CN113497745B

CN113497745B - BMS networking method based on Can communication

Info

Publication number: CN113497745B
Application number: CN202010260035.4A
Authority: CN
Inventors: 李�杰; 蔡学峰
Original assignee: Shenzhen Ubetter Technology Co ltd
Current assignee: Shenzhen Ubetter Technology Co ltd
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2022-11-18
Anticipated expiration: 2040-04-03
Also published as: CN113497745A

Abstract

The invention discloses a BMS networking method based on Can communication, which comprises the following steps: firstly, each BMS collects the voltage value of the BMS as a unique identifier; secondly, each BMS sends a data packet containing a voltage value to a Can bus; then each BMS compares the received voltage values of all BMSs except the BMS on the Can bus, and the BMS with the highest voltage is selected as a server to work; then the server sends a specified data packet to other BMSs to specify the addresses of the other BMSs; and finally, all BMSs perform re-networking according to the addresses. The invention uses the voltage of the battery as the identification of the equipment, thereby solving the problem of how to identify a plurality of BMSs; according to the difference of the time points of sending data according to different voltages, the problem of upper blockage of the Can bus is solved, all BMSs Can receive and send data, and the working stability of the whole system is ensured.

Description

BMS networking method based on Can communication

Technical Field

The invention relates to the field of batteries, in particular to a BMS networking method based on Can communication.

Background

BMS, BATTERY MANAGEMENT SYSTEM for short, namely a BATTERY management system, is a link between a BATTERY and a user and is mainly used on a vehicle-mounted power BATTERY. The BMS can realize important functions of real-time monitoring, automatic equalization, intelligent charging and discharging and the like of the battery, effectively guarantees the safety of the battery, can realize monitoring of the residual electric quantity of the battery, can improve the endurance mileage of the electric automobile through effective battery management, is an indispensable important part in a power battery pack, and has great significance for the normal operation of the electric automobile.

When a plurality of common batteries are used in parallel, the capacity Can be effectively increased under the condition of not changing a system, but for the BMS, if the batteries are simply connected in parallel, networking conflicts Can be caused, so that the whole Can bus is influenced, and how to solve the networking conflicts is a problem to be urgently solved.

Disclosure of Invention

Aiming at the defects in the technology, the invention provides the BMS networking method based on the Can communication, which Can effectively solve the problem of networking conflict.

In order to achieve the purpose, the application discloses a BMS networking method based on Can communication, which is a networking method suitable for parallel use of a plurality of batteries and comprises the following steps:

s1, each BMS collects the voltage value of the BMS as a unique identifier;

s2, each BMS sends a data packet containing a voltage value to a Can bus;

s3: the voltage values of all BMSs except the BMS on the Can bus received by each BMS are compared, and the BMS with the highest voltage is selected as a server to work; if the BMS voltage of the user is lower than the highest voltage, entering a waiting state;

s4: the server sends a designated data packet to other BMSs, and the addresses of the other BMSs are designated in a manner that the sent voltage values serve as identifiers of the BMSs;

s5: all BMS re-networking according to the address.

Preferably, a plurality of BMSs and a Can bus need to be connected together before step S1, and the Can bus wakes up all the BMSs when communication is performed.

Preferably, in step S2, in order to avoid bus contention, a communication conflict of data of the plurality of BMSs is resolved, and when communication is performed, the remaining number N of the specified value of the battery voltage is waited for as a waiting time, and when the waiting time is reached, a packet is transmitted to the Can data bus.

Preferably, in step S3, before comparing the voltage values, it is necessary to wait for 2*N to ensure that all BMS information can be received; after selecting the corresponding BMS as the server, the address of the server is set to 0XF0.

Preferably, in step S4, after the server determines, a proceed server declaration packet is sent, and then the server sends a data packet whose address indicates the server identifier to the Can bus according to the voltage of the other BMS serving as the identifier, and the respective BMS voltage value designates the address of the other BMS located on the Can bus, so that the other BMS operates as the client.

Preferably, the server further needs to send an inquiry packet to the remaining BMS before step S4 to determine whether the other BMS is online.

Preferably, after the step S5, the method further includes a control step of controlling the other BMSs by the server, and when performing the discharging, sequentially turning on the discharging switches of the BMSs in descending order according to the voltage of each BMS; when charging, the charging switch of the BMS is sequentially turned on in the order from low to high.

Preferably, when the server has determined that a new BMS is added to the Can bus, the server receives the voltage value of the new BMS and sends a declaration packet to the new BMS so that the new BMS receiving the notification is incorporated into the Can bus as a new client of the server.

Preferably, if the server has not been determined, the voltage of the newly added BMS is compared with other previous BMSs, thereby re-networking the determination server.

The beneficial effects of the invention are: the voltage of the battery is used as the identifier of the equipment, and because the voltage of each battery is different, the batteries are connected in series and combined together, and the obtained voltage values of the BMSs are also different, so that the problem of how to identify the BMSs is solved; then according to the difference of the time point of different voltage sending data to the problem of Can bus's last jam has been solved, makes all BMS Can both carry out the receipt and the sending of data, to the BMS that adds afterwards, no matter the size of voltage, directly works as the customer end, has saved the step of network deployment again, ensures the stability of whole Can bus work.

Drawings

FIG. 1 is a flow chart of the steps of the present application;

fig. 2 is a schematic diagram of a single BMS of the present application;

fig. 3 is a schematic diagram of a parallel connection of a plurality of BMSs according to the present application.

Detailed Description

In order to more clearly describe the present invention, the present invention will be further described with reference to the accompanying drawings.

Referring to fig. 1, the present invention discloses a BMS networking method based on Can communication, which is suitable for networking a plurality of batteries in parallel, and includes the following steps:

s1, each BMS collects the voltage value of the BMS as a unique identifier;

s2, each BMS sends a data packet containing a voltage value to a Can bus;

s3: each BMS compares the received voltage values of all BMSs except the BMS on the Can bus, and the BMS with the highest voltage is selected as a server to work; if the BMS voltage is lower than the highest voltage, entering a waiting state;

s4: the server sends a specified data packet to other BMSs, and specifies the addresses of the other BMSs;

s5: all BMS re-networking according to the address.

In this embodiment, by using the above steps, a plurality of BMSs are combined into a Can bus to supply power to an external device, and by selecting the highest-voltage BMS as a server, more specifically, if all the other BMS received by one BMS is lower than its own voltage value, the BMS itself operates as a server; if the BMS voltage of the BMS is lower than the highest voltage, the BMS enters a waiting state, the addresses of other BMSs are designated after the address of the server is determined, so that all BMSs have unique addresses, the voltage values sent are used as identifiers of other BMSs in a determining mode, and each BMS has an independent voltage acquisition value to perform networking again according to the addresses, so that networking conflicts are effectively solved, and the capacity is effectively increased under the condition of not changing the system.

In a specific embodiment, the Can bus wakes up all BMS when communicating; in order to avoid bus contention, communication conflict of data of a plurality of BMSs is solved, when communication is carried out, the specified numerical value remainder N of the battery voltage is waited for as waiting time, and after the waiting time is reached, a data packet is sent to the Can data bus. Different BMSs can not be distinguished from each other in terms of hardware, but because the batteries forming the BMSs are different, the internal resistances of the batteries are different, and the voltages of the batteries are different, the different BMSs can be distinguished from each other according to the voltage; for example, 20 strings of batteries are used, the collected voltage interval is 54000-84000mV, the probability of voltage equality is very low, and in addition, because AD sampling is carried out, the data sampled every time are different, the voltage can be used as a mark; and because different BMSs have different voltages, the problem of bus congestion is solved by using the fact that the time points of sending data by using different voltages are different, all BMSs are mounted on a bus, only one BMS can send data at the same time, and other BMSs can only monitor. To avoid bus congestion, when the BMS wakes up, data is sent simultaneously, with the remainder of time N of this voltage as the base point. When arriving at the device, communication is started, so as to avoid interference, and certainly in order to realize fast networking, N takes a small value as much as possible, in an embodiment, the communication rate of the Can bus is generally 250 kbps, the bytes sent per second is about 30 kbytes, the size of the Can data packet is 12 bytes, the number of the Can data packets sent per second is 2604 data packets, and therefore, for one BMS, the probability of collision per second is 1/2604, and therefore, the probability of collision is very low.

In a specific embodiment, the time of 2*N needs to be waited before the voltage values are compared; after the BMS is selected as the server, setting the address of the server to be 0XF0, and certainly, carrying out self-defining setting on the address by related professionals according to requirements; after the server determines that the voltage of other BMSs is used as an identifier, the server sends an address reference data packet to the address reference data packet so as to designate the addresses of the other BMSs and enable the other BMSs to work as clients; the server also needs to send out inquiry packets to the other BMSs to determine whether the other BMSs are in an online state. More specifically, the BMS having the highest voltage is used as a server, a server announcement packet is transmitted to the other BMSs located on the same bus to inform the other BMSs that the server already exists, and the voltage is used as an identifier to determine the address of each BMS.

Certainly, the method also comprises a control step except the steps, wherein the server controls other BMSs, and when the BMSs are discharged, the discharge switches of the BMSs are turned on according to the voltage difference of each BMS and the sequence from high to low; when charging, the charging switch of the BMS is sequentially turned on in the order from low to high. After the step S5, an adding step is further included, when the server has determined that the new BMS to be added enters the Can bus, the server receives the voltage value of the new BMS and sends a declaration packet to the new BMS, so that the new BMS that is received is incorporated into the Can bus as a new client of the server to work. If the server is not determined, the voltage of the newly added BMS is compared with other previous BMSs, thereby re-networking the determined server. In a specific embodiment, if the current network is completely assembled, the later-accessed BMS detects the existence of the server, the later-accessed BMS directly joins the service network as one client, so that the operation is more convenient and faster, and if the later-accessed BMS does not detect the server, all BMSs on the Can bus are re-assembled.

The invention has the advantages that:

1) Different BMSs are identified by having different voltages;

2) The time points of sending data by different voltages are different, and the problem of bus blockage is solved.

3) The BMS of the rear access bus is quickly networked.

The above disclosure is only an example of the present invention, but the present invention is not limited thereto, and any variations that can be made by those skilled in the art should fall within the scope of the present invention.

Claims

1. A BMS networking method based on Can communication is characterized in that the method is suitable for networking a plurality of batteries which are used in parallel, and comprises the following steps:

s1, each BMS collects the voltage value of the BMS as a unique identifier; s2, each BMS sends a data packet containing a voltage value to a Can bus; s3: the BMS receives voltage values of all BMSs except the BMS on the Can bus, compares the voltage values, and selects the BMS with the highest voltage as a server to work; if the BMS voltage of the battery is lower than the highest voltage, entering a waiting state; s4: the server sends a designated data packet to other BMSs, and the addresses of the other BMSs are designated in a manner that the sent voltage values serve as identifiers of the BMSs;

s5: all BMSs perform re-networking according to the addresses;

in step S2, in order to avoid bus contention, communication conflict of data of a plurality of BMSs is solved, when communication is carried out, the remainder N of the battery voltage designated numerical value is waited as waiting time, and when the waiting time is reached, a data packet is sent to a Can data bus;

in step S3, before comparing the voltage values, it is necessary to wait for 2*N to ensure that all BMS information can be received; after the corresponding BMS is selected as the server, the address of the server is set to 0XF0.

2. The BMS networking method according to Can communication of claim 1, characterized in that a plurality of BMSs and Can buses need to be connected together before step S1, and when communication is performed, the Can buses wake up all BMS.

3. The Can communication-based BMS networking method according to claim 1, wherein in step S4, after the server determines, a server declaration packet is sent, and then the server sends a data packet with an address indicating a server identifier to the Can bus according to voltage values of other BMS as an identifier, and assigns other BMS addresses on the Can bus according to the BMS voltage values, so that the other BMS Can work as a client.

4. The BMS networking method according to claim 1, wherein the server further needs to send an inquiry packet to the remaining BMSs to determine whether the other BMSs are online before step S4.

5. The Can communication-based BMS networking method according to claim 1, further comprising a control step after step S5, wherein the server controls other BMSs and turns on the discharge switches of the BMSs in the descending order according to the voltage difference of each BMS when discharging; when charging, according to from low to high order, turn on BMS's charge switch according to this.

6. The Can communication-based BMS networking method according to claim 1, further comprising an adding step after the step S5, wherein when the server has determined that a new BMS is added to the Can bus, the server receives a voltage value of the new BMS and sends a declaration packet to the new BMS so that the new BMS operates as a new client of the server incorporated into the Can bus.

7. The Can communication-based BMS networking method of claim 6, wherein if the server has not been determined, the newly added BMS is compared in voltage with other previous BMSs to re-network the determined server.