Detection circuit and method, communication device and method, battery balancing control method

Abstract

The present disclosure provides a battery voltage detection circuit for a series lithium battery system, including N single cells connected in series, wherein N≥1, and including: a multiplexing module connected to the N single cells connected in series, so as to receive the battery voltage signal of each single cell in the N single cells through the multiplexing module, and select the battery voltage signal of one single cell in the N single cells for output each time; a reference voltage generating unit for generating a variable reference voltage value; and a comparator for receiving the battery voltage signal output by the multiplexing module, and receiving the variable reference voltage value, and comparing the received battery voltage signal and the reference voltage value multiple times according to the variable reference voltage value to output a measured voltage of a single cell. The present disclosure also provides a communication device, a detection method, a communication method of a lithium battery system, and a battery balancing control method of a lithium battery system.

Description

Technical Field

[0001] The present disclosure relates to a battery voltage detection circuit of a series-connected lithium battery system, a communication device of the lithium battery system, a detection method of the battery voltage detection circuit of the series-connected lithium battery system, a communication method of the lithium battery system, and a battery balancing control method of the lithium battery system. Background Art

[0002] Lithium batteries have very high requirements for charging and discharging. When overcharging, over-discharging, overcurrent and short circuit occur, the internal pressure and heat of the lithium battery will increase greatly, which is easy to produce sparks, combustion and even explosion. Therefore, it is necessary to protect the lithium battery pack from overcharging and over-discharging.

[0003] In the pre-charging stage when the lithium battery voltage is low, a smaller charging current is required to protect the battery. Due to the inconsistency of each single battery, necessary balancing measures are required during charging to ensure its safety and stability.

[0004] The commonly used lithium battery pack balancing detection method is to compare the voltage of each single cell. If the voltage difference between the current single cell and any single cell exceeds the threshold, and the voltage of all single cells exceeds the balancing starting voltage, then the current battery needs to be balanced.

[0005] In this field, how to measure the voltage of a single cell is the key to accurately detecting whether battery balancing is required. Summary of the invention

[0006] In order to solve one of the above technical problems, the present disclosure provides a battery voltage detection circuit of a series lithium battery system, a communication device of a lithium battery system, a detection method of the battery voltage detection circuit of a series lithium battery system, a communication method of a lithium battery system, and a battery balancing control method of a lithium battery system.

[0007] According to one aspect of the present disclosure, a battery voltage detection circuit of a series lithium battery system, wherein the series lithium battery system includes N single batteries connected in series, wherein N ≥ 1, includes:

[0008] A multiplexing module, the multiplexing module is connected to the N single cells connected in series, so as to receive the battery voltage signal of each single cell in the N single cells through the multiplexing module, and select the battery voltage signal of one single cell in the N single cells for output each time;

[0009] a reference voltage generating unit, the reference voltage generating unit being configured to generate a varying reference voltage value; and

[0010] a comparator, the comparator being used to receive the battery voltage signal output by the multiplexing module and the changing reference voltage value, and to compare the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output the measured voltage of the single battery,

[0011] The reference voltage value changes within a preset range between the lowest equalization starting voltage and the highest battery voltage, and during the comparison process of the comparator, the reference voltage value changes for each comparison in the process of measuring the battery voltage of each single battery. The comparator compares the received battery voltage signal and the reference voltage value that changes each time to output the measured voltage of the battery voltage of each single battery.

[0012] According to at least one embodiment of the present disclosure, the change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range.

[0013] According to at least one embodiment of the present disclosure, N-2 reference voltage points are preset within a preset range, wherein N-2 is a natural number; the reference voltage values ​​decrease in sequence from the highest voltage, N-2 reference voltage points to the equilibrium starting voltage; or the reference voltage values ​​increase in sequence from the equilibrium starting voltage, N-2 reference voltage values ​​to the highest voltage.

[0014] According to at least one embodiment of the present disclosure, when the reference voltage value is one of the highest voltage, N-2 reference voltage points and the equalization starting voltage, the identification bit corresponding to the current reference voltage value is set to a first preset value; when the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to a second preset value.

[0015] According to at least one embodiment of the present disclosure, when the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as an identification bit corresponding to the current reference voltage value.

[0016] According to at least one embodiment of the present disclosure, the voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

[0017] According to at least one embodiment of the present disclosure, the reference voltage value is represented by M bits. When the reference voltage value changes, the highest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

[0018] According to at least one embodiment of the present disclosure, if the battery voltage signal is less than a first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on other bits.

[0019] According to at least one embodiment of the present disclosure, the reference voltage value is represented by M bits. When the reference voltage value changes, the lowest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the lowest bit remains unchanged.

[0020] According to at least one embodiment of the present disclosure, if the battery voltage signal is less than a first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0, then the previous bit of the lowest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the previous bit of the lowest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the previous bit of the lowest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on other bits.

[0021] According to at least one embodiment of the present disclosure, a first filter is further included, wherein for the same reference voltage value, the battery voltage signal output by the multiplexing module is collected at least twice, and the comparator compares the same reference voltage with the battery voltage signal output by the multiplexing module at least twice, respectively, to obtain at least two comparison results, and the at least two comparison results are input to the first filter, and the first filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal.

[0022] According to at least one embodiment of the present disclosure, the first filter is an FIR filter, and for the same reference voltage value, the battery voltage signal output by the four-time multiplexing module is collected, and the same reference voltage and the battery voltage signal output by the four-time multiplexing module are used to obtain four comparison results. The FIR filter multiplies the four comparison results by corresponding weights and then superimposes them, and outputs the superimposed signal.

[0023] According to at least one embodiment of the present disclosure, when the output of the first filter is within an unreliable range, the output of the first filter is taken as an unreliable measurement result.

[0024] According to at least one embodiment of the present disclosure, a second filter is further included, which receives the battery voltage of each single battery output by the first filter, corrects the battery voltage of each single battery, and uses the corrected battery voltage of each single battery as the final battery voltage of each single battery.

[0025] According to at least one embodiment of the present disclosure, a second filter is further included, which receives the battery voltage of each single battery output by the first filter, corrects the battery voltage of each single battery, and uses the corrected battery voltage of each single battery as the final battery voltage of each single battery.

[0026] According to at least one embodiment of the present disclosure, the second filter is a Kalman filter.

[0027] According to at least one embodiment of the present disclosure, when measuring the battery voltage signal of each single cell, each single cell is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter.

[0028] According to at least one embodiment of the present disclosure, after the battery voltages of all the single cells are obtained, the system minimum voltage value of the single cells in the series lithium battery system is obtained by comparing the battery voltages of the individual single cells.

[0029] According to at least one embodiment of the present disclosure, when the system minimum voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the system minimum voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

[0030] According to another aspect of the present disclosure, a communication device of a lithium battery system comprises: two or more battery voltage detection circuits according to any one of claims 1 to 19,

[0031] The lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects N single cells among the plurality of single cells connected in series, and obtains the lowest voltage value of the single cells among the N single cells based on the measured voltage output by each battery voltage detection circuit, and the lowest voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain the lowest voltage value of the system single cell of the lithium battery system.

[0032] According to another aspect of the present disclosure, a detection method of a battery voltage detection circuit of a series-connected lithium battery system, wherein the series-connected lithium battery system includes N single batteries connected in series, where N ≥ 1, includes:

[0033] A multiplexing module is connected to the N single cells connected in series, so that the battery voltage signal of each single cell in the N single cells is received through the multiplexing module, and the battery voltage signal of one single cell in the N single cells is selected for output each time; and

[0034] The comparator receives the battery voltage signal output by the multiplexing module and receives the changing reference voltage value, and compares the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output the measured voltage of the single battery.

[0035] The reference voltage value changes within a preset range between the lowest equalization starting voltage and the highest battery voltage, and during the comparison process of the comparator, the reference voltage value changes for each comparison in the process of measuring the battery voltage of each single battery. The comparator compares the received battery voltage signal and the reference voltage value that changes each time to output the measured voltage of the battery voltage of each single battery.

[0036] According to at least one embodiment of the present disclosure, the change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range.

[0037] According to at least one embodiment of the present disclosure, N-2 reference voltage points are preset within a preset range, wherein N-2 is a natural number; the reference voltage values ​​decrease in sequence from the highest voltage, N-2 reference voltage points to the equilibrium starting voltage; or the reference voltage values ​​increase in sequence from the equilibrium starting voltage, N-2 reference voltage values ​​to the highest voltage.

[0038] According to at least one embodiment of the present disclosure, when the reference voltage value is one of the highest voltage, N-2 reference voltage points and the equalization starting voltage, the identification bit corresponding to the current reference voltage value is set to a first preset value; when the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to a second preset value.

[0039] According to at least one embodiment of the present disclosure, when the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as an identification bit corresponding to the current reference voltage value.

[0040] According to at least one embodiment of the present disclosure, the voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

[0041] According to at least one embodiment of the present disclosure, the reference voltage value is represented by M bits. When the reference voltage value changes, the highest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

[0042] According to at least one embodiment of the present disclosure, if the battery voltage signal is less than a first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on other bits.

[0043] According to at least one embodiment of the present disclosure, the reference voltage value is represented by M bits. When the reference voltage value changes, the lowest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the lowest bit remains unchanged.

[0044] According to at least one embodiment of the present disclosure, if the battery voltage signal is less than a first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0, then the previous bit of the lowest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the previous bit of the lowest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the previous bit of the lowest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on other bits.

[0045] According to at least one embodiment of the present disclosure, for the same reference voltage value, the battery voltage signal output by the multiplexing module is collected at least twice, and the comparator compares the same reference voltage and the battery voltage signal output by the multiplexing module at least twice, respectively, to obtain at least two comparison results, and the at least two comparison results are input to the first filter, and the first filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal.

[0046] According to at least one embodiment of the present disclosure, the first filter is an FIR filter, and for the same reference voltage value, the battery voltage signal output by the four-time multiplexing module is collected, and the same reference voltage and the battery voltage signal output by the four-time multiplexing module are used to obtain four comparison results. The FIR filter multiplies the four comparison results by corresponding weights and then superimposes them, and outputs the superimposed signal.

[0047] According to at least one embodiment of the present disclosure, when the output of the first filter is within an unreliable range, the output of the first filter is taken as an unreliable measurement result.

[0048] According to at least one embodiment of the present disclosure, the second filter receives the battery voltage of each single cell output by the first filter, corrects the battery voltage of each single cell, and uses the corrected battery voltage of each single cell as the final battery voltage of each single cell.

[0049] According to at least one embodiment of the present disclosure, the second filter receives the battery voltage of each single cell output by the first filter, corrects the battery voltage of each single cell, and uses the corrected battery voltage of each single cell as the final battery voltage of each single cell.

[0050] According to at least one embodiment of the present disclosure, the second filter is a Kalman filter.

[0051] According to at least one embodiment of the present disclosure, when measuring the battery voltage signal of each single cell, each single cell is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter.

[0052] According to at least one embodiment of the present disclosure, after the battery voltages of all the single cells are obtained, the lowest voltage value of the single cells in the series lithium battery system is obtained by comparing the battery voltages of the individual single cells.

[0053] According to at least one embodiment of the present disclosure, when the lowest voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the lowest voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

[0054] According to another aspect of the present disclosure, a communication method of a lithium battery system is provided, wherein the lithium battery system comprises two or more battery voltage detection circuits as described above.

[0055] The lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects N single cells among the plurality of single cells connected in series, and obtains the lowest voltage value of the single cells among the N single cells based on the measured voltage output by each battery voltage detection circuit, and the lowest voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain the system lowest voltage value of the single cells of the lithium battery system.

[0056] According to another aspect of the present disclosure, a battery balancing control method for a lithium battery system obtains the system minimum voltage value through the communication method as described above. When the system minimum voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the system minimum voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0058] Figure 1 A schematic diagram of a series lithium battery stacking system according to an embodiment of the present disclosure is shown.

[0059] Figure 2 A schematic diagram of a series lithium battery stacking system according to an embodiment of the present disclosure is shown.

[0060] Figure 3 A schematic diagram of a communication frame according to an embodiment of the present disclosure is shown.

[0061] Figure 4 A schematic diagram of a sampling method according to an embodiment of the present disclosure is shown.

[0062] Figure 5 A flow chart of a communication method for a series-connected lithium battery stack system according to an embodiment of the present disclosure is shown.

[0063] Figure 6 A schematic diagram of a battery voltage detection circuit of a series-connected lithium battery system according to an embodiment of the present disclosure is shown.

[0064] Figure 7 A schematic diagram of a FIR filter according to one embodiment of the present disclosure is shown.

[0065] Figure 8 A schematic diagram of a Kalman filter according to one embodiment of the present disclosure is shown.

[0066] Fig. 9 A flow chart of a detection method of a battery voltage detection circuit of a series lithium battery system according to an embodiment of the present disclosure is shown.

[0067] Fig.10 A schematic diagram showing minimum voltage transmission according to one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0068] The present disclosure is further described in detail below in conjunction with the accompanying drawings and implementations. It is understood that the specific implementations described herein are only used to explain the relevant content, rather than to limit the present disclosure. It should also be noted that, for ease of description, only the parts related to the present disclosure are shown in the accompanying drawings.

[0069] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present disclosure can be combined with each other. The technical solution of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0070] Unless otherwise specified, the exemplary embodiments / embodiments shown will be understood as providing exemplary features of various details of some ways in which the technical concept of the present disclosure can be implemented in practice. Therefore, unless otherwise specified, the features of the various embodiments / embodiments can be combined, separated, interchanged and / or rearranged without departing from the technical concept of the present disclosure.

[0071] The use of cross-hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise specified, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the described order. In addition, the same figure numbers represent the same components.

[0072] When a component is referred to as being "on" or "over," "connected to," or "coupled to" another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being "directly on," "directly connected to," or "directly coupled to" another component, there are no intervening components. For this purpose, the term "connected" may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0073] For descriptive purposes, the present disclosure may use spatially relative terms such as "under," "beneath," "under," "down," "over," "upper," "above," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, components described as "under" or "beneath" other components or features would subsequently be positioned "over" the other components or features. Thus, the exemplary term "under" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0074] The terms used here are for the purpose of describing specific embodiments, and are not intended to be restrictive. As used here, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, it is explained that there are stated features, integral bodies, steps, operations, parts, assemblies and / or their groups, but it is not excluded that there are or add one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups. It should also be noted that, as used here, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values ​​and / or the values ​​provided that will be recognized by those of ordinary skill in the art.

[0075] According to one aspect of the present disclosure, a communication device for a series lithium battery stack system is provided.

[0076] Figure 1 A communication device 10 for a series-connected lithium battery stack system according to one embodiment of the present disclosure is shown.

[0077] The series lithium battery stack system is composed of N-level series lithium battery units and the first-level lithium battery units in series, where N ≥ 1. Figure 1As shown, the series lithium battery stacking system includes a first-level lithium battery unit 201, a second-level lithium battery unit 202 in N-level series lithium battery units, ..., and an n-th level lithium battery unit 20n. The first-level lithium battery unit 201, the second-level lithium battery unit 202, ..., and the n-th level lithium battery unit 20n are sequentially connected in series to form a series lithium battery stacking system. The negative electrode of the battery in the first-level lithium battery unit 201 constitutes the negative terminal and is grounded, and the positive electrode of the battery in the n-th level lithium battery unit 20n constitutes the positive terminal and is the highest voltage VCC of the stacking system.

[0078] Each of the N-stage series-connected lithium battery cells may include one lithium battery or more than two lithium batteries. The first-stage lithium battery cell may include one lithium battery or more than two lithium batteries.

[0079] The positive and negative terminals of the series-connected lithium battery stack system can be connected to an external charger or an external load. When the external charger is connected, the series-connected lithium batteries can be charged by the external charger, thereby performing a charging operation. When the external load is connected, the series-connected lithium batteries can provide electrical energy to the external load, thereby performing a discharge operation.

[0080] The communication device may include: a master battery chip 101 and N-level slave battery chips 102 ˜ 10n , where N≥1.

[0081] The main battery chip 101 is used to obtain the status information of the first-level lithium battery unit 201. The status information may include event flags and the lowest voltage of the lithium battery unit.

[0082] The event flags may include flags of a charge protection state, a discharge protection state, and / or a pre-charge state.

[0083] The ports V+ and V- of the main battery chip 101 can be connected to the positive and negative electrodes of the first-level lithium battery unit 201, respectively. When the first-level lithium battery unit 201 is a single-cell battery, the main battery chip 101 can obtain the voltage of the single-cell battery. When the first-level lithium battery unit 201 is a plurality of batteries connected in series, the main battery chip 101 can obtain the voltage of the plurality of batteries connected in series.

[0084] The N-stage slave battery chips include a first-stage slave battery chip 102 to an N-th-stage slave battery chip 10 n .

[0085] The first-level slave battery chip 102 is used to obtain the status information of the second-level lithium battery unit 202. The status information may include event flags and the lowest voltage of the lithium battery unit.

[0086] The event flags may include flags of a charge protection state, a discharge protection state, and / or a pre-charge state.

[0087] The ports V+ and V- of the first-stage slave battery chip 102 can be respectively connected to the positive and negative electrodes of the second-stage lithium battery unit 202. When the second-stage lithium battery unit 202 is a single-cell battery, the first-stage slave battery chip 102 can obtain the voltage of the single-cell battery. When the second-stage lithium battery unit 202 is a plurality of batteries connected in series, the first-stage slave battery chip 102 can obtain the voltage of the plurality of batteries connected in series.

[0088] The Nth-stage slave battery chip 10n is used to obtain the status information of the Nth-stage lithium battery unit 20n, wherein the status information may include event flags and the lowest voltage of the lithium battery unit.

[0089] The event flags may include flags of a charge protection state, a discharge protection state, and / or a pre-charge state.

[0090] The ports V+ (which can be the highest voltage VCC of the stacking system) and V- of the N-th level slave battery chip 10n can be connected to the positive and negative electrodes of the N-th level lithium battery unit 20n, respectively. When the N-th level lithium battery unit 20n is a single battery, the N-th level slave battery chip 10n can obtain the voltage of the single battery. When the N-th level lithium battery unit 20n is a multi-cell battery connected in series, the N-th level slave battery chip 10n can obtain the voltage of the multi-cell battery connected in series.

[0091] According to the above description, it can be known that a level-one slave battery chip in the N-level slave battery chip is used to obtain the status information of the level-one lithium battery cell in the N-level series lithium battery cell. When each level of slave battery chip obtains the status information of each level of lithium battery cell, the upper level slave battery chip transmits the status information of the upper level lithium battery cell to the current level slave battery chip. After the current level slave battery chip processes the status information of the upper level lithium battery cell and the status information of the current level lithium battery cell, the processing result is provided to the next level slave battery chip. The next level slave battery chip repeats the above operation, and finally provides the comprehensive status information of the N-level series lithium battery cell to the main battery chip 101. The main battery chip 101 processes according to the received processing result and the status information of the first-level lithium battery cell 201 obtained to obtain the system status information of the N-level series lithium battery cell and the first-level lithium battery cell, so that according to the system status information, the main battery chip 101 controls the discharge switch 300 and the charging switch 400 to control the charging or discharging of the series lithium battery stack system.

[0092] The main battery chip 101 controls the on and off of the discharge switch 300 through the control signal DSG, and controls the on and off of the charge switch 400 through the control signal CHG. In the charging process, the charge switch 300 and the discharge switch 400 can be controlled to control the charging current, and similarly, in the discharging process, the charge switch 300 and the discharge switch 400 can be controlled to control the discharge current.

[0093] In summary, the current level slave battery chip among the N levels of slave battery chips receives status information from the previous level slave battery chip, and the current level slave battery chip processes the status information of the current level series-connected lithium battery cells obtained by the current level slave battery chip and the status information received from the previous level slave battery chip, and transmits the processing result of the current level slave battery chip to the next level slave battery chip, and the next level slave battery chip processes the status information of the next level series-connected lithium battery cells obtained by the next level slave battery chip and the processing result received from the current level slave battery chip, and obtains the processing result of the next level slave battery chip, until the processing results of all slave battery chips are transmitted to the main battery chip.

[0094] In the present disclosure, the transmission of information is realized through an uplink, for example, the N-th level slave battery chip transmits the status information of the N-th level lithium battery unit to the N-1-th level slave battery chip, the N-th level slave battery chip can send information through the uplink transmission port DTX, and the N-1-th level slave battery chip can receive information through the uplink receiving port DRX. The N-1-th level slave battery chip processes the status information of the N-th level lithium battery unit and the status information of the N-1-th level lithium battery unit, and sends the processing result to the uplink receiving port DRX of the N-2-th level slave battery chip through the uplink transmission port DTX of the N-1-th level slave battery chip, and repeats the operation until the master battery chip receives the information through the uplink receiving port DRX, and the master battery chip processes the received information and the status information of the first-level lithium battery unit 201, and finally obtains the status information of the series lithium battery stack system.

[0095] In addition, the main battery chip 101 is also used to detect the current passing through the stacking system. For example, a detection resistor 500 can be connected in series in the current path of the stacking system, and the main battery chip 101 obtains the voltage value across the detection resistor 500 through the detection ports SRP and SRN, and the current value flowing through can be obtained according to the voltage value. The slave battery chip is not used to detect the current, and the current detection is only performed through the main battery chip, which can significantly reduce the chip power consumption.

[0096] The main battery chip 101 can be used as a control factor of the charging switch 300 and the discharging switch 400 according to the detected current value.

[0097] like Figure 1 As shown, the charging switch 300 and the discharging switch 400 can be MOSFETs, and the two can be connected in series, for example, the drains of the two can be interconnected, and the sources of the two can be connected to both sides, and the control signal of the main battery chip 101 can control the gates of the two.

[0098] exist Figure 1 As shown in the figure, the charging switch 300 and the discharging switch 400 are connected to the low voltage side of the stacking system. Of course, those skilled in the art should understand that they can also be connected to the high voltage side, and the connection order of the chips can also be arranged from top right to bottom.

[0099] The specific processing method of the chip will be described below with respect to the uplink.

[0100] When the status information is an event flag, the event flag transmitted from the previous level slave battery chip of the N-level slave battery chip to the current level slave battery chip is bitwise ORed with the event flag obtained from the current level slave battery chip, and the result of the processing is transmitted to the next level slave battery chip or the main battery chip, or the current level slave battery chip transmits the event flag obtained from the current level slave battery chip to the next level slave battery chip or the main battery chip.

[0101] As an example, when there is a master battery chip and a slave battery chip, the event flag collected by the slave battery chip is transmitted to the master battery chip, and the master battery chip performs bitwise OR processing based on the event flag collected by itself and the event flag collected by the slave battery chip. For example, when the event flag of the slave battery chip is 1 and the event flag collected by the master battery chip is 1, the event flag finally determined by the master battery chip is 1; when the event flag of the slave battery chip is 0 and the event flag collected by the master battery chip is 1, the event flag finally determined by the master battery chip is 1; when the event flag of the slave battery chip is 1 and the event flag collected by the master battery chip is 0, the event flag finally determined by the master battery chip is 1; when the event flag of the slave battery chip is 0 and the event flag collected by the master battery chip is 0, the event flag finally determined by the master battery chip is 0. The master battery chip performs bitwise OR processing on the event flag transmitted from the slave battery chip to the master battery chip and the event flag obtained by the master battery chip as the event flag of the series lithium battery stacking system shown.

[0102] As another example, when there is one master battery chip and two slave battery chips, the event flag collected by the second-level slave battery chip is transmitted to the first-level slave battery chip, and the first-level slave battery chip performs bitwise OR processing based on the event flag collected by itself and the event flag collected by the second-level slave battery chip. For example, when the event flag of the second-level slave battery chip is 1, the event flag collected by the first-level slave battery chip is 1, then the event flag finally determined by the first-level slave battery chip is 1; when the event flag of the second-level slave battery chip is 0, the event flag collected by the first-level slave battery chip is 1, then the event flag finally determined by the first-level slave battery chip is 1; when the event flag of the second-level slave battery chip is 1, the event flag collected by the first-level slave battery chip is 0, then the event flag finally determined by the first-level slave battery chip is 1; when the event flag of the second-level slave battery chip is 0, the event flag collected by the first-level slave battery chip is 0, then the event flag finally determined by the first-level slave battery chip is 0.

[0103] The first-level slave battery chip transmits the final event flag to the master battery chip. The master battery chip performs bitwise OR processing based on the event flag collected by itself and the event flag of the first-level slave battery chip. For example, when the event flag of the first-level slave battery chip is 1 and the event flag collected by the master battery chip is 1, the event flag finally determined by the master battery chip is 1; when the event flag of the first-level slave battery chip is 0 and the event flag collected by the master battery chip is 1, the event flag finally determined by the master battery chip is 1; when the event flag of the first-level slave battery chip is 1 and the event flag collected by the master battery chip is 0, the event flag finally determined by the master battery chip is 1; when the event flag of the first-level slave battery chip is 0 and the event flag collected by the master battery chip is 0, the event flag finally determined by the master battery chip is 0. The master battery chip performs bitwise OR processing on the event flag transmitted to the master battery chip by the first-level slave battery chip and the event flag obtained by the master battery chip, and the result is used as the event flag of the series lithium battery stacking system shown. The main battery chip can control the charging switch 300 and the discharging switch 400 according to the final processing result to control the charging and discharging current.

[0104] When the status information is the minimum voltage of the lithium battery cell, the minimum value of the lithium battery cell minimum voltage transmitted from the battery chip of the previous level N slave battery chip to the current level slave battery chip and the minimum value of the lithium battery cell minimum voltage obtained from the battery chip of the current level is transmitted to the next level slave battery chip or the main battery chip, or the lithium battery cell minimum voltage obtained from the battery chip of the current level is transmitted to the next level slave battery chip or the main battery chip.

[0105] The main battery chip uses the minimum value of the lithium battery cell minimum voltage transmitted from the battery chip to the main battery chip and the lithium battery cell minimum voltage obtained by the main battery chip as the lithium battery cell minimum voltage of the series lithium battery stack system.

[0106] As an example, when there is a master battery chip and a slave battery chip, the lowest voltage of the lithium battery cell collected by the slave battery chip is transmitted to the master battery chip, and the master battery chip processes the lowest voltage of the lithium battery cell collected by itself and the lowest voltage collected by the slave battery chip, and obtains the lowest voltage between the two. The master battery chip judges the lowest voltage after the lowest voltage transmitted from the slave battery chip to the master battery chip and the lowest voltage obtained by the master battery chip as the processing result, and regards it as the lowest voltage of the series lithium battery stack system.

[0107] As another example, when there is one master battery chip and two slave battery chips, the lowest voltage collected by the second-level slave battery chip is transmitted to the first-level slave battery chip, and the first-level slave battery chip processes the lowest voltage collected by itself and the lowest voltage collected by the second-level slave battery chip to obtain the lowest voltage.

[0108] The first-stage slave battery chip transmits the obtained minimum voltage to the master battery chip. The master battery chip processes the minimum voltage collected by itself and the minimum voltage of the first-stage slave battery chip to obtain a minimum voltage again. This minimum voltage is used as the minimum voltage of the series lithium battery stack system shown. The master battery chip can control the charging switch 300 and the discharging switch 400 according to the final processing result to control the charging and discharging current.

[0109] In the above description, the state information is taken as the lowest voltage of the lithium battery cell and the state information is taken as the event flag. However, in the present disclosure, the lowest voltage of the lithium battery cell and the event flag can be used as the state information at the same time, and the main battery chip can control the charging switch 300 and the discharging switch 400 according to the state information to control the charging and discharging current. In addition, as described above, the current information detected by the main battery chip can also be considered as a factor of switch control.

[0110] In addition, in the present disclosure, the master battery chip can transmit the status information of the series lithium battery stack system to the slave battery chip, so that the N-level slave battery chips can make a balancing judgment on the single battery corresponding to the current-level slave battery chip based on the received status information of the series lithium battery stack system.

[0111] After the master battery chip obtains the final status information, it can pass the final status information to each slave battery chip through the downlink. For example, the master battery chip 101 can send the final status information to the first-level slave battery chip 102 through the sending port UTX of the downlink, and the first-level slave battery chip 102 receives the final status information through the receiving port URX, and then the first-level slave battery chip 102 sends the final status information to the second-level slave battery chip through the sending port UTX,... until it is transmitted to the Nth-level slave battery chip 10n.

[0112] Each slave battery chip makes a balance judgment based on the received final status information and the status information of the battery cells at this level.

[0113] In the present disclosure, an uplink and a downlink are formed between the slave battery chip and the master battery chip, wherein the downlink is used to transmit the status information of the series-connected lithium battery unit from the slave battery chip to the master battery chip step by step, and the uplink is used to transmit the system status information of the series-connected lithium battery stack system from the master battery chip to the N-level slave battery chips step by step. Thus, a two-line duplex asynchronous communication system is formed between the master battery chip and the slave battery chip.

[0114] In addition, the N-level slave battery chips communicate with each other, and the N-level slave battery chips communicate with the master battery chip using a communication frame in a preset format, wherein the information transmitted by the communication frame in the preset format includes an event flag and the lowest voltage of the lithium battery unit.

[0115] Specifically, Figure 3 As shown, the communication frame includes synchronization signals B0-B4, frame content (Event Flag; Min.Voltage) and a parity bit P; the synchronization signal can be a binary number 11110, and of course other binary numbers can also be selected as the synchronization signal.

[0116] The communication frame content consists of two parts. The first part is the event flag, such as charging protection, discharging protection and pre-charging status; the second part is the minimum voltage of the lithium battery unit.

[0117] In a series lithium battery stack system, the uplink is used to collect the event flag and minimum voltage value of each slave battery chip.

[0118] If the current battery chip works in slave mode, the event flag transmitted to the next level battery chip is the bitwise OR of the event flag transmitted from the previous level and the event flag of this level, and the minimum voltage of the lithium battery cell transmitted to the next level is the minimum value of the minimum voltage of the lithium battery cell transmitted from the previous level and the minimum voltage of the lithium battery cell of this level.

[0119] If the current battery chip works in the main mode, the event flag of the communication frame content is the bitwise OR of the event flag transmitted from the previous level and the event flag of the main battery chip, and the minimum voltage of the lithium battery cell is the minimum value of the minimum voltage of the lithium battery cell transmitted from the previous level and the minimum voltage of the lithium battery cell of the main battery chip.

[0120] Preferably, when sending a communication frame, it can be accomplished by asynchronous communication using 64 local clocks.

[0121] Moreover, the receiving end counts the synchronization pulses using a local clock, and when the count value M is within a certain range, it is considered that the transmission has started.

[0122] When the communication frame starts to be transmitted, the communication frame is sampled every M / 4 clock cycles. In the present disclosure, the starting point of the window is M / 8-2, the ending point is M / 8+2, and there are 5 sampling points in total, for example Figure 4 shown.

[0123] Preferably, soft bits are used to sample the communication frames, that is, a high level is counted as +1, a low level is counted as -1, and the sum of the 5 sampling values ​​in the sampling window is distributed between [-5,5]. If the sum of the sampling values ​​is distributed between [-1,1], it is determined that the sampling is unreliable and the current reception fails. Otherwise, the sign bit of the sum of the sampling values ​​is the hard bit output.

[0124] In addition, since the slave battery chip does not need to collect the charge and discharge current, the ports SRP and SRN of the slave battery chip can be connected to VCC. In this way, the slave battery chip can be configured to work in the slave mode.

[0125] According to an embodiment of the present disclosure, a communication method using the above communication device is also provided.

[0126] Figure 5 FIG. 4 shows a flow chart of the communication method. Figure 5 As shown, the communication method 500 may include the following contents.

[0127] In step 502, N-level slave battery chips obtain status information of the series-connected lithium battery cells corresponding to each level of slave battery chips.

[0128] In step 504, the status information of the series-connected lithium battery cells transmitted from the previous-stage slave battery chip to the current-stage slave battery chip and the status information of the series-connected lithium battery cells obtained from the current-stage slave battery chip are processed.

[0129] In step 506, the processing result is transmitted to the next-level slave battery chip or the main battery chip; alternatively, the N-level slave battery chip transmits the status information of the series-connected lithium battery cells obtained by the current-level slave battery chip to the next-level slave battery chip or the main battery chip.

[0130] In step 508, the main battery chip is used to obtain status information of the first-level lithium battery cells corresponding to the main battery chip, and processes the status information of the series-connected lithium battery cells transmitted from the battery chip to the main battery chip and the status information of the first-level lithium battery cells acquired by the main battery chip, and uses the processing result as the system status information of the series-connected lithium battery stack system.

[0131] According to a further embodiment, when the status information is an event flag, the event flag transmitted from the previous level slave battery chip of the N-level slave battery chip to the current level slave battery chip is bitwise ORed with the event flag obtained from the current level slave battery chip, and the result of the processing is transmitted to the next level slave battery chip or the main battery chip, or the current level slave battery chip transmits the event flag obtained from the current level slave battery chip to the next level slave battery chip or the main battery chip.

[0132] The main battery chip performs a bitwise OR process on the event flag transmitted from the battery chip to the main battery chip and the event flag obtained by the main battery chip, and the result is used as the event flag of the series lithium battery stack system shown.

[0133] The event flags include a charge protection state, a discharge protection state and / or a pre-charge state.

[0134] According to a further embodiment, when the status information is the minimum voltage of the lithium battery cell, the minimum value of the lithium battery cell minimum voltage transmitted from the battery chip of the previous level of the N-level slave battery chip to the current level slave battery chip and the minimum value of the lithium battery cell minimum voltage obtained from the battery chip of the current level is transmitted to the next level slave battery chip or the main battery chip, or the lithium battery cell minimum voltage obtained from the battery chip of the current level is transmitted to the next level slave battery chip or the main battery chip.

[0135] The main battery chip uses the minimum value of the lithium battery cell minimum voltage transmitted from the battery chip to the main battery chip and the lithium battery cell minimum voltage obtained by the main battery chip as the lithium battery cell minimum voltage of the series lithium battery stack system.

[0136] The master battery chip transmits the status information of the series-connected lithium battery stack system to the slave battery chip, so that the N-level slave battery chips can make a balancing judgment on the single battery corresponding to the current-level slave battery chip according to the received status information of the series-connected lithium battery stack system.

[0137] Among them, an uplink and a downlink are formed between the N-level slave battery chips and the master battery chip, wherein the uplink is used to transmit the status information of the series-connected lithium battery units from the slave battery chip to the master battery chip step by step, and the downlink is used to transmit the system status information of the series-connected lithium battery stack system from the master battery chip to the N-level slave battery chips step by step.

[0138] When the current slave battery chip among the N slave battery chips is the slave battery chip farthest from the master battery chip, the status information of the series-connected lithium battery cells obtained by the current slave battery chip is transmitted to the next slave battery chip or the master battery chip.

[0139] The N-level slave battery chips communicate with each other, and the N-level slave battery chips communicate with the master battery chip using a communication frame in a preset format, wherein the preset format can be referred to the above description, which will not be repeated here.

[0140] The master battery chip receives the charge and discharge current information of the series-connected lithium battery stack system, while the N-level slave battery chips do not detect the charge and discharge current information.

[0141] According to a further embodiment of the present disclosure, a series lithium battery stacking system is also provided, comprising: the above-mentioned communication device for the series lithium battery stacking system; and series lithium battery cells, the communication system is used to monitor the status information of the series lithium battery cells, so as to accurately determine the pre-charging state and the equalization condition, etc.

[0142] How to obtain the minimum value among the minimum voltages of the lithium battery cells will be described in detail below.

[0143] Figure 6 A battery voltage detection circuit of a series-connected lithium battery system according to one embodiment of the present disclosure is shown.

[0144] like Figure 6 As shown, a battery voltage detection circuit 600 of a series-connected lithium battery system includes n single cells connected in series, wherein n≥1, and the n single cells connected in series correspond to lithium battery cells of each level (for example, any level of lithium battery cells from the first level to the Nth level). Figure 6 VC1 to VCn shown are the single cell voltages of n single cells respectively.

[0145] The battery voltage detection circuit 600 may include a multiplexing module 610 , a comparator 620 , and a reference voltage generating unit 630 .

[0146] The multiplexing module 610 is connected to n single cells connected in series, so as to receive the battery voltage signal VC1-VCn of each of the n single cells through the multiplexing module, and select the battery voltage signal of one single cell among the n single cells for output each time.

[0147] The comparator 620 is used to receive the battery voltage signal output by the multiplexing module 610 and the changing reference voltage value, and compare the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output a measured voltage of a single battery.

[0148] The reference voltage value changes within a preset range from the lowest equalization starting voltage to the highest battery voltage, and during the comparison process of the comparator 620, the reference voltage value changes for each comparison in the process of measuring the battery voltage of each single battery. The comparator 610 compares the received battery voltage signal and the reference voltage value that changes each time to output the measured voltage of the battery voltage of each single battery.

[0149] The change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range.

[0150] n-2 reference voltage points are preset within a preset range, where n-2 is a natural number; the reference voltage value decreases from the highest voltage, n-2 reference voltage points to the equilibrium starting voltage; or the reference voltage value increases from the equilibrium starting voltage, n-2 reference voltage values ​​to the highest voltage.

[0151] When the reference voltage value is one of the highest voltage, n-2 reference voltage points and the equalization starting voltage, the identification bit corresponding to the current reference voltage value is set to the first preset value; when the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to the second preset value.

[0152] When the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as the identification bit corresponding to the current reference voltage value.

[0153] The voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

[0154] The reference voltage value is represented by m bits. When the reference voltage value changes, the highest bit of the m bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

[0155] If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued for other bits.

[0156] The reference voltage value is represented by m bits. When the reference voltage value changes, the lowest bit of the m bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the lowest bit remains unchanged.

[0157] If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0, then the previous bit of the lowest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the previous bit of the lowest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the previous bit of the lowest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued for other bits.

[0158] The overvoltage protection comparator is reused to measure the voltage of a single battery. The reference voltage range of the comparator is from the lowest equilibrium starting voltage to the highest overvoltage, which is represented by N bits. At the beginning of the measurement, the highest bit of the reference voltage is set to 1 and the remaining bits are 0. If the comparator output is 0 (the battery voltage is less than the reference voltage), the highest bit of the reference voltage is cleared, otherwise it remains unchanged. Then the same operation is performed on the remaining N-1 bits. When the lowest bit measurement is completed, the voltage of the single battery is obtained.

[0159] According to a specific embodiment of the present disclosure, in the present disclosure, the range of the reference voltage is the equalization starting voltage V start To the maximum voltage V max, and when detecting the voltage of the single battery to be detected, the range of the reference voltage can be divided into N-1 segments, and the difference between adjacent reference voltages △V=(V max -V start ) / (N-1), where N-1 is a natural number.

[0160] Define an N-bit data structure, and correspond each bit in the N-bit data structure from high to low to the reference voltage from high to low one by one; that is, the zeroth bit from high to low in the data structure corresponds to the highest voltage, and the last bit (N-1th bit) from high to low in the data structure corresponds to the equalization start voltage; thus, the reference voltage corresponding to the i-th bit from high to low in the data structure is V max -△V*i, where i is 0,…,N-1.

[0161] When detecting the voltage of the single battery to be detected, the value of the bit in the data structure corresponding to the reference voltage is set to 1. When the battery voltage is less than the reference voltage, the value of the bit in the data structure is set to 0, otherwise the data at this position remains unchanged.

[0162] The reference voltage changes from high to low in sequence. When the reference voltage is the battery balancing voltage and the detection is completed, the voltage of the single battery can be obtained.

[0163] For example, the output of the multiplexing module is used as the positive terminal input of the comparator, and the reference voltage is used as the negative terminal input of the comparator; when the detection starts, the reference voltage is the highest voltage, and the zeroth bit from high to low in the N-bit data structure is set to 1, and the values ​​of the remaining bits are set to 0; if the comparator output is 0, it means that the battery voltage is less than the reference voltage, then the value of the bit of the N-bit data structure corresponding to the reference voltage is set to 0; and if the comparator output is 1, it means that the battery voltage is greater than the reference voltage, then the value of the bit remains unchanged.

[0164] Next, the reference voltage is reduced to V max -△V, set the first bit from high to low in the N-bit data structure to 1; if the comparator output is 0, it means that the battery voltage is less than the reference voltage, then the value of the bit of the N-bit data structure corresponding to the reference voltage is set to 0; and if the comparator output is 1, it means that the battery voltage is greater than the reference voltage, then keep the value of the bit unchanged.

[0165] This process is repeated until the reference voltage drops to the battery balancing voltage. At this time, the last bit in the N-bit data structure from high to low is set to 1. If the output of the comparator is 0, which means that the battery voltage is less than the reference voltage, the value of the bit of the N-bit data structure corresponding to the reference voltage is set to 0; and if the output of the comparator is 1, which means that the battery voltage is greater than the reference voltage, the value of the bit is kept unchanged.

[0166] According to an embodiment of the present disclosure, a battery voltage detection circuit of a series lithium battery system further includes a first filter 640, wherein for the same reference voltage value, the battery voltage signal output by the multiplexing module is collected at least twice, and the comparator compares the same reference voltage with the battery voltage signal output by the multiplexing module at least twice, respectively, to obtain at least two comparison results, and the at least two comparison results are input to the first filter, and the first filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal.

[0167] The first filter is an FIR filter, and for the same reference voltage value, the battery voltage signal output by the four-time multiplexing module is collected, and the same reference voltage and the battery voltage signal output by the four-time multiplexing module are used to obtain four comparison results. The FIR filter multiplies the four comparison results by corresponding weights and then superimposes them, and outputs the superimposed signal.

[0168] When the output of the first filter is within the unreliable range, the output of the first filter is taken as an unreliable measurement result.

[0169] Figure 7 A schematic diagram of a FIR filter according to one embodiment of the present disclosure is shown.

[0170] As shown in Figure 7, the same reference voltage is sampled four times in succession, and each sampling result is represented by a soft bit. That is, if the comparator outputs a high level, it is represented by 1, and if the output is a low level, it is represented by -1. After passing through an FIR filter with coefficients of 3, 2, 2, 1, the results are distributed in [-8, 8]. If the results are distributed in [-2, 2], then it can be considered that the measurement result is unreliable. Otherwise, the sign bit of the filter output is inverted as the hard bit of the comparator output.

[0171] According to an embodiment of the present disclosure, the battery voltage detection circuit of the series lithium battery system further includes a second filter 650, which receives the battery voltage of each single cell output by the first filter, corrects the battery voltage of each single cell, and uses the corrected battery voltage of each single cell as the final battery voltage of each single cell.

[0172] According to an embodiment of the present disclosure, the battery voltage detection circuit of the series lithium battery system further includes a second filter 650, which receives the battery voltage of each single cell output by the first filter, corrects the battery voltage of each single cell, and uses the corrected battery voltage of each single cell as the final battery voltage of each single cell.

[0173] like Figure 8 As shown, the second filter is a Kalman filter. When measuring the battery voltage signal of each single battery, each single battery is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter.

[0174] In one example, the obtained single cell voltage is filtered by a Kalman filter with a gain of 0.5 as the final battery voltage. In order to make the Kalman filter stabilize quickly, after the system is powered on, the voltage of each single cell is measured 16 times continuously, and the average value is taken as the initial state of the Kalman filter. In order to ensure the measurement accuracy, the charge and discharge switch can be turned off during this period.

[0175] After the battery voltages of all the single cells are obtained, the system minimum voltage value of the single cells in the series-connected lithium battery system is obtained by comparing the battery voltages of the single cells.

[0176] When the system minimum voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the system minimum voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

[0177] According to one embodiment of the present disclosure, a communication device of a lithium battery system includes: two or more battery voltage detection circuits as described above, the lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects n single cells among the plurality of single cells connected in series, and obtains a minimum voltage value of the single cell among the n single cells based on a measured voltage output by each battery voltage detection circuit, and the minimum voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain the minimum voltage value of the system single cell of the lithium battery system.

[0178] According to a further embodiment of the present disclosure, a detection method for a battery voltage detection circuit of a series lithium battery system is provided, wherein the series lithium battery system comprises n single batteries connected in series, wherein n ≥ 1, such as Fig. 9 As shown, the following steps may be included.

[0179] In step 902 , a multiplexing module is connected to n single cells connected in series, so as to receive a battery voltage signal of each of the n single cells through the multiplexing module, and select a battery voltage signal of one of the n single cells for output each time.

[0180] In step 904, the comparator receives the battery voltage signal output by the multiplexing module and receives the changing reference voltage value, and compares the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output a measured voltage of a single battery.

[0181] In step 906, the reference voltage value changes within a preset range between the lowest equalization starting voltage and the highest battery voltage, and during the comparison process of the comparator, the reference voltage value changes for each comparison in the process of measuring the battery voltage of each single cell. The comparator compares the received battery voltage signal and the reference voltage value that changes each time to output the measured voltage of the battery voltage of each single cell.

[0182] The change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range.

[0183] n-2 reference voltage points are preset within a preset range, where n-2 is a natural number; the reference voltage value decreases from the highest voltage, n-2 reference voltage points to the equilibrium starting voltage; or the reference voltage value increases from the equilibrium starting voltage, n-2 reference voltage values ​​to the highest voltage.

[0184] When the reference voltage value is one of the highest voltage, n-2 reference voltage points and the equalization starting voltage, the identification bit corresponding to the current reference voltage value is set to the first preset value; when the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to the second preset value.

[0185] When the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as the identification bit corresponding to the current reference voltage value.

[0186] The voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

[0187] The reference voltage value is represented by m bits. When the reference voltage value changes, the highest bit of the m bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

[0188] If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued for other bits.

[0189] The reference voltage value is represented by m bits. When the reference voltage value changes, the lowest bit of the m bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the lowest bit remains unchanged.

[0190] If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0, then the previous bit of the lowest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the previous bit of the lowest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the previous bit of the lowest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued for other bits.

[0191] For the same reference voltage value, the battery voltage signal output by the multiplexing module is collected at least twice, and the comparator compares the same reference voltage with the battery voltage signal output by the multiplexing module at least twice, respectively, to obtain at least two comparison results, and the at least two comparison results are input to the first filter, and the first filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal.

[0192] The first filter is an FIR filter, and for the same reference voltage value, the battery voltage signal output by the four-time multiplexing module is collected, and the same reference voltage and the battery voltage signal output by the four-time multiplexing module are used to obtain four comparison results. The FIR filter multiplies the four comparison results by corresponding weights and then superimposes them, and outputs the superimposed signal.

[0193] When the output of the first filter is within the unreliable range, the output of the first filter is taken as an unreliable measurement result.

[0194] The second filter receives the battery voltage of each single battery outputted by the first filter, corrects the battery voltage of each single battery, and uses the corrected battery voltage of each single battery as the final battery voltage of each single battery.

[0195] The second filter receives the battery voltage of each single battery outputted by the first filter, corrects the battery voltage of each single battery, and uses the corrected battery voltage of each single battery as the final battery voltage of each single battery.

[0196] The second filter is a Kalman filter.

[0197] When measuring the battery voltage signal of each single battery, each single battery is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter.

[0198] After the battery voltages of all the single cells are obtained, the lowest voltage value of the single cells in the series-connected lithium battery system is obtained by comparing the battery voltages of the individual single cells.

[0199] When the lowest voltage value is higher than the battery balancing start voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the lowest voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

[0200] According to a further embodiment of the present disclosure, a communication method for a lithium battery system is also provided, wherein the lithium battery system includes more than two battery voltage detection circuits, and the lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects n single cells among the plurality of single cells connected in series, and obtains a lowest voltage value of the single cell among the n single cells based on a measured voltage output by each battery voltage detection circuit, and the lowest voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain a system lowest voltage value of the single cell of the lithium battery system.

[0201] According to a further embodiment of the present disclosure, a battery balancing control method for a lithium battery system is also provided, such as Fig.10 As shown, the system minimum voltage value is obtained through the above communication method. When the system minimum voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the system minimum voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

[0202] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0203] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0204] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A battery voltage detection circuit for a series lithium battery system, wherein the series lithium battery system comprises N single batteries connected in series, wherein N ≥ 1, characterized in that: include: A multiplexing module, the multiplexing module is connected to the N single cells connected in series, so as to receive the battery voltage signal of each single cell in the N single cells through the multiplexing module, and select the battery voltage signal of one single cell in the N single cells for output each time; A reference voltage generating unit, the reference voltage generating unit is used to generate a variable reference voltage value; as well as a comparator, for each selected single cell, the comparator is used to receive the battery voltage signal output by the multiplexing module and the changing reference voltage value, and compare the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output the measured battery voltage of the single cell, The reference voltage value changes within a preset range between the lowest equalization start voltage and the highest battery voltage, and during the comparison process of the comparator, for each of the multiple comparisons in the process of measuring the battery voltage of each single battery, the reference voltage value changes, and the comparator compares the received battery voltage signal and the reference voltage value that changes each time to output the measured battery voltage of each single battery, wherein the change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range, The circuit further comprises: The FIR filter collects the battery voltage signal output by the multiplexing module at least twice for the same reference voltage value, and the comparator compares the same reference voltage with the at least two battery voltage signals respectively to obtain at least two comparison results, and inputs the at least two comparison results into the FIR filter, and the FIR filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal; The Kalman filter receives the battery voltage of each single cell outputted by the FIR filter, and corrects the battery voltage of each single cell, and uses the corrected battery voltage of each single cell as the final battery voltage of each single cell. When measuring the battery voltage signal of each single cell, each single cell is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter. During this period, the charge and discharge switch of the series lithium battery system is turned off.

2. The battery voltage detection circuit of the series lithium battery system according to claim 1, characterized in that: N-2 reference voltage points are preset within a preset range, where N-2 is a natural number; the reference voltage value decreases from the highest voltage, N-2 reference voltage points to the equilibrium starting voltage; or the reference voltage value increases from the equilibrium starting voltage, N-2 reference voltage values ​​to the highest voltage.

3. According to the battery voltage detection circuit of the series lithium battery system according to claim 2, when the reference voltage value is one of the highest voltage, N-2 reference voltage points and the equalization starting voltage, the identification bit corresponding to the current reference voltage value is set to the first preset value; when the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to the second preset value.

4. The battery voltage detection circuit of the series lithium battery system according to claim 3, characterized in that: When the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as the identification bit corresponding to the current reference voltage value.

5. The battery voltage detection circuit of the series lithium battery system according to claim 4, characterized in that: The voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

6. The battery voltage detection circuit of the series lithium battery system as claimed in claim 1, characterized in that: The reference voltage value is represented by M bits. When the reference voltage value changes, the highest bit in the M bits is set to 1 and the remaining bits are set to 0, thereby obtaining a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

7. The battery voltage detection circuit of the series lithium battery system as claimed in claim 6, characterized in that: If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on the remaining bits.

8. The battery voltage detection circuit of the series lithium battery system as claimed in claim 1, characterized in that: The reference voltage value is represented by M bits. When the reference voltage value changes, the lowest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the lowest bit remains unchanged.

9. The battery voltage detection circuit of the series lithium battery system as claimed in claim 8, characterized in that: If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the lowest bit is set to 0, then the previous bit of the lowest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the previous bit of the lowest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the previous bit of the lowest bit remains unchanged. In the case where the battery voltage signal is less than the second reference voltage value, the same operation is continued on the remaining bits.

10. The battery voltage detection circuit of the series lithium battery system as claimed in claim 1, characterized in that: For the same reference voltage value, the battery voltage signal output by the four-multiplexing module is collected, and the same reference voltage and the battery voltage signal output by the four-multiplexing module are obtained to obtain four comparison results. The FIR filter multiplies the four comparison results by corresponding weights and then superimposes them, and outputs the superimposed signal.

11. The battery voltage detection circuit of the series lithium battery system according to claim 1, characterized in that: When the output of the FIR filter is within the unreliable range, the output of the FIR filter is taken as an unreliable measurement result.

12. A communication device for a lithium battery system, characterized in that: include: Two or more battery voltage detection circuits according to any one of claims 1 to 11, The lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects N single cells among the plurality of single cells connected in series, and obtains the lowest voltage value of the single cells among the N single cells based on the measured battery voltage output by each battery voltage detection circuit, and the lowest voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain the lowest voltage value of the system single cell of the lithium battery system.

13. A detection method for a battery voltage detection circuit of a series-connected lithium battery system, wherein the series-connected lithium battery system comprises N single batteries connected in series, wherein N ≥ 1, characterized in that: include: A multiplexing module is connected to the N single cells connected in series, so as to receive a battery voltage signal of each single cell in the N single cells through the multiplexing module, and select a battery voltage signal of one single cell in the N single cells for output each time; as well as For each selected single cell, the comparator receives the battery voltage signal output by the multiplexing module and receives a changing reference voltage value, and compares the received battery voltage signal and the reference voltage value multiple times according to the changing reference voltage value to output the measured battery voltage of the single cell. The reference voltage value changes within a preset range between the lowest equalization start voltage and the highest battery voltage, and during the comparison process of the comparator, for each of the multiple comparisons in the process of measuring the battery voltage of each single battery, the reference voltage value changes, and the comparator compares the received battery voltage signal and the reference voltage value that changes each time to output the measured battery voltage of each single battery, wherein the change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range, The detection method further includes, for the same reference voltage value, collecting at least two battery voltage signals output by the multiplexing module, and the comparator compares the same reference voltage with the at least two battery voltage signals respectively to obtain at least two comparison results, inputting the at least two comparison results into an FIR filter, and the FIR filter multiplies the at least two comparison results by corresponding weights to superimpose them, and outputs the superimposed signal; The Kalman filter receives the battery voltage of each single battery output by the FIR filter, and corrects the battery voltage of each single battery, and uses the corrected battery voltage of each single battery as the final battery voltage of each single battery. When measuring the battery voltage signal of each single cell, each single cell is measured multiple times to obtain multiple battery voltage signals, and the average value of the multiple battery voltage signals is used as the initial state value of the Kalman filter. During this period, the charge and discharge switch of the series lithium battery system is turned off.

14. The detection method according to claim 13, characterized in that: The change of the reference voltage value within the preset range is: the reference voltage value gradually increases within the preset range, or the reference voltage value gradually decreases within the preset range.

15. The detection method according to claim 13, characterized in that: N-2 reference voltage points are preset within a preset range, where N-2 is a natural number; the reference voltage value decreases from the highest voltage, N-2 reference voltage points to the equilibrium starting voltage; or the reference voltage value increases from the equilibrium starting voltage, N-2 reference voltage values ​​to the highest voltage.

16. The detection method according to claim 15, characterized in that: When the reference voltage value is one of the highest voltage, N-2 reference voltage points and the equalization start voltage, setting the flag bit corresponding to the current reference voltage value to a first preset value; When the battery voltage signal output by the multiplexing module is less than the current reference voltage value, the identification bit corresponding to the current reference voltage value is set to a second preset value.

17. The detection method according to claim 16, characterized in that: When the battery voltage signal output by the multiplexing module is greater than or equal to the current reference voltage value, the first preset value is used as the identification bit corresponding to the current reference voltage value.

18. The detection method according to claim 17, characterized in that: The voltage value of each single battery is obtained according to the position where the identification bit is the first preset value.

19. The detection method according to claim 13, characterized in that: The reference voltage value is represented by M bits. When the reference voltage value changes, the highest bit in the M bits is set to 1 and the remaining bits are set to 0 to obtain a first reference voltage value. The first reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0. If the battery voltage signal is greater than the first reference voltage value, the output of the comparator is 1 and the highest bit remains unchanged.

20. The detection method according to claim 19, characterized in that If the battery voltage signal is less than the first reference voltage value, the output of the comparator is 0 and the highest bit is set to 0, then the next bit of the highest bit is set to 0 and the remaining bits are set to 0 to obtain a second reference voltage value, and the second reference voltage value is compared with the received battery voltage signal. If the battery voltage signal is less than the second reference voltage value, the output of the comparator is 0 and the next bit of the highest bit is set to 0. If the battery voltage signal is greater than the second reference voltage value, the output of the comparator is 1 and the next bit of the highest bit remains unchanged, and when the battery voltage signal is less than the second reference voltage value, the same operation is continued on the remaining bits.

21. A communication method for a lithium battery system, characterized in that: The lithium battery system comprises two or more battery voltage detection circuits as claimed in any one of claims 1 to 11, The lithium battery system includes a plurality of single cells connected in series, each battery voltage detection circuit detects N single cells among the plurality of single cells connected in series, and obtains the lowest voltage value of the single cells among the N single cells based on the measured battery voltage output by each battery voltage detection circuit, and the lowest voltage value of the single cell obtained by each battery voltage detection circuit is mutually transmitted and judged in each battery voltage detection circuit to obtain the system lowest voltage value of the single cells of the lithium battery system.

22. A battery balancing control method for a lithium battery system, characterized in that: The system minimum voltage value is obtained by the communication method as described in claim 21. When the system minimum voltage value is higher than the battery balancing starting voltage, it is determined whether the difference between the voltage value of a single cell in the series lithium battery system and the system minimum voltage value is greater than the balancing threshold voltage. If the difference is greater than the balancing threshold voltage, the single cell is balanced.

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