Passive equalization control method and device of BMS, electronic equipment and storage medium

Abstract

The invention provides a passive equalization control method and device of a BMS, electronic equipment and a storage medium, and relates to the technical field of batteries, and the method comprises the steps: obtaining the discharge average voltage corresponding to all battery cells in the previous discharge process, and the charge average voltage corresponding to all battery cells in the previous charge process; determining a discharge voltage deviation corresponding to each battery cell based on the discharge average voltage; determining a charging voltage deviation corresponding to each battery cell based on the charging average voltage; on the basis of the discharging voltage deviation and the charging voltage deviation corresponding to each battery cell, under the condition that a first target battery cell belonging to the series device deviation type is identified, sampling voltage calibration is carried out on the first target battery cell; and performing passive equalization control on all the cells including the calibrated first target cell. According to the invention, the voltage sampling error can be corrected, and the sampling precision of the single voltage is improved, so that the accuracy of passive equalization control of the battery cell by the BMS is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a passive balancing control method, device, electronic device and storage medium of a BMS. Background Art

[0002] The Battery Management System (BMS) is an important management unit of the battery system, which is used for battery data monitoring, state estimation, battery balancing, fault diagnosis, and charge and discharge control. Figure 1 As shown in the figure, the battery pack is composed of multiple cells connected in series. Since the capacity of each cell is different, based on the "short board effect", cells with different charges will cause the total capacity of the battery pack to decrease. In order to keep the charge of all cells consistent as much as possible, the balancing function of the BMS is particularly important. Turning on the balancing function means discharging some cells with higher charges or charging cells with lower charges separately.

[0003] At present, passive balancing technology is used in batteries for household energy storage and smaller-capacity electric appliances. The energy in the larger single cells in the battery system is dissipated through external circuits to achieve the purpose of power balancing.

[0004] However, passive balancing technology is limited by the accuracy of single-cell voltage. There is internal resistance at the connection between the battery cell and devices such as the copper busbar and aluminum busbar connected in series. The accuracy of single-cell voltage is affected by the difference in internal resistance and temperature changes, which causes deviations in the sampled voltage of the battery cell and causes the battery cell balancing to be falsely triggered, resulting in low accuracy of passive balancing control. Summary of the invention

[0005] The present invention provides a passive balancing control method, device, electronic device and storage medium of a BMS, so as to solve the defect that the passive balancing technology in the prior art is limited by the single cell voltage accuracy, and there is internal resistance at the connection between the battery cell and devices such as copper busbars and aluminum busbars connected in series, and the single cell voltage accuracy is affected by the difference in internal resistance and temperature change, resulting in deviation of the sampled voltage of the battery cell, so that the battery cell balancing is falsely triggered, thereby resulting in low accuracy of passive balancing control.

[0006] The present invention provides a passive balancing control method for a BMS, comprising: Obtain the average discharge voltage of all cells in the previous discharge process, and the average charge voltage of all cells in the previous charge process; Based on the average discharge voltage, determining the discharge voltage deviation corresponding to each of the battery cells; based on the average charge voltage, determining the charge voltage deviation corresponding to each of the battery cells; When a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells, sampling voltage calibration is performed on the first target cell; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; Passive balancing control is performed on all cells including the calibrated first target cell.

[0007] According to the passive balancing control method of the BMS provided by the present invention, the first target battery cell belonging to the series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each battery cell, including: For each of the battery cells, when the first voltage deviation of the battery cell is greater than 0 and the second voltage deviation is less than 0, determining the battery cell as a first target battery cell belonging to a series device deviation type; The first voltage deviation includes the discharge voltage deviation or the charge voltage deviation, the second voltage deviation includes the discharge voltage deviation or the charge voltage deviation, and the first voltage deviation and the second voltage deviation are of different deviation types.

[0008] According to the passive balancing control method of the BMS provided by the present invention, the sampling voltage calibration of the first target battery cell includes: Obtaining an average charge and discharge current corresponding to the first target battery cell; Determining a correction calibration coefficient corresponding to the first target battery cell based on an average charge and discharge current, a discharge voltage deviation, and a charge voltage deviation corresponding to the first target battery cell; Based on the correction calibration coefficient, the sampled voltage of the battery cell is calibrated.

[0009] According to the passive balancing control method of the BMS provided by the present invention, the passive balancing control of all the cells including the calibrated first target cell includes: Grouping all the battery cells based on the channel sampling interval corresponding to each of the battery cells and the AC component cycle of each of the battery cells during the charging and discharging process; For each group of battery cells, based on the battery cell voltage and the voltage difference of each battery cell, it is determined whether to perform balancing control on each battery cell; the voltage difference is the voltage difference between the battery cell and the lowest voltage battery cell in the same group of battery cells.

[0010] According to the passive balancing control method of the BMS provided by the present invention, all the cells are grouped based on the channel sampling interval corresponding to each of the cells and the AC component cycle of each of the cells during the charging and discharging process, including: Determine a sampling period corresponding to each of the battery cells based on the number of sampling times corresponding to each of the battery cells and the channel sampling interval; Based on the sampling period and the AC component period, determining a target decimal value corresponding to each of the battery cells; The battery cells corresponding to all target decimal values ​​within the preset range are divided into the same group.

[0011] According to the passive balancing control method of the BMS provided by the present invention, the method further includes: In the case of performing balanced control on the battery cell, determining a pressure difference change speed of the battery cell within a target sampling time; Based on the voltage difference change speed, the charging request current of the battery cell during the balancing control process is adjusted.

[0012] According to the passive balancing control method of the BMS provided by the present invention, the method further includes: When the discharge voltage deviation and the charge voltage deviation of the battery cell are both greater than 0, determining the battery cell as a second target battery cell belonging to the battery cell power deviation type; When the BMS is in a static state, passive balancing control is performed on the second target battery cell.

[0013] The present invention also provides a passive balancing control device for a BMS, comprising: An acquisition module is used to acquire the average discharge voltage of all cells in the previous discharge process and the average charge voltage of all cells in the previous charge process; A determination module, configured to determine a discharge voltage deviation corresponding to each of the battery cells based on the average discharge voltage; and to determine a charge voltage deviation corresponding to each of the battery cells based on the average charge voltage; A calibration module, for performing sampling voltage calibration on a first target cell when a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; The balancing control module is used to perform passive balancing control on all the cells including the calibrated first target cell.

[0014] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the passive balancing control method of the BMS as described above is implemented.

[0015] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the passive balancing control method of the BMS as described in any one of the above is implemented.

[0016] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the passive balancing control method of the BMS as described above is implemented.

[0017] The passive balancing control method, device, electronic device and storage medium of the BMS provided by the present invention, after obtaining the average discharge voltage corresponding to all battery cells in the previous discharge process and the average charging voltage corresponding to all battery cells in the previous charging process, determine the discharge voltage deviation corresponding to each battery cell according to the average discharge voltage, and determine the charging voltage deviation corresponding to each battery cell according to the average charging voltage, and identify the voltage deviation type of the first target battery cell according to the discharge voltage deviation and the charging voltage deviation. When it is identified that the voltage deviation type of the first target battery cell belongs to the series device deviation type, the sampled voltage of the first target battery cell is calibrated, and after the calibration, passive balancing control is performed on all battery cells, the voltage sampling error is corrected, and the sampling accuracy of the single cell voltage is improved, thereby improving the accuracy of the passive balancing control of the battery cells by the BMS. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a connection diagram of a battery pack provided by the prior art.

[0020] Figure 2 It is a schematic diagram of the changes in battery cell voltage and power provided by the prior art.

[0021] Figure 3 It is a connection diagram of battery cells, copper busbars and aluminum busbars provided by the prior art.

[0022] Figure 4 It is a flow chart of a passive balancing control method of a BMS provided in an embodiment of the present invention.

[0023] Figure 5 It is a schematic diagram of an AC component cycle provided by an embodiment of the present invention.

[0024] Figure 6 It is a structural schematic diagram of a passive balancing control device of a BMS provided in an embodiment of the present invention.

[0025] Figure 7 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 2 As shown, in the passive balancing control method of the prior art, since the cell voltage and the amount of electricity have a certain positive correlation, the non-plateau period of the cell voltage is generally selected for sampling. The voltage change in the plateau period is small, and the difference in the amount of electricity of each cell cannot be judged. The specific passive balancing control method includes: sampling the cell voltage during the non-plateau period, and when the cell voltage of a certain sampling channel is greater than the voltage threshold, and the voltage difference between the cell and the lowest voltage cell is greater than the voltage difference threshold, the passive balancing function of the cell can be turned on, that is, the cell is connected in parallel with a resistor to consume electricity and reduce the charging speed of the cell. When the charging of the cell is completed, the charging stops after the cell monomer is triggered to overvoltage, so that the voltage difference of the cell is reduced, thereby turning off the passive balancing function of the cell.

[0028] However, the passive balancing function of the battery cell is limited by the accuracy of the single cell voltage. There is internal resistance at the connection between the battery cell and the copper and aluminum busbars in series. The accuracy of the single cell voltage is affected by the difference in internal resistance and temperature changes, which leads to deviations in the sampled voltage of the battery cell, causing the battery cell balancing to be falsely triggered, resulting in low accuracy of passive balancing control. For example, Figure 3 As shown, the cell voltage of cell 1 = sampling voltage 1-sampling voltage 0, and the cell voltage of cell 2 = sampling voltage 2-sampling voltage 1. If the internal resistance of the welding point between the aluminum busbar connected in series with cell 2 and cell 2 is large, the cell voltage of cell 2 will be too high. The same is true for the copper busbar, and the internal resistance of the welding point between the copper busbar and the aluminum busbar will have a greater impact on the voltage difference. If the voltage is too high, the passive balancing of the cell that does not need to be passively balanced will be mistakenly turned on, resulting in low accuracy of passive balancing control.

[0029] In view of the above problems in the prior art, an embodiment of the present invention provides a passive balancing control method of a BMS. Figure 4 is a flow chart of a passive balancing control method of a BMS provided in an embodiment of the present invention, such as Figure 4 As shown, the method includes the following steps 410 to 440.

[0030] Step 410: Obtain the average discharge voltage corresponding to all the cells in the previous discharge process, and the average charge voltage corresponding to all the cells in the previous charge process.

[0031] Specifically, the discharge sampling voltage of the battery cells in each sampling channel during the previous complete discharge process is obtained. According to the discharge sampling voltages corresponding to all the battery cells, the average discharge voltage corresponding to all the battery cells in the previous discharge process is calculated. The calculation formula for the average discharge voltage is: Ud = (Ud1 + Ud2 + ... + Udi + ... + Udm) / m. Among them, Ud represents the average discharge voltage, Udi represents the average value of the discharge sampling voltage of the battery cell in the i-th sampling channel, and , m represents the total number of sampling channels.

[0032] At the same time, the charging sampling voltage of the battery cells in each sampling channel during the previous complete charging process is obtained. According to the charging sampling voltages corresponding to all the battery cells, the corresponding average charging voltage of all the battery cells during the previous charging process is calculated. The calculation formula for the average charging voltage is: Uc=(Uc1+Uc2+……+Uci+……+Ucm) / m. Among them, Uc represents the average charging voltage, and Uci represents the charging sampling voltage of the battery cell in the i-th sampling channel.

[0033] Optionally, when calculating the average discharge voltage or the average charge voltage corresponding to all cells, the calculation method can be selected according to the number of samples in each sampling channel. For example, taking the calculation of the average discharge voltage as an example, if the number of samples corresponding to each sampling channel is different, the average discharge value corresponding to a single cell can be calculated according to the discharge sampling voltage corresponding to a single cell, and then the average discharge voltage corresponding to all cells can be calculated according to all the discharge average values. It can also be calculated according to the number of samples of all discharge sampling voltages, and the average value is the average discharge voltage. For example, the number of samples corresponding to the first sampling channel is 7, and the sum of the 7 discharge sampling voltages is 45, the number of samples corresponding to the second sampling channel is 9, and the sum of the 9 discharge sampling voltages is 60, then the average discharge voltage can be (45 / 7+60 / 9) / 2, or (45+60) / (7+9). The different number of samples corresponding to each sampling channel may be due to various reasons such as the cell power, data loss and sampling frequency. If the number of samples corresponding to each sampling channel is the same, there is no difference in using the above two methods, and they can be selected arbitrarily, and the embodiment of the present invention does not limit this.

[0034] Step 420: Determine a discharge voltage deviation corresponding to each of the battery cells based on the average discharge voltage; and determine a charge voltage deviation corresponding to each of the battery cells based on the average charge voltage.

[0035] Specifically, after calculating the average discharge voltage and the average charge voltage, for each battery cell, the first difference between the discharge sampling voltage and the average discharge voltage of each battery cell is calculated, and the first difference is the discharge voltage deviation of the battery cell. The calculation formula of the discharge voltage deviation of the battery cell in the i-th sampling channel is: Udxi=Udi-Ud, where Udxi represents the discharge voltage deviation of the battery cell in the i-th sampling channel. At the same time, the second difference between the charge sampling voltage and the average charge voltage of each battery cell is calculated, and the second difference is the charge voltage deviation of the battery cell. The calculation formula of the charge voltage deviation of the battery cell in the i-th sampling channel is: Ucxi=Uci-Uc, where Ucxi represents the charge voltage deviation of the battery cell in the i-th sampling channel.

[0036] Step 430: When a first target battery cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the battery cells, a sampling voltage calibration is performed on the first target battery cell, wherein the series device deviation type is used to characterize the voltage deviation of the first target battery cell caused by the internal resistance at the connection between the first target battery cell and the series device.

[0037] Specifically, the voltage deviation caused by the deviation type of the series device will change with the change of the current direction, that is, the voltage direction acting on the internal resistance at the connection between the battery cell and the series device will change with the change of the current direction. For example, when the battery cell is charged, the internal resistance at the connection between the battery cell and the series device will make the single cell voltage of the battery cell higher, and when the battery cell is discharged, the internal resistance will make the single cell voltage of the battery cell lower. Therefore, in an embodiment of the present invention, for each battery cell, according to the discharge voltage deviation and charging voltage deviation corresponding to the battery cell, it is judged whether the voltage deviation type of the battery cell belongs to the series device deviation type. If the voltage deviation type of the battery cell belongs to the series device deviation type, the battery cell is determined as the first target battery cell. Since the voltage sampling accuracy of the first target battery cell is low, the accuracy of the passive balancing control of the battery cell is low. Therefore, after identifying the first target battery cell, the sampled voltage of the first target battery cell can be calibrated to improve the voltage sampling accuracy of the first target battery cell, thereby avoiding the battery cell from being mistakenly triggered by passive balancing.

[0038] Further, the identifying a first target battery cell belonging to a series device deviation type based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the battery cells includes: For each of the battery cells, when the first voltage deviation of the battery cell is greater than 0 and the second voltage deviation is less than 0, determining the battery cell as a first target battery cell belonging to a series device deviation type; The first voltage deviation includes the discharge voltage deviation or the charge voltage deviation, the second voltage deviation includes the discharge voltage deviation or the charge voltage deviation, and the first voltage deviation and the second voltage deviation are of different deviation types.

[0039] Specifically, the first voltage deviation and the second voltage deviation have different deviation categories, which can be understood as the first voltage deviation and the second voltage deviation have different corresponding power regulation processes, that is, when the first voltage deviation is a discharge voltage deviation, the second voltage deviation is a charge voltage deviation, and when the first voltage deviation is a charge voltage deviation, the second voltage deviation is a discharge voltage deviation. If the first voltage deviation is greater than 0 and the second voltage deviation is less than 0, it indicates that the voltage of the battery cell changes with the change of the current direction, that is, the voltage deviation type of the battery cell belongs to the series device deviation type, and the battery cell is determined as the first target battery cell.

[0040] It should be noted that when the absolute value of the average charging current of the battery cell is close to the absolute value of the average discharging current, the corresponding first voltage deviation and second voltage deviation can be selected for comparison to determine whether the voltage deviation category of the battery cell belongs to the series device deviation type, thereby improving the accuracy of type identification.

[0041] Further, the sampling voltage calibration of the first target battery cell includes: Obtaining an average charge and discharge current corresponding to the first target battery cell; Determining a correction calibration coefficient corresponding to the first target battery cell based on an average charge and discharge current, a discharge voltage deviation, and a charge voltage deviation corresponding to the first target battery cell; Based on the correction calibration coefficient, the sampled voltage of the battery cell is calibrated.

[0042] Specifically, after determining the first target battery cell, the average value of the absolute value of the average charging current and the absolute value of the average discharging current of the first target battery cell can be calculated, and the average value is the average charging and discharging current of the first target battery cell. After calculating the average charging and discharging current, the correction calibration coefficient corresponding to the first target battery cell is calculated according to the average charging and discharging current, the discharge voltage deviation and the charging voltage deviation. The calculation formula of the correction calibration coefficient of the first target battery cell is: R=ABS[(Udxi+Ucxi) / 2Ia]. Among them, R represents the correction calibration coefficient of the first target battery cell, ABS[] represents the absolute value function, and Ia represents the average charging and discharging current of the first target battery cell. After calculating the correction calibration coefficient of the first target battery cell, the sampled voltage of the first target battery cell is calibrated, and the calibration formula can be: Unn=Un-IR. Among them, Unn represents the cell voltage of the first target battery cell after calibration, Un represents the sampled voltage of the first target battery cell before calibration, and I represents the sampled current of the first target battery cell.

[0043] In an embodiment of the present invention, after obtaining the average discharge voltage corresponding to all battery cells in the previous discharge process and the average charge voltage corresponding to all battery cells in the previous charge process, the discharge voltage deviation corresponding to each battery cell is determined according to the average discharge voltage, and the charge voltage deviation corresponding to each battery cell is determined according to the average charge voltage, and the voltage deviation type of the first target battery cell is identified according to the discharge voltage deviation and the charge voltage deviation. When it is identified that the voltage deviation type of the first target battery cell belongs to the series device deviation type, the sampled voltage of the first target battery cell is calibrated to correct the voltage sampling error, and improve the sampling accuracy of the single cell voltage, thereby improving the accuracy of the BMS's passive balancing control of the battery cells.

[0044] Step 440: Perform passive balancing control on all cells including the calibrated first target cell.

[0045] Specifically, after calibrating the sampled voltage of the first target battery cell, passive balancing control can be performed on all the battery cells to maintain the consistency of the battery cells in the battery pack to overcome the "short board effect" of the battery pack.

[0046] In the passive balancing control process, since most of the circuits for charging the battery pack are conversion circuits for alternating current (AC) to direct current (DC). Since the conversion circuit cannot generate stable DC, for example, there is an AC component when the battery pack is connected to an inverter for charging and discharging, which causes large fluctuations in the charging and discharging current, and then causes fluctuations in the sampling voltage. Since the cell voltages of each cell are sampled in turn, that is, there is a channel sampling interval for each cell voltage, the cell voltage fluctuations after sampling are not synchronized, and then the voltage difference of each cell fluctuates greatly, which affects the judgment logic for starting passive balancing. For example, taking the AFE (Analog Front End) chip as an example, the AFE chip uses a fixed frequency to sample the cell voltage of each sampling channel in turn. Take a fixed frequency of 10Hz and a total of 20 sampling channels as an example, that is, the update period is 100ms, and the sampling values ​​of all sampling channels are updated every 100ms, and each sampling channel takes 5ms to sample. When sampling in each sampling channel, the position of the fluctuating voltage is collected randomly, with some sampling channels collecting voltage peaks and some collecting voltage troughs, which results in the voltage difference of the battery cell fluctuating greatly.

[0047] Further, the passive balancing control of all the cells including the calibrated first target cell includes: Grouping all the battery cells based on the channel sampling interval corresponding to each of the battery cells and the AC component cycle of each of the battery cells during the charging and discharging process; For each group of battery cells, based on the battery cell voltage and the voltage difference of each battery cell, it is determined whether to perform balancing control on each battery cell; the voltage difference is the voltage difference between the battery cell and the lowest voltage battery cell in the same group of battery cells.

[0048] Specifically, in order to address the problem that the charge and discharge current of the battery cell has an AC component, which causes large fluctuations in the voltage difference of the battery cell and affects the judgment logic for turning on passive balancing, in an embodiment of the present invention, the sampling frequency of the battery pack is obtained, and then the update period of the battery pack is calculated based on the sampling frequency. The update period is the reciprocal of the sampling frequency. After calculating the update period of the battery pack, the ratio of the update period to the total number of sampling channels is calculated. The ratio is the channel sampling interval of each battery cell. At the same time, the charge and discharge current is sampled, the average current value within the sampling time is calculated, and the time interval between two times that the current average value is exceeded is determined. The time interval is the AC component period of each battery cell during the charge and discharge process. Figure 5 is a schematic diagram of an AC component cycle provided by an embodiment of the present invention, wherein the AC component cycle is as follows Figure 5 As shown. Afterwards, all cells are grouped according to the channel sampling interval and the AC component period, so that the AC component position of each group of cells is the same. For each group of cells, the cell voltage corresponding to each cell is collected, and the lowest voltage cell is determined from the group of cells. The voltage difference between each cell voltage and the lowest voltage cell is calculated, and the voltage difference is the voltage difference of the cell. Since the AC component position of each group of cells is the same, the fluctuation of the voltage difference is reduced, making the voltage difference more stable. Afterwards, the balance judgment is made based on the cell voltage and voltage difference of each cell.

[0049] Furthermore, grouping all the battery cells based on the channel sampling interval corresponding to each of the battery cells and the AC component cycle of each of the battery cells during the charging and discharging process includes: Determine a sampling period corresponding to each of the battery cells based on the number of sampling times corresponding to each of the battery cells and the channel sampling interval; Based on the sampling period and the AC component period, determining a target decimal value corresponding to each of the battery cells; The battery cells corresponding to all target decimal values ​​within the preset range are divided into the same group.

[0050] Specifically, since each battery cell is sampled in turn, the product of the number of sampling times of the battery cell and the channel sampling interval can be calculated. This product is the sampling period when sampling each battery cell, and the sampling period increases with the increase in the number of sampling times. After determining the sampling period, calculate the target decimal value of the quotient of the sampling period and the AC component period. If the target decimal value is within the preset range, it indicates that the AC components of the battery cells corresponding to the target decimal value are in the same position. If the target decimal value is outside the preset range, add 1 to the sampling number, calculate the new sampling period and the new target decimal value, if the new target decimal value is within the preset range, it indicates that the AC components of the battery cells corresponding to the new target decimal value are in the same position. Repeat the above steps to divide the battery cells corresponding to all target decimal values ​​within the preset range into the same group.

[0051] It should be noted that the preset range may be a smaller range to ensure that the AC components within the preset range fluctuate within a very small range near a certain position, so that the AC components within the preset range are regarded as being in the same position. The preset range may be set based on historical experience, for example, the preset range may be [-2%, 2%] or [-5%, 5%], etc., which is not limited in the embodiment of the present invention.

[0052] Further, judging whether to perform balancing control on each of the battery cells based on the battery cell voltage and the voltage difference of each of the battery cells includes: For each of the battery cells, when the battery cell voltage of the battery cell is greater than a first preset threshold value and the voltage difference is greater than a second preset threshold value, performing balancing control on the battery cell; When the cell voltage of the cell is less than the first preset threshold, or the voltage difference is less than a third preset threshold, turning off the balancing control of the cell; The second preset threshold is greater than the third preset threshold.

[0053] For example, taking the battery cells in the battery pack as lithium iron phosphate batteries, the first preset threshold value may be 3.4V, the second preset threshold value may be 20mV, and the third preset threshold value may be 10mV. For each battery cell, if the battery cell voltage of the battery cell is greater than 3.4V and the voltage difference of the battery cell is greater than 20mV, the passive balancing control of the battery cell can be turned on. If the battery cell voltage of the battery cell is less than 3.4V, or the voltage difference of the battery cell is less than 10mV, the passive balancing control of the battery cell can be turned off.

[0054] It should be noted that the first preset threshold is a voltage threshold value for turning on or off the balancing control, the second preset threshold is a voltage difference threshold value for turning on the balancing control, and the third preset threshold is a voltage difference threshold value for turning off the balancing control. The embodiment of the present invention does not limit the values ​​of the first preset threshold value, the second preset threshold value, and the third preset threshold value.

[0055] Furthermore, the method further comprises: In the case of performing balanced control on the battery cell, determining a pressure difference change speed of the battery cell within a target sampling time; Based on the voltage difference change speed, the charging request current of the battery cell during the balancing control process is adjusted.

[0056] Specifically, after the passive balancing of the battery cell is turned on, the voltage at the charging end rises faster, especially when the charging current is large. From the occurrence of the pressure difference to start the balancing, to the closing of the balancing by the single overvoltage protection, it generally lasts for a few minutes, the balancing time is short, and the amount of electricity balanced is small, resulting in poor balancing effect. In view of the above problems, in an embodiment of the present invention, after the balancing control of the battery cell is turned on, the pressure difference changes continuously within the target sampling time, and the pressure difference change speed within the target sampling time can be calculated, so as to adjust the charging request current of the battery cell during the balancing control process according to the pressure difference change speed. For example, if the pressure difference change speed is greater than the fourth preset threshold, it indicates that the pressure difference of the battery cell rises faster. At this time, the charging request current of the battery cell during the balancing control process can be reduced, and the charging time can be extended, thereby extending the balancing time. When the pressure difference change speed is less than the fifth preset threshold, the charging request current of the battery cell during the balancing control process is increased to improve the charging efficiency. Based on this, both the charging efficiency and the balancing effect can be taken into account.

[0057] Furthermore, the method further comprises: When the discharge voltage deviation and the charge voltage deviation of the battery cell are both greater than 0, determining the battery cell as a second target battery cell belonging to the battery cell power deviation type; When the BMS is in a static state, passive balancing control is performed on the second target battery cell.

[0058] In addition, the voltage deviation type of the battery cell may also include a battery cell power deviation type, which is used to characterize that the voltage of the battery cell is inconsistent with the voltage of other battery cells due to the high power of the battery cell, that is, because the battery cell voltage and power of the battery cell have a certain positive correlation, when the power of the battery cell is high, the battery cell voltage of the battery cell is high, so that the voltage deviation between the battery cell voltage and the battery cell voltage of other battery cells is large, resulting in poor consistency of the battery cells in the battery pack, resulting in low accuracy of passive control balancing. If the voltage deviation type of the battery cell is the battery cell power deviation type, whether it is a charging process or a discharging process, the battery cell voltage of the battery cell with a higher power is higher than the battery cell voltage of the battery cell with a lower power. Therefore, after determining the discharge voltage deviation and the charging voltage deviation of each battery cell, if the discharge voltage deviation and the charging voltage deviation of the battery cell are both greater than 0, it indicates that the voltage deviation type of the battery cell belongs to the battery cell power deviation type, so that the chip whose voltage deviation type belongs to the battery cell power deviation type is determined as the second target chip, and the second target battery cell can be passively balanced and discharged separately when the BMS is in a static state.

[0059] In the prior art, since there is no current in the BMS in the static state, no voltage difference will be generated, and the cell voltage is also in a plateau period. Therefore, in the prior art, the BMS will not turn on the balancing control in the static state. In the embodiment of the present invention, the balancing control is performed on the second target chip alone in the static state, which can extend the balancing time and thus improve the effect of passive balancing.

[0060] The passive balancing control device of the BMS provided by the present invention is described below. The passive balancing control device of the BMS described below and the passive balancing control method of the BMS described above can be referred to each other.

[0061] The embodiment of the present invention further provides a passive balancing control device for a BMS. Figure 6 is a schematic diagram of the structure of a passive balancing control device of a BMS provided in an embodiment of the present invention, such as Figure 6 As shown, the passive balancing control device 600 of the BMS includes: an acquisition module 610 , a determination module 620 , a calibration module 630 and a balancing control module 640 .

[0062] The acquisition module 610 is used to acquire the average discharge voltage corresponding to all the battery cells in the previous discharge process, and the average charge voltage corresponding to all the battery cells in the previous charge process.

[0063] The determination module 620 is used to determine the discharge voltage deviation corresponding to each of the battery cells based on the average discharge voltage; and to determine the charge voltage deviation corresponding to each of the battery cells based on the average charge voltage.

[0064] The calibration module 630 is used to perform sampling voltage calibration on the first target battery cell when a first target battery cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charging voltage deviation corresponding to each of the battery cells; the series device deviation type is used to characterize the voltage deviation of the first target battery cell caused by the internal resistance at the connection between the first target battery cell and the series device.

[0065] The balancing control module 640 is used to perform passive balancing control on all the cells including the calibrated first target cell.

[0066] The passive balancing control device of the BMS provided in the embodiment of the present invention determines the discharge voltage deviation corresponding to each battery cell according to the discharge average voltage after obtaining the discharge average voltage corresponding to all battery cells in the previous discharge process and the charge average voltage corresponding to all battery cells in the previous charge process, and determines the charge voltage deviation corresponding to each battery cell according to the charge average voltage, and identifies the voltage deviation type of the first target battery cell according to the discharge voltage deviation and the charge voltage deviation, and calibrates the sampled voltage of the first target battery cell when it is identified that the voltage deviation type of the first target battery cell belongs to the series device deviation type, and performs passive balancing control on all battery cells after calibration, corrects the voltage sampling error, and improves the sampling accuracy of the single cell voltage, thereby improving the accuracy of the passive balancing control of the battery cells by the BMS.

[0067] Optionally, the calibration module 630 is specifically configured to: For each of the battery cells, when the first voltage deviation of the battery cell is greater than 0 and the second voltage deviation is less than 0, determining the battery cell as a first target battery cell belonging to a series device deviation type; The first voltage deviation includes the discharge voltage deviation or the charge voltage deviation, the second voltage deviation includes the discharge voltage deviation or the charge voltage deviation, and the first voltage deviation and the second voltage deviation are of different deviation types.

[0068] Optionally, the calibration module 630 is specifically configured to: Obtaining an average charge and discharge current corresponding to the first target battery cell; Determining a correction calibration coefficient corresponding to the first target battery cell based on an average charge and discharge current, a discharge voltage deviation, and a charge voltage deviation corresponding to the first target battery cell; Based on the correction calibration coefficient, the sampled voltage of the battery cell is calibrated.

[0069] Optionally, the balancing control module 640 is specifically configured to: Grouping all the battery cells based on the channel sampling interval corresponding to each of the battery cells and the AC component cycle of each of the battery cells during the charging and discharging process; For each group of battery cells, based on the battery cell voltage and the voltage difference of each battery cell, it is determined whether to perform balancing control on each battery cell; the voltage difference is the voltage difference between the battery cell and the lowest voltage battery cell in the same group of battery cells.

[0070] Optionally, the balancing control module 640 is specifically configured to: Determine a sampling period corresponding to each of the battery cells based on the number of sampling times corresponding to each of the battery cells and the channel sampling interval; Based on the sampling period and the AC component period, determining a target decimal value corresponding to each of the battery cells; The battery cells corresponding to all target decimal values ​​within the preset range are divided into the same group.

[0071] Optionally, the passive balancing control device 600 of the BMS further includes a regulating module, which is specifically used for: In the case of performing balanced control on the battery cell, determining a pressure difference change speed of the battery cell within a target sampling time; Based on the voltage difference change speed, the charging request current of the battery cell during the balancing control process is adjusted.

[0072] Optionally, the passive balancing control device 600 of the BMS further includes a static balancing module, which is specifically used for: When the discharge voltage deviation and the charge voltage deviation of the battery cell are both greater than 0, determining the battery cell as a second target battery cell belonging to the battery cell power deviation type; When the BMS is in a static state, passive balancing control is performed on the second target battery cell.

[0073] Figure 7 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention, such as Figure 7 As shown, the electronic device may include: a processor 710, a communications interface 720, a memory 730 and a communication bus 740, wherein the processor 710, the communications interface 720 and the memory 730 communicate with each other through the communication bus 740. The processor 710 may call the logic instructions in the memory 730 to execute the passive balancing control method of the BMS, and the method includes: Obtain the average discharge voltage of all cells in the previous discharge process, and the average charge voltage of all cells in the previous charge process; Based on the average discharge voltage, determining the discharge voltage deviation corresponding to each of the battery cells; based on the average charge voltage, determining the charge voltage deviation corresponding to each of the battery cells; When a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells, sampling voltage calibration is performed on the first target cell; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; Passive balancing control is performed on all cells including the calibrated first target cell.

[0074] In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0075] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored in a computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the passive balancing control method of the BMS provided by the above methods, the method includes: Obtain the average discharge voltage of all cells in the previous discharge process, and the average charge voltage of all cells in the previous charge process; Based on the average discharge voltage, determining the discharge voltage deviation corresponding to each of the battery cells; based on the average charge voltage, determining the charge voltage deviation corresponding to each of the battery cells; When a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells, sampling voltage calibration is performed on the first target cell; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; Passive balancing control is performed on all cells including the calibrated first target cell.

[0076] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the passive balancing control method of the BMS provided by the above methods is implemented, and the method includes: Obtain the average discharge voltage of all cells in the previous discharge process, and the average charge voltage of all cells in the previous charge process; Based on the average discharge voltage, determining the discharge voltage deviation corresponding to each of the battery cells; based on the average charge voltage, determining the charge voltage deviation corresponding to each of the battery cells; When a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells, sampling voltage calibration is performed on the first target cell; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; Passive balancing control is performed on all cells including the calibrated first target cell.

[0077] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0078] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive balancing control method for BMS, characterized in that: include: Obtain the average discharge voltage of all cells in the previous discharge process, and the average charge voltage of all cells in the previous charge process; Based on the average discharge voltage, determining the discharge voltage deviation corresponding to each of the battery cells; based on the average charge voltage, determining the charge voltage deviation corresponding to each of the battery cells; When a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells, sampling voltage calibration is performed on the first target cell; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; Passive balancing control is performed on all cells including the calibrated first target cell.

2. The passive balancing control method of BMS according to claim 1, characterized in that: The step of identifying a first target battery cell belonging to a series device deviation type based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the battery cells comprises: For each of the battery cells, when the first voltage deviation of the battery cell is greater than 0 and the second voltage deviation is less than 0, determining the battery cell as a first target battery cell belonging to a series device deviation type; The first voltage deviation includes the discharge voltage deviation or the charge voltage deviation, the second voltage deviation includes the discharge voltage deviation or the charge voltage deviation, and the first voltage deviation and the second voltage deviation are of different deviation types.

3. The passive balancing control method of BMS according to claim 2, characterized in that: The sampling voltage calibration of the first target battery cell includes: Obtaining an average charge and discharge current corresponding to the first target battery cell; Determining a correction calibration coefficient corresponding to the first target battery cell based on an average charge and discharge current, a discharge voltage deviation, and a charge voltage deviation corresponding to the first target battery cell; Based on the correction calibration coefficient, the sampled voltage of the battery cell is calibrated.

4. The passive balancing control method of BMS according to any one of claims 1 to 3, characterized in that: The passive balancing control of all the cells including the calibrated first target cell comprises: Grouping all the battery cells based on the channel sampling interval corresponding to each of the battery cells and the AC component cycle of each of the battery cells during the charging and discharging process; For each group of battery cells, based on the battery cell voltage and the voltage difference of each battery cell, it is determined whether to perform balancing control on each battery cell; the voltage difference is the voltage difference between the battery cell and the lowest voltage battery cell in the same group of battery cells.

5. The passive balancing control method of BMS according to claim 4, characterized in that: The grouping of all the cells based on the channel sampling interval corresponding to each of the cells and the AC component cycle of each of the cells during the charging and discharging process includes: Determine a sampling period corresponding to each of the battery cells based on the number of sampling times corresponding to each of the battery cells and the channel sampling interval; Based on the sampling period and the AC component period, determining a target decimal value corresponding to each of the battery cells; The battery cells corresponding to all target decimal values ​​within the preset range are divided into the same group.

6. The passive balancing control method of BMS according to claim 4, characterized in that: The method further comprises: In the case of performing balanced control on the battery cell, determining a pressure difference change speed of the battery cell within a target sampling time; Based on the voltage difference change speed, the charging request current of the battery cell during the balancing control process is adjusted.

7. The passive balancing control method of BMS according to claim 4, characterized in that: The method further comprises: When the discharge voltage deviation and the charge voltage deviation of the battery cell are both greater than 0, determining the battery cell as a second target battery cell belonging to the battery cell power deviation type; When the BMS is in a static state, passive balancing control is performed on the second target battery cell.

8. A passive balancing control device for a BMS, characterized in that: include: An acquisition module is used to acquire the average discharge voltage of all cells in the previous discharge process and the average charge voltage of all cells in the previous charge process; A determination module, configured to determine a discharge voltage deviation corresponding to each of the battery cells based on the average discharge voltage; and to determine a charge voltage deviation corresponding to each of the battery cells based on the average charge voltage; A calibration module, for performing sampling voltage calibration on a first target cell when a first target cell belonging to a series device deviation type is identified based on the discharge voltage deviation and the charge voltage deviation corresponding to each of the cells; the series device deviation type is used to characterize the voltage deviation of the first target cell caused by the internal resistance at the connection between the first target cell and the series device; The balancing control module is used to perform passive balancing control on all the cells including the calibrated first target cell.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the passive balancing control method of the BMS according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the passive balancing control method of the BMS according to any one of claims 1 to 7 is implemented.

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