A method for handling communication loss between vehicle controller and battery controller

Abstract

This invention relates to the field of electric vehicle control technology, specifically to a method for handling communication loss between the vehicle controller and the battery controller. 1. If the VCU detects that it has not received any key BMS messages or any BMS messages for a certain period of time, the VCU determines that a communication loss fault has occurred with the BMS. 2. When the diagnosis of a BMS communication loss fault is 1, the VCU immediately locks some important vehicle parameters at the time the fault occurred. 3. The VCU makes a judgment based on the important parameters, allowing the vehicle to smoothly transition to a safe state. 5. The VCU sends information to the ICM instrument panel for display, showing the message "BMS communication loss, super limphome mode," and simultaneously illuminates the vehicle system fault light and the battery system fault light to warn the driver. This method solves the problem that currently, when the VCU fails to receive CAN information from the BMS controller, it adopts zero-power processing, leaving the vehicle unable to power on or drive, requiring the driver to wait for assistance, causing economic losses and affecting safety.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle control technology, and more specifically, to a method for handling communication loss between the vehicle controller and the battery controller. Background Technology

[0002] In new energy electric vehicles, the vehicle control unit (VCU) and the battery control system (BMS) are two very important controllers. They communicate with each other via the CAN bus and process control strategies.

[0003] Most manufacturers will report and determine the severity of the vehicle's fault after the VCU fails to receive CAN information from the BMS controller, and take corresponding fault handling measures. The vast majority of these measures involve zero-power handling, which shuts down the motor system and applies high-voltage treatment to the entire vehicle. The vehicle is in a state where it cannot be powered on or driven. In this case, the only option is to wait for roadside assistance and towing, which can cause economic losses to the driver. Sometimes, there are also relatively high towing fees, and the vehicle may be completely stranded and lose power, which can also affect safety. Summary of the Invention

[0004] This invention provides a method for handling communication loss between the vehicle controller and the battery controller. It solves the problem that in the current stage, when the VCU fails to receive CAN information from the BMS controller, it mostly operates at zero power, stops the motor system from enabling, and applies high voltage to the entire vehicle. The vehicle is in a state where it cannot be powered on or driven, and can only wait for rescue and towing, which causes certain economic losses to the driver. Sometimes, there are relatively expensive towing fees, and the vehicle is completely broken down and loses power, which also affects safety.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for handling communication loss between a vehicle controller and a battery controller, comprising a vehicle controller (VCU), a battery controller (BMS), and an engine motor. The engine motor is connected to the battery, and a DC-DC converter, an OBC, an MCU, and a PDU are connected in parallel between the engine motor and the battery. In the vehicle CAN network architecture, the VCU, BMS, MCU, PDU, DC-DC converter, OBC, and ICM exchange information via a CAN bus. The specific steps are as follows:

[0006] Step S1: If the VCU detects that no critical BMS message or no BMS message has been received for a certain period of time, the VCU determines that the communication with the BMS has been lost.

[0007] In step S2, when the diagnosis of BMS communication loss fault = 1, the VCU will immediately lock some important vehicle parameters at the time of the loss fault.

[0008] In step S3, the VCU will make a judgment based on important parameters to ensure that the vehicle smoothly transitions to a safe state.

[0009] In step S4, the VCU sends information to the ICM instrument panel for display, which can display the message "BMS communication lost in super limphome mode". At the same time, the vehicle system fault light and the battery system fault light are illuminated to warn the driver.

[0010] In step S5, the VCU always wakes up the BMS. The BMS can detect various parameters of its own battery system, such as battery voltage, temperature, and whether there are serious faults. If the BMS detects a serious fault during driving, it will disconnect the contactor to protect its own battery system.

[0011] Further specifying, the key parameters in step S2 include battery SOC, the highest / lowest single-cell voltage of the power battery Vmax-Vmin, the highest / lowest single-cell temperature of the power battery Tmax-Tmin, and whether there are other serious faults in the battery system.

[0012] Further specifying, the determination based on important parameters in step S3 refers to whether all of the following conditions are met simultaneously. If so, the VCU outputs "BMS communication lost, super limphome mode = 1"; otherwise, the VCU outputs "BMS communication lost, super limphome mode = 0". The conditions are as follows:

[0013] A. Battery SOC ≥ 30% of rated value;

[0014] B. The maximum single-cell voltage of the power battery is Vmax≥3.4V; the minimum single-cell voltage is Vmin≥3.2V. The specific voltage data are set as calibration values ​​and need to be set and reference values ​​according to the specific cell type and cell voltage performance curve.

[0015] C. The highest single-cell temperature of the power battery is: -10℃≤Tmax≤40℃, and the lowest single-cell temperature is: -10℃≤Tmin≤40℃. The specific temperature data are set as calibration values ​​and need to be set and referenced according to the specific cell type and cell temperature performance curve.

[0016] D. The battery system has no other serious faults.

[0017] Further specifying, during step S2, the VCU will determine the maximum amplification power P of the battery under the current condition based on the battery SOP table stored in memory. The battery SOP is a map table, with the input being the maximum / minimum cell voltage and temperature of the battery cells, and the output being the maximum power value under the current condition. If the current maximum power value P > 10kW, then the VCU sets the current maximum available power of the internal BMS battery system to P(liphome) = 10kW for the use of the entire vehicle. P(liphome) is a calibration value, and the specific setting needs to consider the following factors: 1.1 It can be determined based on the specific battery discharge power matrix map table and the vehicle's driving resistance parameters; 2.1 This value can ensure that the entire vehicle can drive at the standard value of 10km / h; 3.1 It can ensure that the entire vehicle can pass through ordinary speed bumps and lanes with a certain slope; 4.1 Most of the power values ​​in the entire battery discharge power map data are greater than this value, mainly to ensure the battery discharge safety.

[0018] Further specifying, the VCU will transition from the discharge power value at step S2 to the current P(liphome) value with a certain slope gradient to prevent the vehicle from experiencing excessive power loss, which could cause comfort issues and a negative feeling of rapid power loss. The slope gradient can be calibrated to 1 kW / s. At this time, the power output formula of the vehicle is motor power = P(liphome) - P(DCDC) - P_air conditioning. At the same time, the VCU will receive the bus current of the DC-DC converter and the high-voltage bus current of the air conditioning system in real time, and perform ampere-hour integration AH = DC-DC bus current * t + high-voltage bus current of the air conditioning system * t. Time t represents the VCU program calculation cycle, which is 10 ms. The VCU uses the consumed ampere-hour data to estimate the subsequent SOC. If SOC = 0, the VCU will control the vehicle to shut down the high voltage and cannot continue driving. The ampere-hour integration AH = SOC value reported by the battery when communication is lost * battery system stable ampere-hour capacity.

[0019] Furthermore, the serious faults described in step S5 will be carefully constrained and considered during the development process; only when battery over-discharge faults, battery over-temperature faults, and battery thermal runaway faults occur will the BMS activate the secondary redundant self-protection process, allowing the BMS to automatically disconnect the contactor and perform high-voltage power-off.

[0020] The beneficial effects of adopting the above technical solutions are:

[0021] Through the above strategies, even if communication between the VCU and BMS is lost, the vehicle can still continue to operate, ensuring that the driver can go to the repair shop for timely repairs and avoid economic losses such as towing fees. At the same time, the strategy also protects the battery to the greatest extent and provides the vehicle with sufficient maximum power output to ensure a certain level of vehicle power performance. In critical moments, it also provides the BMS battery system with maximum safety protection. In special circumstances, the secondary self-protection measures of the battery system can be activated to protect the safety of the battery and the vehicle. Attached Figure Description

[0022] Figure 1 This is a high-voltage system architecture diagram of the present invention;

[0023] Figure 2 This is a diagram illustrating the network architecture information interaction of this invention.

[0024] Figure 3 This is a schematic diagram illustrating the logical relationships of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0026] This invention provides a method for handling communication loss between the vehicle controller and the battery controller. It addresses the current situation where, when the VCU fails to receive CAN information from the BMS controller, it mostly results in zero-power operation, shutting down the motor system, and subjecting the entire vehicle to high-voltage treatment. This leaves the vehicle in a power-off ready state, unable to drive, requiring the driver to await roadside assistance and towing. This causes economic losses for the driver, sometimes incurring expensive towing fees, and the vehicle becomes completely stranded and powerless, also posing safety risks.

[0027] Specifically, such as Figures 1-3As shown, a method for handling communication loss between a vehicle controller and a battery controller is characterized by: including a vehicle controller (VCU), a battery controller (BMS), and an engine motor. The engine motor is connected to the battery, and a DC-DC converter, an OBC, an MCU, and a PDU are connected in parallel between the engine motor and the battery. In the high-voltage architecture, the pre-charge contactor, the main positive contactor, and the main auxiliary contactor are all bidirectionally controlled by the PDU high-voltage distribution unit and the BMS. That is, as long as one party drives the contactor to close, the contactor will close; only when both parties are in the open state will the contactor be in the open state. The control commands for closing and opening the contactor from the PDU are output by the VCU. In the vehicle CAN network architecture, the VCU, BMS, MCU, PDU, DC-DC converter, OBC, and ICM exchange information via the CAN bus. The specific steps are as follows:

[0028] Step S1: If the VCU detects that no critical BMS messages or the entire BMS message has been received for a certain period of time (the duration is generally 3-5 times the message period), then the VCU determines that the communication with the BMS has been lost.

[0029] In step S2, when the BMS communication loss fault is 1, the VCU will immediately lock some important vehicle parameters at the time of the fault, including battery SOC, the highest / lowest cell voltage Vmax-Vmin of the power battery, the highest / lowest cell temperature Tmax-Tmin of the power battery, and parameters indicating whether there are other serious faults in the battery system, such as insulation or high-voltage interlock. Simultaneously, the VCU will determine the maximum amplification power P of the battery under the current condition based on the battery SOP table stored in memory. The battery SOP is a map table; the input is the maximum / minimum cell voltage / temperature of the battery cells, and the output is the maximum power value under the current condition. If the current maximum power P > 10kW, then the VCU sets the current maximum available power of the internal BMS battery system to P(liphome) = 10kW. This value is for vehicle use. P (liphome) is a calibration value, and its specific setting needs to consider the following factors: 1.1 It can be determined based on the specific battery discharge power matrix map table and the vehicle's driving resistance parameters; 2.1 This value can ensure that the vehicle can drive at the standard speed of 10km / h; 3.1 It can ensure that the vehicle can pass through ordinary speed bumps and lanes with a certain slope; 4.1 Most of the power values ​​in the entire battery discharge power map data are greater than this value, mainly to ensure the safety of battery discharge. The VCU will transition from the discharge power value at step S2 to the current P (liphome) value with a certain slope gradient to prevent the vehicle from losing power too quickly, causing comfort problems and a bad feeling of losing power too quickly; the slope gradient can be calibrated to 1kw / s, at which time the power output formula of the vehicle is motor power = P (liphome) - P (DCDC) - P air conditioner. At the same time, the VCU will receive the bus current of the DC-DC and the high-voltage bus current of the air conditioning system in real time, and perform ampere-hour integration AH = DC-DC bus current * t + high-voltage bus current of the air conditioning system * t. The time t represents the VCU program calculation cycle, which is 10ms. The VCU uses the consumed ampere-hour data to estimate the subsequent SOC. If SOC = 0, the VCU controls the vehicle to shut down the high voltage and cannot continue driving. Ampere-hour integration AH = SOC value reported by the battery when communication is lost * stable ampere-hour capacity of the battery system.

[0030] In step S3, the VCU will determine the appropriate parameters to ensure the vehicle smoothly transitions to a safe state. The VCU will output "BMS communication loss, super limphome mode = 1" when the following conditions are met simultaneously; otherwise, the VCU will output "BMS communication loss, super limphome mode = 0". The conditions are as follows:

[0031] A. Battery SOC ≥ 30% of rated value;

[0032] B. The maximum single-cell voltage of the power battery is Vmax≥3.4V; the minimum single-cell voltage is Vmin≥3.2V. The specific voltage data are set as calibration values ​​and need to be set and reference values ​​according to the specific cell type and cell voltage performance curve.

[0033] C. The highest single-cell temperature of the power battery is: -10℃≤Tmax≤40℃, and the lowest single-cell temperature is: -10℃≤Tmin≤40℃. The specific temperature data are set as calibration values ​​and need to be set and referenced according to the specific cell type and cell temperature performance curve.

[0034] D. The battery system has no other serious faults;

[0035] Step S4: When the VCU outputs "BMS communication lost Super Limphome mode = 1", the VCU simultaneously sends information to the ICM instrument for display. The displayed text can be "BMS communication lost Super Limphome mode". At the same time, the vehicle system fault light and the battery system fault light are illuminated to warn the driver.

[0036] In step S5, the VCU always wakes up the BMS. The BMS can detect various parameters of its own battery system, such as battery voltage, temperature, and whether there are serious faults. If the BMS detects a serious fault during driving, it will disconnect the contactor to protect its own battery system. The detected serious faults will be carefully constrained and considered during the development process. Only when battery over-discharge fault, battery over-temperature fault, or battery thermal runaway fault occurs will the BMS activate the secondary redundant self-protection process, allowing the BMS to disconnect the contactor and perform high-voltage power-off.

[0037] In order for the vehicle controller to receive the information from the battery management system (BMS) to activate the secondary protection, the BMS sends a hard-wired high-level signal to the VCU while outputting the disconnect contactor signal. Normally, this signal is a low-level signal. After receiving the high-level secondary protection signal, the VCU simultaneously sends a contactor disconnect command to the PDU. The PDU also disconnects the contactor. Only then will the high-voltage contactor of the vehicle be completely disconnected, and the vehicle will be in a high-voltage disconnection state to protect the battery from dangerous faults.

[0038] Through the above strategies, even if communication between the VCU and BMS is lost, the vehicle can still continue to operate, ensuring that the driver can go to the repair shop for timely repairs and avoid economic losses such as towing fees. At the same time, the strategy also protects the battery to the greatest extent and provides the vehicle with sufficient maximum power output to ensure a certain level of vehicle power performance. In critical moments, it also provides the BMS battery system with maximum safety protection. In special circumstances, the secondary self-protection measures of the battery system can be activated to protect the safety of the battery and the vehicle.

[0039] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for handling communication loss between a vehicle controller and a battery controller, characterized in that: The system includes a vehicle control unit (VCU), a battery management system (BMS), and an engine motor. The engine motor is connected to the battery, and a DC-DC converter, an OBC, an MCU, and a PDU are connected in parallel between the engine motor and the battery. In the vehicle CAN network architecture, the VCU, BMS, MCU, PDU, DC-DC converter, OBC, and ICM exchange information via the CAN bus. The specific steps are as follows: Step S1: If the VCU detects that no critical BMS message or no BMS message has been received for a certain period of time, the VCU determines that the communication with the BMS has been lost. Step S2, when the diagnosis of BMS communication loss fault = 1, the VCU will immediately lock some important vehicle parameters at the time of the loss fault. The discharge power value of the VCU will transition to the current P (liphome) value with a certain slope gradient to prevent the vehicle from losing power too quickly, causing comfort problems and an unpleasant feeling of losing power too quickly. The slope gradient is calibrated to 1 kW / s. At this time, the power output formula of the whole vehicle is motor power = P(liphome) - P(DCDC) - Pairing air conditioner. At the same time, the VCU will receive the bus current of DCCDC and the high-voltage bus current of the air conditioning system in real time, and perform ampere-hour integration AH = DCCDC bus current * t + high-voltage bus current of air conditioning system * t. Time t represents the VCU program calculation cycle, which is 10 ms. The VCU uses the consumed ampere-hour data to estimate the subsequent SOC. If SOC = 0, the VCU controls the whole vehicle to cut off the high voltage and cannot continue to drive. Ah integration = SOC value that the battery can report when communication is lost * battery system stable ampere-hour capacity; In step S3, the VCU will determine based on important parameters whether all of the following conditions are met simultaneously. If yes, the VCU will output "BMS communication lost, super limphome mode = 1"; otherwise, the VCU will output "BMS communication lost, super limphome mode = 0". The conditions are as follows: A. Battery SOC ≥ 30% of rated value; B. The maximum single-cell voltage of the power battery is Vmax≥3.4V; the minimum single-cell voltage is Vmin≥3.2V. The specific voltage data are set as calibration values ​​and need to be set and reference values ​​according to the specific cell type and cell voltage performance curve. C. The highest single-cell temperature of the power battery is: -10℃≤Tmax≤40℃, and the lowest single-cell temperature is: -10℃≤Tmin≤40℃. The specific temperature data are set as calibration values ​​and need to be set and referenced according to the specific cell type and cell temperature performance curve. D. The battery system has no other serious faults, allowing the vehicle to smoothly transition to a safe state; In step S4, the VCU sends information to the ICM instrument panel for display, which can display the message "BMS communication lost in super limphome mode". At the same time, the vehicle system fault light and the battery system fault light are illuminated to warn the driver. In step S5, the VCU always wakes up the BMS. The BMS can detect various parameters of its own battery system, including battery voltage, temperature, and information on whether there are serious faults. During driving, if the BMS detects a serious fault, it will disconnect the contactor to protect its own battery system.

2. The method for handling communication loss between the vehicle controller and the battery controller according to claim 1, characterized in that: Key parameters in step S2 include battery SOC, the highest / lowest single-cell voltage of the power battery Vmax-Vmin, the highest / lowest single-cell temperature of the power battery Tmax-Tmin, and whether there are other serious faults in the battery system.

3. The method for handling communication loss between the vehicle controller and the battery controller according to claim 1, characterized in that: The serious faults mentioned in step S5 refer to battery over-discharge faults, battery over-temperature faults, and battery thermal runaway faults.

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