Battery management circuit, battery pack, electronic device, and battery management method

Abstract

The invention discloses a battery management circuit, a battery pack, electronic equipment and a battery management method, and relates to the technical field of circuits. The battery management circuit includes a serial-to-parallel conversion circuit, a sensing circuit, and a control circuit. The control circuit can obtain the state information of each battery unit in the battery pack from the sensing circuit, and controls the battery pack to enter a series connection constant current charging mode, a pre-parallel connection mode and a parallel connection constant voltage charging mode in sequence according to the state information. And in the series constant-current charging mode, the series-parallel conversion circuit sets the connection mode of the battery pack into a series mode, and performs constant-current charging on the battery pack. In the pre-parallel mode, the control circuit performs battery equalization on the battery pack. And in the parallel constant-voltage charging mode, the serial-parallel conversion circuit sets the connection mode of the battery pack into a parallel mode, and performs constant-voltage charging on the battery pack. According to the battery management circuit, the charging speed and the voltage consistency between the battery units can be improved, so that the service life of the battery is prolonged.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a battery management circuit, a battery pack, an electronic device, and a battery management method. Background Art

[0002] The high-voltage power battery pack is composed of multiple battery cells, which adopt the working mode of series charging and series discharging. Such working mode requires each battery cell in the battery pack to have extremely high consistency. By screening the consistency of each battery cell in the battery pack, the consistency of each battery cell can be improved.

[0003] However, even if the individual battery cells in the battery pack are screened for consistency, the battery cells may still be over-discharged during the use of the battery pack due to the voltage lag of individual battery cells. If this situation is not corrected in time, it will cause damage to the battery cells and then cause the battery pack to fail. In other words, in existing battery packs, battery cells may be over-discharged due to voltage inconsistency, resulting in a shortened battery pack life. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a battery management circuit, a battery pack, an electronic device and a battery management method, which can improve the voltage consistency between battery cells, thereby increasing the service life of the battery and increasing the charging speed.

[0005] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In the first aspect, the present application provides a battery management circuit. The battery management circuit described in the first aspect includes: a serial-parallel conversion circuit connected to a battery pack, used to control the connection mode between multiple battery cells in the battery pack, the connection mode includes a parallel mode and a series mode; a sensing circuit connected to the battery pack, used to obtain the status information of each battery cell, the status information includes one or more of voltage, current and temperature; and a control circuit connected to the serial-parallel conversion circuit and the sensing circuit, used to obtain the status information from the sensing circuit, and control the battery pack to enter the serial constant current charging mode, the pre-parallel mode and the parallel constant voltage charging mode in sequence according to the status information, wherein the serial constant current charging mode includes: when the voltages of multiple battery cells are all greater than the pre-charging threshold, the serial-parallel conversion circuit is controlled by the control circuit to set the connection mode to the serial mode, and the battery pack is charged with constant current; the pre-parallel mode includes: at the end of the serial constant current charging mode, the control circuit is used to balance the multiple battery cells; the parallel constant voltage charging mode includes: at the end of the pre-parallel mode, the serial-parallel conversion circuit is controlled by the control circuit to set the connection mode to the parallel mode, and the battery pack is charged with constant voltage.

[0007] In a second aspect, the present application provides a battery pack. The battery pack in the second aspect comprises: a battery pack and the battery management circuit in the first aspect, wherein the battery pack is coupled to the battery management circuit.

[0008] In a third aspect, the present application provides an electronic device. The electronic device in the third aspect comprises: a processor, a memory, a battery pack, and the battery management circuit in the first aspect, wherein the battery pack is coupled to the battery management circuit.

[0009] In a fourth aspect, the present application provides a battery management method. The battery management method described in the fourth aspect includes: using a sensing circuit to obtain the status information of each battery cell in the battery pack, the status information includes one or more of voltage, current and temperature; controlling the charging mode of the battery pack according to the status information, the charging mode includes a series constant current charging mode, a pre-parallel mode and a parallel constant voltage charging mode; when the voltages of multiple battery cells in the battery pack are greater than the pre-charging threshold, the battery pack is controlled to operate in a series constant current charging mode; in the series constant current charging mode, the connection mode between the multiple battery cells in the battery pack is set to a series mode by using a series-parallel conversion circuit, and the battery pack is charged with a constant current; at the end of the series constant current charging mode, the battery pack is controlled to enter a pre-parallel mode to balance the multiple battery cells; at the end of the pre-parallel mode, the battery pack is controlled to enter a parallel constant voltage charging mode; and in the parallel constant voltage charging mode, the connection mode is set to a parallel mode by using a series-parallel conversion circuit, and the battery pack is charged with a constant voltage.

[0010] In the battery management circuit provided in the above embodiment: the constant current charging process in the series constant current charging mode can achieve fast charging of the battery by increasing the supply voltage. The battery balancing process in the pre-parallel mode can make the voltages between the various battery cells consistent before entering the parallel constant voltage charging mode. The constant voltage charging process in the parallel constant voltage charging mode can make the voltages between the various battery cells consistent and can complete the charging at the same time, that is, make the voltages between the fully charged battery cells consistent. Therefore, the battery management circuit provided in the present application can increase the charging speed and can improve the voltage consistency between the battery cells, thereby increasing the service life of the battery.

[0011] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0013] Figure 1 What is shown is a module block diagram of an example of a battery management circuit provided in an embodiment of the present application;

[0014] Figure 2 What is shown is a circuit diagram of an example of a battery management circuit provided in an embodiment of the present application;

[0015] Figure 3 What is shown is a schematic diagram of a process flow of switching the charge and discharge modes of a battery pack provided in an embodiment of the present application;

[0016] Figure 4 A schematic diagram showing the charge state and voltage changes of a battery pack provided by an embodiment of the present application during the charge and discharge process is shown;

[0017] Figure 5 What is shown is a schematic diagram of an example method for estimating the state of charge of a battery pack provided in an embodiment of the present application;

[0018] Figure 6 Shown is a flow chart of a battery management method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The following is a description of exemplary embodiments of the present application in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0020] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same samples. Other explicit and implicit definitions may also be included below.

[0021] In the embodiments of the present application, "coupled" may mean "electrically connected" or "connected". For example, A coupled to B may mean that A and B are electrically connected.

[0022] As described above, in the existing battery pack, the battery cells may be over-discharged due to voltage inconsistency, resulting in a shortened service life of the battery pack. Therefore, in order to at least partially solve the above problems and one or more of other potential problems, the exemplary embodiment of the present application proposes a corresponding solution, which includes: a battery management circuit, a battery pack, an electronic device and a battery management method. The battery management circuit includes a serial-parallel conversion circuit, a sensing circuit and a control circuit. In the battery management circuit, the control circuit can obtain the state information of each battery cell in the battery pack from the sensing circuit, and control the battery pack to enter the serial constant current charging mode, the pre-parallel mode and the parallel constant voltage charging mode in sequence according to the state information. In the serial constant current charging mode, the control circuit can control the serial-parallel conversion circuit to set the connection mode of the battery pack to the serial mode, and perform constant current charging on the battery pack. In the pre-parallel mode, the control circuit can perform battery balancing on the battery pack. In the parallel constant voltage charging mode, the control circuit can control the serial-parallel conversion circuit to set the connection mode of the battery pack to the parallel mode, and perform constant voltage charging on the battery pack. The battery management circuit can increase the charging speed and improve the voltage consistency between the battery cells, thereby increasing the service life of the battery.

[0023] In addition, the state of charge (SOC) is one of the important parameters of the battery and can be used to estimate the expected available power of the battery. Accurate estimation of the state of charge can not only avoid damage to the battery due to overcharging or over-discharging, so that the battery is within a safe operating range, but also make full use of the battery power, thereby achieving reasonable use of the battery and increasing the battery life. In the process of charging the battery pack, the control circuit in the battery management circuit provided in the embodiment of the present invention can also accurately estimate the SOC of the battery.

[0024] The following will be combined Figure 1-Figure 6 The battery management circuit, battery pack, electronic device and battery management method provided in the embodiments of the present invention are described.

[0025] Please refer to Figure 1 , Figure 1 The module block diagram of an example of a battery management circuit in an embodiment of the present application is shown. The battery management circuit 110 includes: a serial-to-parallel conversion circuit 111, a sensing circuit 112, and a control circuit 113. The serial-to-parallel conversion circuit 111 and the sensing circuit 112 are coupled to the control circuit 113. In addition, the serial-to-parallel conversion circuit 111 and the sensing circuit 112 are coupled to the battery pack 120.

[0026] The battery pack 120 may include a plurality of battery cells BAT1-BAT N In one embodiment, the battery cells BAT1-BAT N For example, the battery cell BAT1-BAT N It can include lithium-ion (Li-ion) battery cells. For example, battery cells BAT1-BAT N The battery cells may include lead-acid battery cells, nickel-cadmium (NiCd) battery cells, nickel-metal hydride (NiMH) battery cells, etc. In one embodiment, the battery cells BAT1-BAT N It is a lithium-ion battery cell with high consistency that has been selected through group matching. In addition, it should be understood that in the description of this article, N represents a natural number greater than 1.

[0027] exist Figure 1 In the illustrated embodiment, the serial-to-parallel conversion circuit 111 can control the battery cells BAT1-BAT2 in the battery pack 120. N The connection mode between the battery cells BAT1-BAT N Connected in parallel, the series mode represents the battery cells BAT1-BAT N In parallel mode, the battery cells BAT1-BAT N Can be charged or powered to a load in parallel connection; in series mode, the battery cells BAT1-BAT N The devices can be connected in series to be charged or to supply power to a load.

[0028] The sensing circuit 112 can sense the battery pack 120 to obtain the status information of each battery cell in the battery pack 120. The status information may include one or more of voltage, current and temperature. The sensing circuit 112 may include an analog to digital converter (ADC), which can be used to sense the status information of each battery cell in the battery pack 120.

[0029] The control circuit 113 can obtain the state information from the sensing circuit 112, and control the charging mode of the battery pack 120 according to the state information. Among them, the charging mode of the battery pack 120 may include: series constant current charging mode, pre-parallel mode and parallel constant voltage charging mode. The control circuit 113 can control the battery pack 120 to enter the series constant current charging mode, pre-parallel mode and parallel constant voltage charging mode in sequence according to the state information. The above charging modes are introduced below:

[0030] 2. Series constant current charging mode, including: connecting battery cells BAT1-BAT N The connection mode between the two is set to series, and the battery cells BAT1-BAT N Perform constant current charging. If the battery cell BAT1-BAT N The voltage is greater than the precharge threshold V PRE_CH , then control the battery unit BAT1-BAT N Works in this series constant current charging mode.

[0031] Specifically, the control circuit 113 can determine the status of each battery cell in the battery pack 120 based on the status information of each battery cell. N Are the voltages greater than the precharge threshold V PRE_CH In the battery cell BAT1-BAT N The voltage is greater than the precharge threshold V PRE_CH When the control circuit 113 controls the serial-to-parallel conversion circuit 111, the battery cells BAT1-BAT N The connection mode between them is set to a series mode, and constant current charging is performed on the battery pack 120. In the constant current charging process of the series constant current charging mode, the battery pack 120 can be quickly charged by increasing the supply voltage (ie, the charging voltage).

[0032] In one embodiment, the charging current in the series constant current charging mode can be relatively stable. More specifically, within a preset time interval, the charging current can be stabilized at a preset constant value. The preset constant value is adjustable. For example, in one embodiment, as the battery cells BAT1-BAT N As the voltage increases, the preset constant value may decrease.

[0033] In one embodiment, the series constant current charging mode may also include a battery balancing process to improve the battery cells BAT1-BAT N Specifically, the battery balancing process in the series constant current charging mode may include: the control circuit 113 determines the battery cells BAT1-BAT2 according to the status information of each battery cell in the battery pack 120. NThe voltage between the battery cells BAT1-BAT N When the voltage between the battery cells BAT1-BAT N Perform battery balancing.

[0034] In one embodiment, the battery cells BAT1-BAT N The battery balancing method may include: N The battery cell with higher voltage is discharged to discharge the battery cell BAT1-BAT N The voltage of each battery cell is adjusted to be equal to or approximately equal to the voltage of the battery cell with the lowest voltage, thereby achieving battery balancing. Specifically, when performing battery balancing on the battery pack 120, the control circuit 113 can turn on the balancing compensation circuit corresponding to the battery cell with a higher voltage in the battery pack 120 to discharge the battery cell with a higher voltage, thereby achieving battery balancing of the battery pack 120. This battery balancing method can achieve battery balancing of the battery pack 120 without changing the series connection mode of the battery pack 120.

[0035] In another embodiment, the battery cells BAT1-BAT N The battery balancing method may include: N The battery cell with lower voltage is charged compensatorily, so that the charging current of the battery cell with lower voltage is greater than that of the battery cell BAT1-BAT N The charging current of the battery cell with higher voltage is used to charge the battery cell BAT1-BAT N The voltage of each battery cell is adjusted to be equal to or approximately equal to the voltage of the battery cell with the highest voltage, thereby achieving battery balancing. This battery balancing method can achieve battery balancing of the battery pack 120 without changing the series mode of the battery pack 120, and can improve the charging efficiency. Among them, the balancing compensation circuit may include a resistor and a switch. Battery cells BAT1-BAT N The battery cell with a higher voltage may refer to a battery cell having a voltage higher than the battery cell with the lowest voltage. N The battery cell with a lower middle voltage may refer to a battery cell having a voltage lower than the battery cell with a highest voltage.

[0036] In yet another embodiment, the battery cells BAT1-BAT N The battery balancing method may include: using the battery cells BAT1-BAT N The battery cells with higher voltage discharge to the battery cells with lower voltage, thus achieving battery balancing. NWhen performing cell balancing, the balancing circuit in the battery pack 120 can be turned on to discharge the battery cells with higher voltage to the battery cells with lower voltage. This cell balancing method can achieve cell balancing of the battery pack 120 without changing the series connection mode of the battery pack 120 and reduce the waste of electric energy.

[0037] In one embodiment, if the battery cells BAT1-BAT N There is a voltage greater than the parallel constant voltage charging threshold V PL_CH The battery cells, and the battery cells BAT1-BAT N The charging current is less than the preset constant current charging current I PRE_CC , then the series constant current charging mode ends. Optionally, the preset constant current charging current I PRE_CC Set to 1A.

[0038] 3. Pre-parallel mode, including: connecting battery cells BAT1-BAT N The connection mode between the two is set to be in series, and the control circuit 113 is used to control the battery cells BAT1-BAT N Perform battery balancing. In one embodiment, if the series constant current charging mode ends, the pre-parallel mode is entered. It should be understood that the battery balancing process in the pre-parallel mode can make the voltages between the battery cells consistent or almost consistent before entering the parallel constant voltage charging mode. Optionally, in the pre-parallel mode, the battery cells BAT1-BAT N The battery balancing method may include: using the battery cells BAT1-BAT N The battery cells with higher voltage discharge to the battery cells with lower voltage, thus achieving battery balancing. N When performing battery balancing, the pre-parallel balancing circuit in the battery pack 120 can be turned on to allow the battery cell with a higher voltage to discharge to the battery cell with a lower voltage. The “almost the same voltage” mentioned here means that in one embodiment, when the battery cells BAT1-BAT N After the balancing operation, due to the non-ideality of the balancing circuit, the battery cells BAT1-BAT N There may be a relatively small difference between the voltages of the MOSFET and the MOSFET, which can be ignored.

[0039] The pre-parallel balancing circuit may include switches and some components for realizing charging and discharging between battery cells.

[0040] In one embodiment, when the battery pack 120 operates in the pre-parallel mode, the battery cells BAT1-BAT NIn another embodiment, when the battery pack 120 operates in the pre-parallel mode, the battery cells BAT1-BAT N Not being charged.

[0041] In one embodiment, if the control circuit 113 completes the battery cells BAT1-BAT N The pre-parallel mode ends if the battery cells BAT1-BAT N If the voltage difference between any two battery cells is less than the preset voltage difference, the pre-parallel mode ends.

[0042] In a preferred embodiment, the control circuit 113 controls the battery pack 120 to operate in a series constant current charging mode. N The voltage is greater than the precharge threshold V PRE_CH When the control circuit 113 only controls the serial-to-parallel conversion circuit 111 to convert the battery cells BAT1-BAT N The connection mode between the two is set to a series mode and the battery pack 120 is charged with a constant current, but the battery cells BAT1-BAT N and the control circuit 113 controls the battery pack 120 to work in the pre-parallel mode, in the battery cells BAT1-BAT N During the battery balancing process, the battery cells BAT1-BAT are also set N Thus, before entering the parallel constant voltage charging mode, the battery pack 120 undergoes a relatively short balancing process to achieve the same voltage among the battery cells, thereby reducing the power consumption caused by balancing and improving the efficiency of battery balancing. In addition, the battery pack 120 is continuously charged during this process, thereby improving the charging efficiency.

[0043] 4. Parallel constant voltage charging mode, including: connecting battery cells BAT1-BAT N The connection mode between the two batteries is set to parallel, and the battery cells BAT1-BAT N If the pre-parallel mode ends, the parallel constant voltage charging mode is entered.

[0044] Specifically, at the end of the pre-parallel mode, the control circuit 113 can control the serial-to-parallel conversion circuit 111 to convert the battery cells BAT1-BAT N The connection mode between them is set to the parallel mode, and the battery pack 120 is charged at a constant voltage. The constant voltage charging process in the parallel constant voltage charging mode can make the voltages between the battery cells consistent and complete the charging at the same time, that is, make the voltages between the fully charged battery cells consistent.

[0045] In one embodiment, if the battery cells BAT1-BAT N The charging current is less than the preset cut-off charging current I END , the parallel constant voltage charging mode ends. Optionally, the preset cut-off charging current I END Set to 300mA.

[0046] It should be understood that in the above embodiment, since the series constant current charging mode can realize fast charging of the battery pack 120, the pre-parallel mode can improve the voltage consistency between the battery cells in the battery pack 120, and the parallel constant voltage charging mode can make the voltage between the battery cells consistent until the charging of the battery pack 120 is completed. Therefore, Figure 1 The illustrated embodiment can increase the charging speed and can improve the voltage consistency between battery cells, thereby increasing the service life of the battery pack 120.

[0047] In one embodiment, the charging mode also includes a pre-charging mode. Before controlling the battery pack 120 to enter the series constant current charging mode, the control circuit 113 may also control the battery pack 120 to enter the pre-charging mode. The pre-charging mode may include: charging the battery cells BAT1-BAT N The connection mode between the two batteries is set to parallel, and the battery cells BAT1-BAT N If the battery cell BAT1-BAT N There is a voltage less than or equal to the precharge threshold V PRE_CH If the battery cell is charged, it enters the pre-charge mode.

[0048] Specifically, in one embodiment: the control circuit 113 can determine the battery cells BAT1-BAT2 according to the status information of each battery cell in the battery pack 120. N Is there a voltage less than or equal to the precharge threshold V PRE_CH In the battery cell BAT1-BAT N There is a voltage less than or equal to the precharge threshold V PRE_CH When the battery cell is connected, the control circuit 113 controls the serial-to-parallel conversion circuit 111 to convert the battery cells BAT1-BAT N The connection mode between the battery pack 120 is set to a parallel mode, and the battery pack 120 is pre-charged. In another embodiment: the control circuit 113 can determine the battery cells BAT1-BAT2 according to the status information of each battery cell in the battery pack 120. N Whether there is a battery cell with an available state of charge (SOC) less than or equal to the pre-charge SOC threshold (e.g., 0%). NWhen there is a battery cell whose available SOC is less than or equal to the pre-charge SOC threshold, the control circuit 113 controls the serial-to-parallel conversion circuit 111 to convert the battery cells BAT1-BAT N The connection mode between them is set to the parallel mode, and the battery pack 120 is pre-charged.

[0049] The charging process in the pre-charging mode can charge the battery pack 120 with a smaller preset current to slowly rejuvenate the battery cells, reduce damage to the battery cells, and extend the life of the battery cells. The value of the preset current can be smaller than the value of the charging current set in the series constant current charging mode and the parallel constant voltage charging mode. For example, the charging process in the pre-charging mode can charge the battery pack 120 with a current of 200mA.

[0050] In one embodiment, if the battery cells BAT1-BAT N The voltage is greater than the precharge threshold V PRE_CH , the pre-charge mode ends.

[0051] Although in the above-mentioned pre-charging mode, when charging the battery pack 120, the control circuit 113 controls the serial-to-parallel conversion circuit 111 to connect the battery cells BAT1-BAT N The connection mode between the battery cells BAT1-BAT2 is controlled to be a parallel mode, but the present invention is not limited thereto. In the pre-charging mode of another embodiment, the control circuit 113 can also control the serial-to-parallel conversion circuit 111 to connect the battery cells BAT1-BAT N The connection mode between them is set to series mode, and in series mode, the battery cells BAT1-BAT N to charge.

[0052] In each of the above-mentioned charging modes, the state information may at least include voltage.

[0053] In one embodiment, the control circuit 113 can control the discharge mode of the battery pack 120, and the discharge mode includes a parallel discharge mode. The parallel discharge mode may include: in the process of controlling the battery pack 120 to discharge, the control circuit 113 controls the serial-to-parallel conversion circuit 111 to convert the battery cells BAT1-BAT N The connection mode between the battery packs 120 is set to a parallel mode so that the battery packs 120 are discharged in parallel. It should be understood that the parallel discharge mode can reduce the battery cells BAT1-BAT N The probability of over-discharge caused by voltage inconsistency between the two batteries can be reduced, thereby extending the service life of the battery pack 120.

[0054] In the above embodiment, the precharge threshold V PRE_CH Less than the parallel constant voltage charging threshold V PL_CHFor example, the precharge threshold V PRE_CH Can be set to 3V, parallel constant voltage charging threshold V PL_CH Can be set to 4.35V.

[0055] Figure 2 FIG. 1 shows a circuit diagram of an example of a battery management circuit in an embodiment of the present application. Figure 2 Will combine Figure 1 Provide explanation. Figure 2 The circuit composed of the control circuit 213, the cell protection circuit 214, the fuel gauge circuit 212 and the serial-to-parallel conversion circuit 211 shown may be an embodiment of the battery management circuit 110. The control circuit 213 may be an embodiment of the control circuit 113, the fuel gauge circuit 212 may be an embodiment of the sensing circuit 112, and the serial-to-parallel conversion circuit 211 may be an embodiment of the serial-to-parallel conversion circuit 111.

[0056] exist Figure 2 In the embodiment, the battery pack (including the battery cells BAT1 and BAT2) may be an embodiment of the battery pack 120 described above. It should be noted that: Figure 2 The number of battery cells in the example is N=2. In practical applications, the number of battery cells can be set according to demand, that is, Figure 2 The number of battery cells in is an example and does not limit the number of multiple battery cells in the battery pack 120 (ie, N).

[0057] exist Figure 2 In the embodiment, the control circuit 213 can be connected to the fuel gauge circuit 212, the battery cell protection circuit 214 and the serial-to-parallel conversion circuit 211. The control circuit 213 can control the serial-to-parallel conversion circuit 211, the fuel gauge circuit 212 and the battery cell protection circuit 214 to realize the functions of serial-to-parallel conversion, state information sensing, charge and discharge protection and charge and discharge control of the battery cells BAT1 and BAT2.

[0058] In one embodiment, the control circuit 213 can control the serial-to-parallel conversion circuit 211 to realize the serial-to-parallel conversion of the battery cells BAT1 and BAT2. Specifically, the control circuit 213 can control the serial-to-parallel conversion circuit 211 to instruct the serial-to-parallel conversion circuit 211 to control the opening (i.e., conduction) and closing (i.e., disconnection) of switches S1, S2, and S3, so that the connection mode between the battery cells BAT1 and BAT2 is set to a parallel mode or a series mode. For example, turning on switches S1 and S2, and turning off switch S3, can set the connection mode between the battery cells BAT1 and BAT2 to a parallel mode. For another example, turning off switches S1 and S2, and turning on switch S3, can set the connection mode between the battery cells BAT1 and BAT2 to a series mode.

[0059] exist Figure 2 In the embodiment, the fuel gauge circuit 212 may include a plurality of ports P7-P13. The ports P7-P13 are connected to the battery cell BAT1, the battery cell BAT2, the resistor RS1 and the resistor RS2 (for specific connection methods, please refer to Figure 2 ). In this embodiment, the control circuit 213 can control the fuel gauge circuit 212 to sense the status information of the battery cells BAT1 and BAT2. Specifically, the control circuit 213 can control the fuel gauge circuit 212 to instruct the fuel gauge circuit 212 to sense the status information (including: voltage, current and temperature) of the battery cells BAT1 and BAT2 through ports P7-P13, thereby sensing the status information of the battery cells BAT1 and BAT2.

[0060] exist Figure 2 In the embodiment, the cell protection circuit 214 may include a plurality of ports P1-P6. The ports P1-P6 are connected to the battery cell BAT1, the battery cell BAT2, the resistor RS1 and the resistor RS2 (for specific connection methods, please refer to Figure 2 ). In addition, the cell protection circuit 214 can also control the opening and closing of switches S4-S7. In this embodiment, the control circuit 213 can control the cell protection circuit 214 to protect the charging process and the discharging process of the battery cells BAT1 and BAT2. Specifically, the control circuit 213 can control the cell protection circuit 214 to instruct the cell protection circuit 214 to sense the status information of the battery cells BAT1 and BAT2 through ports P1-P6, and determine whether the battery cells BAT1 and BAT2 have abnormal conditions such as overvoltage, overcurrent, undervoltage, short circuit, high temperature, low temperature, etc. according to the detected status information. For example, when the battery cells BAT1 and BAT2 have abnormal conditions such as overvoltage or overcurrent, the cell protection circuit 214 can turn off switches S4-S7.

[0061] exist Figure 2 In the embodiment, the control circuit 213 can be connected to the adapter 230. The adapter 230 can be connected to the mains or other equipment that can provide power, and can provide power to the control circuit 213. The control circuit 213 can convert the power provided by the adapter 230 into charging power, and provide the charging power to the battery cells BAT1 and BAT2 to achieve charging control of the battery cells. In addition, the control circuit 213 can also control the battery cells BAT1 and BAT2 to discharge, and provide the power output by the battery cells BAT1 and BAT2 to the load.

[0062] Specifically, the control circuit 213 may include a charger module 215. The charger module 215 may be connected to the adapter 230 via the port VBUS. The charger module 215 may receive power provided by the adapter 230 via the port VBUS, and convert the power provided by the adapter 230 into charging power. The charger module 215 may also be connected to the battery cell BAT2 via the port VOUT, and connected to the battery cell BAT1 via the port VBAT (for specific connection methods, please refer to Figure 2 ).

[0063] In this embodiment, the charging module 215 can provide charging power to the battery cells BAT1 and BAT2 through the port VOUT or the port VBAT, thereby charging the battery cells BAT1 and BAT2. The charging module 215 may include a charge pump, and specifically, the charging module 215 may include a fast charging circuit (fast charger) and a switch charging circuit (switch charger).

[0064] Specifically, when the connection mode between the battery cells BAT1 and BAT2 is in series, the charging module 215 can provide charging power to the battery cells BAT1 and BAT2 along the series charging circuit through the port VOUT, wherein the series charging circuit includes: port VOUT, switch S5, switch S4, resistor RS2, battery cell BAT2, switch S3, battery cell BAT1, resistor RS1 and port PGND. When the connection mode between the battery cells BAT1 and BAT2 is in parallel, the charging module can provide charging power to the battery cells BAT1 and BAT2 along the parallel charging circuit through the port VBAT, wherein the parallel charging circuit includes: port VBAT, switch S7, switch S6, a first path and a second path, and port PGND. The first path and the second path are parallel paths, the first path includes: switch S1, resistor RS2, battery cell BAT2 and switch S2, and the second path includes: battery cell BAT1 and resistor RS1.

[0065] In the above embodiments, the switches S1 - S7 may include metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0066] exist Figure 2 In the embodiment, the control circuit 213 controls the fuel gauge circuit 212, the battery protection circuit 214 and the serial-parallel conversion circuit 211 to enable the battery cells BAT1 and BAT2 to operate in the above-mentioned pre-charging mode, series constant current charging mode, pre-parallel mode, parallel constant voltage charging mode or parallel discharge mode. The specific description of these modes can be referred to the above Figure 1 The embodiment shown.

[0067] Based on the battery management circuit provided in the above embodiment, Figure 3 , Figure 4 A possible relatively complete charging and discharging process of a battery pack controlled by a battery management circuit is described.

[0068] Figure 3 An example of a flow chart of switching the charging and discharging modes of a battery pack provided in an embodiment of the present application is provided. Figure 4 An example of a schematic diagram of the SOC and voltage changes of a battery pack during the charging and discharging process provided in an embodiment of the present application. Figure 3 and Figure 4 Will combine Figure 2 Please refer to Figure 2 , Figure 3 and Figure 4 , the charging and discharging process of the battery pack includes the following steps:

[0069] Step 310, parallel discharge mode.

[0070] At time t0, the control circuit 213 controls the battery pack to enter the parallel discharge mode. After a period of discharge, at time t1, the available SOC of the battery pack is reduced to 0%, and the control circuit 213 controls the battery pack to exit the parallel discharge mode.

[0071] The parallel discharge mode includes: the control circuit 213 controls the serial-to-parallel conversion circuit 211 to set the connection mode between the battery cells BAT1 and BAT2 to the parallel mode. And the control circuit 213 controls the battery cells BAT1 and BAT2 to supply power to the load through the parallel discharge circuit. It can be understood that the parallel discharge circuit and the above-mentioned parallel charging circuit can have the same path, but the current direction is opposite.

[0072] Step 320, pre-charge mode.

[0073] After time t1, the control circuit 213 detects that the voltage in the battery cells BAT1 and BAT2 is less than the pre-charge threshold V PRECH Therefore, the battery pack can be controlled to enter the pre-charge mode to slowly increase the battery voltage. When the voltage of the battery cells BAT1 and BAT2 are both greater than the pre-charge threshold V PRE_CH When (for example, at the time t1+Δt; not at Figure 4 ), the control circuit 213 controls the battery pack to exit the pre-charging mode.

[0074] In one embodiment, the pre-charging mode includes: the control circuit 213 controls the serial-to-parallel conversion circuit 211 to set the connection mode between the battery cells BAT1 and BAT2 to the parallel mode, and the control circuit 213 provides charging power to the battery cells BAT1 and BAT2 along the parallel charging loop through the port VBAT.

[0075] It should be noted that the above-mentioned pre-charging mode is an optional charging process.

[0076] Step 330: Series constant current charging mode.

[0077] At the end of the pre-charge mode (for example, the voltages of the battery cells BAT1 and BAT2 are both greater than the pre-charge threshold V PRE_CH When the battery pack is charged, the control circuit 213 controls the battery pack to enter the series constant current charging mode. In the series constant current charging mode, the charging current is controlled at a preset constant value, and the voltage of the battery cells BAT1 and BAT2 can gradually increase. The control circuit 213 can control the preset constant value to decrease step by step as the voltage of the battery cells BAT1 and BAT2 increases. If it is detected that there is a voltage in the battery cells BAT1 and BAT2 that is greater than the parallel constant voltage charging threshold V PL_CH The battery cells, and the charging current of the battery cells BAT1 and BAT2 is less than the preset constant current charging current I PRE_CC , the control circuit 213 controls the battery pack to exit the series constant current charging mode.

[0078] The series constant current charging mode includes: the control circuit 213 controls the serial-to-parallel conversion circuit 211 to set the connection mode between the battery cells BAT1 and BAT2 to the series mode, and the control circuit 213 provides charging power to the battery cells BAT1 and BAT2 along the series charging loop through the port VOUT.

[0079] Step 340, pre-parallel mode.

[0080] When the battery pack has exited the series constant current charging mode, the control circuit 213 can control the battery pack to enter the pre-parallel mode. The pre-parallel mode may include: the control circuit 213 performs battery balancing on the battery cells BAT1 and BAT2 to improve the voltage consistency between the battery cells BAT1 and BAT2. In this embodiment, the process of the control circuit 213 performing battery balancing on the battery cells BAT1 and BAT2 can be controlled within a preset time period (e.g., 10 seconds). By setting the length of the preset time period, the rapid conversion of the series-parallel mode of the battery pack 120 can be achieved, reducing the energy loss during the conversion process.

[0081] Step 350: Parallel constant voltage charging mode.

[0082] When the pre-parallel mode is completed (e.g., time t2), the control circuit 213 controls the battery pack to enter the parallel constant voltage charging mode to charge the battery pack, and controls the battery pack to exit the parallel constant voltage charging mode when the battery pack is fully charged (e.g., time t3). Specifically, when the charging current of the battery cells BAT1 and BAT2 is less than the preset cut-off charging current I END When , the control circuit 213 controls the battery pack to exit the parallel constant voltage charging mode.

[0083] The parallel constant voltage charging mode may include: the control circuit 213 controls the serial-to-parallel conversion circuit 211 to set the connection mode between the battery cells BAT1 and BAT2 to the parallel mode, and the control circuit 213 provides charging power to the battery cells BAT1 and BAT2 along the parallel charging loop through the port VBAT.

[0084] The above describes the charging and discharging control process of the battery pack 120 by the battery management circuit 110. Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 The method of estimating the SOC of the battery pack 120 by the battery management circuit 110 provided in the embodiment of the present application is illustrated by way of example.

[0085] refer to Figure 1 For example, in the process of charging the battery pack 120, the control circuit 113 can obtain the main state information from the sensing circuit 112, and estimate the first charge state of the battery pack 120 according to the main state information. The main state information includes the battery cells BAT1-BAT N For example, the master status information includes the battery cells BAT1-BAT N The voltage, current and temperature information of the battery cell with the lowest voltage.

[0086] Among them, the process of estimating the first state of charge based on the main state information is applicable to the various charging modes in the above embodiments, that is, when the battery pack 120 is in any one of the charging modes of pre-charging mode, series constant current charging mode, pre-parallel mode and parallel constant voltage charging mode, the control circuit 113 can obtain the main state information and estimate the first state of charge of the battery pack 120 based on the main state information.

[0087] It can be understood that in the above-mentioned series constant current charging mode, the battery cells with higher voltages will be discharged when the battery pack 120 is balanced. Therefore, when the battery pack 120 is balanced in the series constant current charging mode, the average voltage of the battery pack 120 may decrease. In this case, if the battery cells BAT1-BAT N The average voltage of the battery pack 120 is used to estimate the SOC of the battery pack 120. In addition, since the battery cells with higher voltages will discharge to the battery cells with lower voltages during battery balancing in the pre-parallel mode, if the battery cells BAT1-BAT N The state information of the battery cell with higher voltage is used to estimate the SOC of the battery pack 120. The battery pack 120 may also experience a downward jump in SOC. N The first state of charge of the battery pack 120 is estimated based on the state information of the battery cell with the lowest voltage in the battery pack 120, which can avoid the phenomenon that the SOC of the battery pack 120 jumps downward during the charging process, so as to achieve a more accurate estimation of the SOC of the battery.

[0088] In addition, in one embodiment, during the charging process of the battery pack 120, the control circuit 113 may also obtain auxiliary state information from the sensing circuit 112, estimate the second state of charge of the battery pack 120 according to the auxiliary state information, and use the second state of charge to correct the first state of charge to obtain a corrected state of charge. The auxiliary state information includes the battery cells BAT1-BAT N The auxiliary status information includes the status information of the battery cell with the highest voltage. For example, the auxiliary status information includes the battery cells BAT1-BAT N The voltage, current and temperature information of the battery cell with the highest voltage.

[0089] In one embodiment, the modified state of charge can be determined based on the difference between the second state of charge and the first state of charge and the first state of charge. Specifically, the modified state of charge can be calculated using the following formula 1:

[0090] SOC re =SOC1+k1*D SOC(Formula 1)

[0091] In Formula 1, SOC re represents the value of the corrected state of charge, SOC1 represents the value of the first state of charge, and DSOC represents the difference between the second state of charge (the second state of charge is recorded as SOC2) and the first state of charge, that is, D SOC =SOC2-SOC1, k1 represents the weight value, and the value range of k1 can be set to 0 to 0.5, which is represented by (0, 0.5) below. For example, assuming k1 = 0.2, the estimated first state of charge is 60%, and the second state of charge is 62%, then SOC re =60%+0.2×(62%-60%)=60.4%.

[0092] By setting the value range of k1 to (0, 0.5), the value of the corrected state of charge can be greater than SOC1 and less than (SOC1+SOC2) / 2. Since the actual state of charge of the battery pack 120 is the same or approximately the same as (SOC1+SOC2) / 2, compared with estimating the first state of charge of the battery pack 120 based on the main state information, setting the value range of k1 to (0, 0.5) and setting the specific value of K1 based on experience can achieve the condition of avoiding the battery pack 120 from having a downward jump in the SOC, so that the corrected state of charge (that is, the estimated SOC) is closer to the actual state of charge of the battery pack 120, thereby improving the accuracy of the estimated SOC.

[0093] Optionally, the size of k1 can be preset. When calculating the corrected state of charge, the D SOC Specifically, k1 can be adjusted with D SOC negatively correlated, that is: k1=f(D SOC ), and in D SOC Within the range of f(D SOC ) is a decreasing function. In this embodiment, when D SOC When it is larger, k1 can be set to a smaller value so that SOC re It can be changed within a relatively small range based on SOC1. In this way, this embodiment can reduce the fluctuation of the corrected state of charge when the deviation between the second state of charge and the first state of charge becomes larger.

[0094] In another embodiment, the modified state of charge may be determined based on the first state of charge and the second state of charge. Specifically, the modified state of charge may be calculated using the following formula 2:

[0095] SOC′ re =k2*SOC1+(1-k2)*SOC2 (Formula 2)

[0096] In Formula 2, SOC′ re represents the value of the corrected state of charge, SOC1 represents the value of the first state of charge, SOC2 represents the second state of charge, k2 represents the weight value, and the value range of k2 can be set to 0.5 to 1, which is represented by (0.5, 1) below. For example, assuming k2 = 0.6, the estimated first state of charge is 60%, and the second state of charge is 62%, then SOC′ re =0.6*60%+0.4×62%=60.8%.

[0097] By setting the value range of k2 to (0.5, 1), the value of the corrected state of charge can be greater than SOC1 and less than (SOC1+SOC2) / 2. Since the actual state of charge of the battery pack 120 is the same or approximately the same as (SOC1+SOC2) / 2, compared with estimating the first state of charge of the battery pack 120 based on the main state information, setting the value range of k2 to (0.5, 1) and setting the specific value of K2 based on experience can achieve the condition of avoiding the battery pack 120 from experiencing a downward jump in the SOC, so that the corrected state of charge (that is, the estimated SOC) is closer to the actual state of charge of the battery pack 120, thereby improving the accuracy of the estimated SOC.

[0098] Similar to k1, the size of k2 can be preset. re When SOC2 is equal to SOC1, the difference between SOC2 and SOC1 (that is, D SOC ) to adjust k2. Specifically, k2 can be adjusted with D SOC positively correlated, that is: k2=g(D SOC ), and in D SOC Within the range of g(D SOC ) is an increasing function. In this embodiment, when D SOC When it becomes larger, k2 can be set to a larger value so that SOC′ re It can be changed within a relatively small range based on SOC1. In this way, this embodiment can reduce the fluctuation of the corrected state of charge when the deviation between the second state of charge and the first state of charge becomes larger.

[0099] It should be understood that in the above embodiment, the SOC of the battery pack 120 can be estimated mainly based on the state information of the battery cell with the lowest voltage and supplemented by the state information of the battery cell with the highest voltage to obtain a corrected state of charge. Compared with the above-mentioned first state of charge, the corrected state of charge is closer to the actual state of charge of the battery pack 120, that is, the accuracy of the corrected state of charge is higher, and the phenomenon of the SOC of the battery pack 120 jumping downward can be effectively avoided.

[0100] It should be noted that the method of "using the state information of the battery cell with the lowest voltage as the main factor and the state information of the battery cell with the highest voltage as the auxiliary factor to estimate the SOC of the battery pack 120" in the above embodiment can also be applied to Figure 4 The SOC of the battery pack can be estimated. Figure 4 As shown, during the entire charging process, the battery SOC rises steadily without any downward jump.

[0101] In one embodiment, the control circuit 113 can estimate the SOC of the battery pack 120 according to the state information of the battery pack 120 and one or more state of charge estimation algorithms to obtain an estimated state of charge (denoted as SOC est1 The status information of the battery pack 120 may include the above-mentioned main status information or auxiliary status information, as well as other status information (for example, the battery cells BAT1-BAT N The estimated state of charge SOC est1 The above-mentioned first state of charge and / or second state of charge may be included.

[0102] When multiple state of charge estimation algorithms are used to estimate the SOC of the battery pack 120, the control circuit 113 may perform a fusion estimation of the SOC according to the multiple state of charge estimation algorithms to obtain an estimated state of charge SOC. est1 Specifically, the SOCs estimated by the various state of charge estimation algorithms can be fused to obtain a fused SOC, and the fused SOC can be used as the estimated state of charge SOC. est1 For an example of a method for calculating the fused SOC, please refer to Formula 3 below.

[0103] Furthermore, in one embodiment, the above-mentioned fusion estimation method includes using a preset algorithm set. The control circuit 113 can use the preset algorithm set to estimate the SOC of the battery pack 120 to obtain an estimated state of charge SOC est1 . Among them, the preset algorithm set may include but is not limited to one or more of the following state of charge estimation algorithms: a state of charge estimation algorithm based on a lookup table, a state of charge estimation algorithm based on a trained neural network model, and a state of charge estimation algorithm based on a Kalman filter (KF) algorithm. Taking the estimation of the first state of charge of the battery pack 120 as an example, the estimation method of the first state of charge may include: estimating the first state of charge of the battery pack 120 according to the main state information and using the preset algorithm set. Specifically, the first state of charge can be calculated using the following formula 3:

[0104]

[0105] Wherein, SOC1 represents the value of the first state of charge, Q n Indicates the weight value corresponding to the nth state of charge estimation algorithm in the preset algorithm set, SOCK n represents the value obtained by estimating the state of charge of the battery pack 120 using the main state information and the nth state of charge estimation algorithm, and N represents the number of types of state of charge estimation algorithms in the preset algorithm set. Formula 3 may be referred to as multi-SOC estimation algorithm fusion.

[0106] It can be understood that the process of estimating SOC by fusing multiple SOC estimation algorithms can reduce the impact of the estimation error of a single state of charge estimation algorithm on SOC estimation. It should be noted that the above-mentioned SOC estimation algorithm (including estimating SOC by fusing multiple SOC estimation algorithms) can be used not only to estimate the first state of charge, but also to estimate the second state of charge, without limitation.

[0107] In one embodiment, Q n The size of can be preset and can be adjusted according to the needs under different working conditions. n Adjustment can make the estimated SOC as close to the actual SOC as possible, thereby improving the accuracy of SOC estimation. For example, different Q n , thereby improving the SOC estimation accuracy and expanding the applicable conditions of the above-mentioned SOC estimation algorithm.

[0108] The execution process of the above-mentioned state of charge estimation algorithm based on the lookup table may include: the control circuit 113 estimates the state of charge of the battery pack 120 according to the state information of the battery pack 120 and the preset lookup table. Among them, the state information of the battery pack 120 may include voltage. The preset lookup table may include a state of charge lookup table, and the state of charge lookup table may include: multiple voltage values ​​and multiple states of charge corresponding to the multiple voltage values.

[0109] The execution process of the above-mentioned state of charge estimation algorithm based on the trained neural network model (which can be referred to as the AI ​​estimation algorithm) may include: the control circuit 113 inputs the state information of the battery pack 120 into the trained neural network model, and uses the state of charge output by the neural network model as the estimated state of charge. The state information of the battery pack 120 may include voltage, current and temperature.

[0110] The neural network model can be trained by a first training set. The first training set may include multiple sets of training data, each set of training data may include voltage, current, temperature and corresponding state of charge. When training the neural network model, the voltage, current and temperature in each set of training data can be used as input variables of the neural network model, and the state of charge in each set of training data can be used to train the neural network model together with the output variables of the neural network model. A large amount of charge and discharge test data (including voltage, current, temperature and corresponding state of charge) of the battery pack 120 can be collected, and the charge and discharge test data can be used as multiple sets of training data in the first training set.

[0111] The structure of the neural network model may include an input layer, a hidden layer, and an output layer. The input layer is used to receive input variables. The hidden layer includes a series of neurons, each of which has a set of adjustable parameters (including weight values ​​and biases). The hidden layer can calculate a series of intermediate values ​​based on the input variables. The output layer is used to calculate the output variable, that is, the estimated state of charge, based on the intermediate values ​​output by the hidden layer.

[0112] When the neural network model is trained using the first training set, a round of training process may include: using the voltage, current and temperature in a set of training data as input variables of the input layer; obtaining the output variables of the output layer after calculation; and then adjusting the adjustable parameters of the hidden layer according to the state of charge of the set of training data and the output variables of the output layer and using the preset neural network training algorithm. When the training process reaches a preset number of times or the accuracy of the neural network model meets the preset standard, the training of the neural network model can be completed.

[0113] In one embodiment, the activation function of the above neural network model may include a linear function, a relu function and a leaky function. The linear function, the relu function and the leaky function are simple to operate. Using these functions as the activation function of the neural network model can reduce the amount of calculation and improve the training efficiency. In other embodiments, the activation function of the neural network model may include a Tanh function, a Sigmoid function, a Mish function, etc., which is not limited. Optionally, the number of hidden layers in the neural network model can be designed to be 2 layers, and each hidden layer can include multiple neurons.

[0114] The execution process of the above-mentioned state of charge estimation algorithm based on the Kalman filter algorithm (which may be referred to as the Kalman filter estimation algorithm) may include: the control circuit 113 inputs the state information of the battery pack 120 into a preset Kalman filter equation to estimate the SOC of the battery pack 120. The state information may include the voltage, current and initial state of charge of the battery pack 120, and the initial state of charge may be the state of charge of the battery pack 120 estimated before executing the Kalman filter estimation algorithm.

[0115] Specifically, the preset Kalman filter equation may include a state equation and a measurement equation. The state equation may refer to the following formula:

[0116]

[0117] The measurement equation can refer to the following formula:

[0118] U t,j =U oc -U p,j -R0*I j +v1

[0119] j represents the number of iterations of the Kalman filter equation (including the state equation and the measurement equation), U p,j represents the polarization voltage of the battery pack 120 in the jth iteration, U t,j represents the measured voltage (which may be the terminal voltage) of the battery pack 120 in the jth iteration, SOC j represents the state of charge of the battery pack 120 in the jth iteration. Δt represents the sampling time, C N represents the rated capacity of the battery pack 120, R0 represents the internal resistance of the battery pack 120, τ represents the time constant, and U oc represents the open circuit voltage of the battery pack 120, I j represents the current of the battery pack 120 in the jth iteration, w1 and w2 represent system noise, and v1 represents measurement noise. oc , w1, w2, v1 and v2 can be calculated by the equivalent circuit model of the battery pack 120. In each iteration, U t，j ,I j The value is obtained by measuring the battery pack 120 .

[0120] When j = 1, that is, when the first iteration of the Kalman filter equation begins to execute, U p，0 is the polarization voltage of the battery pack 120 before the first iteration is performed, SOC0 is the state of charge of the battery pack 120 before the first iteration is performed (ie, the initial state of charge), and I0 is the current of the battery pack 120 before the first iteration is performed. p，0The voltage across the battery pack 120 may be used as an approximate substitute.

[0121] It can be understood that by using the above-mentioned state equation and measurement equation to perform SOC estimation, it is possible to implement iterative update of SOC estimation, thereby reducing the generation of noise and improving the stability of SOC estimation.

[0122] In one embodiment, the Kalman filter algorithm includes an extended Kalman filter (EKF) algorithm.

[0123] In the above-mentioned Kalman filter estimation algorithm, the measurement value of the Kalman filter estimation algorithm may include: the SOC of the battery pack 120 estimated based on the AI ​​estimation algorithm, the SOC of the battery pack 120 estimated based on the state of charge estimation algorithm of the lookup table, or the SOC of the battery pack 120 estimated using the open circuit voltage method. In other words, the Kalman filter estimation algorithm in this embodiment can be combined with other SOC estimation algorithms to estimate the SOC of the battery pack 120.

[0124] When the measured value includes the SOC of the battery pack 120 estimated based on the AI ​​estimation algorithm, the measurement equation in the above-mentioned Kalman filter estimation algorithm can be replaced by the following formula:

[0125]

[0126] Among them, SOC AI represents the SOC of the battery pack 120 estimated based on the AI ​​estimation algorithm, and v2 represents the measurement noise. Figure 5 First, the control circuit 113 can input the state information of the battery pack 120 into the above-mentioned neural network model to obtain the state of charge SOC output by the neural network model. 1A Then, the state of charge SOC 1A The measured value is input into the Kalman filter estimation algorithm to perform SOC estimation and obtain the state of charge SOC 1B , thereby realizing SOC estimation of the battery pack 120. Figure 5 The Kalman filter algorithm includes initialization, prediction update, measurement update and iterative update processes. The specific implementation methods of the initialization, prediction update, measurement update and iterative update can refer to the relevant instructions of the Kalman filter algorithm.

[0127] It can be understood that the above embodiment uses a neural network to estimate the state of charge of the battery, and combines it with the Kalman filter algorithm for filtering, which can further improve the SOC estimation accuracy of the battery.

[0128] In the Kalman filter estimation algorithm, the state information of the battery pack 120 may also include the temperature of the battery pack 120. That is, the temperature parameter of the battery pack 120 may also be added to the Kalman filter estimation algorithm to estimate the SOC of the battery.

[0129] In one embodiment, when the battery pack 120 is in the constant voltage charging stage, the control circuit 113 can estimate the first cut-off state of charge of the battery pack 120 when the constant voltage charging stage is cut off according to the first estimation formula, and calculate the previously estimated state of charge (recorded as SOC est2 ) is adjusted. The previously estimated state of charge SOC est2 The state of charge SOC in the above embodiment may be included est1 In other words, the state of charge SOC est2 The method of obtaining the state of charge SOC can be the same as the above est1 The method of obtaining is similar.

[0130] Among them, the first estimation formula includes:

[0131]

[0132] SOC end1 Indicates the value of the first cut-off state of charge, SOC cv The value representing the state of charge of the battery pack 120 when it enters the constant voltage charging stage, I cv represents the current when the battery pack 120 enters the constant voltage charging stage, I represents the current current of the battery pack 120, and I eoc Indicates the constant voltage charging cut-off current of the battery pack 120 .

[0133] Further, according to the first cut-off state of charge SOC end1 The previously estimated state of charge SOC est2 The adjustment may include: adjusting the state of charge SOC according to the first cut-off state of charge SOC end1 The expected state of charge corresponding to the current of the battery pack 120 is determined by the constant voltage charging cut-off current, and the previously estimated state of charge SOC is calculated by using the expected state of charge est2 Adjustments are made to obtain the adjusted state of charge. Specifically, the expected state of charge can be calculated using the following formula:

[0134]

[0135] The adjusted state of charge can be calculated using the following formula:

[0136] SOC ADJ =k3*SOC E +(1-k3)*SOC est2

[0137] SOC E The value representing the desired state of charge, SOC ADJ Indicates the adjusted state of charge value, SOC est2 represents the previously estimated state of charge, and k3 represents a preset weight value. This embodiment can make the later estimated state of charge SOC ADJ Towards the desired state of charge SOC E closer, thereby making the estimated SOC more accurate.

[0138] In one embodiment, when the battery pack 120 is in the constant current charging stage, the control circuit 113 can estimate the second cut-off state of charge of the battery pack 120 when the constant current charging stage is cut off according to the second estimation formula, and calculate the previously estimated state of charge (recorded as SOC est3 ) is adjusted. The previously estimated state of charge SOC est3 The state of charge SOC in the above embodiment may be included est1 In other words, the state of charge SOC est3 The method of obtaining the state of charge SOC can be the same as the above est1 The method of obtaining is similar.

[0139] The second estimation formula includes:

[0140]

[0141] SOC end2 Indicates the value of the second cut-off state of charge, SOC cc The value indicating the state of charge of the battery pack 120 when it enters the constant current charging stage, U cc represents the voltage of the battery pack 120 when it enters the constant current charging stage, U represents the current voltage of the battery pack 120, and U eoc represents the constant current charging cut-off voltage of the battery pack 120. Wherein, "the previously estimated state of charge SOC is calculated based on the second cut-off state of charge est3 The execution process of "adjusting the previously estimated state of charge SOC according to the first cut-off state of charge" is the same as the above-mentioned "adjusting the previously estimated state of charge SOC according to the first cut-off state of charge est2 For specific implementation methods, please refer to the above embodiments.

[0142] In one embodiment, when the battery pack 120 is in the discharge stage, the control circuit 113 can estimate the third cutoff state of charge of the battery pack 120 when the discharge stage is terminated according to the third estimation formula, and calculate the previously estimated state of charge (recorded as SOC est4 ) is adjusted. The previously estimated state of charge SOC est4The state of charge SOC in the above embodiment may be included est1 In other words, the state of charge SOC est4 The method of obtaining the state of charge SOC can be the same as the above est1 The method of obtaining is similar.

[0143] Among them, the third estimation formula includes:

[0144]

[0145] SOC end3 Indicates the value of the third cut-off state of charge, SOC ds The value of the state of charge of the battery pack 120 when entering the discharge stage, I ds represents the current when the battery pack 120 enters the discharge stage, I represents the current current of the battery pack 120, and I eoc represents the discharge phase cut-off current of the battery pack 120. Wherein, "the previously estimated state of charge SOC ... est4 The execution process of "adjusting the previously estimated state of charge SOC according to the first cut-off state of charge" is the same as the above-mentioned "adjusting the previously estimated state of charge SOC according to the first cut-off state of charge est2 For specific implementation methods, please refer to the above embodiments.

[0146] It should be noted that the SOC estimation process in the above embodiment can be performed by Figure 1 The control circuit 113 shown in the figure may also be executed by the sensing circuit 112, or by the sensing circuit 112 and the control circuit 113 in cooperation with each other, which is not limited. Figure 2 In the embodiment, the fuel gauge circuit 212 can perform the SOC estimation process in the above embodiment, or the fuel gauge circuit 212 and the control circuit 213 can cooperate to perform the SOC estimation process in the above embodiment.

[0147] It can be understood that in the above embodiment, the battery management circuit 110 can estimate the SOC of the battery pack 120 in the following three ways: estimating the SOC using a lookup table, estimating the SOC using a trained neural network model, and estimating the SOC using a Kalman filter algorithm. In one embodiment, these three ways of estimating the SOC can be applied separately to the charge and discharge control process (including the discharge mode and each of the charging modes) in the above embodiment. In other embodiments, at least two of the three ways of estimating the SOC can be combined with each other and applied to the charge and discharge control process in the above embodiment, without limitation.

[0148] Figure 6 FIG. 1 is a flow chart of a battery management method according to an embodiment of the present invention. Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 right Figure 6 It will be understood by those skilled in the art that Figure 6 The specific steps covered are only examples. That is, the present invention is applicable to other reasonable processes or Figure 6 Steps to make improvements, e.g. Figure 6 The embodiment of the method 600 shown may also include the above Figure 1-Figure 5 The steps that can be performed by each module in the circuit embodiment shown.

[0149] In step 610 , the sensing circuit 112 is used to obtain status information of each battery cell in the battery pack 120 .

[0150] The status information includes one or more of voltage, current, and temperature.

[0151] In step 620 , the charging mode of the battery pack 120 is controlled according to the status information.

[0152] The charging modes include series constant current charging mode, pre-parallel mode and parallel constant voltage charging mode.

[0153] In step 630, the voltages of the plurality of battery cells in the battery pack 120 are all greater than the pre-charge threshold value V PRE_CH When the battery pack 120 is controlled to operate in a series constant current charging mode.

[0154] In step 640 , in the series constant current charging mode, the connection mode between the plurality of battery cells in the battery pack 120 is set to the series mode by using the serial-to-parallel conversion circuit 111 , and the battery pack 120 is charged with a constant current.

[0155] In step 650 , when the series constant current charging mode ends, the battery pack 120 is controlled to enter the pre-parallel mode to perform battery balancing on the multiple battery cells.

[0156] In step 660 , when the pre-parallel mode ends, the battery pack 120 is controlled to enter the parallel constant voltage charging mode.

[0157] In step 670 , in the parallel constant voltage charging mode, the serial-to-parallel conversion circuit 111 is used to set the connection mode to the parallel mode, and the battery pack 120 is charged at a constant voltage.

[0158] In one embodiment, the specific execution process of steps 610-670 can refer to the above Figure 1-Figure 5 Description of the illustrated embodiment.

[0159] The present application also provides a battery pack. The battery pack includes a battery pack 120 and a battery management circuit 110 coupled to the battery pack 120. The implementation of the battery management circuit 110 may include the above Figure 1-Figure 6 The battery management circuit 110 shown in any one of the items, the specific description of the battery management circuit 110 can be referred to above, and will not be repeated here.

[0160] The embodiment of the present application also provides an electronic device, which includes a processor, a memory, a battery pack 120, and a battery management circuit 110 coupled to the battery pack 120. The battery management circuit 110 is also coupled to the processor and the memory respectively. The implementation of the battery management circuit 110 may include the above Figure 1-Figure 6 The battery management circuit 110 shown in any one of the items, the specific description of the battery management circuit 110 can refer to the above, and will not be repeated here. For example, the electronic device provided in the embodiment of the present application may include: a mobile phone, a tablet computer, a laptop computer, an electric vehicle, etc., which is not limited to this.

[0161] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A battery management circuit, characterized in that: include: A serial-to-parallel conversion circuit connected to the battery pack, used to control a connection mode between a plurality of battery cells in the battery pack, wherein the connection mode includes a parallel mode and a series mode; A sensing circuit connected to the battery pack, used to obtain status information of each of the battery cells, wherein the status information includes one or more of voltage, current and temperature; as well as A control circuit connected to the serial-to-parallel conversion circuit and the sensing circuit is used to obtain the state information from the sensing circuit, and control the battery pack to enter a series constant current charging mode, a pre-parallel mode and a parallel constant voltage charging mode in sequence according to the state information, wherein: The series constant current charging mode includes: when the voltages of the plurality of battery cells are all greater than the pre-charging threshold, using the control circuit to control the series-to-parallel conversion circuit to set the connection mode to the series mode, and performing constant current charging on the battery pack. The pre-parallel mode includes: when the series constant current charging mode ends, the control circuit is used to perform battery balancing on the multiple battery cells. The parallel constant voltage charging mode includes: when the pre-parallel mode ends, using the control circuit to control the serial-to-parallel conversion circuit to set the connection mode to the parallel mode, and performing constant voltage charging on the battery pack.

2. The battery management circuit according to claim 1, characterized in that: Before controlling the battery pack to enter the series constant current charging mode, the control circuit is also used to control the battery pack to enter a pre-charging mode, wherein: The pre-charging mode includes: when there is a battery cell with a voltage lower than the pre-charging threshold value among the plurality of battery cells, using the control circuit to control the serial-to-parallel conversion circuit to set the connection mode to the parallel mode, and charging the battery pack; The series constant current charging mode further includes: when it is detected that the voltages of the multiple battery cells are unbalanced, using the control circuit to perform battery balancing on the multiple battery cells.

3. The battery management circuit according to claim 2, characterized in that: If the voltages of the plurality of battery cells are all greater than the pre-charging threshold, the pre-charging mode ends; If there is a battery cell among the multiple battery cells whose voltage is greater than the parallel constant voltage charging threshold, and the charging current of the multiple battery cells is less than the preset constant current charging current, the series constant current charging mode ends, wherein the parallel constant voltage charging threshold is greater than the pre-charging threshold; as well as If the charging current of the plurality of battery cells is less than the preset cut-off charging current, the parallel constant voltage charging mode ends.

4. The battery management circuit according to claim 1, characterized in that: During charging of the battery pack, the control circuit is further used to obtain status information of the battery cell with the lowest voltage among the multiple battery cells from the sensing circuit to obtain main status information, and estimate a first charge state of the battery pack based on the main status information.

5. The battery management circuit according to claim 4, characterized in that: During the process of charging the battery pack, the control circuit is also used to obtain status information of the battery cell with the highest voltage among the multiple battery cells from the sensing circuit to obtain auxiliary status information, estimate the second state of charge of the battery pack based on the auxiliary status information, and use the second state of charge to correct the first state of charge to obtain a corrected state of charge.

6. The battery management circuit according to claim 5, characterized in that: The modified state of charge is determined based on a difference between the second state of charge and the first state of charge and the first state of charge.

7. The battery management circuit according to claim 6, characterized in that: The corrected state of charge is calculated using the following formula: SOC re =SOC1+k*D SOC , Among them, SOC re represents the value of the modified state of charge, SOC1 represents the value of the first state of charge, D SOC represents the difference between the second state of charge and the first state of charge, and k represents a weight value.

8. The battery management circuit according to claim 7, characterized in that: k and D SOC Negative correlation.

9. The battery management circuit according to claim 4, characterized in that: The first state of charge is calculated using the following formula: Wherein, SOC1 represents the value of the first state of charge, Q n Indicates the weight value corresponding to the nth state of charge estimation algorithm in the preset algorithm set, SOCK n represents the value obtained by estimating the state of charge of the battery pack using the main state information and the nth state of charge estimation algorithm, N represents the number of types of state of charge estimation algorithms in the preset algorithm set, and the preset algorithm set includes one or more of the following state of charge estimation algorithms: a state of charge estimation algorithm based on a lookup table, a state of charge estimation algorithm based on a trained neural network model, and a state of charge estimation algorithm based on a Kalman filter algorithm.

10. The battery management circuit according to claim 9, characterized in that: When the battery pack is in the constant voltage charging stage, the control circuit is further used to estimate the first cut-off state of charge of the battery pack when the constant voltage charging stage is cut off according to a first estimation formula, and adjust the first state of charge according to the first cut-off state of charge; wherein, The first estimation formula includes: Among them, SOC end1 The value of the first cut-off state of charge, SOC cv represents the value of the state of charge of the battery pack when it enters the constant voltage charging stage, I cv represents the current of the battery pack when it enters the constant voltage charging stage, I represents the current current of the battery pack, and I eoc Indicates the constant voltage charging cut-off current of the battery pack.

11. The battery management circuit according to claim 9, characterized in that: When the battery pack is in the constant current charging stage, the control circuit is further used to estimate the second cut-off state of charge of the battery pack when the constant current charging stage is cut off according to a second estimation formula, and adjust the first state of charge according to the second cut-off state of charge; wherein, The second estimation formula includes: Among them, SOC end2 The value of the second cut-off state of charge, SOC cc The value indicating the state of charge of the battery pack when it enters the constant current charging stage, U cc represents the voltage of the battery pack when it enters the constant current charging stage, U represents the current voltage of the battery pack, and U eoc Indicates the constant current charging cut-off voltage of the battery pack.

12. The battery management circuit according to claim 9, characterized in that: The measurement values ​​in the state of charge estimation algorithm based on the Kalman filter algorithm include: the state of charge of the battery pack estimated by the state of charge estimation algorithm based on the trained neural network model or the state of charge of the battery pack estimated by the state of charge estimation algorithm based on the lookup table.

13. The battery management circuit according to any one of claims 1 to 12, characterized in that: During the discharge of the battery pack, the control circuit is further used to control the serial-to-parallel conversion circuit to set the connection mode to the parallel mode, so that the battery pack is discharged in parallel.

14. A battery pack, characterized in that: The invention comprises a battery pack and a battery management circuit as claimed in any one of claims 1 to 13, wherein the battery pack is coupled to the battery management circuit.

15. An electronic device, characterized in that: The invention comprises a processor, a memory, a battery pack and a battery management circuit according to any one of claims 1 to 13, wherein the battery pack is coupled to the battery management circuit.

16. A battery management method, characterized in that: include: Acquire status information of each battery cell in the battery pack by using a sensing circuit, wherein the status information includes one or more of voltage, current and temperature; Controlling a charging mode of the battery pack according to the state information, the charging mode comprising a series constant current charging mode, a pre-parallel mode and a parallel constant voltage charging mode; When the voltages of the plurality of battery cells in the battery pack are all greater than a pre-charging threshold, controlling the battery pack to operate in the series constant current charging mode; In the series constant current charging mode, a series-to-parallel conversion circuit is used to set the connection mode between the multiple battery cells in the battery pack to a series mode, and the battery pack is charged with a constant current; When the series constant current charging mode ends, controlling the battery pack to enter the pre-parallel mode to perform battery balancing on the multiple battery cells; When the pre-parallel mode ends, controlling the battery pack to enter the parallel constant voltage charging mode; as well as In the parallel constant voltage charging mode, the connection mode is set to the parallel mode by using the serial-to-parallel conversion circuit, and the battery pack is charged at a constant voltage.

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