Circuit and software strategy method for improving CAN communication stability

Abstract

The invention discloses a circuit for improving CAN communication stability and a software strategy method, the circuit comprises an ECU module and a BCU module, the ECU module comprises a plurality of ECUs, the ECUs are connected with the BCU module through CAN wire harnesses, the ECUs are connected with each other through wire harnesses, each wire harness is provided with an MOS tube, and the on-off of the MOS tubes is enabled by using a BMS high-side drive so as to control the on-off of the wire harnesses among the ECUs; the CAN wire harness is also provided with an MOS tube, and the on-off of the MOS tube is enabled by using a BMS high-side drive so as to control the on-off of the CAN wire harness; and the BMS high-side drive realizes on-off through software logic. According to the circuit and the method, the situation that the ECU cannot communicate due to the fact that the CANH-CANL loop is abnormal when the ECU at a certain position is completely lost can be avoided, the situation that communication of the ECU at a certain position of the whole vehicle is lost and cannot be recovered normally is avoided, the running stability of the whole vehicle is improved, and maintenance is convenient.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of CAN communication, and particularly relates to a circuit and a software strategy method for improving CAN communication stability. BACKGROUND

[0002] At present, a large commercial vehicle often uses CAN communication with strong transmission capacity and long transmission distance as the main mode of controller communication due to the large vehicle volume, long distance between ECUs, large battery pack volume and long wiring distance. However, the CAN loop does not have a loop design similar to the daisy chain communication. Abnormality of the CANH-CANL loop at any place often leads to complete loss of an ECU at a certain place of the vehicle, causes the vehicle to be unable to collect information about the ECU, directly causes the ECU at the place to completely fail to realize the function, the function loss of the vehicle cannot be self-recovered, and the vehicle triggers a serious fault, which must be returned to the factory for on-site maintenance by after-sales personnel. The maintenance process is complex, affects the driving experience of the customer, and wastes more after-sales cost. SUMMARY

[0003] The purpose of the application is to provide a circuit and a software strategy method for improving CAN communication stability, which can avoid the communication failure of the ECU caused by the abnormality of the CANH-CANL loop when the ECU at a certain place is completely lost, avoid the communication loss of the ECU at a certain place of the vehicle and the normal self-recovery, improve the running stability of the vehicle, and facilitate maintenance.

[0004] To achieve the above purpose, the application provides a circuit for improving CAN communication stability, which comprises an ECU module and a BCU module. The ECU module comprises a plurality of ECUs. The ECUs and the BCU module are connected through a CAN wire harness. Each ECU is connected with each other through a wire harness. Each wire harness is provided with a MOS tube. A BMS high-side drive is used to enable the MOS tube to be on or off, so as to control the on or off of the wire harness between each ECU. The CAN wire harness is also provided with a MOS tube. The BMS high-side drive is used to enable the MOS tube to be on or off, so as to control the on or off of the CAN wire harness. The BMS high-side drive realizes the on or off through software logic.

[0005] As a further scheme of the application, the ECU module comprises at least three ECUs.

[0006] As a further solution of the present invention: the three ECUs are ECU-A, ECU-B, and ECU-C. ECU-A is connected to the A-CANH interface and the A-CANL interface on the BCU respectively through two wiring harnesses, that is, forming an ACAN. A MOS transistor MOS-AH is provided on the wiring harness connected to the A-CANH interface, and a MOS transistor MOS-AL is provided on the wiring harness connected to the ECU-A and the A-CANL interface; the MOS transistors MOS-AH and MOS-AL are respectively connected to the BMS high-side driver AH and high-side driver AL on the BCU module; ECU-B is connected to the B-CANH interface and the B-CANL interface on the BCU respectively through two wiring harnesses, that is, forming a BCAN. A MOS tube MOS-BH is provided on the wiring harness connecting ECU-B and the B-CANL interface, and a MOS tube MOS-BL is provided on the wiring harness connecting ECU-B and the B-CANL interface. The MOS tubes MOS-BH and MOS-BL are respectively connected to the BMS high-side driver BH and high-side driver BL on the BCU module; ECU-C is respectively connected to the C-CANH interface and the C-CANL interface on the BCU through two wiring harnesses, that is, forming CCAN, a MOS tube MOS-CH is provided on the wiring harness connected to the C-CANH interface, and a MOS tube MOS-CL is provided on the wiring harness connecting ECU-C and the C-CANL interface. The MOS tubes MOS-CH and MOS-CL are respectively connected to the BMS high-side driver CH and high-side driver CL on the BCU module;

[0007] Two wiring harnesses are also connected to the wiring harness of the MOS tube MOS-AH near the ECU-A end. One wiring harness is connected to the wiring harness of the MOS tube MOS-BH through the MOS tube MOS-ABH, and the connection point is located between the MOS tube MOS-BH and ECU-B; the other wiring harness is connected to the wiring harness of the MOS tube MOS-CH through the MOS tube MOS-ACH, and the connection point is located between the MOS tube MOS-CH and ECU-C; the wiring harness of the MOS tube MOS-AL near the ECU-A end is connected to two wiring harnesses, one of which is connected to the wiring harness of the MOS tube MOS-BL through the MOS tube MOS-ABL, and the connection point is located between the MOS tube MOS-BH and The wiring harness connecting the MOS tube MOS-BH to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCH to the wiring harness connecting the MOS tube MOS-CH, and the connection point is between the MOS tube MOS-CH and ECU-C; the wiring harness connecting the MOS tube MOS-BL to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCL to the wiring harness connecting the MOS tube MOS-CL, and the connection point is between the MOS tube MOS-CL and ECU-C.

[0008] A software strategy method for improving CAN communication stability is applied to the above-mentioned circuit for improving CAN communication stability, including the following steps: the BMS is compatible with all communication protocols and functional processes of ACAN, BCAN, and CCAN on any CAN channel of ACAN, BCAN, and CCAN, and its respective CAN functional modules are defined as SOFT-A, SOFT-B, and SOFT-C, and the theoretical CAN load rate of each branch is calculated as LOAD-A, LOAD-B, and LOAD-C respectively; the number of ACAN communication faults, BCAN communication faults, or CCAN communication faults and the duration of single triggering are recorded separately, and different degrees of fault handling are performed according to the number and duration of fault triggering. The specific plan is as follows:

[0009] 1) When the number of ACAN communication timeout fault triggering times is ≥10 times or the duration of a single ACAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the ACAN, and the fault is recorded as FAULT-ACAN;

[0010] 2) When the number of BCAN communication timeout fault triggering times is ≥10 times or the duration of a single BCAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the BCAN and the fault is recorded as FAULT-BCAN;

[0011] 3) When the number of CCAN communication timeout fault triggers is ≥10 times or the duration of a single CCAN communication timeout is >1 hour or the cumulative fault trigger duration is >24 hours, it is considered that there is a serious CCAN communication abnormality and the fault is recorded as FAULT-CCAN;

[0012] When the system detects that any one of FAULT-ACAN, FAULT-BCAN or FAULT-CCAN is triggered, the BMS requests to limit the power to 0%. When the vehicle bus current is less than 1A, the vehicle is considered to be stationary and the plan A, plan B, plan C or plan D is executed.

[0013] As a further solution of the present invention: Solution A: When the BMS confirms FAULT-ACAN and the BMS does not perform any detection on the ACAN circuit, the FAULT status of the BCAN and CCAN is determined.

[0014] a: If both FAULT-BCAN and FAULT-CCAN exist, no processing is performed;

[0015] b: If FAULT-BCAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-A function is compatible with BCAN;

[0016] c: If FAULT-BCAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-A function is compatible with CCAN;

[0017] d: If FAULT-BCAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of BCAN and CCAN, disconnects the BMS high-side driver MOS-AH and MOS-AL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-ACH and MOS-ACL, making the BMS SOFT-A function compatible with BCAN or CCAN;

[0018] Solution B: When the BMS confirms FAULT-BCAN and the BMS does not perform any detection on the BCAN circuit, determine the FAULT status of ACAN and CCAN.

[0019] a: FAULT-ACAN and FAULT-CCAN both exist, no processing is done

[0020] b: If FAULT-ACAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-B function is compatible with ACAN;

[0021] c: If FAULT-ACAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-BCH and MOS-BCL to be closed, and the BMS SOFT-B function is compatible with CCAN;

[0022] d: If FAULT-ACAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of ACAN and CCAN, disconnects MOS-BH and MOS-BL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-BCH and MOS-BCL, making the BMS's SOFT-B function compatible with ACAN or CCAN;

[0023] Solution C: When the BMS confirms FAULT-CCAN and the BMS does not perform any detection on the CCAN circuit, determine the FAULT status of ACAN and BCAN.

[0024] a: If both FAULT-ACAN and FAULT-BCAN exist, no processing is performed;

[0025] b: If FAULT-ACAN exists and FAULT-BCAN does not exist, the BMS high-side driver enables MOS-CH and MOS-CL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-C function is compatible with ACAN;

[0026] c: If FAULT-ACAN does not exist and FAULT-BCAN exists, the BMS enables MOS-CH and MOS-CL to be disconnected and MOS-BCH and MOS-BCL to be closed and the BMS SOFT-C function to be compatible with BCAN;

[0027] d: If FAULT-ACAN and FAULT-BCAN exist, the BMS high-side driver determines the theoretical load rate of ACAN and BCAN. The BMS enables MOS-CH and MOS-CL to be disconnected and selects the CAN loop with the smaller load rate: closes MOS-ACH and MOS-ACL or closes MOS-BCH and MOS-BCL, making the BMS SOFT-C function compatible with ACAN or BCAN.

[0028] Solution D: When the BMS detects FAULT-ACAN, FAULT-BCAN, and FAULT-CCAN at the same time, the BMS believes that there is a serious communication failure in the communication line, BMS hardware, or other ECUs, which seriously affects driving safety. It requests the vehicle to reduce high voltage and sends the solution D information to the backend big data platform through the DTU inherited by the BMS, prompting after-sales service to go to the site for inspection.

[0029] Compared with the prior art, the present invention realizes stability control of the CAN circuit through wiring harness redundancy design and BMS reliable switching of MOS tubes. When the wiring harness is abnormal, individual CAN interface pins of the BMS are lost, or individual CAN circuit transceivers are abnormal, the present invention has the ability to graft abnormal CAN circuits to normal CAN circuits. By integrating the functions of various CAN channels through software, the problem can be substantially solved through logical judgment without unpacking and repairing. The circuit and method of the present invention can avoid the ECU being unable to communicate due to CANH-CANL circuit abnormalities when a certain ECU is completely lost, avoid the loss of communication of an ECU in a certain part of the vehicle and the inability to self-recover, improve the operation stability of the whole vehicle, and facilitate maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a circuit connection diagram when there are three ECUs in the present invention.

[0031] Figure 2 It is a functional flow chart of the method in the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings.

[0033] The present invention provides a circuit for improving CAN communication stability, comprising an ECU module and a BCU module. The ECU module comprises a plurality of ECUs. The ECU and the BCU module are connected via a CAN wiring harness. The ECUs are connected to each other via the wiring harness. A MOS tube is provided on each wiring harness. A BMS high-side driver is used to enable the MOS tube to be turned on and off, thereby controlling the on and off of the wiring harnesses between the ECUs. A MOS tube is also provided on the CAN wiring harness. A BMS high-side driver is used to enable the MOS tube to be turned on and off, thereby controlling the on and off of the CAN wiring harness. The BMS high-side driver realizes on and off through software logic.

[0034] The ECU module includes at least three ECUs. The following takes three ECUs as an example to specifically illustrate the connection method of the circuit of the present invention. Figure 1As shown, the three ECUs are ECU-A, ECU-B, and ECU-C. ECU-A is connected to the A-CANH interface and the A-CANL interface on the BCU through two wiring harnesses, forming an ACAN. A MOS tube MOS-AH is provided on the wiring harness connected to the A-CANH interface, and a MOS tube MOS-AL is provided on the wiring harness connected to the ECU-A and the A-CANL interface; the MOS tubes MOS-AH and MOS-AL are respectively connected to the BMS high-side driver AH and high-side driver AL on the BCU module, and the high-side driver AH and high-side driver AL are used to control the on and off of the MOS tubes MOS-AH and MOS-AL; ECU-B is connected to the B-CANH interface and the B-CANL interface on the BCU through two wiring harnesses, forming a BCAN. A MOS tube MOS-BH is provided on the wiring harness connected to the B-CANH interface, and a MOS tube MOS-BH is provided on the wiring harness connected to the ECU-B A MOS transistor MOS-BL is provided on the wiring harness connected to the B-CANL interface. The MOS transistors MOS-BH and MOS-BL are respectively connected to the BMS high-side driver BH and high-side driver BL on the BCU module. The high-side driver BH and high-side driver BL are used to control the on / off of the MOS transistors MOS-BH and MOS-BL. The ECU-C is respectively connected to the C-CANH interface and C-CANL interface on the BCU via two wiring harnesses, forming the CCAN. A MOS transistor MOS-CH is provided on the wiring harness connected to the C-CANH interface, and a MOS transistor MOS-CL is provided on the wiring harness connecting the ECU-C and the C-CANL interface. The MOS transistors MOS-CH and MOS-CL are respectively connected to the BMS high-side driver CH and high-side driver CL on the BCU module. The high-side driver CH and high-side driver CL are used to control the on / off of the MOS transistors MOS-CH and MOS-CL.

[0035] Two wiring harnesses are also connected to the wiring harness of the MOS tube MOS-AH near the ECU-A end. One wiring harness is connected to the wiring harness of the MOS tube MOS-BH through the MOS tube MOS-ABH, and the connection point is located between the MOS tube MOS-BH and ECU-B; the other wiring harness is connected to the wiring harness of the MOS tube MOS-CH through the MOS tube MOS-ACH, and the connection point is located between the MOS tube MOS-CH and ECU-C; the wiring harness of the MOS tube MOS-AL near the ECU-A end is connected to two wiring harnesses, one of which is connected to the wiring harness of the MOS tube MOS-BL through the MOS tube MOS-ABL, and the connection point is located between the MOS tube MOS-BH and The wiring harness connecting the MOS tube MOS-BH to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCH to the wiring harness connecting the MOS tube MOS-CH, and the connection point is between the MOS tube MOS-CH and ECU-C; the wiring harness connecting the MOS tube MOS-BL to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCL to the wiring harness connecting the MOS tube MOS-CL, and the connection point is between the MOS tube MOS-CL and ECU-C.

[0036] The software strategy method for improving CAN communication stability includes the following steps:

[0037] BMS is compatible with all communication protocols and functional processes of ACAN, BCAN and CCAN on any CAN channel of ACAN, BCAN and CCAN. It defines the functional modules of each CAN channel as SOFT-A, SOFT-B and SOFT-C, and calculates the theoretical CAN load rate of each branch as LOAD-A, LOAD-B and LOAD-C respectively. It counts the number of ACAN communication faults, BCAN communication faults or CCAN communication faults and records the duration of single triggering. It also performs different degrees of fault handling according to the number and duration of fault triggering. The specific plan is as follows:

[0038] 1) When the number of ACAN communication timeout fault triggering times is ≥10 times or the duration of a single ACAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the ACAN, and the fault is recorded as FAULT-ACAN;

[0039] 2) When the number of BCAN communication timeout fault triggering times is ≥10 times or the duration of a single BCAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the BCAN and the fault is recorded as FAULT-BCAN;

[0040] 3) When the number of CCAN communication timeout fault triggers is ≥10 times or the duration of a single CCAN communication timeout is >1 hour or the cumulative fault trigger duration is >24 hours, it is considered that there is a serious CCAN communication abnormality and the fault is recorded as FAULT-CCAN;

[0041] When the system detects that any of the FAULT-ACAN, FAULT-BCAN, or FAULT-CCAN is triggered, the BMS requests power limiting to 0%. If the vehicle bus current is less than 1A, the vehicle is considered stationary and the following plan is implemented:

[0042] Solution A: When the BMS confirms FAULT-ACAN and the BMS does not perform any detection on the ACAN circuit, determine the FAULT status of BCAN and CCAN.

[0043] a: If both FAULT-BCAN and FAULT-CCAN exist, no processing is performed;

[0044] b: If FAULT-BCAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-A function is compatible with BCAN;

[0045] c: If FAULT-BCAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-A function is compatible with CCAN;

[0046] d: If FAULT-BCAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of BCAN and CCAN, disconnects the BMS high-side driver MOS-AH and MOS-AL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-ACH and MOS-ACL, making the BMS SOFT-A function compatible with BCAN or CCAN;

[0047] Solution B: When the BMS confirms FAULT-BCAN and the BMS does not perform any detection on the BCAN circuit, determine the FAULT status of ACAN and CCAN.

[0048] a: FAULT-ACAN and FAULT-CCAN both exist, no processing is done

[0049] b: If FAULT-ACAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-B function is compatible with ACAN;

[0050] c: If FAULT-ACAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-BCH and MOS-BCL to be closed, and the BMS SOFT-B function is compatible with CCAN;

[0051] d: If FAULT-ACAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of ACAN and CCAN, disconnects MOS-BH and MOS-BL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-BCH and MOS-BCL, making the BMS's SOFT-B function compatible with ACAN or CCAN;

[0052] Solution C: When the BMS confirms FAULT-CCAN and the BMS does not perform any detection on the CCAN circuit, determine the FAULT status of ACAN and BCAN.

[0053] a: If both FAULT-ACAN and FAULT-BCAN exist, no processing is performed;

[0054] b: If FAULT-ACAN exists and FAULT-BCAN does not exist, the BMS high-side driver enables MOS-CH and MOS-CL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-C function is compatible with ACAN;

[0055] c: If FAULT-ACAN does not exist and FAULT-BCAN exists, the BMS enables MOS-CH and MOS-CL to be disconnected and MOS-BCH and MOS-BCL to be closed and the BMS SOFT-C function to be compatible with BCAN;

[0056] d: If FAULT-ACAN and FAULT-BCAN exist, the BMS high-side driver determines the theoretical load rate of ACAN and BCAN. The BMS enables MOS-CH and MOS-CL to be disconnected and selects the CAN loop with the smaller load rate: closes MOS-ACH and MOS-ACL or closes MOS-BCH and MOS-BCL, making the BMS SOFT-C function compatible with ACAN or BCAN.

[0057] Solution D: When the BMS detects FAULT-ACAN, FAULT-BCAN, and FAULT-CCAN at the same time, the BMS believes that there is a serious communication failure in the communication line, BMS hardware, or other ECUs, which seriously affects driving safety. It requests the vehicle to reduce high voltage and sends the solution D information to the backend big data platform through the DTU inherited by the BMS, prompting after-sales service to go to the site for inspection.

Claims

1. A circuit for improving CAN communication stability, comprising an ECU module and a BCU module, characterized in that: The ECU module includes several ECUs. The ECU and the BCU module are connected through a CAN wiring harness. The ECUs are connected to each other through wiring harnesses. A MOS tube is provided on each wiring harness. The BMS high-side driver is used to enable the MOS tube to be turned on and off to control the on and off of the wiring harnesses between the ECUs. A MOS tube is also provided on the CAN wiring harness. The BMS high-side driver is used to enable the MOS tube to be turned on and off to control the on and off of the CAN wiring harness. The BMS high-side driver realizes on and off through software logic.

2. A circuit for improving CAN communication stability according to claim 1, characterized in that: The ECU module includes at least three ECUs.

3. A circuit for improving CAN communication stability according to claim 2, characterized in that: The three ECUs are ECU-A, ECU-B, and ECU-C. ECU-A is connected to the A-CANH interface and the A-CANL interface on the BCU through two wiring harnesses, forming an ACAN. A MOS transistor MOS-AH is provided on the wiring harness connected to the A-CANH interface, and a MOS transistor MOS-AL is provided on the wiring harness connected to the ECU-A and the A-CANL interface. The MOS transistors MOS-AH and MOS-AL are respectively connected to the BMS high-side driver AH and high-side driver AL on the BCU module; ECU-B is connected to the B-CANH and B-CANL interfaces on the BCU through two wiring harnesses, forming the BCAN. A MOS transistor MOS-BH is provided on the wiring harness connected to the B-CANH interface, and a MOS transistor MOS-BL is provided on the wiring harness connecting ECU-B to the B-CANL interface. The MOS transistors MOS-BH and MOS-BL are connected to the BMS high-side driver BH and high-side driver BL on the BCU module, respectively. ECU-C is connected to the C-CANH and C-CANL interfaces on the BCU through two wiring harnesses, forming CCAN. MOS transistor MOS-CH is provided on the wiring harness connected to the C-CANH interface, and MOS transistor MOS-CL is provided on the wiring harness connecting the ECU-C and the C-CANL interface. MOS transistors MOS-CH and MOS-CL are respectively connected to the BMS high-side driver CH and high-side driver CL on the BCU module; Two wiring harnesses are also connected to the wiring harness of the MOS tube MOS-AH near the ECU-A end. One wiring harness is connected to the wiring harness of the MOS tube MOS-BH through the MOS tube MOS-ABH, and the connection point is located between the MOS tube MOS-BH and ECU-B; the other wiring harness is connected to the wiring harness of the MOS tube MOS-CH through the MOS tube MOS-ACH, and the connection point is located between the MOS tube MOS-CH and ECU-C; the wiring harness of the MOS tube MOS-AL near the ECU-A end is connected to two wiring harnesses, one of which is connected to the wiring harness of the MOS tube MOS-BL through the MOS tube MOS-ABL, and the connection point is located between the MOS tube MOS-BH and The wiring harness connecting the MOS tube MOS-BH to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCH to the wiring harness connecting the MOS tube MOS-CH, and the connection point is between the MOS tube MOS-CH and ECU-C; the wiring harness connecting the MOS tube MOS-BL to ECU-B is also connected to a wiring harness connecting the MOS tube MOS-BCL to the wiring harness connecting the MOS tube MOS-CL, and the connection point is between the MOS tube MOS-CL and ECU-C.

4. A software strategy method for improving CAN communication stability, characterized in that: The method is applied to the circuit for improving CAN communication stability as described in any one of claims 1 to 3, comprising the following steps: the BMS is compatible with all communication protocols and functional processes of ACAN, BCAN, and CCAN on any CAN of ACAN, BCAN, and CCAN, and its CAN functional modules are defined as SOFT-A, SOFT-B, and SOFT-C, and the theoretical CAN load rate of each branch is calculated as LOAD-A, LOAD-B, and LOAD-C respectively; the number of ACAN communication faults, BCAN communication faults, or CCAN communication faults and the duration of single triggering are recorded separately, and different degrees of fault handling are performed according to the number and duration of fault triggering. The specific scheme is as follows: 1) When the number of ACAN communication timeout fault triggering times is ≥10 times or the duration of a single ACAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the ACAN, and the fault is recorded as FAULT-ACAN; 2) When the number of BCAN communication timeout fault triggering times is ≥10 times or the duration of a single BCAN communication timeout is >1 hour or the cumulative fault triggering duration is >24 hours, it is considered that there is a serious communication abnormality in the BCAN and the fault is recorded as FAULT-BCAN; 3) When the number of CCAN communication timeout fault triggers is ≥10 times or the duration of a single CCAN communication timeout is >1 hour or the cumulative fault trigger duration is >24 hours, it is considered that there is a serious CCAN communication abnormality and the fault is recorded as FAULT-CCAN; When the system detects that any one of FAULT-ACAN, FAULT-BCAN or FAULT-CCAN is triggered, the BMS requests to limit the power to 0%. When the vehicle bus current is less than 1A, the vehicle is considered to be stationary and the plan A, plan B, plan C or plan D is executed.

5. A software strategy method for improving CAN communication stability according to claim 4, characterized in that: Solution A: When the BMS confirms FAULT-ACAN and the BMS does not perform any detection on the ACAN circuit, the FAULT status of BCAN and CCAN is determined. a: If both FAULT-BCAN and FAULT-CCAN exist, no processing is performed; b: If FAULT-BCAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-A function is compatible with BCAN; c: If FAULT-BCAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-AH and MOS-AL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-A function is compatible with CCAN; d: If FAULT-BCAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of BCAN and CCAN, disconnects the BMS high-side driver MOS-AH and MOS-AL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-ACH and MOS-ACL, making the BMS SOFT-A function compatible with BCAN or CCAN; Solution B: When the BMS confirms FAULT-BCAN and the BMS does not perform any detection on the BCAN circuit, determine the FAULT status of ACAN and CCAN. a: FAULT-ACAN and FAULT-CCAN both exist, no processing is done b: If FAULT-ACAN exists and FAULT-CCAN does not exist, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-ABH and MOS-ABL to be closed, and the BMS SOFT-B function is compatible with ACAN; c: If FAULT-ACAN does not exist and FAULT-CCAN exists, the BMS high-side driver enables MOS-BH and MOS-BL to be disconnected and MOS-BCH and MOS-BCL to be closed, and the BMS SOFT-B function is compatible with CCAN; d: If FAULT-ACAN and FAULT-CCAN exist, the BMS determines the theoretical load rate of ACAN and CCAN, disconnects MOS-BH and MOS-BL, and selects the CAN loop with the smaller load rate: closes MOS-ABH and MOS-ABL or closes MOS-BCH and MOS-BCL, making the BMS's SOFT-B function compatible with ACAN or CCAN; Solution C: When the BMS confirms FAULT-CCAN and the BMS does not perform any detection on the CCAN circuit, determine the FAULT status of ACAN and BCAN. a: If both FAULT-ACAN and FAULT-BCAN exist, no processing is performed; b: If FAULT-ACAN exists and FAULT-BCAN does not exist, the BMS high-side driver enables MOS-CH and MOS-CL to be disconnected and MOS-ACH and MOS-ACL to be closed, and the BMS SOFT-C function is compatible with ACAN; c: If FAULT-ACAN does not exist and FAULT-BCAN exists, the BMS enables MOS-CH and MOS-CL to be disconnected and MOS-BCH and MOS-BCL to be closed and the BMS SOFT-C function to be compatible with BCAN; d: If FAULT-ACAN and FAULT-BCAN exist, the BMS high-side driver determines the theoretical load rate of ACAN and BCAN. The BMS enables MOS-CH and MOS-CL to be disconnected and selects the CAN loop with the smaller load rate: closes MOS-ACH and MOS-ACL or closes MOS-BCH and MOS-BCL, making the BMS SOFT-C function compatible with ACAN or BCAN. Solution D: When the BMS detects FAULT-ACAN, FAULT-BCAN, and FAULT-CCAN at the same time, the BMS believes that there is a serious communication failure in the communication line, BMS hardware, or other ECUs, which seriously affects driving safety. It requests the vehicle to reduce high voltage and sends the solution D information to the backend big data platform through the DTU inherited by the BMS, prompting after-sales service to go to the site for inspection.

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