A household energy storage series-parallel dual-purpose BMS circuit, battery pack and control method

Abstract

The application provides a household energy storage series-parallel dual-purpose BMS circuit, a battery pack and a control method. The household energy storage series-parallel dual-purpose BMS circuit comprises a battery pack, the battery pack comprises a plurality of series-connected battery monomers, the negative electrode of the battery pack is connected with a current sampling device and a negative electrode relay in series, the negative electrode relay is connected with a pre-charging circuit in parallel, the pre-charging circuit comprises a pre-charging relay and a pre-charging resistor connected in series, a voltage sampling device is electrically connected between the positive electrode and the negative electrode of the battery pack, the circuit further comprises an MCU, the MCU is electrically connected with the current sampling device, the voltage sampling device, a negative electrode relay driver and a pre-charging relay driver respectively, an AFE is further electrically connected between the positive electrode and the negative electrode of the battery pack, and the MCU is in communication connection with the AFE. The circuit can be compatible with high-voltage and low-voltage household energy storage schemes, has good universality and low cost, and a control method is provided, so that the installation difficulty of the battery pack is reduced, any setting is not needed, and high-voltage and low-voltage scenes can be automatically identified.

Description

TECHNICAL FIELD

[0001] The application relates to the field of household energy storage, in particular to a household energy storage series-parallel dual-purpose BMS circuit, a battery pack and a control method. BACKGROUND

[0002] In the existing household energy storage BMS, for example, Figure 1 , a low-voltage BMS parallel scheme is connected to both ends of an inverter through parallel connection of power lines, the inverter communicates with the battery pack through CAN communication, and the battery packs communicate with each other through CAN and 485. Figure 2 , a high-voltage BMS series scheme, the battery packs are connected in series with each other, and then the output of the total positive and total negative of the battery is controlled through a high-voltage control box to form a charging and discharging circuit, the high-voltage control box communicates with the battery pack through CAN, and the high-voltage control box communicates with the inverter through CAN.

[0003] In the early household energy storage BMS, the low-voltage scheme is mostly used, and now the high-voltage scheme is mostly used. At present, the low-voltage energy storage is developed first, and the high-voltage energy storage shows explosive growth. The existing market scheme separates the design and assembly of the high-voltage BMS and the low-voltage BMS, which increases the manufacturing difficulty and the project advancement speed. SUMMARY

[0004] The application provides a household energy storage series-parallel dual-purpose BMS circuit, a battery pack and a control method, which solves the defects that the high-voltage BMS and the low-voltage BMS scheme are separately designed and assembled in the existing market, which increases the manufacturing difficulty and the project advancement speed.

[0005] The technical scheme of the application is as follows:

[0006] The application provides a household energy storage series-parallel dual-purpose BMS circuit, a battery pack and a control method, which solves the defects that the high-voltage BMS and the low-voltage BMS scheme are separately designed and assembled in the existing market, which increases the manufacturing difficulty and the project advancement speed.

[0007] Further, the current sampling device is a current sensor or a current sampling circuit, and the voltage sampling device is a voltage collector or a voltage sampling circuit.

[0008] Further, more than one household energy storage series-parallel dual-purpose BMS circuit is connected through MCU communication, and the MCUs are connected through CAN and / or 485 mode communication.

[0009] The application further provides a battery pack, wherein the battery pack is provided with the household energy storage series-parallel dual-purpose BMS circuit.

[0010] Further, more than one battery pack is connected through MCU communication.

[0011] Further, the MCUs are connected through CAN and / or 485 mode communication.

[0012] The application further provides a control method, comprising the following steps:

[0013] (1) the BMS in the household energy storage series-parallel dual-purpose BMS circuit is started, enters self-checking, and after successful self-checking, communicates with other online BMS in the form of sending broadcast frames to inform other online BMS and enter competition;

[0014] (2) when there is only one BMS online, the corresponding pre-charging relay is closed, the negative electrode relay is disconnected, the battery pack is pre-charged, after pre-charging is completed, the pre-charging relay is disconnected, the negative electrode relay is closed, only one battery pack works, there is no series connection and parallel connection logic, and normal work is performed;

[0015] (3) when the number of online BMS is greater than 1, master-slave competition is performed according to the number of responding BMS, comparison is performed according to the SN number of the BMS, the BMS with a smaller SN number is used as the master, and the others are used as slaves;

[0016] (4) the master first closes the pre-charging relay and disconnects the negative electrode relay to enter pre-charging, after pre-charging is completed, the pre-charging relay is disconnected and the negative electrode relay is closed, the master commands the slave to pre-charge, and the slave receives the command and first detects whether the voltage sampling device has collected valid voltage through the MCU of the slave;

[0017] (5) when the voltage sampling device has collected valid voltage, it is indicated that the battery pack is in parallel mode, the slave informs the master and other slaves of the running mode being parallel, and the master and the slave run in parallel mode; in the parallel mode, each battery pack needs to be pre-charged, the pre-charging relay is closed, the negative electrode relay is disconnected, after pre-charging is completed, the negative electrode relay is closed, and the pre-charging relay is disconnected;

[0018] (6) when the voltage sampling device has not collected valid voltage, it is indicated that the battery pack is in series mode, the slave informs the master and other slaves of the running mode being series, and the master and the slave run in series mode; in the series mode, only the last battery pack after series connection needs to be pre-charged, the pre-charging relay is closed, the negative electrode relay is disconnected, and other battery packs can directly close the negative electrode relay and do not need to be pre-charged.

[0019] The circuit of the application can be compatible with high and low voltage household energy storage solutions, has good versatility, does not need to produce high voltage household energy storage BMS circuits and low voltage household energy storage BMS circuits separately, has low cost, and is easy to install; and a control method is proposed, which reduces the installation difficulty of the battery pack and does not need any setting, and automatically identifies high and low voltage scenes. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0021] Figure 1 For the existing low-voltage BMS parallel scheme;

[0022] Figure 2 For the existing high-voltage BMS series scheme;

[0023] Figure 3 For the circuit diagram of the household energy storage series-parallel dual-purpose BMS circuit of embodiment 1;

[0024] Figure 4 For the block diagram of the control method of embodiment 3.

[0025] In the drawings, reference numerals: 1-battery pack, 11-battery cell, 2-current sampling device, 3-negative relay, 4-charging relay, 5-pre-charging resistor, 6-voltage sampling device, 7-MCU, 8-AFE. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments only constitute some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0027] BMS (Battery Management System) battery system is commonly known as battery nanny or battery housekeeper, which is mainly for intelligent management and maintenance of each battery cell, preventing overcharging and overdischarging of the battery, prolonging the service life of the battery, and monitoring the state of the battery.

[0028] AFE (analog front end) is a battery sampling chip used in BMS to collect data such as cell voltage and temperature.

[0029] SN stands for Product Serial Number, also known as Machine Code, Authentication Code, or Registration Request Code.

[0030] Example 1

[0031] Reference Figure 3 A dual-purpose (series-parallel) BMS circuit for residential energy storage includes a battery pack comprising several battery cells connected in series. A current sampling device and a negative relay are connected in series at the negative terminal of the battery pack. A pre-charge circuit is connected in parallel to the negative relay, comprising a pre-charge relay and a pre-charge resistor connected in series. The negative relay is electrically connected to a negative relay driver, and the pre-charge relay is electrically connected to a pre-charge relay driver. A voltage sampling device is electrically connected between the positive and negative terminals of the battery pack. The circuit also includes an MCU, which is electrically connected to the current sampling device, the voltage sampling device, the negative relay driver, and the pre-charge relay driver. An AFE is also electrically connected between the positive and negative terminals of the battery pack, and the MCU is communicatively connected to the AFE.

[0032] Furthermore, the current sampling device is a current sensor or a current sampling circuit, and the voltage sampling device is a voltage acquisition device or a voltage sampling circuit.

[0033] Furthermore, one or more residential energy storage series-parallel dual-use BMS circuits are connected via MCU communication, and the MCUs are connected via CAN and / or 485 communication.

[0034] Example 2

[0035] The battery pack includes a dual-purpose (series-parallel) BMS circuit for residential energy storage. One or more of the battery packs are interconnected via an MCU, which in turn communicates with each other via CAN and / or RS-485.

[0036] Example 3

[0037] Reference Figure 4 A control method comprising the following steps:

[0038] (1) When the BMS in the dual-use BMS circuit of household energy storage series and parallel is started, it enters the BMS self-test. After the self-test is successful, it communicates with other online BMS by sending broadcast frames, notifies other online BMS and enters the competition.

[0039] (2) When there is only one BMS online, the corresponding pre-charging relay is closed, the negative relay is disconnected, the battery pack is pre-charged, after the pre-charging is completed, the pre-charging relay is disconnected, the negative relay is closed, only one battery pack works, there is no series and parallel logic, and normal work is performed;

[0040] (3) When the online BMS is greater than 1, according to the number of responding BMS, master-slave competition is performed, comparison is performed according to SN numbers of the BMS, the BMS with a smaller SN number is taken as a master, and others are taken as slaves;

[0041] (4) The master first closes the pre-charging relay, disconnects the negative relay, enters pre-charging, after the pre-charging is completed, the pre-charging relay is disconnected, the negative relay is closed, the master commands the slave to pre-charge, and the slave receives the command and first detects whether the voltage sampling device has collected an effective voltage through the self MCU;

[0042] (5) When the voltage sampling device has collected an effective voltage, it is indicated that the battery pack is in parallel mode, the slave informs the master and other slaves of the running mode being parallel, and the master and the slave run in parallel mode; in the parallel mode, each battery pack needs to be pre-charged, the pre-charging relay is closed, the negative relay is disconnected, after the pre-charging is completed, the negative relay is closed, and the pre-charging relay is disconnected;

[0043] (6) When the voltage sampling device has not collected an effective voltage, it is indicated that the battery pack is in series mode, the slave informs the master and other slaves of the running mode being series, and the master and the slave run in series mode; in the series mode, only the last battery pack after series needs to be pre-charged, the pre-charging relay is closed, the negative relay is disconnected, and other battery packs can directly close the negative relay and do not need to be pre-charged.

[0044] The circuit of the application can be compatible with high and low voltage household energy storage schemes, has good universality, does not need to produce high voltage household energy storage BMS circuits and low voltage household energy storage BMS circuits separately, has low cost, and is convenient to install; and a control method is provided, the installation difficulty of the battery pack is reduced, any setting is not needed, and high and low voltage scenes are automatically identified.

[0045] The above only describes preferred embodiments of the application and is not used to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A dual-use BMS circuit for residential energy storage series and parallel connection, characterized in that: The system includes a battery pack, which comprises several battery cells connected in series. A current sampling device and a negative relay are connected in series at the negative terminal of the battery pack. A pre-charge circuit is connected in parallel to the negative relay. The pre-charge circuit includes a pre-charge relay and a pre-charge resistor connected in series. The negative relay is electrically connected to a negative relay driver, and the pre-charge relay is electrically connected to a pre-charge relay driver. A voltage sampling device is electrically connected between the positive and negative terminals of the battery pack. The system also includes an MCU, which is electrically connected to the current sampling device, the voltage sampling device, the negative relay driver, and the pre-charge relay driver. An AFE is also electrically connected between the positive and negative terminals of the battery pack, and the MCU communicates with the AFE. The control method includes the following steps: (1) When the BMS in the dual-use BMS circuit of household energy storage series and parallel is started, it enters the BMS self-test. After the self-test is successful, it communicates with other online BMS by sending broadcast frames to notify other online BMS and enter the competition. (2) When only one BMS is online, the corresponding pre-charge relay is closed and the negative relay is opened, and the battery pack is pre-charged. After the pre-charge is completed, the pre-charge relay is opened and the negative relay is closed. Only one battery pack is working. There is no series or parallel logic, and it works normally. (3) When the number of online BMS is greater than 1, master-slave competition is carried out according to the number of responding BMS. The BMS with the smaller SN number is selected as the master and the others are slaves. (4) The host first closes the pre-charge relay and opens the negative relay to enter the pre-charge. After the pre-charge is completed, the host opens the pre-charge relay and closes the negative relay. The host commands the slave to perform pre-charge. After receiving the command, the slave first checks whether the voltage sampling device has collected an effective voltage through its own MCU. (5) When the voltage sampling device collects an effective voltage, it indicates that the battery pack is in parallel mode. The slave device notifies the master device and other slave devices that the operation mode is parallel. The master device and slave devices operate in parallel mode. In parallel mode, each battery pack needs to be pre-charged. Close the pre-charge relay and open the negative relay. After pre-charging, close the negative relay and open the pre-charge relay. (6) When the voltage sampling device does not collect an effective voltage, it indicates that the battery pack is in series mode. The slave device notifies the master and other slave devices that the operation mode is series. The master and slave devices operate in series mode. In series mode, only the last battery pack in series needs to be pre-charged. Close the pre-charge relay and open the negative relay. Other battery packs can directly close the negative relay without pre-charging.

2. The dual-purpose (series and parallel) BMS circuit for residential energy storage as described in claim 1, characterized in that: The current sampling device is a current sensor or a current sampling circuit, and the voltage sampling device is a voltage acquisition device or a voltage sampling circuit.

3. The dual-purpose (series and parallel) BMS circuit for residential energy storage as described in claim 1, characterized in that: One or more residential energy storage series-parallel dual-use BMS circuits are connected via MCU communication, and the MCUs are connected via CAN and / or 485 communication.

4. A battery pack, characterized in that: The battery pack includes the residential energy storage series-parallel dual-purpose BMS circuit as described in claim 1.

5. The battery pack as described in claim 4, characterized in that: One or more of the battery packs are connected via MCU communication.

6. The battery pack as described in claim 5, wherein the MCUs are connected via CAN and / or 485 communication.

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