Battery management system of sodium salt battery

Abstract

The invention relates to the technical field of battery management, and discloses a battery management system of sodium salt batteries, which comprises an upper computer and a battery management system BMS of at least two sodium salt batteries, each BMS corresponds to a battery pack consisting of a plurality of sodium salt batteries, and each BMS is used for collecting battery data of each sodium salt battery in the corresponding battery pack in real time, drawing a voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into a plurality of segments according to the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to one platform voltage of the sodium salt battery, so that the sodium salt battery is controlled to be charged and discharged in each segment according to charging and discharging parameters preset for each platform voltage of the sodium salt battery; wherein all the BMSs are connected in parallel, so that the upper computer controls all the BMSs at the same time. The BMS can adapt to the charging and discharging characteristics of the sodium salt battery, and the performance of the sodium salt battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a battery management system for a sodium salt battery. Background Art

[0002] Sodium-nickel chloride battery, also known as sodium salt battery, is a new type of secondary battery developed from sodium sulfur battery. Compared with sodium sulfur battery, lead-acid battery and lithium battery, sodium salt battery has the advantages of high safety, stable properties, easy access to raw materials, economical cost and environmental friendliness, so sodium salt battery has attracted much attention in the market.

[0003] A battery management system (BMS) is a system used to monitor and protect rechargeable batteries (such as lithium-ion batteries) to ensure that the batteries operate in a safe, reliable and efficient state. BMS systems are very important in electric vehicles, energy storage systems, power tools and other equipment that use rechargeable batteries.

[0004] However, most of the current BMS systems are designed for lithium iron batteries, while sodium salt batteries started later than traditional lithium iron batteries and developed more slowly than lithium iron batteries. Many manufacturers do not know enough about sodium salt batteries. There are significant differences in the charge and discharge characteristics of sodium salt batteries and lithium iron batteries. For example, sodium salt batteries have multiple platform voltages during the charge and discharge process, while lithium iron batteries only have one platform voltage; sodium salt batteries have a wider discharge platform, the battery cell can be discharged to 0V, and the single cell voltage can be discharged below 1.2V in actual use, while the discharge voltage platform of lithium iron batteries is usually between 3.2V and 3.4V.

[0005] Therefore, the BMS system of lithium-iron batteries cannot adapt to the charging and discharging characteristics of sodium salt batteries, and has poor compatibility with sodium salt batteries, which limits the performance of sodium salt batteries. Summary of the invention

[0006] The object of the present invention is to provide a battery management system for a sodium salt battery, which can adapt to the charge and discharge characteristics of the sodium salt battery.

[0007] To solve the above technical problems, an embodiment of the present invention provides a battery management system for sodium salt batteries, comprising: a host computer and at least two battery management systems BMS, each BMS corresponding to a battery pack consisting of a plurality of sodium salt batteries; Each BMS is used to collect battery data of each sodium salt battery in the corresponding battery pack in real time, and draw a voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into a plurality of segments according to the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to a platform voltage of the sodium salt battery, so as to control the charging and discharging of the sodium salt battery in each segment by the charge and discharge parameters preset for each platform voltage of the sodium salt battery; Among them, each BMS is provided with a P+ interface, a P- interface, an upper communication interface and a lower communication interface, and all BMSs are connected in parallel in the following manner: the P+ interfaces of two adjacent BMSs are connected to each other, the P- interfaces are connected to each other, and the P+ interface and P- interface of each BMS are connected to the power supply; the lower communication interface of the previous level BMS is connected to the upper communication interface of the next level BMS, and the upper communication interface of the first level BMS is connected to the host computer, so that the host computer controls the battery packs of at least two BMSs; each BMS receives messages sent by the host computer or the previous level BMS through the upper communication interface, and sends messages to the next level BMS through the lower communication interface, so that the host computer controls all BMSs at the same time.

[0008] Optionally, the communication upper interface of the first-level BMS includes a CAN-H interface and a CAN-L interface; The first-level BMS is connected to the H interface of the CAN box through the CAN-H interface, and is connected to the L interface of the CAN box through the CAN-L interface, and the CAN box is connected to the host computer, so that the host computer and at least two BMSs communicate through the CAN box.

[0009] Optionally, each of the BMSs further includes an EMS communication interface, the EMS communication interface of the first-level BMS is connected to an EMS communication power supply, and the EMS communication interfaces of two adjacent BMSs are connected to each other, so that at least two BMSs communicate through the EMS.

[0010] Optionally, each of the BMS further comprises: a charging relay, a discharging relay, a diode, a shunt, a fuse and a lotus plug; When charging the battery pack of each BMS, the charging relay is closed, and the input current of the external power supply flows into the battery pack through the circuit composed of the P+ interface, the diode, the charging relay, and the positive electrode of the shunt, and the circuit composed of the P- interface, the fuse, and the negative electrode of the shunt; When discharging the battery pack of each BMS, the discharge relay is closed, and the discharge current of the battery pack flows into the external power supply through the circuit composed of the lotus plug, the positive pole of the shunt, the diode, the discharge relay, and the P+ interface, and the circuit composed of the lotus plug, the negative pole of the shunt, the fuse, and the P- interface.

[0011] Optionally, any one of the at least two BMSs is a master control BMS, and the remaining BMSs are slave control BMSs; The master BMS is used to control the battery packs of all slave BMSs according to the messages sent by the host computer.

[0012] Optionally, each of the BMSs is further used to charge and discharge the sodium salt battery in the corresponding battery pack when the sodium salt battery is at 250-350° C. according to the battery data collected in real time.

[0013] Optionally, each of the BMSs is further configured to charge and discharge the sodium salt battery in the corresponding battery pack when the sodium salt battery is at 280° C. according to the battery data collected in real time.

[0014] Optionally, the operating environment temperature of each BMS is -40°C to 60°C.

[0015] The battery management system for sodium salt batteries provided by the present invention has at least the following beneficial effects: In the case of sodium salt batteries, each BMS in the battery management system of the present invention collects the battery data of each sodium salt battery in the corresponding battery pack in real time, and draws the voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into multiple segments by the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to a platform voltage of the sodium salt battery, so as to control the sodium salt battery to charge and discharge in each segment by the preset charge and discharge parameters for each platform voltage of the sodium salt battery. Taking into account the unique charge and discharge characteristics of the sodium salt battery, different charge and discharge strategies are adopted in different stages of charge and discharge (different platform voltages), which can effectively improve the performance of the sodium salt battery.

[0016] Moreover, by connecting at least two sodium salt battery BMSs in parallel, the host computer can control all sodium salt batteries in multiple BMSs through the parallel structure, which can not only increase the total capacity of the sodium salt battery group and extend the effective service time and energy storage capacity of the sodium salt battery, but also the characteristics of different sodium salt batteries are different. The parallel use can balance the state between each individual sodium salt battery, thereby improving the stability of the entire system. Among them, when each BMS is connected in parallel, the interface used for communication between each BMS is divided into an upper communication interface and a lower communication interface. Each BMS receives a message sent by the host computer or the previous level BMS through the upper communication interface, and sends a message to the next level BMS through the lower communication interface. The channels for sending and receiving messages are separated, which can improve the management efficiency of the sodium salt battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0018] Figure 1 is a schematic diagram of a battery management system for a sodium salt battery provided according to an embodiment of the present invention; Figure 2 is a schematic diagram of the charging and discharging principle of a sodium salt battery provided according to an embodiment of the present invention; Figure 3 is a schematic diagram of a housing of a BMS provided according to an embodiment of the present invention; Figure 4 It is a structural diagram of a BMS provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other without contradiction.

[0020] One embodiment of the present invention relates to a battery management system for a sodium salt battery. The implementation details of the battery management system for a sodium salt battery of this embodiment are described in detail below. The following content is only provided for the convenience of understanding the implementation details and is not necessary for implementing this solution.

[0021] The specific structure of the battery management system of the sodium salt battery of this embodiment can be as follows: Figure 1 As shown, it includes: a host computer and a battery management system BMS ( Figure 1 Only two BMSs are shown in the figure, wherein each BMS corresponds to a battery pack consisting of a plurality of sodium salt batteries, and each BMS is provided with a P+ interface, a P- interface, a communication upper interface and a communication lower interface.

[0022] The at least two BMSs are connected in parallel in the following manner: the P+ interfaces of two adjacent BMSs are connected to each other, the P- interfaces are connected to each other, and the P+ interface and P- interface of each BMS are connected to a power source; the lower communication interface of the previous BMS is connected to the upper communication interface of the next BMS, and the upper communication interface of the first BMS is connected to a host computer, so that the host computer controls the battery packs of at least two BMSs; wherein each BMS receives a message sent by the host computer or the previous BMS through the upper communication interface, and sends a message to the next BMS through the lower communication interface. After at least two BMSs are connected in parallel, the host computer can manage the sodium salt batteries in at least two BMSs, for example, collect battery parameters of the sodium salt batteries, control the charge and discharge of the sodium salt batteries through the P+ interface and the P- interface, etc.

[0023] Among them, each BMS is used to collect battery data of each sodium salt battery in the corresponding battery pack in real time, and draw a voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into multiple segments according to the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to a platform voltage of the sodium salt battery, so as to control the charging and discharging of the sodium salt battery in each segment through the charge and discharge parameters preset for each platform voltage of the sodium salt battery.

[0024] In the specific implementation, continue to see Figure 1 , the upper communication interface of the first-level BMS includes a CAN-H interface and a CAN-L interface. The first-level BMS is connected to the H interface of the CAN box through the CAN-H interface, and is connected to the L interface of the CAN box through the CAN-L interface, so that the host computer and at least two BMSs communicate through the CAN box. Among them, the upper communication interface of the first-level BMS is connected to the H interface and L interface of the CAN box through the RS-485 bus and the CAN bus, and then connected to the host computer. The host computer can display the specific parameters of the sodium salt battery of each BMS. At the same time, the lower communication interface of the first-level BMS is connected to the upper communication interface of the next level through the RS-485 bus, so as to be connected in parallel with it. If the number of BMS exceeds two, the parallel connection method of the subsequent BMS is similar, which will not be repeated here.

[0025] at the same time, Figure 1 The EMS communication interface and power supply interface (i.e., 12V / DET) of each BMS are also shown. The EMS communication interfaces of two adjacent BMSs are also interconnected. The EMS communication interface of the first-level BMS is connected to the EMS communication power supply, so that EMS communication can be performed between the host computer and at least two BMSs; the power supply interface is used to supply power to each BMS.

[0026] Due to the existence of the above-mentioned parallel BMS, the battery management system of the sodium salt battery of this embodiment has a higher battery terminal voltage acquisition range, which makes the battery terminal voltage acquisition range narrower and the acquisition accuracy higher; it also has a higher system voltage acquisition range, which makes the system voltage acquisition range narrower and the acquisition accuracy higher. At the same time, the parallel connection mode of the BMS also has the function of protecting the circuit. The distribution of current in the parallel circuit can protect the circuit components and prevent a certain component from being overloaded. At the same time, it can reduce interference and improve the quality of power supply. At the same time, it can also improve the reliability of the entire system and make the entire multifunctional battery management system more reliable. At the same time, it can also save costs, making the overall multifunctional battery management system more cost-effective. At the same time, it is also easier to maintain, which facilitates the maintenance of the overall multifunctional battery management system.

[0027] In one example, any one of the at least two BMSs is the master BMS, and the remaining BMSs are slave BMSs. The master BMS is used to control the battery packs of all slave BMSs. That is to say, in this embodiment, not only can each BMS be controlled by the host computer, but each slave BMS can also be controlled by the master BMS. Among them, each battery pack can be used as a master control. When a parallel battery pack has a master control, the slave control needs a machine number, and the slave control can automatically generate a machine number. The parallel connection method can be connected in parallel within 110. All batteries are consistent internally, and all batteries can be hosts. It is fool-proof and automatically connected, which is simple and convenient. At the same time, it has flexibility. Each BMS in the parallel circuit can be centrally controlled by the main switch or separately controlled by the branch switch to achieve independent work without affecting each other. The implementation method is to import a program that can be paralleled into the BMS, and then input relative command control through the BMS host computer to select the corresponding battery pack as the main control, reducing mutual interference between different branches, and solving the current problems that BMS cannot freely select any battery pack as the main control target, making it difficult to connect and complicated to operate, and the connection method is more flexible.

[0028] It should be noted that the battery management system of the sodium salt battery of this embodiment, when charging and discharging the battery pack of each BMS, specifically when the temperature of the battery pack of each BMS is between 250°C and 350°C, charges and discharges the battery pack of each BMS through the P+ interface and the P- interface. In actual implementation, specifically when the temperature of the battery pack of each BMS is at 280°C, charges and discharges the battery pack of each BMS through the P+ interface and the P- interface.

[0029] Each BMS also includes: a charging relay, a discharging relay, a diode, a shunt, a fuse, a lotus plug and a PCB board. The charging relay, the diode, the shunt, the fuse, the lotus plug and the PCB board are connected in sequence, and the discharging relay, the diode, the shunt, the fuse, the lotus plug and the PCB board are also connected in sequence.

[0030] At this time, the battery pack of each BMS is charged in the following manner: the charging relay is controlled to be closed, and current is input into the battery pack through an external power supply, so that the current passes through the charging relay, diode, shunt, fuse, lotus plug and PCB board of the battery pack in sequence; and the battery pack of each BMS is discharged in the following manner: the discharge relay is controlled to be closed, so that the discharge current of the battery pack passes through the PCB board, lotus plug, fuse, shunt, diode, discharge relay of the battery pack in sequence and then flows into the external power supply.

[0031] In the specific implementation, the charging and discharging principle of each BMS battery pack is as follows: Figure 2 As shown, when charging, the host computer program sends a charging instruction to control the charging relay to close, and the external power supply current enters the BMS through the charge and discharge +→diode→charging relay→shunt+; charge and discharge-→fuse, and shunt-line to start charging. When discharging, the host computer program sends a discharge instruction to control the discharge relay to close, and the discharge current enters the external load from the BMS through the lotus plug→shunt+→diode→discharge relay→charge and discharge+; lotus plug→shunt-→fuse→charge and discharge-.

[0032] In a specific example, the structure of each BMS is as follows Figure 3 and Figure 4As shown, it specifically includes: a shell 0, a heat sink 1, a PCB board 2, a connector 3, a switch 4, a relay 5, a diode 6 and a copper bus 7 arranged in the shell 0, and a positive power interface P+8, a negative power interface P-9, a display screen 10, a 12V power supply interface 11, an EMS communication interface 12, an upper communication interface 13, and a lower communication interface 14 arranged on the side of the shell 0. Among them, the radiator 1 in the BMS plays the role of allowing the BMS to dissipate heat better to reduce the temperature; the PCB board 2 controls the charging and discharging of the sodium salt battery; the connector 3 plays the role of connecting data; the switch 4 plays the role of controlling the start and stop of the BMS; the relay 5 plays the role of automatic adjustment, safety protection, conversion circuit, etc. in the BMS; the diode 6 plays the role of limiting the current protection circuit; the copper bus 7 plays the role of transmitting current and connecting electrical equipment in the circuit; the positive power supply interface 8 plays the role of inputting positive current; the negative power supply interface 9 plays the role of inputting negative current; the display screen 10 plays the role of displaying the relevant parameters of the BMS; the 12V power supply interface 11 plays the role of power supply; the EMS communication interface 12 plays the role of controlling EMS communication; the upper communication interface 13 plays the role of connecting the host computer; the lower communication interface 14 plays the role of connecting other BMS in parallel. The communication interface 13 arranged on the side of the BMS shell is connected to the H interface and L interface of the CAN box through the RS-485 bus and the CAN bus, and then connected to the host computer, so that the host computer can display the specific parameters of the sodium salt battery; the communication interface 14 arranged on the side of the BMS shell is connected in parallel with the CAN interface on the side of the shell of the BMS to be connected in parallel through the RS-485 bus when the parallel function is required, so as to realize the parallel function of the BMS.

[0033] Under the above structure, the working principle of the battery management system of the sodium salt battery of this embodiment is: the switch controls the startup of the entire BMS system. When the switch is turned on, the display screen starts to highlight, the system starts self-checking, and after the self-checking is completed, the display screen starts to display various parameters inside the sodium salt battery. If there is a fault, the corresponding fault code will be displayed on the display screen, otherwise it will not be displayed. When in use, turn on the button on the shell, start power supply, the display screen starts to highlight, the system starts self-checking, and when there is no fault, the real-time temperature, real-time voltage, real-time current and remaining capacity of the sodium salt battery will be displayed on the display screen. The host computer can detect the real-time temperature, voltage and current of the sodium salt battery through the probe in the sodium salt battery, so as to control the closing and shutting down of each protection circuit of the parallel BMS through the host computer. For example, when the temperature / voltage probe detects that the real-time temperature / voltage is higher than the threshold of the host computer over-temperature / over-voltage protection, the host computer performs over-temperature / over-voltage protection and shuts down the operation of the BMS. When the temperature / voltage is lower than the threshold again, the system self-checks and resumes normal operation when there is no fault.

[0034] The battery management system of the sodium salt battery of this embodiment is described in detail below: 1. Hardware parameters

[0035] 2. Basic control logic Its application modes are divided into manual mode and automatic mode.

[0036] (1) Manual mode: The voltage is not collected when the temperature is below 240°C. There are no functions or protections in this state.

[0037] (2) Automatic mode: BMS power activation - BMS cold state detection (BMS is defined as cold state when it is below 240°C. The BMS itself does not detect the battery pack voltage, nor does it allow external devices to detect the battery voltage) - heating (battery pack target temperature 285°C) - heating diagnosis (whether the temperature is greater than 285°C, and whether the battery pack insulation resistance, heating module, and acquisition unit are all normal) - preparation stage - charging and discharging. The operating temperature range of the BMS is 250-350°C (generally working at around 285°C). Each state switch requires corresponding time to switch.

[0038] (3) Protective disconnection: protective disconnection occurs when a fault occurs. This fault is a recoverable fault and the fault will be classified.

[0039] (4) Fault status, irrecoverable faults and human-intentioned software disconnection operations.

[0040] (5) Manual state switching: When the temperature meets the requirements, the system can switch to manual state from cold state detection, heating, temperature detection, system detection, operation, protective disconnection, and fault, and can control the BMS main power switch and heating switch.

[0041] A. The BMS main power switch and heating switch can only be controlled in manual mode.

[0042] B. The relay status can only be changed by manual clicking.

[0043] (6) Protective disconnection state switching: A. Protective disconnection can be achieved from cold detection, heating, temperature detection, system detection, operation, and manual mode.

[0044] B. The fault condition cannot lead to protective disconnection.

[0045] C. Recoverable: When entering protective disconnection, the system will automatically determine if the problem is resolved and can be used normally.

[0046] (7) Fault state switching: In case of man-made fault, cold state detection, heating, temperature detection, system detection, operation, manual mode, and protective disconnection can all go to fault state in any state.

[0047] Fault status release: The machine can only run after the fault is cleared. Click Clear Fault and the BMS will perform a self-check. If there is no abnormality, the machine will enter normal use.

[0048] 3. Functions: About the power-on self-test function: (1) Contactor: Determine whether the contactor is faulty by comparing the contactor switch status with the current collection value.

[0049] (2) Heater: Determine whether the heater is faulty by detecting the current value under different states.

[0050] (3) Battery temperature sensor: By comparing the temperature difference collected by the two RTDs, determine whether there is a fault.

[0051] (4) Battery voltage detection circuit: Determine whether there is a fault through the self-calibration circuit.

[0052] (5) Battery current detection circuit: By comparing the current values ​​collected at the positive and negative ends of the battery, determine whether there is a fault.

[0053] (6) RS485 and CAN communication circuit: Determine whether there is a fault based on the communication status.

[0054] About the functions of the system software: (1) Full power reset function; charge and discharge protection; detection sensor diagnosis; heater diagnosis; PID temperature control; temperature protection function; grounding diagnosis; electrical insulation diagnosis; short circuit diagnosis; thermal diagnosis; cold state diagnosis; thermal failure diagnosis; clock diagnosis; BMS panel temperature diagnosis; failed battery detection; power limitation; thermal insulation and other functions.

[0055] (2) BMS has built-in underlying default parameters, which can be modified later.

[0056] About hardware acquisition function: (1) Real-time clock recording. When the system is connected to a computer, the time can be updated synchronously with the computer.

[0057] (2) Voltage acquisition, which is divided into system voltage (external input voltage), bus real voltage and battery string voltage detection (string voltage is the middle point voltage in a string, which is the voltage of 10 batteries).

[0058] (3) Battery pack temperature collection and temperature detection on the BMS board (there are 2 temperature sensors in the battery pack, and the temperature sensor is RTD1000).

[0059] (4) Insulation detection and ground voltage detection require testing the leakage resistance of the positive and negative electrodes of the battery to the battery pack casing.

[0060] (5) Battery current collection and battery heating circuit current collection.

[0061] About hardware control function: (1) The 12V power supply system of BMS is powered by the external main power supply - high voltage. When there is no external power, it switches to battery power supply. At the same time, it can be connected to an external 12V power supply.

[0062] (2) Thermal management function: The heating circuit is turned on and off by a relay to control the battery to operate in the optimal temperature range.

[0063] (3) Relay control: Controls the opening and closing of the main power switch according to a certain main logic.

[0064] (4) Voltage collection circuit: When the battery temperature is low, the battery voltage will not be collected.

[0065] About communication and display functions: (1) CAN communication interface: can be used when cascading multiple battery packs to communicate with the host computer. Any cascade communication can be connected to the host computer software.

[0066] (2) The external LED displays the working status of the battery pack, which corresponds to the description in the logic.

[0067] (3) There is an indicator light on the outside, and the indicator light displays the following status: On: The system is powered on; Off: The system stops powering on; (4) The outside is equipped with a display screen, which can display the following: Battery pack ID number; total voltage; total current; battery capacity; battery temperature; fault code; (5) Host computer: The host computer can display some basic parameters, such as external voltage (can be displayed with external power supply), battery voltage (changes according to temperature), current, heating current, temperature, battery string voltage, etc. Secondly, it can also display the battery logic change status diagram.

[0068] Among them, the BMS host computer displays the built-in parameters (default parameters) of the lower computer, and at the same time realizes self-configurable functions (such as battery termination voltage, alarm fault voltage, alarm fault current, nominal capacity, etc.). This function configuration requires certain permissions to configure, and ordinary customers do not have the permission to modify it; the BMS host computer can control command buttons and view the logic diagram status. The command buttons of ordinary customers include "automatic operation", and those with development permissions will add some command buttons, "manual button", "heating switch", "main power switch"; the BMS host computer can input BMS code and battery pack code and other information, and this function configuration requires certain permissions to configure; the BMS design host computer needs to reserve this function. When the battery pack is replaced with a new BMS, the BMS can realize the transfer of the old system built-in data and historical accumulated data; the host computer can record the BMS data and store them in their respective folders; the host computer needs to display fault information; the host computer is in Chinese and English; Regarding troubleshooting and data logging: (1) Fault information: The fault diagnosis function includes relay fault diagnosis (such as relay adhesion detection), heater fault diagnosis, current sensor fault diagnosis, voltage acquisition circuit fault diagnosis, thermal insulation fault diagnosis and temperature sensor fault diagnosis, etc. The fault module will have a fault list.

[0069] (2) BMS data recording and exporting functions: It has certain data tracing and battery pack usage status functions. The data is divided into two categories: the first is the files stored inside the BMS, which need to be manually saved by the host computer; the second is that the battery is connected to the host computer to automatically create a folder with the battery pack serial number on the computer (naming rules: battery serial number_year, month, day), so as to record in real time.

[0070] In this embodiment, facing the sodium salt battery, each BMS in the battery management system collects the battery data of each sodium salt battery in the corresponding battery pack in real time, and draws the voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into multiple segments by the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to a platform voltage of the sodium salt battery, so as to control the sodium salt battery to charge and discharge in each segment by the charge and discharge parameters preset for each platform voltage of the sodium salt battery. Taking into account the unique charge and discharge characteristics of the sodium salt battery, different charge and discharge strategies are adopted at different stages of charge and discharge (different platform voltages), which can effectively improve the performance of the sodium salt battery.

[0071] Moreover, by connecting at least two sodium salt battery BMSs in parallel, the host computer can control all sodium salt batteries in multiple BMSs through the parallel structure, which can not only increase the total capacity of the sodium salt battery group and extend the effective service time and energy storage capacity of the sodium salt battery, but also the characteristics of different sodium salt batteries are different. The parallel use can balance the state between each individual sodium salt battery, thereby improving the stability of the entire system. Among them, when each BMS is connected in parallel, the interface used for communication between each BMS is divided into an upper communication interface and a lower communication interface. Each BMS receives a message sent by the host computer or the previous level BMS through the upper communication interface, and sends a message to the next level BMS through the lower communication interface. The channels for sending and receiving messages are separated, which can improve the management efficiency of the sodium salt battery.

[0072] Those skilled in the art can understand that the above embodiments are specific embodiments of the present invention, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention, so the protection scope of the embodiments of the present invention shall be based on the scope defined in the claims.

Claims

1. A battery management system for a sodium salt battery, characterized in that: include: A host computer and at least two battery management systems BMS, each BMS corresponding to a battery pack consisting of multiple sodium salt batteries; Each BMS is used to collect battery data of each sodium salt battery in the corresponding battery pack in real time, and draw a voltage-capacity curve of the sodium salt battery according to the battery data; the voltage-capacity curve is divided into a plurality of segments according to the voltage change rate indicated by the voltage-capacity curve, and each segment corresponds to a platform voltage of the sodium salt battery, so as to control the charging and discharging of the sodium salt battery in each segment by the charge and discharge parameters preset for each platform voltage of the sodium salt battery; Among them, each BMS is provided with a P+ interface, a P- interface, an upper communication interface and a lower communication interface, and all BMSs are connected in parallel in the following manner: the P+ interfaces of two adjacent BMSs are connected to each other, the P- interfaces are connected to each other, and the P+ interface and P- interface of each BMS are connected to the power supply; the lower communication interface of the previous level BMS is connected to the upper communication interface of the next level BMS, and the upper communication interface of the first level BMS is connected to the host computer, so that the host computer controls the battery packs of at least two BMSs; each BMS receives messages sent by the host computer or the previous level BMS through the upper communication interface, and sends messages to the next level BMS through the lower communication interface, so that the host computer controls all BMSs at the same time.

2. The battery management system for sodium salt batteries according to claim 1, characterized in that: The communication upper interface of the first-level BMS includes a CAN-H interface and a CAN-L interface; The first-level BMS is connected to the H interface of the CAN box through the CAN-H interface, and is connected to the L interface of the CAN box through the CAN-L interface, and the CAN box is connected to the host computer, so that the host computer and at least two BMSs communicate through the CAN box.

3. The battery management system for sodium salt batteries according to claim 1, characterized in that: Each of the BMSs further includes an EMS communication interface. The EMS communication interface of the first-level BMS is connected to an EMS communication power supply. The EMS communication interfaces of two adjacent BMSs are connected to each other, so that at least two BMSs can communicate with each other through the EMS.

4. The battery management system for sodium salt batteries according to claim 1, characterized in that: Each of the BMSs further includes: a charging relay, a discharging relay, a diode, a shunt, a fuse and a lotus plug; When charging the battery pack of each BMS, the charging relay is closed, and the input current of the external power supply flows into the battery pack through the circuit composed of the P+ interface, the diode, the charging relay, and the positive electrode of the shunt, and the circuit composed of the P- interface, the fuse, and the negative electrode of the shunt; When discharging the battery pack of each BMS, the discharge relay is closed, and the discharge current of the battery pack flows into the external power supply through the circuit composed of the lotus plug, the positive pole of the shunt, the diode, the discharge relay, and the P+ interface, and the circuit composed of the lotus plug, the negative pole of the shunt, the fuse, and the P- interface.

5. The battery management system for sodium salt batteries according to claim 1, characterized in that: Any one of the at least two BMSs is a master control BMS, and the remaining BMSs are slave control BMSs; The master BMS is used to control the battery packs of all slave BMSs according to the messages sent by the host computer.

6. The battery management system for sodium salt batteries according to claim 1, characterized in that: Each of the BMSs is also used to charge and discharge the sodium salt battery in the corresponding battery pack when the sodium salt battery is at 250-350° C. according to the battery data collected in real time.

7. The battery management system for sodium salt batteries according to claim 6, characterized in that: Each of the BMSs is also used to charge and discharge the sodium salt battery in the corresponding battery pack when the sodium salt battery is at 280° C. according to the battery data collected in real time.

8. The battery management system for sodium salt batteries according to claim 1, characterized in that: The operating environment temperature of each BMS is -40°C to 60°C.

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