to the data processing module.

[0014] In some embodiments, the data processing module includes: a resistance signal acquisition unit connected to the resistance signal processing module via a multiplexer, used to acquire the calibration resistance signal; a second filtering unit, a first terminal connected to the output terminal of the resistance signal acquisition unit, used to filter the signal output by the resistance signal acquisition unit; a battery signal acquisition unit connected to the battery pack via the multiplexer, used to acquire the battery pack response signal; and a calculation unit, a first terminal connected to the second terminal of the second filtering unit, a second terminal connected to the battery signal acquisition unit, a third terminal of the calculation unit used to receive the calibration resistance signal, and the calculation unit used to determine the impedance information of the battery pack based on the battery pack response signal and the calibration resistance signal.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a structural block diagram of a battery management system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a battery management system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a signal processing module according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a signal coupling unit according to an embodiment of the present invention; Figure 5This is a schematic diagram of a battery management system according to another embodiment of the present invention; Figure 6 This is a schematic diagram of a battery management system according to another embodiment of the present invention; Figure 7 This is a schematic diagram of a battery management system according to another embodiment of the present invention; Figure 8 This is a schematic diagram of the filtering effect of a filtering unit according to an embodiment of the present invention.

[0017] Figure label: Battery Management System 1000; Signal processing module 1; Battery signal processing module 2; Data processing module 3; Storage module 4; Resistance signal processing module 5; Digital logic memory 6; First communication module 7; Second communication module 8; Microcontroller unit 9; Power supply module 10; Signal generation unit 11; Digital-to-analog conversion unit 12; Signal coupling unit 13; Resistance signal acquisition unit 31; Second filtering unit 32; Battery signal acquisition unit 33; Arithmetic unit 34; Multiplexer 35; First current conversion unit 131; Transformer 132; First signal suppression unit 133; Second signal suppression unit 134; Addition unit 135; Second current conversion unit 136; Differential operation unit 51; First filtering unit 52; Equalization module 62; Digital logic memory 66; Third filtering unit 35; Fifth resistor R5; Sixth resistor R6; Seventh resistor R7; Eighth resistor R8; Ninth resistor R9; Tenth resistor R10; Eleventh resistor R11; Twelfth resistor R12; Thirteenth resistor R13; Fourteenth resistor R14; Fifteenth resistor R15; Sixteenth resistor R16; Seventeenth resistor R17; Eighteenth resistor R18; Nineteenth resistor R19; Twentieth resistor R20; Twenty-first resistor R21; Twenty-second resistor R22; Twenty-third resistor R23; Twenty-fourth resistor R24; Twenty-fifth resistor R25; Twenty-sixth resistor R26; Twenty-seventh resistor R27; Twenty-eighth resistor R28; Twenty-ninth resistor R29; Thirtieth resistor R30; Thirty-first resistor R31; First operational amplifier OP1; Second operational amplifier OP2; Third operational amplifier OP3; Fourth operational amplifier OP4; Fifth operational amplifier OP5; Sixth operational amplifier OP6; Seventh operational amplifier OP7; First capacitor C1; Second capacitor C2; Fourth capacitor C3; Battery pack V; Calibration resistor R CAL . Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0019] Currently, electrochemical impedance spectroscopy (EIS) is the mainstream dynamic internal resistance testing method for battery management systems. This involves applying a small-amplitude excitation signal, following a sinusoidal pattern, to the battery under stable DC polarization conditions, and studying the relationship between the electrochemical AC impedance and frequency. Because this method detects signals of known frequencies, it is highly resistant to interference. However, when performing impedance testing on lithium batteries, the battery system must be linear, with the input and output signals having the same frequency. But most battery systems are nonlinear. For ease of analysis, the amplitude of the input excitation signal must be sufficiently small; that is, the amplitude of the sinusoidal voltage must be less than the thermal voltage, typically not exceeding 25mV, to approximate a linear system. However, lithium battery impedance is in the mΩ range, resulting in low power AC excitation signals. Currently, the common practice to couple a low-power current signal to a high-voltage battery is to use capacitors for DC blocking.

[0020] DC blocking utilizes the "blocking DC and passing AC" characteristic of capacitors. Choosing a high-voltage DC blocking capacitor is the simplest approach. However, since a small AC current signal needs to excite the battery, and this signal has a very low frequency, while a DC voltage signal exists across the battery terminals, to ensure the current source signal is unaffected by the battery voltage (for example, a 10Hz AC current signal), a capacitor of at least 50F is required. Therefore, for very low frequency AC signals in the mHz range, even higher capacitance values ​​are needed, which does not meet practical design requirements. Using a passive high-pass filter circuit composed of a small capacitor and a large resistor not only fails to filter out the DC signal but also increases the impedance of the entire circuit, causing a sharp increase in the voltage at the AC signal source output, thus increasing the likelihood of battery management system malfunctions.

[0021] To address the aforementioned problems, a first aspect of the present invention provides a battery management system. This system uses an excitation signal applied to both ends of a battery pack to create an AC disturbance, thereby enabling impedance testing of the battery pack. The excitation signal causes minimal voltage fluctuation in the battery, thus avoiding a sharp increase in battery pack voltage and reducing the probability of battery management system malfunction.

[0022] Since the invention of battery packs, researchers have discovered that the internal resistance of the battery pack is a crucial parameter reflecting the performance of lithium batteries. However, due to factors such as the development of semiconductor technology and the complexity of internal battery parameters, breakthroughs in battery pack internal resistance monitoring, especially dynamic monitoring, have been slow. For the same type of power battery pack, its discharge capacity is inversely proportional to its internal resistance. In other words, by monitoring the internal resistance of the battery pack, the parameters of the charging and discharging system can be directly adjusted to achieve balanced battery power management. Furthermore, even for the same battery pack, its internal resistance variation curve changes with the activity of the chemical substances inside the battery. By monitoring these changes, the battery life and aging level can be accurately calculated, and the battery management system can promptly identify problematic individual cells, ensuring the overall safety of the system.

[0023] The following is for reference. Figure 1 The battery management system 1000 of this invention is described in the following embodiments: Figure 1 As shown, the battery management system 1000 includes: a signal processing module 1.

[0024] The signal processing module 1 is connected to the battery pack V and is used to change the power or potential of the excitation signal when performing impedance testing on the battery pack V, and apply the changed excitation signal to the battery pack V. The battery pack V can be a lithium battery pack or a sodium battery, without specific limitations.

[0025] Specifically, due to insufficient excitation signal power, the excitation signal provided by the excitation signal source cannot be applied to the two ends of the battery pack V, resulting in AC disturbance. Since the potential of the battery pack V is the same as the potential of the excitation signal, the excitation signal provided by the excitation signal source cannot be applied to the two ends of the battery pack V to form AC disturbance. To solve this problem, this application designs a signal processing module 1 to change the power or potential of the excitation signal when performing impedance testing on the battery pack V. Specifically, the signal processing module 1 increases the power of the excitation signal so that the excitation signal provided by the excitation signal source can be applied to the two ends of the battery pack V to form AC disturbance. This enables impedance testing of the battery pack V through the excitation signal, thus achieving active impedance testing. Furthermore, the excitation signal causes minimal disturbance to the battery voltage, preventing a sharp increase in the voltage of the battery pack V and reducing the probability of malfunction in the battery management system 1000.

[0026] According to an embodiment of the battery management system 1000 of the present invention, when performing impedance testing on a battery pack V, the signal processing module 1 changes the power or potential of the excitation signal so that the excitation signal provided by the excitation signal source can be applied to both ends of the battery pack V to form an AC disturbance, thereby enabling impedance testing of the battery pack V through the excitation signal. Therefore, compared to the prior art method of coupling a low-power excitation signal to the battery pack V through the DC blocking and AC passing characteristics of a capacitor, the battery management system 1000 of this application increases the power of the excitation signal through the signal processing module 1, so that the excitation signal provided by the excitation signal source can be applied to both ends of the battery pack V to form an AC disturbance to achieve impedance testing of the battery pack V. Since the excitation signal causes minimal disturbance to the battery voltage, the problem of a sharp increase in the battery pack V voltage is avoided, reducing the probability of battery management system 1000 malfunctioning.

[0027] In some embodiments, such as Figure 2 As shown, the signal processing module 1 includes: a signal generation unit 11, a digital-to-analog conversion unit 12, and a signal coupling unit 13.

[0028] The system includes a signal generation unit 11 for generating an initial excitation signal; a digital-to-analog converter 12 connected to the signal generation unit 11 for performing digital-to-analog conversion on the initial excitation signal to output the converted excitation signal; and a signal coupling unit 13 connected to the second end of the digital-to-analog converter 12 and the second end of the signal coupling unit 13 connected to the battery pack V. The signal coupling unit 13 is used to change the potential of the excitation signal through isolation by a transformer 132 and apply the changed excitation signal to the battery pack V, or to change the power of the excitation signal by superimposing the voltage of the battery pack V with the excitation signal and apply the changed excitation signal to the battery pack V. Therefore, when performing impedance testing on the battery pack V, the battery management system 1000 of this application changes the power or potential of the excitation signal through the signal processing module 1, so that the excitation signal provided by the excitation signal source can be loaded onto both ends of the battery pack V to form an AC disturbance, thereby enabling impedance testing of the battery pack V through the excitation signal.

[0029] In this embodiment, the signal generation unit 11 can be a DDS (Direct Digital Synthesis) signal generator, and the digital-to-analog conversion unit 12 can be a voltage-type analog-to-digital converter, capable of generating high-precision and easily controlled AC current signals.

[0030] In some embodiments, such as Figure 3 As shown, the signal coupling unit 13 includes: a first current conversion unit 131, a transformer 132, a first signal suppression unit 133, and a second signal suppression unit 134.

[0031] In this circuit, the first terminal of the first current conversion unit 131 is connected to the second terminal of the digital-to-analog conversion unit 12, and the second terminal of the first current conversion unit 131 is grounded, used to convert the excitation signal into a current signal; the first terminal of the primary side of the transformer 132 is connected to the third terminal of the first current conversion unit 131, such as... Figure 3 As shown, port 1 of transformer 132 is connected to the third terminal of the first current conversion unit 131, and the first terminal of the secondary side of transformer 132 is connected to the battery pack V, as follows. Figure 3 As shown, port 4 of transformer 132 is connected to battery pack V. The second terminal of the primary winding of transformer 132 and the second terminal of the secondary winding of transformer 132 are both grounded. Figure 3 As shown, ports 3 and 6 of transformer 132 are both grounded to change the potential of the current signal and apply the changed current signal to battery pack V. Transformer 132 is used to isolate the DC voltage and current signal across battery pack V. The conversion factor of transformer 132 is 1, and its output impedance should be high to meet the special low-frequency signal transmission requirements in impedance detection. The first terminal of the first signal suppression unit 133 is connected to the third terminal of the primary side of transformer 132, as shown below. Figure 3 As shown, port 2 of transformer 132 is connected to the first terminal of the first signal suppression unit 133, and the second terminal of the first signal suppression unit 133 is grounded for filtering the current signal; the first terminal of the second signal suppression unit 134 is connected to the third terminal of the secondary side of transformer 132, as shown. Figure 3 As shown, port 5 of transformer 132 is connected to the first end of the second signal suppression unit 134, and the second end of the second signal suppression unit 134 is grounded to filter the altered current signal.

[0032] Transformer 132 isolation refers to the transmission of alternating current of a signal to another circuit through the shared magnetic ring of transformer 132. In current coupling, the current excitation of the input circuit generates a magnetic field through the magnetic induction coil of transformer 132. This magnetic field is transmitted to the output circuit through magnetic coupling, thereby generating a current change in the output circuit and realizing signal transmission. Since the principle of transformer 132 is based on Faraday's law of electromagnetic induction, only an alternating magnetic field can induce voltage, therefore it can only be used for AC signals with higher frequencies above 1Hz.

[0033] Specifically, after receiving the converted excitation signal DAC_OUT from the digital-to-analog converter 12, the first current conversion unit 131 converts the excitation signal into a current signal and inputs the current signal to the transformer 132. The transformer 132 performs electromagnetic changes on the current signal to alter its potential, making the potential of the current signal different from the potentials on both sides of the battery pack V. Therefore, the current signal can be applied to both ends of the battery pack V. Thus, in this application, the electromagnetic changes of the current signal by the transformer 132 enable the application of a current signal to the battery pack V. The current signal is at the A level, but the battery impedance is at the milliohm and microohm level. Therefore, according to Ohm's law, the voltage disturbance caused by the current signal is very small, so there will be no problem of a sharp increase in the voltage of the battery pack V, reducing the probability of failure of the battery management system 1000. Moreover, the transformer 132 has a low cost, which can effectively reduce the impedance testing cost of the battery pack V.

[0034] In an embodiment, such as Figure 3As shown, the first current conversion unit 131 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second operational amplifier OP2, and a third operational amplifier OP3. The first terminal of the fifth resistor R5 is connected to the second terminal of the digital-to-analog converter 12, and the second terminal of the fifth resistor R5 is connected to the non-inverting input terminal of the second operational amplifier OP2. The first terminal of the sixth resistor R6 is grounded, and the second terminal of the sixth resistor R6 is connected to the inverting input terminal of the second operational amplifier OP2. The first terminal of the seventh resistor R7 is connected to the second terminal of the sixth resistor R6 and the inverting input terminal of the second operational amplifier OP2, and the second terminal of the seventh resistor R7 is connected to the output terminal of the second operational amplifier OP2. The first terminal of the eighth resistor R8 is connected to the non-inverting input terminal of the second operational amplifier OP2, and the second terminal of the eighth resistor R8 is connected to the output terminal and the inverting input terminal of the third operational amplifier OP3. The first terminal of the ninth resistor R9 is connected to the second terminal of the seventh resistor R7. The second terminal of the ninth resistor R9 is connected to the non-inverting input terminal of the third operational amplifier OP3 and the first terminal of the primary side of transformer 132. The first terminal of the tenth resistor R10 is connected to the first terminal of the ninth resistor R9. The second terminal of the tenth resistor R10 is connected to the second terminal of the ninth resistor R9. The first terminal of the eleventh resistor R11 is connected to the first terminal of the tenth resistor R10. The second terminal of the eleventh resistor R11 is connected to the second terminal of the tenth resistor R10. The first terminal of the twelfth resistor R12 is connected to the first terminal of the eleventh resistor R11. The second terminal of the twelfth resistor R12 is connected to the second terminal of the eleventh resistor R11. Among them, the eighth resistor R8 and the third operational amplifier OP3 form a follower circuit. The fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12 and the second operational amplifier OP2 form a non-inverting summation circuit. Because the current signal converted by the first current conversion unit 131 is too large, a single resistor cannot carry the large current signal. Therefore, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12 are connected in parallel, all acting as voltage divider resistors to carry the large current signal and share the power consumption caused by the large current signal. Thus, the first current conversion unit 131 fulfills the requirement that the excitation signal in the impedance detection process is in the form of a constant current source.

[0035] In an embodiment, such as Figure 3 As shown, the first signal suppression unit 133 includes a thirteenth resistor R13 and a first capacitor C1. The first terminal of the thirteenth resistor R13 is connected to the third terminal of the primary winding of the transformer 132, as shown. Figure 3As shown, port 2 of transformer 132 is connected to the first end of the thirteenth resistor R13, and the second end of the thirteenth resistor R13 is connected to the first end of the first capacitor C1. The second end of the first capacitor C1 is grounded. The thirteenth resistor R13 is a tapped resistor, and the first capacitor C1 is a tapped capacitor, used to filter the current signal to remove common-mode interference signals.

[0036] In an embodiment, such as Figure 3 As shown, the second signal suppression unit 134 includes a fourteenth resistor R14 and a second capacitor C2. The first terminal of the fourteenth resistor R14 is connected to the third terminal of the secondary side of the transformer 132, as shown. Figure 3 As shown, port 5 of transformer 132 is connected to the first end of the fourteenth resistor R14, the second end of the fourteenth resistor R14 is connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is grounded. The fourteenth resistor R14 is a tapped resistor, and the second capacitor C2 is a tapped capacitor, which are used to filter the current signal to filter out the common-mode interference signal in the modified current signal.

[0037] In some embodiments, such as Figure 4 As shown, the signal coupling unit 13 includes: an addition unit 135 and a second current conversion unit 136.

[0038] The first terminal of the addition unit 135 is connected to the second terminal of the digital-to-analog converter 12, and the second terminal of the addition unit 135 is connected to the battery pack V. It is used to perform addition operations on the voltage of the battery pack V and the excitation signal to output the superimposed excitation signal. The first terminal of the second current conversion unit 136 is connected to the third terminal of the addition unit 135, the second terminal of the second current conversion unit 136 is connected to the battery pack V, and the third terminal of the second current conversion unit 136 is grounded. It is used to convert the superimposed excitation signal into a current signal and apply the current signal to the battery pack V.

[0039] Specifically, when using a constant current signal as the excitation signal for the lithium battery, the amplitude should be maximized, but excessive amplitude will affect the linear relationship between the battery pack response signal and the excitation signal. When the amplitude of the sinusoidal voltage is less than the thermal voltage, the linearity of the impedance scanning imaging test can be guaranteed. Therefore, the amplitude of the excitation signal is controlled within 5% to 10% of the system operating current, and the voltage disturbance caused by the excitation signal is controlled below 25mV. Thus, the excitation signal power is much smaller than the DC voltage inherent in the battery pack V itself. Therefore, when applying an AC excitation signal to the battery pack V, it is necessary not only to prevent reverse current from flowing into the battery pack V and burning out the circuit chips, but also to consider how to couple the small current excitation signal to a high-power DC signal, and to ensure that the excitation signal applied to the battery pack V does not cause distortion in the subsequent measurement circuit. In this application, the addition unit 135 is connected to the battery pack V and the digital-to-analog converter 12. After receiving the converted excitation signal DAC_OUT from the digital-to-analog converter 12, the addition unit 135 calculates the battery pack V voltage and the excitation signal and performs an addition operation, that is, the addition unit 135 increases the power (amplitude) of the excitation signal. In other words, the superimposed excitation signal is output to the second current conversion unit 136. The second current conversion unit 136 performs current conversion on the sum of the battery pack V voltage and the excitation signal. Assuming the internal resistance of the battery pack is 50mΩ, if a voltage fluctuation of 5mV is caused across the battery pack, a 100mA AC excitation signal is required. Based on this 100mA AC signal, the excitation signal is increased by the current converted from the voltage across the battery terminals, forming an AC excitation signal with a certain DC bias, i.e., a current signal. This current signal is in the A-level range. However, the battery impedance is in the milliohm and microohm range; therefore, according to Ohm's law, the voltage disturbance caused by the current signal is very small, thus preventing a sharp increase in the battery pack voltage (V) and reducing the probability of battery management system 1000 malfunction. Consequently, the DC signal generated by the battery pack voltage (V) itself truly couples the excitation signal to both ends of the battery pack, enabling it to perform AC changes. During this process, an alternating process of cathode and anode occurs on the electrodes, with opposite effects. Even with prolonged operation, it does not lead to the cumulative development of polarization or cumulative changes in the electrode surface state; this is a quasi-steady-state method.

[0040] Therefore, this application increases the power of the excitation signal through the addition unit 135, so that the superimposed excitation current can be converted into a current signal and applied to the battery pack V, and there is no need to set up a transformer, which can effectively reduce costs.

[0041] In an embodiment, such as Figure 4As shown, the signal coupling unit 13 can also be composed of an adder unit 135 and a second current conversion unit 136. The adder unit 135 includes a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, and a fourth operational amplifier OP4. The first terminal of the fifteenth resistor R15 is connected to the second terminal of the digital-to-analog converter unit 12, and the second terminal of the fifteenth resistor R15 is connected to the non-inverting input terminal of the fourth operational amplifier OP4. The first terminal of the sixteenth resistor R16 is grounded, and the first terminal of the sixteenth resistor R16 is connected to the second terminal of the digital-to-analog converter unit 12. The first terminal of the seventeenth resistor R17 is connected to the second terminal of the sixteenth resistor R16 and the inverting input terminal of the fourth operational amplifier OP4. The second terminal of the seventeenth resistor R17 is connected to the output terminal of the fourth operational amplifier OP4. The first terminal of the eighteenth resistor R18 is connected to the non-inverting input terminal of the fourth operational amplifier OP4. The second terminal of the eighteenth resistor R18 is connected to the battery pack V. The first terminal of the nineteenth resistor R19 is connected to the first terminal of the eighteenth resistor R18. The second terminal of the nineteenth resistor R19 is grounded. The battery pack voltage and the excitation signal are input to the non-inverting input terminal of the fourth operational amplifier OP4. The battery pack voltage and the excitation signal are added together. The output terminal of the fourth operational amplifier OP4 outputs the superimposed excitation signal, thereby increasing the excitation power of the excitation signal.

[0042] In an embodiment, such as Figure 4As shown, the second current conversion unit 136 includes a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a fifth operational amplifier OP5, and a sixth operational amplifier OP6. The first terminal of the twentieth resistor R20 is connected to the second terminal of the seventeenth resistor R27 and the output terminal of the fourth operational amplifier OP4. The second terminal of the twentieth resistor R20 is connected to the non-inverting input terminal of the fifth operational amplifier OP5. The first terminal of the twenty-first resistor R21 is grounded, and the second terminal of the twenty-first resistor R21 is connected to the inverting input terminal of the fifth operational amplifier OP5. The first terminal of the twenty-second resistor R22 is connected to the second terminal of the twenty-first resistor R21 and the inverting input terminal of the fifth operational amplifier OP5. The second terminal of the twenty-second resistor R22 is connected to the output terminal of the fifth operational amplifier OP5. The first terminal of the twenty-third resistor R23 is connected to the second terminal of the twentieth resistor R20. The first terminal of the 24th resistor R24 ​​is connected to the second terminal of the 22nd resistor R22 and the output terminal of the 5th operational amplifier OP5. The second terminal of the 24th resistor R24 ​​is connected to the non-inverting input terminal of the 6th operational amplifier OP6. The non-inverting input terminal of the 6th operational amplifier OP6 is connected to the battery pack V. The first terminal of the 25th resistor R25 is connected to the first terminal of the 24th resistor R24. The first terminal of the 25th resistor R25 is connected to the second terminal of the 24th resistor R24. The first terminal of the 26th resistor R26 is connected to the first terminal of the 25th resistor R25. The first terminal of the 27th resistor R27 is connected to the first terminal of the 26th resistor R26. The first terminal of the 27th resistor R27 is connected to the second terminal of the 26th resistor R26. Based on this, the second current conversion unit 136 converts the superimposed excitation signal into a current signal and applies the current signal to the battery pack V.

[0043] In some embodiments, such as Figure 2 and Figure 5 As shown, the battery management system 1000 also includes a battery signal processing module 2 and a data processing module 3.

[0044] The battery signal processing module 2 is connected to the battery pack V and is used to acquire the battery pack response signal generated under the action of the excitation signal. The data processing module 3 is connected to the battery signal processing module 2 and is used to determine the impedance information of the battery pack V based on the battery pack response signal and the calibration resistor signal. The impedance information includes the impedance and phase of the battery pack V. In other words, the battery signal processing module 2 acquires the battery pack response signal generated by the battery pack V under the action of the excitation signal. The battery pack response signal is the real-time voltage of the battery pack V under the action of the excitation signal. The voltage change of the battery pack V is calculated by using the real-time voltage and the steady-state voltage of the battery pack V before the impedance test. The voltage change is UBAT. The module also acquires the calibration resistor signal, which is the real-time voltage across the calibration resistor under the action of the excitation signal. The voltage change of the calibration resistor is calculated by using the real-time voltage across the calibration resistor and the steady-state voltage of the calibration resistor. The impedance of the battery pack V can then be expressed as Z. BAT =RCAL×UBAT / URCAL, where RCAL is the resistance value of the calibration resistor. Therefore, in this application, the impedance of the battery pack V is calculated using the battery pack response signal and the calibration resistor signal.

[0045] In some embodiments, such as Figure 2 As shown, the battery management system 1000 also includes: storage module 4.

[0046] The storage module 4 is connected to the data processing module 3 and is used to store the calibration resistor signal. When performing impedance testing on the battery pack V, the storage module 4 provides the calibration resistor signal to the data processing module 3. The storage module 4 can be a register. Specifically, the storage module 4 stores the real-time voltage across the calibration resistor under the excitation signal (pre-tested by the tester) as the calibration resistor signal, and also stores the steady-state voltage of the calibration resistor. When calculating the impedance information of the battery pack V, the data processing module 3 can read the calibration resistor signal and the steady-state voltage of the calibration resistor. Alternatively, it can directly record the AC voltage change value generated by the calibration resistor under AC current signals of the same amplitude at different frequencies, which is the URCAL value, and record it in the storage module 4. Therefore, when testing the impedance of the battery pack V at a certain frequency, this application can directly extract the AC voltage change value or the calibration resistor signal from the storage module 4 to directly calculate the impedance, avoiding the influence of battery pack temperature on the accuracy of impedance calculation and improving the accuracy of impedance testing.

[0047] In some embodiments, such as Figure 6 As shown, the battery pack V is connected in series with a calibration resistor R. CAL ,like Figure 2 As shown, the battery management system 1000 also includes a resistor signal processing module 5.

[0048] Among them, the resistance signal processing module 5 and the calibration resistor R CAL The signal coupling unit 13 and data processing module 3 are connected to calculate the voltage difference across the calibration resistor and provide this voltage difference as a calibration resistor signal to the data processing module 3. The proportional measurement method is a variant of the Ohm's law. An external calibration resistor can provide a reference for battery impedance measurement, improving its accuracy. However, in commercially available proportional measurement methods, the calibration resistor and battery pack are scanned separately, doubling the measurement time. Especially since the battery impedance frequency measurement range is wide, doubling the time in the low-frequency range means that even if the state of the battery pack V changes drastically, it cannot be monitored in time, thus making it unsuitable for practical engineering needs. Therefore, the calibration resistor R... CAL When combined in series with the battery pack V, the impedance calculation is performed by testing and calibrating the resistance signal through the resistance signal processing module 5. Only one frequency sweep is required, and the minimum time delay and consistency of the current signal are guaranteed, thus improving the measurement accuracy.

[0049] In some embodiments, such as Figure 6 and Figure 7 As shown, the calibration resistor R CAL The first terminal is connected to the second terminal of the signal coupling unit 13, and the calibration resistor R CAL The second end is connected to the positive terminal of battery pack V; as shown Figure 7 As shown, the resistor signal processing module 5 includes: a first resistor R1, a second resistor R2, a first operational amplifier OP1, a third resistor R3, and a fourth resistor R4.

[0050] Wherein, the first terminal of the first resistor R1 is connected to the calibration resistor R CAL The first terminal is connected; the first terminal of the second resistor R2 is connected to the calibration resistor R. CAL The second terminal of the first operational amplifier OP1 is connected to the battery pack V; the non-inverting input terminal of the first operational amplifier OP1 is connected to the second terminal of the first resistor R1, the inverting input terminal of the first operational amplifier OP1 is connected to the second terminal of the second resistor R2, and the output terminal of the first operational amplifier OP1 is connected to the data processing module 3; the first terminal of the third resistor R3 is connected to the inverting input terminal of the first operational amplifier OP1, and the second terminal of the third resistor R3 is connected to the output terminal of the first operational amplifier OP1 and the data processing module 3; the first terminal of the fourth resistor R4 is connected to the non-inverting input terminal of the first operational amplifier OP1 and the second terminal of the first resistor R1, and the second terminal of the fourth resistor R4 is grounded.

[0051] Specifically, the first resistor R1, the second resistor R2, the first operational amplifier OP1, the third resistor R3, and the fourth resistor R4 form a differential proportional operational circuit. That is, the non-inverting input of the first operational amplifier OP1 is the high-voltage side voltage of the calibration resistor, the inverting input of the first operational amplifier OP1 is the low-voltage side voltage of the calibration resistor, and the output of the first operational amplifier OP1 outputs the voltage difference across the calibration resistor. This voltage difference is used as the calibration resistor signal RCAL_OUT, which is the real-time voltage across the calibration resistor under the action of the excitation signal.

[0052] Specifically, the battery management system 1000 in this application can calculate the impedance of the battery pack V by setting a calibration resistor; that is, the calibration resistor R... CAL The first terminal is connected to the second terminal of the signal coupling unit 13, and the calibration resistor R CAL The second terminal is connected to the positive terminal of the battery pack V. The superimposed excitation signal output by the signal coupling unit 13 can be applied to the calibration resistor. At the same time, the voltage difference calculated by the first operational amplifier OP1 of the resistor signal processing module 5 is used as the calibration resistor signal. Thus, the calibration resistor signal is the real-time voltage across the calibration resistor under the action of the excitation signal. Therefore, when designing the calibration resistor to calculate the impedance of the battery pack V, the calibration resistor signal is obtained through the resistor signal processing module 5, so that the impedance information of the battery pack V can be calculated through the calibration resistor signal. The resistor signal processing module 5 is also used to remove the DC bias of the calibration resistor caused by the voltage inherent in the battery pack V itself.

[0053] In some embodiments, such as Figure 6 and Figure 7 As shown, the calibration resistor R CAL The first terminal is connected to the second terminal of the signal coupling unit 13, and the calibration resistor R CAL The second end is connected to the positive terminal of battery pack V; as shown Figure 6 As shown, the resistor signal processing module 5 includes a differential operation unit 51 and a first filtering unit 52.

[0054] Among them, the first terminal of the differential operation unit 51 is connected to the calibration resistor R. CAL The first terminal is connected, and the second terminal of the differential operation unit 51 is connected to the calibration resistor R. CALThe second terminal of the differential operation unit 51 is connected to the battery pack V, and the third terminal of the differential operation unit 51 is grounded. This is used to calculate the voltage difference across the calibration resistor, which is then used as the calibration resistor signal. The first terminal of the first filter unit 52 is connected to the fourth terminal of the differential operation unit 51, the second terminal of the first filter unit 52 is grounded, and the third terminal of the first filter unit 52 is connected to the data processing module 3. This is used to filter the calibration resistor signal and provide it to the data processing module 3. The first filter unit 52 can be a passive high-pass filter circuit, such as... Figure 6 The diagram shows the designed passive high-pass filter circuit, with a cutoff frequency of 5MHz. Figure 8 The simulation results show the effect of the filter circuit.

[0055] Specifically, the battery management system 1000 in this application can calculate the impedance of the battery pack V by setting a calibration resistor; that is, the calibration resistor R... CAL The first terminal is connected to the second terminal of the signal coupling unit 13, and the calibration resistor R CAL The second terminal is connected to the positive terminal of the battery pack V. The superimposed excitation signal output by the signal coupling unit 13 can be applied to the calibration resistor. At the same time, the voltage difference calculated by the differential operation unit 51 is used as the calibration resistor signal. Thus, the calibration resistor signal is the real-time voltage across the calibration resistor under the action of the excitation signal. Due to the DC voltage across the lithium battery, the DC bias current generated by the second current conversion unit 136 will generate a DC bias voltage of about 2mV across the calibration resistor. Therefore, when acquiring the voltage signal across the calibration resistor, the calibration resistor signal needs to be filtered by the first filtering unit 52 to remove small DC components before outputting RCAL_OUT to the data processing module 3. Thus, when designing the calibration resistor to calculate the impedance of the battery pack V, the differential operation unit 51 obtains the calibration resistor signal, so that the impedance information of the battery pack V can be calculated using the calibration resistor signal.

[0056] In an embodiment, such as Figure 6 As shown, the differential operation unit 51 includes a twenty-eighth resistor R28, a twenty-ninth resistor R29, a thirtieth resistor R30, a thirty-first resistor R31, and a seventh operational amplifier OP7. The first terminal of the twenty-eighth resistor R28 is connected to the calibration resistor R... CAL The second terminal of the twenty-eighth resistor R28 is connected to the inverting input terminal of the seventh operational amplifier OP7, and the first terminal of the twenty-ninth resistor R29 is connected to the calibration resistor R. CALThe second terminal of the 29th resistor R29 is connected to the non-inverting input of the 7th operational amplifier OP7. The first terminal of the 30th resistor R30 is connected to the second terminal of the 28th resistor R28 and the inverting input of the 7th operational amplifier OP7. The second terminal of the 30th resistor R30 is connected to the output of the 7th operational amplifier OP7. The first terminal of the 31st resistor R31 is connected to the second terminal of the 29th resistor R29 and the non-inverting input of the 7th operational amplifier OP7. The second terminal of the 31st resistor R31 is grounded. Therefore, the non-inverting input of the 7th operational amplifier OP7 is the high-voltage side voltage of the calibration resistor, the inverting input of the 7th operational amplifier OP7 is the low-voltage side voltage of the calibration resistor, and the output of the 7th operational amplifier OP7 outputs the voltage difference across the calibration resistor. This voltage difference is used as the calibration resistor signal, which is the real-time voltage across the calibration resistor under the action of the excitation signal.

[0057] In an embodiment, such as Figure 6 As shown, the first filtering unit 52 includes a fourth capacitor C4 and a thirty-second resistor R32. The first terminal of the fourth capacitor C4 is connected to the second terminal of the thirty-first resistor R30 and the output terminal of the seventh operational amplifier OP7. The second terminal of the fourth capacitor C4 is connected to the first terminal of the thirty-second resistor R32 and the data processing module 3. The second terminal of the thirty-second resistor R32 is grounded. Based on this, the first filtering unit 52 filters the calibration resistor signal and provides it to the data processing module 3.

[0058] In some embodiments, such as Figure 2 and Figure 5 As shown, the data processing module 3 includes: a resistance signal acquisition unit 31, a second filtering unit 32, a multiplexer 35, a battery signal acquisition unit 33, and a processing unit 34.

[0059] The resistor signal acquisition unit 31 is connected to the resistor signal processing module 5 via a multiplexer 35 to acquire the calibration resistor signal. The multiplexer activates the corresponding detection function upon receiving an operation command, essentially acting as a selection switch. The first terminal of the second filtering unit 32 is connected to the output terminal of the resistor signal acquisition unit 31 to filter the signal output by the resistor signal acquisition unit 31. The battery signal acquisition unit 33 is connected to the battery pack V via a multiplexer 35 to acquire the battery pack response signal, which is obtained by removing the DC bias from the battery pack response signal by the battery signal processing module 2. The first terminal of the arithmetic unit 34 is connected to the second terminal of the second filtering unit 32, and the second terminal of the arithmetic unit 34 is connected to the battery signal acquisition unit 33. The third terminal of the arithmetic unit 34 receives the calibration resistor signal and determines the impedance information of the battery pack V based on the battery pack response signal and the calibration resistor signal. The arithmetic unit 34 can be an on-chip DFT (Discrete Fourier Transform) hardware accelerator. The battery signal acquisition unit 33 and the resistance signal acquisition unit 31 can be ADCs (Analog-to-digital converters). The ADCs can be successive approximation analog-to-digital converters to meet the requirements of high sampling rate and low latency.

[0060] Specifically, the resistance signal acquisition unit 31 is connected to the resistance signal processing module 5 through the multiplexer 35, so that the resistance signal unit can acquire the calibration resistance signal. The battery signal processing module 2 is connected to the battery pack V through the multiplexer 35, so that the battery signal processing module 2 can acquire the battery pack response signal. Thus, the calculation unit 34 can determine the impedance information of the battery pack V through the battery pack response signal and the calibration resistance signal. Furthermore, the resistance signal acquisition unit 31 and the battery signal acquisition unit 33 achieve simultaneous signal acquisition, meeting the requirements of high sampling rate and low latency.

[0061] In an embodiment, such as Figure 2 and Figure 5As shown, the battery management system 1000 also includes: an balancing module 62, a power supply module 10, a digital logic memory 66, a first communication module 7, a third filtering unit 35, a second communication module 8, and a microcontroller unit 9. The digital logic memory 66 can be a register; the first communication module 7 and the second communication module 8 can be SPI (Serial Peripheral Interface) communication modules; the balancing module 62 performs balancing management on the battery pack V; the power supply module 10 supplies power to the battery management system 1000; the digital logic memory 66 stores impedance information, which is then sent to the microcontroller unit 9 via the first communication module 7 and the second communication module 8. The third filtering unit 35 filters the battery pack response signal. The first communication module 7 interacts with the microcontroller unit 9 via wired communication.

[0062] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0063] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery management system, characterized in that, include: A signal processing module, connected to the battery pack, is used to change the power or potential of the excitation signal when performing impedance testing on the battery pack, and to apply the changed excitation signal to the battery pack.

2. The battery management system according to claim 1, characterized in that, The signal processing module includes: A signal generation unit is used to generate an initial excitation signal; A digital-to-analog converter unit, the first end of which is connected to the signal generation unit, is used to perform digital-to-analog conversion on the initial excitation signal to output the converted excitation signal; A signal coupling unit is provided, wherein a first end of the signal coupling unit is connected to a second end of the digital-to-analog converter, and a second end of the signal coupling unit is connected to the battery pack. The signal coupling unit is used to change the potential of the excitation signal by means of transformer isolation and apply the changed excitation signal to the battery pack, or to change the power of the excitation signal by superimposing the battery pack voltage with the excitation signal and apply the changed excitation signal to the battery pack.

3. The battery management system according to claim 2, characterized in that, The signal coupling unit includes: A first current conversion unit, wherein a first terminal of the first current conversion unit is connected to a second terminal of a digital-to-analog conversion unit, and the second terminal of the first current conversion unit is grounded, is used to convert the excitation signal into a current signal; A transformer, wherein the first end of the primary side of the transformer is connected to the third end of the first current conversion unit, the first end of the secondary side of the transformer is connected to the battery pack, and the second ends of both the primary and secondary sides of the transformer are grounded, for changing the potential of the current signal and applying the changed current signal to the battery pack; A first signal suppression unit, wherein a first terminal of the first signal suppression unit is connected to a third terminal of the primary side of the transformer, and a second terminal of the first signal suppression unit is grounded, is used to filter the current signal; The second signal suppression unit has its first end connected to the third end of the secondary side of the transformer, and its second end grounded, and is used to filter the altered current signal.

4. The battery management system according to claim 2, characterized in that, The signal coupling unit includes: An addition unit, wherein the first end of the addition unit is connected to the second end of the digital-to-analog converter unit, and the second end of the addition unit is connected to the battery pack, is used to perform an addition operation on the battery pack voltage and the excitation signal to output a superimposed excitation signal; The second current conversion unit has a first terminal connected to the third terminal of the addition unit, a second terminal connected to the battery pack, and a third terminal grounded. It is used to convert the superimposed excitation signal into a current signal and apply the current signal to the battery pack.

5. The battery management system according to any one of claims 2-4, characterized in that, Also includes: A battery signal processing module is connected to the battery pack and is used to generate a battery pack response signal under the action of the excitation signal. A data processing module, connected to a battery signal processing module, is used to determine the impedance information of the battery pack based on the battery pack response signal and the calibration resistor signal.

6. The battery management system according to claim 5, characterized in that, Also includes: A storage module, connected to the data processing module, is used to store calibration resistance signals and provide the calibration resistance signals to the data processing module when performing impedance testing on the battery pack.

7. The battery management system according to claim 5, characterized in that, The battery pack is connected in series with a calibration resistor, and the battery management system further includes: A resistance signal processing module, which is connected to the calibration resistor, the signal coupling unit, and the data processing module, is used to calculate the voltage difference across the calibration resistor and provide the voltage difference as the calibration resistor signal to the data processing module.

8. The battery management system according to claim 7, characterized in that, The first end of the calibration resistor is connected to the second end of the signal coupling unit, and the second end of the calibration resistor is connected to the positive terminal of the battery pack. The resistance signal processing module includes: A first resistor, wherein a first end of the first resistor is connected to a first end of the calibration resistor; The second resistor has its first end connected to the second end of the calibration resistor and the battery pack. A first operational amplifier, wherein the non-inverting input terminal of the first operational amplifier is connected to the second terminal of the first resistor, the inverting input terminal of the first operational amplifier is connected to the second terminal of the second resistor, and the output terminal of the first operational amplifier is connected to the data processing module. The third resistor has its first end connected to the inverting input terminal of the first operational amplifier, and its second end connected to the output terminal of the first operational amplifier and the data processing module. The fourth resistor has its first end connected to the non-inverting input of the first operational amplifier and the second end of the first resistor, and its second end grounded.

9. The battery management system according to claim 7, characterized in that, The first end of the calibration resistor is connected to the second end of the signal coupling unit, and the second end of the calibration resistor is connected to the positive terminal of the battery pack. The resistance signal processing module includes: A differential operation unit is provided, wherein a first terminal of the differential operation unit is connected to a first terminal of the calibration resistor, a second terminal of the differential operation unit is connected to a second terminal of the calibration resistor and the battery pack, and a third terminal of the differential operation unit is grounded. The differential operation unit is used to calculate the voltage difference across the calibration resistor and use the voltage difference as the calibration resistor signal. The first filtering unit has a first terminal connected to the fourth terminal of the differential operation unit, a second terminal grounded, and a third terminal connected to the data processing module. It is used to filter the calibration resistor signal and provide it to the data processing module.

10. The battery management system according to claim 7, characterized in that, The data processing module includes: A resistance signal acquisition unit is connected to the resistance signal processing module via a multiplexer to acquire the calibration resistance signal. The second filtering unit has its first end connected to the output end of the resistance signal acquisition unit, and is used to filter the signal output by the resistance signal acquisition unit. A battery signal acquisition unit, which is connected to the battery pack via a multiplexer, is used to acquire the response signal of the battery pack; The arithmetic unit has a first terminal connected to the second terminal of the second filtering unit, a second terminal connected to the battery signal acquisition unit, and a third terminal for receiving the calibration resistor signal. The arithmetic unit is used to determine the impedance information of the battery pack based on the battery pack response signal and the calibration resistor signal.

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