A battery parallel management method, device, equipment and system

Abstract

The present application provides a battery parallel management method, device, equipment and system, the method comprising: when it is determined that the battery needs to be connected in parallel, judging whether the first battery with a closed discharge MOS is connected to the bus; if the first battery is connected to the bus, selecting the second battery to be connected in parallel from the batteries not connected to the bus; when it is determined that the voltage of the second battery is less than the bus voltage, closing the discharge MOS of the second battery; monitoring the battery parameters of the second battery, and when it is determined that the voltage difference between the second battery and the bus meets the set conditions according to the battery parameters, closing the charging MOS of the second battery to complete the parallel connection. The present application solves the problem that the capacity of a single battery is limited, the backup power capacity is weak, and the battery is easily damaged by impact and circulating current when the battery is connected in parallel.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a battery parallel management method, device, equipment and system. Background Art

[0002] With the development of science and technology, the application of lithium batteries in various industries is maintaining a high-speed growth trend. In the actual application process, breaking the capacity limitation of lithium battery use is the need of current development. How to solve the problem of lithium battery capacity limitation is the core pain point in the current field of lithium battery technology, which can greatly improve the user experience of equipment using lithium batteries in various industries.

[0003] In order to increase the battery capacity, when two or more lithium batteries are directly connected in parallel, the voltage difference is too large, which can easily cause the battery box to generate a large instantaneous current, forming a circulation between the batteries, causing battery damage and posing a safety hazard. At the same time, for a single lithium battery, in actual application and use, when a battery fails, there is no other alternative battery, or when the battery is exhausted and needs to be charged, it cannot be guaranteed that the lithium battery is in a dischargeable state under any circumstances, and the backup power capacity is weak. Summary of the invention

[0004] The purpose of this application is to provide a battery parallel management method, device, equipment and system to solve the problem of limited single battery capacity, weak backup power capability, and easy impact and circulation when batteries are connected in parallel, which may cause battery damage, so as to ensure that the load can always be powered.

[0005] In a first aspect, the present application provides a battery parallel management method, comprising:

[0006] When it is determined that the battery needs to be connected in parallel, it is determined whether the first battery with the discharge MOS closed is connected to the bus;

[0007] If the first battery is connected to the bus, selecting a second battery to be connected in parallel from batteries not connected to the bus;

[0008] When it is determined that the voltage of the second battery is less than the bus voltage, closing the discharge MOS of the second battery;

[0009] The battery parameters of the second battery are monitored, and when it is determined according to the battery parameters that the voltage difference between the second battery and the bus meets a set condition, the charging MOS of the second battery is closed to complete the parallel connection.

[0010] In some possible embodiments, determining, according to the battery parameters, that the voltage difference between the second battery and the bus satisfies a set condition includes:

[0011] monitoring the voltage of the second battery, and determining that when a voltage difference between the voltage of the second battery and the bus is less than a first threshold, determining that the voltage difference between the second battery and the bus satisfies a set condition;

[0012] or

[0013] The discharge current of the second battery is monitored to determine whether the discharge current is greater than a second threshold value, and whether the voltage difference between the second battery and the bus satisfies a set condition.

[0014] In some possible embodiments, monitoring the voltage of the second battery includes:

[0015] When it is determined that the first battery is in an idle state or a charging state, the voltage of the second battery is monitored.

[0016] In some possible embodiments, monitoring the discharge current of the second battery includes:

[0017] When it is determined that the first battery is in a discharging state, the discharging current of the second battery is monitored.

[0018] In some possible embodiments, when the discharge MOS of the second battery is closed, the method further includes:

[0019] When it is determined that the first battery is in a charging state and the voltage difference between the second battery and the bus is greater than or equal to a first threshold, closing the pre-charge MOS of the second battery;

[0020] The voltage difference between the second battery and the bus or the voltage of the second battery is monitored, and when it is determined that the voltage difference is less than a first threshold or the voltage of the second battery is greater than a third threshold, the pre-charge MOS is disconnected.

[0021] In some possible embodiments, it further includes:

[0022] When it is determined that the voltage of the second battery is greater than the bus voltage, closing the discharge MOS of the second battery;

[0023] The voltage difference between the second battery and the bus voltage is monitored, and when it is determined according to the voltage difference that a set condition is met, the charging MOS of the second battery is closed to complete the parallel operation.

[0024] In some possible embodiments, when it is determined according to the voltage difference that a set condition is satisfied, closing the discharge MOS of the second battery includes:

[0025] When it is determined that the voltage difference is less than the first threshold, it is determined that the set condition is met, and the discharge MOS of the battery to be connected is closed.

[0026] In some possible embodiments, closing the charging MOS of the second battery includes:

[0027] When it is determined that the first battery is in an idle state, a charging state, or a discharging state, the charging MOS of the battery to be connected is closed.

[0028] In some possible embodiments, monitoring the voltage difference between the second battery and the bus voltage includes:

[0029] When it is determined that the first battery is in a charging state, a voltage difference between the second battery and a bus voltage is monitored.

[0030] In some possible embodiments, it further includes:

[0031] If the first battery is not connected to the bus, determining whether a third battery with a closed charging MOS is connected to the bus;

[0032] If a third battery with a closed charging MOS is connected to the bus, a second battery with a voltage lower than the third battery is selected from batteries not connected to the bus;

[0033] The discharge MOS of the second battery is closed.

[0034] In some possible embodiments, it further includes:

[0035] If the first battery is not connected to the bus, determining whether a third battery with a closed charging MOS is connected to the bus;

[0036] If the third battery with a closed charging MOS is not connected to the bus, a fourth battery with the highest voltage is selected from the batteries not connected to the bus;

[0037] The discharge MOS and the charge MOS of the fourth battery are closed.

[0038] In some possible embodiments, it further includes:

[0039] When it is determined that a battery needs to be connected in a stand-alone manner, a fifth battery is selected from batteries not connected to the bus;

[0040] The fifth battery charging MOS and discharging MOS are closed to complete the parallel operation.

[0041] In a second aspect, the present application provides a battery parallel management device, the device comprising:

[0042] A judgment module, when determining that a battery needs to be connected in parallel, judges whether the first battery with a closed discharge MOS is connected to the bus;

[0043] A selection module, if the first battery is connected to the bus, selects a second battery to be connected in parallel from batteries not connected to the bus;

[0044] A first closing module, closing the discharge MOS of the second battery when determining that the voltage of the second battery is less than the bus voltage;

[0045] The second closing module monitors the battery parameters of the second battery and the bus voltage, and closes the charging MOS of the second battery to complete the parallel operation when it is determined according to the battery parameters that a set condition is met.

[0046] In a third aspect, the present application provides a battery parallel management device, the battery parallel management device comprising:

[0047] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a method as described in any one of the first aspects.

[0048] In a fourth aspect, the present application provides a battery management system, including:

[0049] A battery pack includes a plurality of battery circuits, each battery circuit includes a power source, a charging MOS, a discharging MOS and a pre-charging MOS, the charging MOS and the pre-charging MOS are connected in parallel, the positive electrode of each power source is connected to the positive electrode of the bus, and the negative electrode of each power source is connected to the negative electrode of the bus via the charging MOS and the discharging MOS connected in series;

[0050] The battery parallel management device described in the third aspect is connected to the bus and controls the charging MOS, discharging MOS and pre-charging MOS of each battery circuit respectively through control signals.

[0051] In the embodiment of the present application, the problem of limited capacity of a single battery during use is solved by using multiple batteries in parallel. When the battery voltage difference is within a safe range, the battery boxes are directly connected in parallel to prevent instantaneous large currents from being generated between the battery boxes. When the battery is connected, the discharge MOS of the battery to be connected with a lower voltage is closed first to power the external device. When the voltage difference of the battery to be connected and the bus voltage are within a safe range, the charging MOS of the battery to be connected is closed to complete the parallel connection. This can ensure that at least one battery in normal working condition in the system is in a dischargeable state, and can ensure that all batteries can be used for backup power, with strong backup power capability. For the use scenario of UPS, the backup power capability of the battery can be fully utilized.

[0052] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings introduced 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 creative work.

[0054] Figure 1 A schematic diagram of the main power circuit of a 48V lithium battery provided in an embodiment of the present application;

[0055] Figure 2 A schematic diagram of multiple lithium batteries connected in parallel provided in an embodiment of the present application;

[0056] Figure 3 A flow chart of a battery parallel management method provided in an embodiment of the present application;

[0057] Figure 4 A logic flow chart of battery parallel connection provided in an embodiment of the present application;

[0058] Figure 5 A logic flow chart of high-voltage battery access provided in an embodiment of the present application;

[0059] Figure 6 A logic flow chart of low-voltage battery access provided in an embodiment of the present application;

[0060] Figure 7 A diagram of a battery parallel management device provided in an embodiment of the present application;

[0061] Figure 8 A diagram of a battery parallel management device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present application will be described clearly and in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0063] To further illustrate the technical solution provided by the embodiment of the present application, this is described in detail below in conjunction with the accompanying drawings and specific implementation methods. Although the embodiment of the present application provides the method operation steps as shown in the following embodiments or drawings, more or fewer operation steps may be included in the method based on routine or no creative labor. In the steps where there is no necessary causal relationship logically, the execution order of these steps is not limited to the execution order provided by the embodiment of the present application. The method can be executed in the order of the method shown in the embodiment or drawings or in parallel during the actual processing process or when the control device is executed.

[0064] Given that the capacity of a single lithium battery is limited and its backup capacity is weak, it is impossible to achieve backup power for normal batteries at any time and under any working conditions. When multiple batteries are connected in parallel, when the voltage difference of the batteries exceeds the safe range, a large instantaneous current will be generated between the battery boxes, causing battery damage and creating safety hazards. To solve the above problems, this application proposes a battery parallel management method for achieving battery capacity expansion, improving safety, and enhancing battery backup capacity, that is, in any case, at least one battery in a battery pack under normal working conditions is in a dischargeable state.

[0065] The present application proposes a battery parallel management method for achieving battery capacity expansion, improving safety, and enhancing battery backup capability.

[0066] In view of this, the present application proposes a battery parallel management method for realizing battery capacity expansion, improving safety, and enhancing battery backup capacity. The inventive concept of the present application is: when it is necessary to parallel the batteries, select the battery with the highest voltage among the batteries to be connected to close the charging MOS and discharging MOS, and other batteries belong to low-voltage batteries when the high-voltage battery is online. When the battery is connected, close the discharge MOS of the battery to be connected with a lower voltage to realize power supply to the external device. When the voltage difference of the battery to be connected and the bus voltage are within the safe range, close the charging MOS of the battery to be connected to complete the parallel connection, which can realize that at least one battery in normal working condition in the system is in a dischargeable state, and can ensure that all batteries can be backed up, with strong backup capacity. For the use scenario of uninterruptible power supply UPS, the backup capacity of the battery can be fully utilized.

[0067] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.

[0068] The battery parallel management method in the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0069] The charge and discharge control of the battery in the present invention is implemented by a battery management system (BMS). The battery management system BMS includes a battery pack, and the battery pack includes multiple battery circuits. Each battery circuit includes a battery group (the battery group may include one battery or multiple batteries), a charging MOS, a charging MOS and a pre-charging MOS. The pre-charging MOS and the charging MOS are connected in parallel, the positive electrode of each battery group is connected to the positive electrode of the bus, and the negative electrode of each battery group is connected to the negative electrode of the bus via the charging MOS and the discharging MOS connected in series.

[0070] like Figure 1 As shown, the present invention takes a 48V lithium battery as a specific embodiment. The battery pack in this embodiment specifically refers to a battery box, which refers to a collection of all 48V single lithium batteries waiting to be connected in parallel. A single lithium battery is a battery circuit, and a battery circuit includes a battery pack part and a switch for controlling charging and discharging. Figure 1 , which is a schematic diagram of the main power circuit of a single 48V lithium battery provided in this embodiment, the P end is the bus end, connecting the charger and the device that needs power supply, and the B end is the power supply, that is, the battery end. Figure 1 The rated voltage of lithium battery is 48V, C1, C2...C16 are 16 cells, the rated voltage of a single cell is 3V, 16 cells are connected in series to form a 48V lithium battery box. In practice, C1, C2...C16 are not limited to cells, they can be battery cells. Each lithium battery has a discharge MOS that controls the discharge, that is, Figure 1 The DSG MOSFET in the control circuit controls the charging MOS, that is, Figure 1 The CHG MOSFET in the circuit also has a pre-charge MOS for current limiting charging when the voltage difference is too large. The charging MOS and the discharging MOS are connected in series. The pre-charge MOS is located in the pre-charge loop. The pre-charge loop is Figure 1Pre Charge Buck DC / DC in. Normally, the pre-charge MOS is in the disconnected state. When the battery needs to be protected, the pre-charge MOS is closed, and the DC / DC integrated circuit module where the pre-charge MOS is located divides the voltage on the bus. When only the charging MOS is closed (the discharging MOS is in the disconnected state), the battery has only the charging capability and cannot supply power to external devices; when only the discharging MOS is closed (the charging MOS is in the disconnected state), the battery has only the discharging capability and can supply power to external devices but cannot charge; when both the charging MOS and the discharging MOS are closed, the battery has both the charging capability and the discharging capability and is in the online state. When the bus voltage is higher than the battery voltage, the battery is in the charging state and the voltage gradually rises; when the bus voltage is lower than the battery voltage, the battery is in the discharging state and the voltage gradually decreases. When there is the discharge capability, when an external device is connected to the P terminal, the current flows in the direction of P-, B-, B+, P+; when there is the charging capability, when the P terminal is connected to the charger, the current flows in the direction of P+, B+, B-, P-. In addition, the charging MOS and the pre-charging MOS cannot be closed at the same time. If they are closed at the same time, the circuit where the pre-charging MOS is located cannot play a role in voltage division for the battery.

[0071] like Figure 2 As shown, when multiple lithium batteries are connected in parallel, the positive electrode of each battery pack is connected to the positive electrode of the bus, and the negative electrode of each battery pack is connected to the negative electrode of the bus through the charging MOS and discharging MOS connected in series. Specifically, the first lithium battery box to the Nth lithium battery box are connected in parallel to the bus at the P terminal. When the lithium battery box is connected to the bus, each battery box can collect the bus voltage, that is, the P terminal voltage. Each battery box has an independent microcontroller unit MCU. The microcontroller unit MCU decides to close or disconnect the charging MOS / discharging MOS based on the current system state and voltage difference based on the safety principle. The system state includes: battery temperature, battery voltage, battery current and other status information and whether external power supply is required. When the battery power is low and in an over-discharge state, the discharging MOS is disconnected. When the battery is fully charged and in an over-charged state, the charging MOS is disconnected to protect the battery. Possibly, when it is detected that the constituent single battery fails, the battery pack has a problem, or when an abnormal condition of the battery or circuit such as an over-high battery temperature is detected, the MCU controls the charging MOS and the discharging MOS to disconnect, so that the battery exits the system. Each battery box can communicate with other battery boxes. When the battery box turns off the charging MOS and the discharging MOS, it is in the battery exit state, and other battery boxes cannot detect the existence of the battery box with the charging MOS and the discharging MOS turned off.

[0072] Specifically, in order to solve the problem that the capacity of a single battery is limited, the backup capacity is weak, and the batteries are easily damaged by impact and circulation when connected in parallel, and to ensure that the load can always be powered, this application proposes a battery parallel management method, which is described in detail below using a 48V lithium battery as an example.

[0073] In some possible embodiments, the batteries to be connected in parallel are all of the same type of batteries. For the 48V lithium battery in this embodiment, when the battery is fully charged, the actual possible voltage is 54V, and when the battery is discharged, the actual possible voltage is 42V. For batteries of the same model, when the battery power is different, the corresponding voltage is also different. The high-voltage battery and the low-voltage battery in the embodiment of the present application refer to the relative voltage state of the battery waiting to be connected in parallel relative to the battery in the connected state.

[0074] Specifically, when more than one battery box is required to be connected in parallel, such as Figure 3 As shown, it is a flow chart of the battery parallel management method provided by this application, including:

[0075] Step 301, when it is determined that a battery needs to be connected in parallel, it is determined whether a first battery with a closed discharge MOS is connected to the bus;

[0076] The BMS lithium battery management system receives signals from the outside, determines the backup power requirements of multiple batteries, and performs backup power operations for battery parallel operation.

[0077] The first battery refers to a battery with a closed discharge MOS, which includes two states: one is a battery box with a closed discharge MOS and a disconnected charge MOS, and the other is a battery box with both a closed discharge MOS and a closed charge MOS. When the discharge MOS is closed, it means that there is a battery on the bus with discharge capability, and the voltage released by the battery can be detected on the bus, i.e., the P terminal, which means that there is a battery online on the bus.

[0078] In some possible embodiments, when it is determined that a battery needs to be connected in a stand-alone manner, a fifth battery is selected from batteries not connected to the bus;

[0079] The fifth battery is any battery selected from unconnected batteries according to certain principles that can meet the power supply requirements. The fifth battery is an online battery to be connected that has no faults, is not over-discharged, etc., and can power the device.

[0080] When there is no parallel demand in the system and only one battery circuit is needed for power supply, the fifth battery is selected from the bus, and the charging MOS and the discharging MOS of the battery are closed to complete the parallel operation.

[0081] Step 302, if the first battery is connected to the bus, select a second battery to be connected in parallel from batteries not connected to the bus;

[0082] The second battery refers to a battery that is not connected to the bus and can perform normal parallel operation.

[0083] Step 303, when it is determined that the voltage of the second battery is less than the bus voltage, closing the discharge MOS of the second battery;

[0084] The second battery detects the bus voltage and determines the voltage difference. When the bus voltage is lower than that of the second battery, the discharge MOS of the second battery is closed. If the charging MOS of the second battery is closed at the same time, the voltage difference of the battery exceeds the safety range, and the high-voltage battery has an instantaneous impact on the low-voltage battery. A large instantaneous current will be generated between the battery boxes, causing battery damage. In this step, the discharge MOS of the second battery is closed first, which can supply power to the external load without causing damage to itself.

[0085] Step 304, monitoring the battery parameters of the second battery, and when it is determined according to the battery parameters that the voltage difference between the second battery and the bus meets a set condition, closing the charging MOS of the second battery to complete the parallel connection.

[0086] After the discharge MOS of the second battery is closed, the bus voltage is monitored and judged. When the difference between the bus voltage and the voltage of the second battery is reduced to a safe range, the charging MOS of the second battery is closed to complete the parallel connection of the batteries.

[0087] In some possible embodiments, determining, according to the battery parameters, that the voltage difference between the second battery and the bus satisfies a set condition includes:

[0088] monitoring the voltage of the second battery, and determining that when a voltage difference between the voltage of the second battery and the bus is less than a first threshold, determining that the voltage difference between the second battery and the bus satisfies a set condition;

[0089] or

[0090] The discharge current of the second battery is monitored to determine whether the discharge current is greater than a second threshold value, and whether the voltage difference between the second battery and the bus satisfies a set condition.

[0091] According to the safety principle, in a 48V lithium battery, the first threshold is 0.8V. When the voltage difference meets this condition, it is confirmed to be safe after testing. The second threshold is 2A. When the lithium battery discharge current is greater than 2A, the voltage difference is judged to be within a safe range.

[0092] In some possible embodiments, monitoring the voltage of the second battery includes:

[0093] When it is determined that the first battery is in an idle state or a charging state, the voltage of the second battery is monitored.

[0094] In some possible embodiments, monitoring the discharge current of the second battery includes:

[0095] When it is determined that the first battery is in a discharging state, the discharging current of the second battery is monitored.

[0096] When the first battery is a high voltage battery and the second battery is a low voltage battery, the high voltage battery has three states as shown in the parallel table of Table 1: idle state, charging state, and discharging state.

[0097] Table 1

[0098]

[0099] For a high-voltage battery with a closed discharge MOS, when the battery to be connected is a low-voltage battery, only the discharge MOS of the low-voltage battery is closed to achieve the maximum backup power capacity, and the state of powering external devices can be realized immediately. The low-voltage battery has no charging capability, and the high-voltage battery cannot cause damage to the low-voltage battery. Therefore, no matter whether the low-voltage battery is in an idle, discharging, or charging state, the discharge MOS of the low-voltage battery can be closed first without affecting the circuit.

[0100] When the online battery is in idle or charging state, the charge / discharge / pre-charge MOS action is determined by directly monitoring the voltage difference; when the online battery is in discharge state, the discharge current of the battery to be connected is monitored to confirm that the voltage difference is within a safe range, thereby determining the charge / discharge MOS action and realizing battery parallel operation.

[0101] In some possible embodiments, when the discharge MOS of the second battery is closed, the method further includes:

[0102] When it is determined that the first battery is in a charging state and the voltage difference between the second battery and the bus is greater than or equal to a first threshold, closing the pre-charge MOS of the second battery;

[0103] The voltage difference between the second battery and the bus or the voltage of the second battery is monitored, and when it is determined that the voltage difference is less than a first threshold or the voltage of the second battery is greater than a third threshold, the pre-charge MOS is disconnected.

[0104] The battery to be connected first determines the voltage difference with the bus. When the voltage difference is less than 0.8V, it is considered safe after testing. Secondly, the system status is determined. The system status includes three types: idle, charging or discharging. When the system status is idle or charging, the charging MOS of the low-voltage battery to be connected is closed to complete the parallel connection.

[0105] When the system is in the discharge state, it means that the P terminal is connected to a load, the system is supplying power to the outside, the voltage of the online battery gradually decreases, and the current of the low-voltage battery to be connected, which only closes the discharge MOS, gradually increases, and the voltage gradually decreases. However, since the high-voltage battery and the low-voltage battery supply power to external devices at the same time, the discharge current of the high-voltage battery is large and the discharge speed is fast. As the voltage of the high-voltage battery gradually decreases, the discharge current of the low-voltage battery gradually increases and tends to be stable, and the voltage difference between the low-voltage battery and the high-voltage battery gradually decreases. In this embodiment, after testing, when the discharge current of the low-voltage battery reaches 2A, after 3 seconds of continuous confirmation, it is judged that the voltage difference between the low-voltage battery and the high-voltage battery is within the safe range of 0.2V. At this time, the charging MOS of the low-voltage battery can be closed to complete the battery connection.

[0106] In some possible embodiments, Figure 4 As shown, the battery to be connected determines the voltage difference with the bus. When the voltage difference is greater than or equal to 0.8V, the system status is determined. When the system status is idle, the discharge MOS is closed and the charging MOS is disconnected. When the system status is discharging, similarly, due to the continuous discharge of the online high-voltage battery, the voltage gradually decreases. At this time, the current of the connected low-voltage battery is monitored. When the current reaches 2A, it is observed for 3 seconds. If the current is stable, it is considered that the voltage difference is less than 0.2V according to the actual test. Within the safe range, the charging MOS of the low-voltage battery to be connected is closed to complete the parallel operation.

[0107] When the system is in charging state, the bus voltage is greater than the voltage of the battery to be connected. If the charging MOS of the low-voltage battery to be connected is closed, the voltage difference is too large, which will impact the low-voltage battery. In order to quickly back up the power and increase the battery's backup capacity, based on the principle of safety, the pre-charge MOS of the battery to be connected is closed at this time. The pre-charge circuit where the pre-charge MOS is located divides the high voltage at the P end so that the B end has a matching voltage. At this time, if there is an external charger, the high-voltage battery and the low-voltage battery are both in a charging state. If there is no external charger, the high-voltage battery performs current-limited charging for the low-voltage battery. As the charging process proceeds, when the voltage difference is less than 0.8V, it is considered safe, the pre-charge MOS of the low-voltage battery is disconnected, the charging MOS is closed, and the parallel connection is completed. In a possible embodiment, when the pre-charge MOS of the low-voltage battery is closed, during the charging process, when the voltage of the low-voltage battery reaches 55V, the battery is considered fully charged. To prevent the battery from overcharging, the pre-charge MOS is disconnected, the charging MOS is closed, and the parallel connection is completed.

[0108] Specifically, for the logic flow chart of high-voltage battery online and low-voltage battery access, such as Figure 4 As shown:

[0109] Step S401, determine the voltage difference between the low-voltage battery to be connected and the online high-voltage battery, if the voltage difference is greater than or equal to 0.8V, execute step S402, if not, execute step S403;

[0110] Step S402, determining whether the online high-voltage battery is in a charging state, if so, executing step S404; if not, executing step S405;

[0111] Step S403, determining whether the online high-voltage battery is in a discharging state, if so, executing step S413; if not, executing step S414;

[0112] Step S404, closing the pre-charge MOS and the discharge MOS of the battery to be connected;

[0113] Step S405, determining whether the online battery status is discharging, if so, executing step S408; if not, executing step S409;

[0114] Step S406, determine the voltage difference between the low-voltage battery to be connected and the online battery. If the voltage difference is less than 0.8V, execute step S407; if not, execute step S401;

[0115] Step S407, disconnect the pre-charge MOS of the battery to be connected, close the charge MOS and the discharge MOS, and complete the parallel operation;

[0116] Step S408, disconnect the charging MOS of the low-voltage battery to be connected, and close the discharging MOS;

[0117] Step S409, determining whether the online high-voltage battery is in an idle state, if so, executing step S412; if not, executing step S401;

[0118] Step S410, determine whether the voltage difference is less than 0.2V or whether the low-voltage battery discharge current is greater than 2A, if so, execute step S411; if not, execute step S401;

[0119] Step S411, closing the charging MOS and discharging MOS of the low-voltage battery to be connected to complete the parallel operation;

[0120] Step S412, disconnect the charging MOS of the low-voltage battery to be connected, and close the discharging MOS;

[0121] Step S413, disconnect the charging MOS of the low-voltage battery to be connected, and close the discharging MOS;

[0122] Step S414, determining whether the online battery is in a charging state, if so, executing step S416, if not, executing step S417;

[0123] Step S415, determining the voltage difference between the low-voltage battery to be connected and the online high-voltage battery, if the voltage difference is less than 0.2V or the discharge current of the low-voltage battery is greater than 2A, executing step S416; if not, executing step S401;

[0124] Step S416, closing the charging MOS and the discharging MOS of the low-voltage battery to be connected to complete the parallel operation;

[0125] Step S417, determine whether the online high-voltage battery status is idle, if so, execute step S416; if not, execute step S401.

[0126] In some possible embodiments, when it is determined that the voltage of the second battery is greater than the bus voltage, the discharge MOS of the second battery is closed;

[0127] The voltage difference between the second battery and the bus voltage is monitored, and when it is determined according to the voltage difference that a set condition is met, the charging MOS of the second battery is closed to complete the parallel operation.

[0128] The second battery performs a voltage difference judgment. When the voltage of the bus is higher than that of the second battery, the charging MOS of the second battery is closed. If the discharging MOS of the second battery is closed at the same time, the voltage difference of the battery exceeds the safety range, and a large instantaneous current will be generated between the battery boxes, causing battery damage. In this step, the charging MOS of the second battery is closed first. At this time, the second battery cannot discharge to the outside and will not cause damage to the first battery.

[0129] In some possible embodiments, when it is determined according to the voltage difference that a set condition is satisfied, closing the discharge MOS of the second battery includes:

[0130] When it is determined that the voltage difference is less than the first threshold, it is determined that the set condition is met, and the discharge MOS of the battery to be connected is closed.

[0131] According to safety principles, in a 48V lithium battery, the first threshold is 0.2V.

[0132] In some possible embodiments, closing the charging MOS of the second battery includes:

[0133] When it is determined that the first battery is in an idle state, a charging state, or a discharging state, the charging MOS of the battery to be connected is closed.

[0134] When the first battery is a low-voltage battery and the second battery is a high-voltage battery, similarly, the low-voltage battery has three states as shown in the parallel table of Table 2: an idle state, a charging state, and a discharging state.

[0135] Table 2

[0136]

[0137] For a connected low-voltage battery with the discharge MOS closed, the battery has discharge capability and may have charging capability. When a high-voltage battery is connected, the charging MOS of the high-voltage battery is closed. The high-voltage battery has no discharge capability and will not cause impact on the low-voltage battery. Therefore, no matter the connected low-voltage battery is in idle, discharge, or charging state, the charging MOS of the high-voltage battery can be closed first without affecting the circuit.

[0138] In some possible embodiments, monitoring the voltage difference between the second battery and the bus voltage includes:

[0139] When it is determined that the first battery is in a charging state, a voltage difference between the second battery and a bus voltage is monitored.

[0140] When the online battery is in an idle state, that is, when no power is supplied to external devices, the online battery voltage remains unchanged. At this time, only the charging MOS of the high-voltage battery can be closed, and the discharging MOS is disconnected; when the total voltage decreases, the online battery is judged to be in a discharging state, indicating that the P terminal is connected to a load and the system is powered externally. At this time, the discharging MOS of the high-voltage battery cannot be closed to complete the parallel operation; when the total voltage increases, the online battery is judged to be in a charging state, indicating that the P terminal is connected to a charger to charge the battery. Due to the influence of the voltage difference, the charging speed of the low-voltage battery is higher than that of the high-voltage battery. At this time, the control system continuously monitors the bus voltage. When it is confirmed that the voltage difference is within the safe range of 0.2V, the discharging MOS of the high-voltage battery is closed, and the high-voltage battery is successfully connected to the system to complete the parallel operation. 0.2V is the actual test value, which changes according to the actual situation of the battery properties.

[0141] Specifically, the logic flow chart of low-voltage battery online and high-voltage battery access is as follows: Figure 5 Detailed description is given below. Specifically:

[0142] Step S501, determine that the low-voltage battery is online and the high-voltage battery is connected;

[0143] Step S502, determining whether the online battery is in a discharging state, if so, executing step S503; if not, executing step S504;

[0144] Step S503, close the charging MOS to be connected to the high-voltage battery, disconnect the discharging MOS, and execute step S501;

[0145] Step S504, determining whether the state of the online low-voltage battery is an idle state, if so, executing step S505; if not, executing step S506;

[0146] Step S505, close the charging MOS to be connected to the high-voltage battery, disconnect the discharging MOS, and execute step S501;

[0147] Step S506, determining whether the online battery status is in a charging state, if so, executing step S507; if not, executing step S501;

[0148] Step S507, determining whether the voltage difference between the high-voltage battery to be connected and the voltage difference between the online battery is less than 0.2V, if so, executing step S508; if not, executing step S509;

[0149] Step S508, closing the charging MOS and the discharging MOS of the high-voltage battery to be connected to complete the parallel operation;

[0150] Step S509, close the charging MOS to be connected to the high-voltage battery, disconnect the discharging MOS, and execute step S501.

[0151] In some possible embodiments, when it is determined that a battery needs to be connected in parallel, if the first battery is not connected to the bus, it is determined whether a third battery with a closed charging MOS is connected to the bus;

[0152] The third battery refers to a battery in which the bus is in a state where the discharge MOS is disconnected and the charge MOS is closed. This battery may have some faults, or the BMS automatically disconnects the discharge MOS due to actual needs or because the battery needs discharge protection. Since the third battery only closes the discharge MOS, the voltage of the third battery cannot be detected at the P terminal. Because it can communicate with other batteries, other batteries can sense the existence of the third battery and know the voltage of the B terminal of the third battery.

[0153] If a third battery with a closed charging MOS is connected to the bus, a fourth battery with the lowest voltage is selected from the batteries not connected to the bus;

[0154] The discharge MOS of the fourth battery is closed.

[0155] When there is a third battery in the bus and parallel connection is required, and the external load has a power supply demand, in order to prevent the voltage difference between the battery to be paralleled and the third battery from being too large, causing impact on the third battery and causing damage, the battery with the lowest voltage, that is, the fourth battery, is selected from the battery box to be paralleled, and the discharge MOS of the fourth battery is closed to realize power supply to the external device.

[0156] In some possible embodiments, if the first battery is not connected to the bus, and the third battery with closed charging MOS is not connected, then there is no battery online on the bus at this time, and the fourth battery with the highest voltage is selected from the batteries not connected to the bus, and the discharge MOS and charging MOS of the fourth battery are closed to complete the parallel connection. The other batteries to be connected are all low-voltage batteries relative to the fourth battery, and the parallel connection is completed one by one according to the parallel connection logic of Table 1.

[0157] The complete parallel connection process of the embodiment of the present application is described in detail below.

[0158] like Figure 6 As shown in the logical parallel diagram, it mainly includes:

[0159] Step S601, receiving a bus message, determining whether parallel connection is required, if so, executing step S603; if not, executing step S602;

[0160] Step S602: Determine to connect a single battery, close the charging MOS and the discharging MOS, and complete the parallel operation;

[0161] Step S603, determining whether there is a battery pack with a closed discharge MOS on the bus, if yes, executing step S604; if not, executing step S609;

[0162] Step S604: Determine the voltage of the battery to be connected and the bus voltage. If the voltage of the battery to be connected is greater than the bus voltage, execute step S605; if not, execute step S607;

[0163] Step S605, executing the sub-process of low-voltage battery online and high-voltage battery connected;

[0164] Step S606, determine the actions of the charging MOS and the discharging MOS according to the current state of the charger, and complete the parallel operation. For the specific process, refer to the above-mentioned logic process of low-voltage battery online and high-voltage battery connected;

[0165] Step S607, executing the sub-process of high-voltage battery online and low-voltage battery connected;

[0166] Step S608, determine the actions of the charging MOS and the discharging MOS according to the current state of the charger, and complete the parallel operation. For the specific process, refer to the above logic process of the high-voltage battery being online and the low-voltage battery being connected;

[0167] Step S609, determine whether there is a battery pack with a closed charging MOS on the bus, if yes, execute step S610; if no, execute step S611;

[0168] Step S610, closing the discharge MOS of the battery pack with the lowest total voltage, and the battery pack with the lowest total voltage completes parallel operation;

[0169] Step S611: Select the battery pack with the lowest voltage from the battery packs to be connected, close the charge and discharge MOS of the battery pack with the lowest total voltage, and complete the parallel connection.

[0170] In some possible embodiments, step S609 is described in detail: when no discharge is detected on the bus, the battery boxes communicate with each other to confirm whether there is a package with a closed charging MOS on the bus. According to the judgment process, the discharge MOS of the battery box with a closed charging MOS is disconnected at this time. Under normal circumstances, when the online battery box works normally, the charging and discharging MOS are both closed. One of the possible working conditions of the battery box with only a closed charging MOS is that the battery is in a discharge protection state and cannot supply power to the outside, and only has charging capability. At this time, in order to supply power to external devices and minimize the damage to the battery box with only a closed charging MOS on the bus, the battery box with the lowest total voltage is selected from the batteries to be connected, and the discharge MOS of the battery box is closed. At this time, power supply to external devices can be achieved and parallel connection is completed. Under appropriate conditions, such as when a charger is connected to the bus, the battery with over-discharge protection recovers its power, and the discharge MOS is closed within the safe voltage difference range with the bus.

[0171] In some possible embodiments, step S611 is described in detail: when there is neither a battery box with a closed discharge MOS nor a closed charge MOS on the bus, this is a case where multiple batteries are powered on at the same time. According to the parallel connection method of the present application, in order to achieve the maximum backup power capacity, the battery box with the highest total voltage is selected, and the charge MOS and discharge MOS of the battery box are closed. The other batteries to be connected are low-voltage batteries relative to the high-voltage batteries. According to Table 1 and Figure 4 The parallel logic completes the paralleling one by one.

[0172] In some possible embodiments, when the lithium battery with the highest total voltage is first connected to the bus, other batteries can close the discharge MOS first even if they do not meet the parallel requirements, so that all connected batteries can be online for backup power, and then the charging MOS can be closed one by one according to the parallel table.

[0173] In some possible embodiments, when the highest voltage lithium battery whose charge and discharge MOS is closed in the system exits, other lithium batteries whose charge and discharge MOS are not fully closed are also determined according to the maximum backup power principle and safety principle to close the charge and discharge MOS with the highest total voltage.

[0174] After the lithium battery is connected in parallel, it will not automatically exit the system unless there is a fault. The lithium battery will not affect the normal operation of other batteries when it is connected in and out of the system.

[0175] In the embodiment of the present application, the problem of limited capacity of a single battery during use is solved by using multiple batteries in parallel. When the battery voltage difference is within a safe range, the battery boxes are directly connected in parallel to prevent instantaneous large currents from being generated between the battery boxes. When the battery is connected, the discharge MOS of the battery to be connected with a lower voltage is closed first to power the external device. When the voltage difference of the battery to be connected and the bus voltage are within a safe range, the charging MOS of the battery to be connected is closed to complete the parallel connection. This can ensure that at least one battery in normal working condition in the system is in a dischargeable state, and can ensure that all batteries can be used for backup power, with strong backup power capability. For the use scenario of UPS, the backup power capability of the battery can be fully utilized.

[0176] Based on the same technical concept, Figure 7 The schematic diagram of the structure of a battery parallel management device provided by an embodiment of the present invention is exemplarily shown. The device can execute the process of the battery parallel management method. The device specifically includes:

[0177] The judgment module 701 determines whether the first battery with a closed discharge MOS is connected to the bus when it is determined that the battery needs to be connected in parallel;

[0178] A selection module 702 selects a second battery to be connected in parallel from batteries not connected to the bus if the first battery is connected to the bus;

[0179] A first closing module 703, closing the discharge MOS of the second battery when determining that the voltage of the second battery is less than the bus voltage;

[0180] The second closing module 704 monitors the battery parameters of the second battery and the bus voltage, and closes the charging MOS of the second battery to complete the parallel operation when it is determined according to the battery parameters that a set condition is met.

[0181] In some possible embodiments, the second closing module 704 determines, according to the battery parameters, that the voltage difference between the second battery and the bus meets a set condition, including:

[0182] monitoring the voltage of the second battery, and determining that when a voltage difference between the voltage of the second battery and the bus is less than a first threshold, determining that the voltage difference between the second battery and the bus satisfies a set condition;

[0183] or

[0184] The discharge current of the second battery is monitored to determine whether the discharge current is greater than a second threshold value, and whether the voltage difference between the second battery and the bus satisfies a set condition.

[0185] In some possible embodiments, the second closing module 704 monitors the voltage of the second battery, including:

[0186] When it is determined that the first battery is in an idle state or a charging state, the voltage of the second battery is monitored.

[0187] In some possible embodiments, the second closing module 704 monitors the discharge current of the second battery, including:

[0188] When it is determined that the first battery is in a discharging state, the discharging current of the second battery is monitored.

[0189] In some possible embodiments, when the first closing module 703 closes the discharge MOS of the second battery, it also includes:

[0190] When it is determined that the first battery is in a charging state and the voltage difference between the second battery and the bus is greater than or equal to a first threshold, closing the pre-charge MOS of the second battery;

[0191] The voltage difference between the second battery and the bus or the voltage of the second battery is monitored, and when it is determined that the voltage difference is less than a first threshold or the voltage of the second battery is greater than a third threshold, the pre-charge MOS is disconnected.

[0192] In some possible embodiments, the first closing module 703 further executes:

[0193] When it is determined that the voltage of the second battery is greater than the bus voltage, closing the discharge MOS of the second battery;

[0194] The voltage difference between the second battery and the bus voltage is monitored, and when it is determined according to the voltage difference that a set condition is met, the charging MOS of the second battery is closed to complete the parallel operation.

[0195] In some possible embodiments, the first closing module 703 closes the discharge MOS of the second battery when determining, according to the voltage difference, that a set condition is satisfied, including:

[0196] When it is determined that the voltage difference is less than the first threshold, it is determined that the set condition is met, and the discharge MOS of the battery to be connected is closed.

[0197] In some possible embodiments, the first closing module 703 closes the charging MOS of the second battery, including:

[0198] When it is determined that the first battery is in an idle state, a charging state, or a discharging state, the charging MOS of the battery to be connected is closed.

[0199] In some possible embodiments, the first closing module 703 monitors the voltage difference between the second battery and the bus voltage, including:

[0200] When it is determined that the first battery is in a charging state, a voltage difference between the second battery and a bus voltage is monitored.

[0201] In some possible embodiments, the selection module 702 further executes:

[0202] If the first battery is not connected to the bus, determining whether a third battery with a closed charging MOS is connected to the bus;

[0203] If a third battery with a closed charging MOS is connected to the bus, a second battery with a voltage lower than the third battery is selected from batteries not connected to the bus;

[0204] The discharge MOS of the second battery is closed.

[0205] In some possible embodiments, the selection module 702 further executes:

[0206] If the first battery is not connected to the bus, the determination module 701 determines whether a third battery with a closed charging MOS is connected to the bus;

[0207] If the third battery with closed charging MOS is not connected to the bus, the selection module 702 selects the fourth battery with the highest voltage from the batteries not connected to the bus;

[0208] The discharge MOS and the charge MOS of the fourth battery are closed.

[0209] In some possible embodiments, the determination module 701 further executes:

[0210] When it is determined that the battery needs to be connected in a single-machine mode, the selection module selects a fifth battery from the batteries not connected to the bus;

[0211] The fifth battery charging MOS and discharging MOS are closed to complete the parallel operation.

[0212] Based on the same inventive concept, a battery parallel management device is also provided in the embodiment of the present application, and the battery parallel management device can realize the functions of the aforementioned battery parallel management device, referring to Figure 8 , the electronic device comprises:

[0213] At least one processor 801, and a memory 802 connected to the at least one processor 801. The specific connection medium between the processor 801 and the memory 802 is not limited in the embodiment of the present application. Figure 8 In the example, the processor 801 and the memory 802 are connected via a bus 800. Figure 8 The connections between other components are shown in bold lines, and are not intended to be limiting. The bus 800 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, Figure 8Only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. Alternatively, the processor 801 can also be called a controller, and there is no limitation on the name.

[0214] In the embodiment of the present application, the memory 802 stores instructions that can be executed by at least one processor 801. The at least one processor 801 can execute the battery parallel management method discussed above by executing the instructions stored in the memory 802. The processor 801 can implement Figure 7 The functions of each module in the device shown.

[0215] Among them, the processor 801 is the control center of the device, and can use various interfaces and lines to connect the various parts of the entire control device. By running or executing instructions stored in the memory 802 and calling the data stored in the memory 802, the various functions of the device and process data, the device can be monitored as a whole.

[0216] In one possible design, the processor 801 may include one or more processing units, and the processor 801 may integrate an application processor and a modem processor, wherein the application processor mainly processes an operating system, a user interface, and application programs, and the modem processor mainly processes wireless communications. It is understandable that the modem processor may not be integrated into the processor 801. In some embodiments, the processor 801 and the memory 802 may be implemented on the same chip, and in some embodiments, they may also be implemented separately on separate chips.

[0217] The processor 801 may be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present application. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the battery parallel management method disclosed in the embodiments of the present application may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0218] The memory 802 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 802 may include at least one type of storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory, a random access memory (Random Access Memory, RAM), a static random access memory (Static Random Access Memory, SRAM), a programmable read-only memory (Programmable Read Only Memory, PROM), a read-only memory (Read Only Memory, ROM), an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), a magnetic memory, a disk, an optical disk, etc. The memory 802 is any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. The memory 802 in the embodiment of the present application can also be a circuit or any other device that can realize a storage function, for storing program instructions and / or data.

[0219] By programming the processor 801, the code corresponding to the battery parallel management method described in the above embodiment can be fixed into the chip, so that the chip can execute the code when running. Figure 3 The steps of the battery parallel management method of the embodiment shown are as follows: How to design and program the processor 801 is a technology well known to those skilled in the art and will not be described in detail here.

[0220] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0221] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0222] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0223] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0224] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A battery parallel management method, characterized in that: include: When it is determined that the battery needs to be connected in parallel, it is determined whether the first battery with the discharge MOS closed is connected to the bus; If the first battery is connected to the bus, selecting a second battery to be connected in parallel from batteries not connected to the bus; When it is determined that the voltage of the second battery is less than the bus voltage, closing the discharge MOS of the second battery; The battery parameters of the second battery are monitored, and when it is determined according to the battery parameters that the voltage difference between the second battery and the bus meets a set condition, the charging MOS of the second battery is closed to complete the parallel connection.

2. The method according to claim 1, characterized in that Determining, according to the battery parameters, whether the voltage difference between the second battery and the bus meets a set condition includes: monitoring the voltage of the second battery, and determining that when a voltage difference between the voltage of the second battery and the bus is less than a first threshold, determining that the voltage difference between the second battery and the bus satisfies a set condition; or The discharge current of the second battery is monitored to determine whether the discharge current is greater than a second threshold value, and whether the voltage difference between the second battery and the bus satisfies a set condition.

3. The method according to claim 2, characterized in that Monitoring the voltage of the second battery includes: When it is determined that the first battery is in an idle state or a charging state, the voltage of the second battery is monitored.

4. The method according to claim 2, characterized in that: Monitoring the discharge current of the second battery, comprising: When it is determined that the first battery is in a discharging state, the discharging current of the second battery is monitored.

5. The method according to any one of claims 1 to 4, characterized in that: When the discharge MOS of the second battery is closed, the method further comprises: When it is determined that the first battery is in a charging state and the voltage difference between the second battery and the bus is greater than or equal to a first threshold, closing the pre-charge MOS of the second battery; The voltage difference between the second battery and the bus or the voltage of the second battery is monitored, and when it is determined that the voltage difference is less than a first threshold or the voltage of the second battery is greater than a third threshold, the pre-charge MOS is disconnected.

6. The method according to any one of claims 1 to 4, characterized in that: Also includes: When it is determined that the voltage of the second battery is greater than the bus voltage, closing the discharge MOS of the second battery; The voltage difference between the second battery and the bus voltage is monitored, and when it is determined according to the voltage difference that a set condition is met, the charging MOS of the second battery is closed to complete the parallel operation.

7. The method according to claim 6, characterized in that When it is determined according to the voltage difference that a set condition is met, closing the discharge MOS of the second battery includes: When it is determined that the voltage difference is less than the first threshold, it is determined that the set condition is met, and the discharge MOS of the battery to be connected is closed.

8. The method according to claim 6, characterized in that Closing the charging MOS of the second battery, comprising: When it is determined that the first battery is in an idle state, a charging state, or a discharging state, the charging MOS of the battery to be connected is closed.

9. The method according to claim 8, characterized in that Monitoring the voltage difference between the second battery and the bus voltage, comprising: When it is determined that the first battery is in a charging state, a voltage difference between the second battery and a bus voltage is monitored.

10. The method according to any one of claims 1 to 4, characterized in that: Also includes: If the first battery is not connected to the bus, determining whether a third battery with a closed charging MOS is connected to the bus; If a third battery with a closed charging MOS is connected to the bus, a second battery with a voltage lower than the third battery is selected from batteries not connected to the bus; The discharge MOS of the second battery is closed.

11. The method according to any one of claims 1 to 4, characterized in that: Also includes: If the first battery is not connected to the bus, determining whether a third battery with a closed charging MOS is connected to the bus; If the third battery with a closed charging MOS is not connected to the bus, a fourth battery with the highest voltage is selected from the batteries not connected to the bus; The discharge MOS and the charge MOS of the fourth battery are closed.

12. The method according to any one of claims 1 to 4, characterized in that: Also includes: When it is determined that a battery needs to be connected in a stand-alone manner, a fifth battery is selected from batteries not connected to the bus; The fifth battery charging MOS and discharging MOS are closed to complete the parallel operation.

13. A battery parallel management device, characterized in that: The device comprises: A judgment module, when determining that a battery needs to be connected in parallel, judges whether the first battery with a closed discharge MOS is connected to the bus; A selection module, if the first battery is connected to the bus, selects a second battery to be connected in parallel from batteries not connected to the bus; A first closing module, closing the discharge MOS of the second battery when determining that the voltage of the second battery is less than the bus voltage; The second closing module monitors the battery parameters of the second battery, and when it is determined according to the battery parameters that a set condition is met, closes the charging MOS of the second battery to complete the parallel operation.

14. A battery parallel management device, characterized in that: The battery parallel management device comprises: At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute the battery parallel management method as described in any one of claims 1-12.

15. A battery management system, characterized in that: include: A battery pack includes a plurality of battery circuits, each battery circuit includes a power source, a charging MOS, a discharging MOS and a pre-charging MOS, the charging MOS and the pre-charging MOS are connected in parallel, the positive electrode of each power source is connected to the positive electrode of the bus, and the negative electrode of each power source is connected to the negative electrode of the bus via the charging MOS and the discharging MOS connected in series; The battery parallel management device as described in claim 14 is connected to the bus and controls the charging MOS, discharging MOS and pre-charging MOS of each battery circuit respectively through control signals.

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