Method for monitoring thermal runaway by using RTC to wake up BMS

Abstract

The invention discloses a method for monitoring thermal runaway by awakening a battery management system (BMS) through a real-time clock (RTC), which comprises the following steps of: when a whole vehicle is in a dormant state, generating an awakening signal according to a preset period through the RTC, and triggering the BMS to be switched from a dormant mode to a working mode; after the BMS is awakened, battery cell voltage, battery cell temperature and fault diagnosis information are collected, analysis is carried out based on a preset thermal runaway judgment condition group, and whether a thermal runaway fault occurs or not is judged; if the analysis result meets any thermal runaway judgment condition group, the BMS reports a thermal runaway fault to a vehicle control unit (VCU) through vehicle-mounted CAN communication, and the BMS cooperates with the VCU to execute a corresponding fault emergency processing flow; and if the analysis result does not meet any thermal runaway judgment condition group, it is judged that no thermal runaway fault occurs, the BMS enters the sleep mode again, and the monitoring process is executed again after the RTC is awakened next time. On the basis of not increasing the cost, the occurrence of the thermal runaway event can be continuously monitored after the BMS is dormant.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery management systems for electric vehicles, and more particularly to a method for using an RTC to wake up the BMS to monitor thermal runaway. Background Art

[0002] With the widespread application of new energy vehicles, the safety issues of power batteries have attracted increasing attention. During the operation of power batteries, thermal runaway events may occur. If not detected and handled in a timely manner, it is very likely to cause serious safety accidents. For this reason, two monitoring methods are usually adopted in the prior art to detect thermal runaway: one is to externally install thermal runaway sensors to monitor the temperature change of the battery pack in real time, and the other is to periodically poll key parameters of the battery pack through an AFE chip to identify potential thermal runaway risks.

[0003] However, both of the above methods have obvious deficiencies when the vehicle is in a dormant state. The externally installed thermal runaway sensor not only increases the system complexity but also raises the vehicle cost; while the AFE chip with functional safety will also significantly increase the cost of the BMS system. More importantly, there are still a large number of battery packs on the market that are not equipped with thermal runaway sensors, and the thermal runaway risk cannot be continuously monitored during the dormant state.

[0004] Therefore, there is an urgent need for a technical solution that can continuously monitor thermal runaway and give an alarm in a timely manner during vehicle dormancy without increasing additional hardware costs, so as to improve the safety of the power battery system. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for using an RTC to wake up the BMS to monitor thermal runaway, aiming to solve the problem of continuously monitoring the occurrence of thermal runaway events after the BMS goes into dormancy without increasing costs, and a method for giving an alarm to remind the vehicle user in a timely manner after the event occurs.

[0006] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0007] A method for using an RTC to wake up the BMS to monitor thermal runaway, comprising the following steps:

[0008] S1. When the whole vehicle is in a dormant state, a wake-up signal is generated by a real-time clock (RTC) according to a preset period, triggering the battery management system (BMS) to switch from the dormant mode to the working mode;

[0009] S2. After the BMS is woken up, the cell voltage, cell temperature, and fault diagnosis information are collected, and analyzed based on a preset thermal runaway determination condition group to determine whether a thermal runaway fault has occurred;

[0010] S3. If the analysis result meets any of the thermal runaway determination condition groups, the BMS reports the thermal runaway fault to the vehicle control unit (VCU) via in-vehicle CAN communication, and the BMS cooperates with the VCU to execute the corresponding fault emergency handling process.

[0011] S4. If the analysis result does not meet any of the thermal runaway determination condition groups, it is determined that no thermal runaway fault has occurred. The BMS re-enters the sleep mode and waits to execute the above monitoring process again after being awakened by the next RTC.

[0012] Preferably, the RTC wake-up adopts a periodic timing method. After each wake-up, the BMS compares the real-time time with the time recorded at the last wake-up. If the time interval reaches the preset threshold, the battery cell parameter acquisition and thermal runaway determination process are executed.

[0013] Preferably, the thermal runaway determination condition group includes one or more of the following combinations:

[0014] a) The temperature at any monitoring point of the module exceeds the preset temperature threshold and lasts for at least the preset time.

[0015] b) The temperature rise rate at any monitoring point of the module exceeds the preset rate threshold and lasts for at least the preset time.

[0016] c) The temperature difference between any monitoring point of the module and other monitoring points is greater than the preset temperature difference threshold, or the difference between any monitoring point and the average temperature exceeds half of the preset temperature difference threshold, and lasts for at least the preset time.

[0017] d) The voltage of a single battery cell is lower than the preset voltage threshold and lasts for at least the preset time.

[0018] e) The NTC temperature acquisition line in the module has a disconnection fault and lasts for at least the preset time.

[0019] f) The voltage sampling line has an open circuit fault, and at the same time, the battery cell temperature exceeds the preset temperature threshold.

[0020] Preferably, the preset temperature threshold is 65°C ± 3°C;

[0021] and / or the preset time is 3 - 5 s;

[0022] and / or the preset rate threshold is 1°C / s;

[0023] and / or the preset temperature difference threshold is 25 - 30°C;

[0024] and / or the preset voltage threshold is 1.8 V.

[0025] Preferably, the preset period in step S1 is not less than 3 min.

[0026] Preferably, the condition for the RTC to generate a wake-up signal is as follows:

[0027] The whole vehicle is turned off, the BMS powers off from the ON position and switches to the sleep state, and records the initial time T0.

[0028] When the BMS is in the sleep state, it records the sleep time T1.

[0029] The current moment is recorded as T2.

[0030] If T2 - T0 ≤ the first preset time threshold and T2 - T1 ≥ the preset period, the RTC generates a wake-up signal to wake up the BMS and records the wake-up time T3.

[0031] If T2 - T0 > the first preset time threshold, it is judged whether a wake-up signal from a non-RTC source is received.

[0032] If a wake-up signal from a non-RTC source is received, the BMS is immediately woken up, T0 is cleared, and the whole vehicle starts.

[0033] If a wake-up signal from a non-RTC source is not received, the BMS continues to remain in the sleep state.

[0034] Preferably, in step S2, after the BMS is woken up, it first determines whether the battery voltage meets the minimum voltage requirement for subsequent monitoring work:

[0035] If the battery voltage ≥ the minimum working voltage, the relationship between T3 and the second preset time threshold is judged.

[0036] If T3 ≥ the second preset time threshold, the BMS re-enters the sleep state and updates the current moment to T1.

[0037] If a wake-up signal from a non-RTC source is not received at this time, return to step S1 to re-determine the condition for generating a wake-up signal.

[0038] If a wake-up signal from a non-RTC source is received at this time, the BMS is immediately woken up and T0 is cleared.

[0039] If T3 < the second preset time threshold, the detection and analysis of the thermal runaway determination condition group are executed.

[0040] If the battery voltage < the minimum working voltage, the BMS directly enters the sleep state unless a wake-up signal from a non-RTC wake-up is received.

[0041] Preferably, the first preset time threshold is 4 - 5h.

[0042] Preferably, the second preset time threshold is 2min.

[0043] Preferably, the minimum working voltage is 10V.

[0044] Compared with the prior art, the advantages of the present invention are as follows:

[0045] 1. By introducing a wake-up mechanism that links the real-time clock RTC with the battery management system BMS, the present invention can periodically wake up the BMS to actively detect safety-critical parameters such as the temperature and voltage of the battery cells in the power-off and dormant state of the whole vehicle, realizing early warning and real-time prevention of thermal runaway. Compared with the traditional monitoring method that relies on the wake-up of the whole vehicle, the present invention can effectively detect battery abnormalities during the vehicle parking stage, especially for the hidden dangers of thermal runaway caused by high-temperature environments and potential failures, achieving full-time domain monitoring coverage and greatly improving the safety and reliability of the battery system.

[0046] 2. By setting reasonable decision condition groups and multi-level detection logics, the present invention not only reduces the risk of false alarms but also avoids ineffective energy consumption, improving the accuracy and stability of system response, and is particularly suitable for the battery thermal safety protection system of new energy electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a flow chart of the BMS waking up the VCU and sending a thermal runaway fault signal in the present invention;

[0049] Figure 2 It is a flow chart of the RTC wake-up strategy in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] The following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0051] Embodiment 1

[0052] A method for monitoring battery thermal runaway by waking up the BMS based on RTC, applicable to new energy electric vehicles, adopts the following specific process:

[0053] 1) When the whole vehicle is in the off state and the BMS signal is lost, it switches from the ON gear power-off to the dormant state, and records the current time as the initial time T0.

[0054] 2) The BMS enters the sleep state and records the sleep time T1; the first recorded sleep time T1 = T0 after the vehicle is turned off, and the second recorded T1 is generally greater than T0 + a preset period.

[0055] 3) The RTC chip periodically generates a wake-up signal according to the set 3-minute wake-up period, and the current time is recorded as T2.

[0056] If T2 - T0 > the first preset time threshold, it is judged whether a wake-up signal from a non-RTC source is received; if a non-RTC wake-up signal is received, the BMS is immediately awakened, T0 is cleared, and the vehicle starts; if a non-RTC wake-up signal is not received, the BMS continues to remain in the sleep state.

[0057] If T2 - T0 ≤ 5H and T2 - T1 ≥ 3min, the RTC generates a wake-up signal to wake up the BMS to enter the working mode, and at the same time records the wake-up time T3.

[0058] 4) After the BMS is awakened, it first detects whether the battery voltage is ≥ 10V. If it is lower than 10V, it directly re-enters the sleep state and waits to be awakened by a non-RTC wake-up signal.

[0059] 5) If the battery voltage meets the requirements and T3 is greater than or equal to 2 minutes, the BMS re-enters the sleep state and updates the current time to T1; if a non-RTC wake-up signal is not received at this time, it returns to step 1) and re-enters the process of determining and generating a wake-up signal; if a non-RTC wake-up signal is received at this time, the BMS is immediately awakened and T0 is cleared.

[0060] If the battery voltage meets the requirements and T3 is less than 2 minutes, the BMS collects the voltages, cell temperatures, and fault diagnosis information of all battery module cells, and analyzes based on a preset set of thermal runaway determination conditions to determine whether a thermal runaway fault has occurred.

[0061] The set of thermal runaway determination conditions is specifically:

[0062] If the temperature at any monitoring point of the battery module ≥ 65°C and lasts for 3 seconds;

[0063] If the temperature rise rate at any monitoring point of the battery module ≥ 1°C / second;

[0064] If the temperature difference between any monitoring point of the module and other monitoring points is greater than 30°C, or the deviation of any monitoring point from the average temperature exceeds 15°C, and lasts for 3 seconds;

[0065] If the voltage of a single cell is lower than 1.8V and lasts for 3 seconds;

[0066] If the NTC drops out and lasts for 3 seconds

[0067] If there is an open circuit fault in the sampling line and the temperature exceeds 65°C.

[0068] 6) If the analysis result meets any of the thermal runaway determination condition groups, the BMS reports the thermal runaway fault signal to the vehicle controller VCU via the CAN bus, triggers the emergency handling logic, and executes corresponding safety measures, such as disconnecting the high-voltage circuit and starting the heat dissipation system.

[0069] 7) If the above conditions are not met, after the BMS finishes detection, it automatically re-enters the sleep state and waits to be woken up by the next RTC signal to ensure that the battery monitoring is in a low-power cyclic guarding state.

[0070] Through the above process, this embodiment can achieve active monitoring and real-time warning of battery thermal runaway in the vehicle power-off state, improve the safety protection level of the vehicle battery system, ensure timely detection and handling of abnormalities in the early stage of thermal runaway, and prevent the expansion of accidents.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for using RTC to wake up BMS to monitor thermal runaway, characterized in that: The steps include: S1. When the vehicle is in a dormant state, the real-time clock RTC generates a wake-up signal according to a preset period, triggering the battery management system BMS to switch from the dormant mode to the working mode; S2. After the BMS is awakened, it collects the cell voltage, cell temperature and fault diagnosis information, and analyzes it based on the preset thermal runaway judgment condition group to determine whether a thermal runaway fault occurs; S3. If the analysis result meets any of the thermal runaway judgment condition groups, the BMS reports the thermal runaway fault to the vehicle controller VCU through the on-board CAN communication, and the BMS cooperates with the VCU to execute the corresponding fault emergency processing process; S4. If the analysis result does not meet any of the thermal runaway judgment condition groups, it is determined that no thermal runaway fault has occurred, and the BMS re-enters the sleep mode and executes the above monitoring process again after the next RTC wake-up.

2. The method for using RTC to wake up BMS to monitor thermal runaway according to claim 1, characterized in that: The RTC wake-up adopts a periodic timing mode. After each wake-up, the BMS compares the real time with the last wake-up record time. If the time interval reaches the preset threshold, the battery cell parameter collection and thermal runaway judgment process is executed.

3. The method for using RTC to wake up BMS to monitor thermal runaway according to claim 1, characterized in that: The thermal runaway judgment condition group includes one or more of the following combinations: a) The temperature of any monitoring point of the module exceeds the preset temperature threshold and lasts for at least the preset time; b) The temperature rise rate of any monitoring point of the module exceeds the preset rate threshold and lasts for at least the preset time; c) The temperature difference between any monitoring point of the module and other monitoring points is greater than the preset temperature difference threshold, or the difference between any monitoring point and the average temperature exceeds half of the preset temperature difference threshold and lasts for at least the preset time; d) The cell voltage is lower than the preset voltage threshold and lasts for at least the preset time; e) The NTC temperature acquisition circuit in the module is disconnected and lasts for at least the preset time; f) The voltage sampling circuit has a short circuit fault and at the same time the battery cell temperature exceeds the preset temperature threshold.

4. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 3, characterized in that: The preset temperature threshold is 65°C ± 3°C; And / or the preset time is 3-5s; and / or the preset rate threshold is 1°C / s; And / or the preset temperature difference threshold is 25-30°C; And / or the preset voltage threshold is 1.8V.

5. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 1, characterized in that: The preset period in step S1 is not less than 3 minutes.

6. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 5, characterized in that: The conditions for the RTC to generate a wake-up signal are: The vehicle is turned off, and the BMS switches from the ON position to the sleep position and records the initial time T0; When BMS is in sleep mode, it records the sleep time T1; The current time is recorded as T2; If T2-T0≤the first preset time threshold, and T2-T1≥the preset period, the RTC generates a wake-up signal to wake up the BMS, and records the wake-up time T3; If T2-T0>the first preset time threshold, determine whether a wake-up signal from a non-RTC source is received; If a wake-up signal other than RTC is received, the BMS is immediately awakened, T0 is cleared, and the vehicle starts; If no non-RTC wake-up signal is received, the BMS continues to remain in sleep mode.

7. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 6, characterized in that: In step S2, after the BMS is awakened, it first determines whether the battery voltage meets the minimum voltage requirement for subsequent monitoring work: If the battery voltage is ≥ the minimum operating voltage, determine the relationship between T3 and the second preset time threshold; If T3 ≥ the second preset time threshold, the BMS re-enters the sleep state and updates the current time to T1; If no non-RTC wake-up signal is received at this time, return to step S1 to re-determine the conditions for generating a wake-up signal; If a wake-up signal other than RTC is received at this time, BMS wakes up immediately and clears T0; If T3 < the second preset time threshold, then the detection and analysis of the thermal runaway determination condition group is performed; If the battery voltage is less than the minimum operating voltage, the BMS goes into sleep mode directly unless it receives a wake-up signal other than the RTC wake-up signal.

8. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 6, characterized in that: The first preset time threshold is 4-5 hours.

9. The method of using RTC to wake up BMS to monitor thermal runaway according to claim 7, characterized in that: The second preset time threshold is 2 minutes.

10. The method for using RTC to wake up BMS to monitor thermal runaway according to claim 7, characterized in that: The minimum operating voltage is 10V.

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