Thermal runaway monitoring method and system for power battery and electric vehicle

Abstract

The invention discloses a thermal runaway monitoring method and system for a power battery and an electric automobile, and the method comprises the steps that when the power automobile is in a high-voltage power-off state, a battery management system takes electricity from a power battery pack through a DC-DC step-down converter so as to carry out thermal runaway monitoring on the power battery pack in the power-off state; wherein the high-voltage end of the direct current-direct current step-down converter is connected to the total positive and the total negative of the power battery pack, and the low-voltage end of the direct current-direct current step-down converter is connected to the battery management system; when the power automobile is in a high-voltage power-on state, the battery management system takes electricity from the power battery pack through a high-voltage distributor so as to carry out thermal runaway monitoring on the power battery pack in the power-on state; a switch control assembly in the DC-DC step-down converter is controlled to automatically cut off a power supply line connected with the battery management system; wherein the high-voltage distributor is connected to the total positive electrode and the total negative electrode of the power battery pack and is controlled by the battery management system.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a thermal runaway monitoring method and system for a power battery and an electric vehicle. Background Art

[0002] At present, electric vehicles have the advantages of zero tail gas emissions and low energy costs. However, thermal runaway accidents of electric vehicle power batteries have had a significant negative impact on the development of the new energy vehicle industry and have become an important factor restricting its development.

[0003] In order to prevent thermal runaway accidents of power batteries, a battery management system (BMS) is usually used to monitor and manage the status of the power batteries.

[0004] The battery management system requires power to maintain the operation of its electronic components and can only monitor the thermal runaway state of the battery pack when awake. When the system is powered off, the power battery no longer supplies power, and the monitoring of the battery management system will be affected in many ways.

[0005] For example, most of the relevant equipment of the battery management system (data logger, temperature sensor, etc.) cannot work normally, the BMS cannot communicate normally with external equipment (such as the host computer monitoring system), and some key electronic components in the BMS have limited functions when powered off, which may cause battery status data loss. When the system is powered on again, the battery management system cannot accurately obtain the previous complete status information of the battery, thereby affecting the effective monitoring and management of the battery.

[0006] Therefore, the problem with the prior art is that it is difficult for the battery management system to monitor the power battery around the clock due to power supply problems. Summary of the invention

[0007] In order to solve or partially solve the technical problem that a battery management system is difficult to perform all-weather monitoring of a power battery due to power supply problems, the present invention provides a method, system and electric vehicle for thermal runaway monitoring of a power battery. When the electric vehicle is in a high-voltage power-off state, the battery management system draws power from the power battery pack through a DC-DC buck converter to perform thermal runaway monitoring on the power battery pack in the power-off state; when the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through a high-voltage distributor to perform thermal runaway monitoring on the power battery pack in the power-on state, and controls the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system, thereby enabling all-weather monitoring of the power battery and ensuring the safety of the electric vehicle 24 hours a day.

[0008] In order to solve the above technical problems, the first aspect of the present invention discloses a thermal runaway monitoring method for a power battery, the method comprising:

[0009] When the electric vehicle is in a high-voltage power-off state, the battery management system draws power from the power battery pack through a DC-DC buck converter to monitor the thermal runaway of the power battery pack in the power-off state; wherein the high-voltage end of the DC-DC buck converter is connected to the total positive and total negative of the power battery pack, and the low-voltage end of the DC-DC buck converter is connected to the battery management system;

[0010] When the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through the high-voltage distributor to monitor the thermal runaway of the power battery pack in the power-on state, and controls the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system; wherein the high-voltage distributor is connected to the total positive and total negative of the power battery pack and is controlled by the battery management system.

[0011] Optionally, after controlling the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system, the method further includes:

[0012] If the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system.

[0013] Optionally, the thermal runaway monitoring of the power battery pack in a power-off state specifically includes:

[0014] Collecting operating status parameters of the power battery pack in real time;

[0015] Uploading the operating status parameters to a cloud server, and receiving a thermal runaway warning signal sent by the cloud server when detecting that the operating status parameters meet a thermal runaway preset condition;

[0016] The warning processing strategy is triggered to execute according to the thermal runaway warning signal; wherein, the warning processing strategy includes: sending thermal runaway warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0017] Optionally, the thermal runaway monitoring of the power battery pack in a powered-on state specifically includes:

[0018] Collecting operating status parameters of the power battery pack in real time;

[0019] Using thermal runaway preset conditions to detect the operating state parameters;

[0020] When the preset conditions for thermal runaway are met, the early warning processing strategy is triggered to execute; wherein, the early warning processing strategy includes: sending thermal runaway early warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0021] Optionally, the operating status parameters include: one or more of: battery pressure rise rate, battery pressure increase, battery cell minimum voltage value, battery temperature rise rate, battery cell maximum temperature value, battery cell maximum temperature difference value, battery management system communication line fault signal, voltage sampling short circuit fault signal, thermistor failure signal, and reverse wake-up signal of the battery management system;

[0022] The thermal runaway preset condition is a combination of one or more of the following conditions:

[0023] Condition A: The battery pressure rise rate is higher than the pressure rise rate threshold and the number of times continues to meet the standard;

[0024] Condition B: The battery pressure increase is greater than the thermal runaway pressure increase threshold and the number of consecutive times meets the standard; wherein, the battery pressure increase is the difference between the current collected pressure and the average value of the previous N historical collected pressures at the current moment;

[0025] Condition C: The minimum voltage value of the battery cell is less than or equal to the thermal runaway voltage warning threshold;

[0026] Condition D: The battery temperature rise rate is higher than the temperature rise rate threshold and the duration meets the standard;

[0027] Condition E: The maximum temperature of the battery cell is greater than or equal to the thermal runaway temperature warning threshold and the duration meets the standard;

[0028] Condition F: The maximum temperature difference of the battery cell is greater than or equal to the thermal runaway temperature difference warning threshold and the duration meets the standard;

[0029] Condition G: The daisy chain communication line fault signal of the battery management system is reported and the duration meets the standard;

[0030] Condition H: The voltage sampling short-circuit fault signal of the battery management system is reported and the duration meets the standard;

[0031] Condition I: The thermistor failure signal is reported and the number of failures reaches the standard;

[0032] Condition J: The reverse wake-up signal of the battery management system is reported.

[0033] Optionally, the battery management system is connected to the active fuse via a fuse control component;

[0034] The controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation specifically includes:

[0035] The battery management system uses the fuse control component to control the active fuse to perform a fuse operation.

[0036] Optionally, the battery management system is connected to the active fuse via an auxiliary controller;

[0037] The controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation specifically includes:

[0038] The vehicle controller controls the auxiliary controller to generate a driving current to drive the active fuse to perform a fusing operation;

[0039] The backflow prevention component inside the battery management system is used to block the driving current from flowing to the internal chip of the battery management system; wherein the backflow prevention component is designed in the circuit connecting the internal chip of the battery management system and the auxiliary controller.

[0040] A second aspect of the present invention discloses a thermal runaway monitoring system for a power battery, the system comprising:

[0041] A power battery pack, comprising a number of battery cells;

[0042] A DC-DC buck converter, the high voltage of which is connected to the total positive and total negative of the power battery pack, and the low voltage of which is connected to the battery management system; the DC-DC buck converter is used to draw power from the power battery pack to power the battery management system when the power vehicle is in a high voltage power-off state;

[0043] A high-voltage distributor connected to the total positive and negative of the power battery pack and controlled by the battery management system, and used to draw power from the power battery pack to supply power to the battery management system when the power vehicle is in a high-voltage power-on state;

[0044] The battery management system is used to monitor the thermal runaway of the power battery pack in the power-off state when the power vehicle is in the high-voltage power-off state; and to monitor the thermal runaway of the power battery pack in the power-on state when the power vehicle is in the high-voltage power-on state, and control the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system.

[0045] Optionally, if the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system.

[0046] Optionally, the battery management system is specifically used for:

[0047] Collecting operating status parameters of the power battery pack in real time;

[0048] Uploading the operating status parameters to a cloud server, and receiving a thermal runaway warning signal sent by the cloud server when detecting that the operating status parameters meet a thermal runaway preset condition;

[0049] The warning processing strategy is triggered to execute according to the thermal runaway warning signal; wherein, the warning processing strategy includes: sending thermal runaway warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0050] Optionally, the battery management system is specifically used for:

[0051] Collecting operating status parameters of the power battery pack in real time;

[0052] Using thermal runaway preset conditions to detect the operating state parameters;

[0053] When the preset conditions for thermal runaway are met, the early warning processing strategy is triggered to execute; wherein, the early warning processing strategy includes: sending thermal runaway early warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0054] Optionally, the operating status parameters include: one or more of: battery pressure rise rate, battery pressure increase, battery cell minimum voltage value, battery temperature rise rate, battery cell maximum temperature value, battery cell maximum temperature difference value, battery management system communication line fault signal, voltage sampling short circuit fault signal, thermistor failure signal, and reverse wake-up signal of the battery management system;

[0055] The thermal runaway preset condition is a combination of one or more of the following conditions:

[0056] Condition A: The battery pressure rise rate is higher than the pressure rise rate threshold and the number of times continues to meet the standard;

[0057] Condition B: The battery pressure increase is greater than the thermal runaway pressure increase threshold and the number of consecutive times meets the standard; wherein, the battery pressure increase is the difference between the current collected pressure and the average value of the previous N historical collected pressures at the current moment;

[0058] Condition C: The minimum voltage value of the battery cell is less than or equal to the thermal runaway voltage warning threshold;

[0059] Condition D: The battery temperature rise rate is higher than the temperature rise rate threshold and the duration meets the standard;

[0060] Condition E: The maximum temperature of the battery cell is greater than or equal to the thermal runaway temperature warning threshold and the duration meets the standard;

[0061] Condition F: The maximum temperature difference of the battery cell is greater than or equal to the thermal runaway temperature difference warning threshold and the duration meets the standard;

[0062] Condition G: The daisy chain communication line fault signal of the battery management system is reported and the duration meets the standard;

[0063] Condition H: The voltage sampling short-circuit fault signal of the battery management system is reported and the duration meets the standard;

[0064] Condition I: The thermistor failure signal is reported and the number of failures reaches the standard;

[0065] Condition J: The reverse wake-up signal of the battery management system is reported.

[0066] Optionally, the battery management system is connected to the active fuse via a fuse control component, and is used to control the active fuse to perform a fuse operation using the fuse control component.

[0067] Optionally, the battery management system is connected to the active fuse through an auxiliary controller to trigger the auxiliary controller to generate a driving current to drive the active fuse to perform a fusing operation; and uses an anti-backflow component inside the battery management system to block the driving current from flowing to the internal chip of the battery management system; wherein the anti-backflow component is designed in the circuit connecting the internal chip of the battery management system and the auxiliary controller.

[0068] The third aspect of the present invention discloses an electric vehicle, including a memory, a battery management system, and a computer program stored in the memory and executable on the battery management system, wherein the battery management system implements the steps of the above method when executing the program.

[0069] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages:

[0070] The present invention provides a method and system for monitoring thermal runaway of a power battery and an electric vehicle. When the electric vehicle is in a high-voltage power-off state, a battery management system draws power from a power battery pack through a DC-DC buck converter to monitor thermal runaway of the power battery pack in the power-off state; when the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through a high-voltage distributor to monitor thermal runaway of the power battery pack in the power-on state, and controls a switch control component inside the DC-DC buck converter to automatically cut off a power supply line connected to the battery management system, thereby enabling all-weather monitoring of the power battery and ensuring the safety of the electric vehicle 24 hours a day.

[0071] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0073] Figure 1 An internal structure diagram of a thermal runaway monitoring system for a power battery according to an embodiment of the present invention is shown;

[0074] Figure 2 A schematic diagram showing the connection between a step-down DC-DC and a battery management system according to an embodiment of the present invention is shown;

[0075] Figure 3 A schematic diagram of the design of a backflow prevention assembly according to an embodiment of the present invention is shown;

[0076] Figure 4 A flow chart of a method for monitoring thermal runaway of a power battery according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0077] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0079] First, as Figure 1 As shown, the embodiment of the present invention first introduces the internal structure of the thermal runaway monitoring system for the power battery.

[0080] The thermal runaway monitoring system of the power battery of the present invention comprises: a battery management system, a power battery pack, a high-voltage distributor (BDU, Battle Dress Uniform), and a DC-DC buck converter (also called: buck DC-DC).

[0081] The power battery pack includes a plurality of battery cells. Specifically, the plurality of battery cells are connected in series to form the power battery pack, and the power battery pack has two connection terminals, a total positive terminal and a total negative terminal.

[0082] The high-voltage end of the step-down DC-DC is connected to the total positive and negative of the power battery pack, which can avoid being controlled by the high-voltage distributor and its relays; the low-voltage end of the step-down DC-DC is connected to the battery management system.

[0083] The step-down DC-DC is used to draw power from the power battery pack to power the battery management system when the power vehicle is in a high-voltage power-down state. Of course, the step-down DC-DC can also draw power from the high-voltage battery pack all day and convert it into 12V low voltage to supply the battery management system and other electrical appliances.

[0084] By installing a step-down DC-DC inside the power battery to power the battery management system, the vehicle-mounted DC / DC and low-voltage 12V battery originally connected to the battery management system can be eliminated, thereby avoiding the battery management system wake-up failure caused by low power of the 12V battery.

[0085] In an optional embodiment, a switch control component is provided inside the step-down DC-DC, which is used to automatically cut off the power supply line connected to the battery management system when the power vehicle is in a high-voltage power-on state, and to connect the power supply line connected to the battery management system when the power vehicle is in a high-voltage power-off state. Optionally, if the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system to power the battery management system around the clock. Specifically, the switch control component can be manually controlled by a technician to connect the power supply line connected to the battery management system. Of course, it can also automatically trigger the connection of the power supply line connected to the battery management system.

[0086] In an optional embodiment, a high-voltage fuse component is provided inside the step-down DC-DC to cut off the power supply line connected to the battery management system in the event of a high-voltage fault, thereby ensuring the safety of the vehicle.

[0087] The battery management system is used to monitor thermal runaway of the power battery pack in the power-off state when the power vehicle is in the high-voltage power-off state.

[0088] See also Figure 2 , is a connection diagram of a DC-DC buck converter (also called: buck DC-DC) and a battery management system.

[0089] exist Figure 2 In the process, the total positive and negative of the power battery pack are connected to the high voltage end of the DC-DC buck converter; the low voltage end of the DC-DC buck converter is connected to the battery management system.

[0090] When the electric vehicle is in a high-voltage power-off state (the vehicle is turned off or in sleep mode), the low-power monitoring mode is automatically activated. At this time, the internal switch control component of the step-down DC-DC conducts the connection line with the battery management system, so that the step-down DC-DC takes power from the power battery pack and converts it into 12V power supply for the battery management system, supporting the battery management system to complete a seamless process chain from data acquisition, data storage, data transmission, analysis and calculation, command issuance and execution, and realize all-round, all-weather online monitoring of the power battery and its related circuits in the high-voltage power-off state.

[0091] In this mode, the battery management system includes but is not limited to realizing functions such as battery cell parameter collection, data upload, fault warning, and command issuance.

[0092] In addition, the step-down DC-DC is connected to low-voltage electrical appliances on the vehicle side (including but not limited to sentinel mode, OTA upgrade, data networking, car refrigerator and other equipment). The battery management system receives the power supply request of the low-voltage electrical appliances on the vehicle side, and controls the step-down DC-DC to draw power from the power battery pack, converts it into low-voltage electricity and distributes power to the low-voltage electrical appliances on the vehicle side, supporting the operation of the low-voltage electrical appliances on the vehicle side. It can be seen that even in the high-voltage power-down state of the electric vehicle, the design of the present invention can also support the operation of the low-voltage electrical appliances on the vehicle side.

[0093] When the electric vehicle is in a high-voltage power-on state (vehicle start, running), the battery management system automatically exits the low-power monitoring mode and activates all functions.

[0094] The high-voltage distributor is connected to the total positive and negative terminals of the power battery pack and is controlled by the battery management system. It is used to draw power from the power battery pack to power the battery management system when the power vehicle is in the high-voltage power-on state.

[0095] Specifically, the battery positive interface and battery negative interface of the high-voltage distributor are respectively connected to the total positive (positive electrode of the power battery pack) and total negative (negative electrode of the power battery pack) of the power battery pack. Through various circuits and components inside the high-voltage distributor, the distribution and control of the power battery pack's electric energy are realized. It is responsible for distributing the high-voltage electric energy of the power battery pack to various high-voltage components of the vehicle, such as motor controllers, chargers, etc., to ensure that these components can obtain stable and reliable power supply.

[0096] Furthermore, a relay is provided inside the high-voltage distributor. One end of the total positive relay is connected to the total positive of the power battery pack, and the other end is connected to the discharge positive electrode interface and other related circuits; one end of the total negative relay is connected to the total negative of the power battery pack, and the other end is connected to the charging negative electrode interface, the discharge negative electrode interface and other related circuits. According to different operating modes of the vehicle, such as charging mode, discharging mode, pre-charging mode, etc., the opening and closing of the relay is controlled to achieve the switching and management of the circuit, ensuring that the charging and discharging process of the power battery pack can be carried out safely and efficiently.

[0097] The battery management system is used to monitor thermal runaway of the power battery pack when the power vehicle is in a high-voltage power-on state. Specifically, the battery management system is connected to each battery cell or battery module in the power battery pack through a signal line to monitor the battery voltage, current, temperature and other parameters in real time. In addition, the battery management system is also connected to the relay control terminal in the high-voltage distributor to control the closing and opening of the relay according to the battery status and the vehicle's operating requirements, thereby achieving management and protection of the power battery pack's charging and discharging process.

[0098] In order to support the battery management system in executing the early warning processing strategy of thermal runaway in hardware, the active fuse is connected to the battery management system through the fuse control component.

[0099] Specifically, active fuses are usually connected in series in the power supply circuit of the power battery pack. When the power battery pack itself fails (such as an internal short circuit) or there is a problem with the external load (such as a motor controller short circuit) causing the current to increase abnormally, such as reaching the warning threshold, the active fuse will be blown to ensure the safety of the power battery.

[0100] In order to facilitate the control of the blowing timing of the active fuse, the battery management system connects the active fuse through the fuse control component, and uses the fuse control component to control the active fuse to perform the blowing operation. Specifically, the fuse control component is an independent chip, and the battery management system generates a driving signal by controlling the fuse control component to drive the active fuse to perform the blowing operation.

[0101] Furthermore, the fuse control component also has a feedback diagnosis function. Specifically, the fuse control component is also used to store the drive signal voltage and use CAN communication for feedback when the drive signal voltage is higher than the set voltage (for example, 8V).

[0102] In order to facilitate the control of the blowing timing of the active fuse, the battery management system is connected to the active fuse through the auxiliary controller. The auxiliary controller has the function of triggering the blowing of the active fuse.

[0103] Specifically, both the battery management system and the auxiliary controller (such as the airbag controller ACU) can trigger the active fuse to perform a fusing operation. In order to prevent the battery management system hardware from absorbing the auxiliary controller driving current, resulting in the inability to trigger the active fuse to perform the operation of fusing the power battery pack, an anti-backflow component is designed inside the battery management system. The anti-backflow component is designed in the line connecting the internal chip of the battery management system and the auxiliary controller.

[0104] See also Figure 3 , is a design schematic diagram of the backflow prevention component.

[0105] When the power supply of the battery management system is disabled due to a vehicle collision failure and the auxiliary controller power supply is normally supplied, the auxiliary controller current will be fed back to the battery management system power supply through the circuit, causing abnormal voltage at both ends of the battery management system chip IC. The diode D1 may be broken down, resulting in communication abnormalities and even failures of other electronic components under the same power supply.

[0106] In order to prevent the battery management system hardware from absorbing the auxiliary controller driving current, a diode D3 and a pull-up resistor R are added to the signal lines of the auxiliary controller and the battery management system. Diode D3 is used to block the backflow current path. When the auxiliary controller outputs a high level, the pull-up resistor R gives the battery management system chip IC a high level; when the auxiliary controller outputs a low level, the battery management system IC is clamped to a low level by diode D3. If the battery management system cannot be powered on, the high level output by the auxiliary controller cannot be fed to the battery management system through diode D3, thereby blocking the driving current from flowing to the battery management system.

[0107] The above is the hardware improvement of the present invention to realize the all-weather monitoring design of the power battery. When the electric vehicle is in the high-voltage power-off state, the battery management system draws power from the power battery pack through the DC-DC buck converter to monitor the thermal runaway of the power battery pack in the power-off state; when the power vehicle is in the high-voltage power-on state, the battery management system draws power from the power battery pack through the high-voltage distributor to monitor the thermal runaway of the power battery pack in the power-on state, so that the power battery can be monitored all-weather and the safety of the electric vehicle can be guaranteed 24 hours a day.

[0108] In a second aspect, based on the same inventive concept as the thermal runaway monitoring system for a power battery provided in the embodiment of the first aspect, an embodiment of the present invention further provides a thermal runaway monitoring method for a power battery.

[0109] See also Figure 4 The thermal runaway monitoring method of a power battery according to an embodiment of the present invention comprises at least the following steps:

[0110] S401, when the power vehicle is in a high-voltage power-off state, the battery management system draws power from the power battery pack through a DC-DC buck converter to monitor thermal runaway of the power battery pack in the power-off state.

[0111] The high voltage end of the DC-DC buck converter is connected to the total positive and negative voltages of the power battery pack, and the low voltage end of the DC-DC buck converter is connected to the battery management system. This design can power the battery management system in its dormant state, allowing the battery management system to maintain all-weather monitoring of the power battery.

[0112] Specifically, in the process of thermal runaway monitoring of the power battery pack in the power-off state, the following steps are specifically performed:

[0113] S4011, collect operating status parameters of the power battery pack in real time.

[0114] Among them, the operating status parameters include: one or more of the battery pressure rise rate, battery pressure increase, battery cell minimum voltage value, battery temperature rise rate, battery cell maximum temperature value, battery cell maximum temperature difference value, battery management system communication line fault signal, voltage sampling short circuit fault signal, thermistor failure signal, and battery management system reverse wake-up signal.

[0115] S4012, uploading the operating status parameters to the cloud server, and receiving a thermal runaway warning signal sent by the cloud server when it is detected that the operating status parameters meet a thermal runaway preset condition.

[0116] In the high voltage power-off state, the operating state parameters are uploaded to the cloud server for analysis. It is worth noting that in this embodiment, the operating state parameters can be detected on the cloud or on the vehicle side using the thermal runaway preset conditions. The inspection process of the two is consistent and will be described in detail later, so it will not be repeated here.

[0117] Specifically, the vehicle side communicates with the cloud server using wired data transmission or wireless data transmission to receive the thermal runaway warning signal.

[0118] Wired data transmission communication includes but is not limited to the use of one or more of the following devices: switches, wired routers, fiber optic transceivers, fiber optic cables, digital microwave equipment. Wireless data transmission communication includes but is not limited to the use of one or more of the following devices: wireless LAN, Bluetooth, network card, Zigbee. For example, the battery management system bypasses the vehicle controller and uploads data to the cloud server in real time through the dedicated line of the vehicle communication terminal T-BOX.

[0119] S4013, triggering execution of a warning processing strategy according to the thermal runaway warning signal, wherein the warning processing strategy includes: sending thermal runaway warning data to the vehicle controller, and / or controlling an active fuse located in an internal circuit of the power battery pack to perform a fuse operation.

[0120] The above is the all-weather monitoring process of the high-voltage power state. The battery management system draws power from the step-down DC-DC inside the power battery to achieve all-weather data real-time collection, storage, processing and transmission to the cloud server to ensure that when thermal runaway occurs, the cloud server will synchronize real-time analysis and timely feedback to the vehicle side, reducing the computing consumption of the vehicle side and maximizing the safety of user life and property.

[0121] S402, when the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through the high-voltage distributor to monitor the thermal runaway of the power battery pack in the power-on state, and controls the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system.

[0122] Among them, the high-voltage distributor is connected to the total positive and negative of the power battery pack and is controlled by the battery management system. The execution logic of the high-voltage distributor and the battery management system has been introduced in the aforementioned hardware structure and will not be repeated here.

[0123] In an optional embodiment, after controlling the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system, if the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system.

[0124] The process of thermal runaway monitoring of the power battery pack in the powered-on state specifically includes the following steps:

[0125] S4021, collect operating status parameters of the power battery pack in real time.

[0126] Among them, the operating status parameters include: one or more of the battery pressure rise rate, battery pressure increase, battery cell minimum voltage value, battery temperature rise rate, battery cell maximum temperature value, battery cell maximum temperature difference value, battery management system communication line fault signal, voltage sampling short circuit fault signal, thermistor failure signal, and battery management system reverse wake-up signal.

[0127] S4022, using thermal runaway preset conditions to detect operating status parameters.

[0128] Specifically, the battery management system itself uses the thermal runaway preset conditions to detect the operating status parameters. The specific detection process will be introduced later and will not be repeated here.

[0129] S4023, triggering the execution of the early warning processing strategy when the preset conditions for thermal runaway are met.

[0130] Among them, the warning processing strategy includes: sending thermal runaway warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0131] It is worth noting that no matter the electric vehicle is in a high-voltage power-on state or a high-voltage power-off state, the battery management system will monitor the operating status parameters of the power battery pack in real time, and store them in the storage medium after converting the data format for subsequent use.

[0132] Furthermore, in order to save vehicle-side computing power, whether the electric vehicle is in a high-voltage power-on state or a high-voltage power-off state, the operating status parameters can be uploaded to the cloud server, and the cloud server uses the thermal runaway preset conditions to detect the operating status parameters, thereby saving vehicle-side computing resources. Of course, if the electric vehicle is in a high-voltage power-on state, the vehicle itself can also use the thermal runaway preset conditions to detect the operating status parameters.

[0133] Specifically, the thermal runaway preset condition is one or more of the following combinations:

[0134] Condition A: The battery pressure rise rate is higher than the pressure rise rate threshold and the number of consecutive times meets the standard.

[0135] Specifically, the battery pressure rise rate is calculated as:

[0136] Vn=(v j -v i ) / 0.5

[0137] Among them, Vn represents the rate of increase of battery pressure, n represents the number of statistics, and v i represents the pressure of the ith battery, v j represents the jth battery pressure, v i In v j It was previously calculated that there is any battery pressure between j and i.

[0138] Specifically, after each battery pressure is counted, the battery pressure rising rate is calculated using the above formula.

[0139] Refer to Table 1, set the pressure rise rate threshold v0, and calculate the pressure rise rate Vn in real time according to the above formula:

[0140] If the time series of the air pressure signal reported by the air pressure sensor is:

[0141] Table 1

[0142] Time (ms) 0 100 200 300 400 500 600 700 …… Battery pressure <![CDATA[v1]]> <![CDATA[v2]]> <![CDATA[v3]]> <![CDATA[v4]]> <![CDATA[v5]]> <![CDATA[v6]]> <![CDATA[v7]]> <![CDATA[v8]]> ……

[0143] According to Table 1, the calculated pressure rise rates are: v n =(v6-v1) / 0.5, (v7-v2) / 0.5, (v8-v3) / 0.5,….

[0144] When Vn>V0, and the number of times lasts is greater than N times, condition A is satisfied.

[0145] Condition B: The battery pressure increase is greater than the thermal runaway pressure increase threshold.

[0146] The battery pressure increase is the difference between the current collected pressure and the average value of the previous N historical collected pressures.

[0147] Specifically, the thermal runaway pressure increase threshold △P0 is set, and the pressure increase △P is calculated according to the following method:

[0148] Collect the current air pressure value P n Among them, the interval time of collecting air pressure is 1s, the current air pressure value is P1, the next air pressure value is P2, and so on.

[0149] The current collected air pressure and the average value P0 of the previous N historical collected air pressures at the current moment.

[0150] Calculate the increase in battery pressure: △P = Pn-P0.

[0151] If △P>△P0 and the number of consecutive times reaches the standard, condition B is met.

[0152] Condition C: The minimum voltage value of the battery cell is less than or equal to the thermal runaway voltage warning threshold.

[0153] Specifically, the thermal runaway voltage warning threshold U0 is set, and the minimum voltage value of the battery cell collected in real time is U min . If U min ≤U0, then the C condition is satisfied.

[0154] Condition D: The battery temperature rise rate is higher than the temperature rise rate threshold and the duration meets the requirement.

[0155] Specifically, the battery temperature rise rate is calculated as follows:

[0156] Kn=(T j -T i )

[0157] Among them, Kn represents the battery temperature rise rate, n represents the number of statistics, T i represents the temperature of the ith battery, T j represents the jth battery temperature, T i In Tj It was previously calculated that there is any battery temperature between j and i.

[0158] Specifically, after each battery pressure is counted, the battery temperature rise rate is calculated using the above formula.

[0159] Refer to Table 2, set the temperature rise rate threshold k0, and calculate the battery temperature rise rate Kn according to the above formula:

[0160] If the time series of the air pressure signal reported by the temperature sensor is:

[0161] Table 2

[0162] Time (ms) 0 200 400 600 800 1000 1200 1400 …… Battery temperature value T1 T2 T3 T4 T5 T6 T7 T8 ……

[0163] According to Table 2, the calculated temperature rise rates are Kn=(T6-T1), (T7-T2), (T8-T3), ... in sequence.

[0164] When Kn>k0, and the number of times is greater than N, condition D is satisfied.

[0165] Condition E: The maximum temperature of the battery cell is greater than or equal to the thermal runaway temperature warning threshold and the duration meets the standard.

[0166] Specifically, the thermal runaway temperature warning threshold T0 is set, and the maximum temperature value of the battery cell collected in real time is Tn.

[0167] If Tn≥T0 and duration ≥2s, condition E is met.

[0168] Condition F: The maximum temperature difference of the battery cell is greater than or equal to the thermal runaway temperature difference warning threshold and the duration meets the standard.

[0169] Specifically, the thermal runaway temperature difference warning threshold △T0 is set, and the maximum temperature difference of the battery cell is calculated in real time:

[0170] △Tn=Tn max -Tn min

[0171] Among them, Tn max Indicates the maximum temperature of the battery cell with the largest temperature difference, Tn min It is the lowest temperature of the battery cell with the largest temperature difference.

[0172] If △Tn≥△T0 and duration ≥2s, condition F is met.

[0173] Condition G: The daisy chain communication line fault signal of the battery management system is reported and the duration meets the requirement.

[0174] For example, if the daisy chain communication disconnection fault signal of the battery management system is reported and lasts for ≥8s, condition G is met.

[0175] Condition H: The voltage sampling short-circuit fault signal of the battery management system is reported and the duration meets the standard.

[0176] For example, if the voltage sampling short circuit fault signal is reported and the duration is ≥8s, then condition H is met.

[0177] Condition I: Thermistor failure signal is reported and the number of failures meets the standard.

[0178] For example, if a thermistor failure signal is issued and the number of temperature sampling open circuits is ≥ 4, condition I is met.

[0179] Condition J: The reverse wake-up signal of the battery management system is reported. For example, if the pressure sensor reversely wakes up the battery management system in the dormant state, condition J is met.

[0180] In the process of detecting the operating state parameters using the thermal runaway preset conditions, the thermal runaway preset conditions may be obtained by combining the above-mentioned multiple conditions to detect the operating state parameters.

[0181] For example, the thermal runaway preset condition is:

[0182] Condition combination 1: (A||B||J) and (C||E||G||H||D||F) are satisfied simultaneously within 10 minutes. “||” indicates an OR relationship.

[0183] Condition combination 2: C and (D||E||F) are met simultaneously within 10 minutes.

[0184] Condition combination 3: After conditions D||E||F are met, condition H is met within 10 minutes.

[0185] Condition combination 4: After the E||F condition is met, the G||I condition is met within 10 minutes.

[0186] If the operating status parameters meet any of the above conditions, it means that the thermal runaway preset conditions are met and the early warning processing strategy is triggered.

[0187] The early warning processing strategy includes one or more of the following combinations:

[0188] Warning processing strategy 1: Send thermal runaway warning related data to the vehicle controller. Specifically, the battery management system sends thermal runaway warning related data through network messages, such as: alarm path and thermal runaway specific data.

[0189] Warning processing strategy 2: Clear the warning only through diagnostic service instructions, and prohibit the high-voltage action and sleep wake-up action to recover from thermal runaway faults.

[0190] Early warning processing strategy 3: Control the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

[0191] As an optional implementation, since the battery management system is connected to the active fuse through a fuse control component, in the process of controlling the active fuse located in the internal circuit of the power battery pack to perform a fuse operation, the battery management system uses the fuse control component to drive the active fuse to perform a fuse operation.

[0192] Furthermore, the battery management system is connected to the active fuse via the auxiliary controller. Both the battery management system and the auxiliary controller can control the fusing operation of the active fuse.

[0193] Specifically, the battery management system or the vehicle controller triggers the auxiliary controller to generate a driving current to drive the active fuse to perform a blowing operation. In order to prevent the battery management system hardware from absorbing the auxiliary controller driving current, resulting in the inability to trigger the active fuse to perform a blowing operation, an anti-backflow component is designed inside the battery management system. Among them, the anti-backflow component is designed in the line connecting the internal chip of the battery management system and the auxiliary controller. After the auxiliary controller generates the driving current, the anti-backflow component inside the battery management system is used to block the driving current from flowing to the internal chip of the battery management system.

[0194] In an optional implementation, if the operating state parameters satisfy the thermal runaway condition combination including condition J, it indicates that the electric vehicle has thermal runaway in the dormant state. After the early warning processing strategy is triggered according to the thermal runaway early warning signal, the air pressure operating state parameters for the first n seconds that meet the thermal runaway preset conditions are transmitted to the battery management system, and the thermal runaway air pressure increase threshold, thermal runaway voltage early warning threshold, and air pressure rise rate threshold are latched for 5 seconds, so that the battery management system can obtain the relevant status information of the previous battery after the vehicle is powered on again, thereby realizing effective monitoring and management of the battery.

[0195] In the third aspect, based on the same inventive concept as the thermal runaway monitoring method for a power battery provided in the embodiment of the first aspect, an embodiment of the present invention further discloses an electric vehicle, comprising a memory, a battery management system, and a computer program stored in the memory and executable on the battery management system, wherein the battery management system implements the steps of any of the methods described above when executing the program.

[0196] Through one or more embodiments of the present invention, the present invention has the following beneficial effects or advantages:

[0197] The present invention provides a method and system for monitoring thermal runaway of a power battery and an electric vehicle. When the electric vehicle is in a high-voltage power-off state, a battery management system draws power from a power battery pack through a DC-DC buck converter to monitor thermal runaway of the power battery pack in the power-off state; when the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through a high-voltage distributor to monitor thermal runaway of the power battery pack in the power-on state, thereby enabling all-weather monitoring of the power battery and ensuring the safety of the electric vehicle 24 hours a day.

[0198] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0199] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for monitoring thermal runaway of a power battery, characterized in that: The method comprises: When the electric vehicle is in a high-voltage power-off state, the battery management system draws power from the power battery pack through a DC-DC buck converter to monitor the thermal runaway of the power battery pack in the power-off state; wherein the high-voltage end of the DC-DC buck converter is connected to the total positive and total negative of the power battery pack, and the low-voltage end of the DC-DC buck converter is connected to the battery management system; When the power vehicle is in a high-voltage power-on state, the battery management system draws power from the power battery pack through the high-voltage distributor to monitor the thermal runaway of the power battery pack in the power-on state, and controls the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system; wherein the high-voltage distributor is connected to the total positive and total negative of the power battery pack and is controlled by the battery management system.

2. The method according to claim 1, characterized in that After controlling the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system, the method further includes: If the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system.

3. The method according to claim 1, characterized in that The thermal runaway monitoring of the power battery pack in a power-off state specifically includes: Collecting operating status parameters of the power battery pack in real time; Uploading the operating status parameters to a cloud server, and receiving a thermal runaway warning signal sent by the cloud server when detecting that the operating status parameters meet a thermal runaway preset condition; The warning processing strategy is triggered to execute according to the thermal runaway warning signal; wherein, the warning processing strategy includes: sending thermal runaway warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

4. The method according to claim 1, characterized in that The thermal runaway monitoring of the power battery pack in a powered-on state specifically includes: Collecting operating status parameters of the power battery pack in real time; Using thermal runaway preset conditions to detect the operating state parameters; When the preset conditions for thermal runaway are met, the early warning processing strategy is triggered to execute; wherein, the early warning processing strategy includes: sending thermal runaway early warning data to the vehicle controller, and / or controlling the active fuse located in the internal circuit of the power battery pack to perform a fusing operation.

5. The method according to claim 3 or 4, characterized in that The operating state parameters include: one or more of: battery pressure rise rate, battery pressure increase, battery cell minimum voltage value, battery temperature rise rate, battery cell maximum temperature value, battery cell maximum temperature difference value, battery management system communication line fault signal, voltage sampling short circuit fault signal, thermistor failure signal, and reverse wake-up signal of the battery management system; The thermal runaway preset condition is a combination of one or more of the following conditions: Condition A: The battery pressure rise rate is higher than the pressure rise rate threshold and the number of times continues to meet the standard; Condition B: The battery pressure increase is greater than the thermal runaway pressure increase threshold and the number of consecutive times meets the standard; wherein, the battery pressure increase is the difference between the current collected pressure and the average value of the previous N historical collected pressures at the current moment; Condition C: The minimum voltage value of the battery cell is less than or equal to the thermal runaway voltage warning threshold; Condition D: The battery temperature rise rate is higher than the temperature rise rate threshold and the duration meets the standard; Condition E: The maximum temperature of the battery cell is greater than or equal to the thermal runaway temperature warning threshold and the duration meets the standard; Condition F: The maximum temperature difference of the battery cell is greater than or equal to the thermal runaway temperature difference warning threshold and the duration meets the standard; Condition G: The daisy chain communication line fault signal of the battery management system is reported and the duration meets the standard; Condition H: The voltage sampling short-circuit fault signal of the battery management system is reported and the duration meets the standard; Condition I: The thermistor failure signal is reported and the number of failures reaches the standard; Condition J: The reverse wake-up signal of the battery management system is reported.

6. The method according to claim 3 or 4, characterized in that The battery management system is connected to the active fuse via a fuse control component; the control of the active fuse located in the internal circuit of the power battery pack to perform a fuse operation specifically includes: The battery management system uses the fuse control component to control the active fuse to perform a fuse operation.

7. The method according to claim 6, characterized in that The battery management system is connected to the active fuse via an auxiliary controller; the control of the active fuse located in the internal circuit of the power battery pack to perform a fuse operation specifically includes: The battery management system triggers the auxiliary controller to generate a driving current to drive the active fuse to perform a fusing operation; The backflow prevention component inside the battery management system is used to block the driving current from flowing to the internal chip of the battery management system; wherein the backflow prevention component is designed in the circuit connecting the internal chip of the battery management system and the auxiliary controller.

8. A thermal runaway monitoring system for a power battery, characterized in that: The system comprises: A power battery pack, comprising a number of battery cells; A DC-DC buck converter, the high voltage of which is connected to the total positive and total negative of the power battery pack, and the low voltage of which is connected to the battery management system; the DC-DC buck converter is used to draw power from the power battery pack to power the battery management system when the power vehicle is in a high voltage power-off state; A high-voltage distributor connected to the total positive and negative of the power battery pack and controlled by the battery management system, and used to draw power from the power battery pack to supply power to the battery management system when the power vehicle is in a high-voltage power-on state; The battery management system is used to monitor the thermal runaway of the power battery pack in the power-off state when the power vehicle is in the high-voltage power-off state; and to monitor the thermal runaway of the power battery pack in the power-on state when the power vehicle is in the high-voltage power-on state, and control the switch control component inside the DC-DC buck converter to automatically cut off the power supply line connected to the battery management system.

9. The system according to claim 8, characterized in that If the high-voltage distributor fails, the switch control component is controlled to connect the power supply line connected to the battery management system.

10. An electric vehicle, comprising a memory, a battery management system, and a computer program stored in the memory and operable on the battery management system, characterized in that: When the battery management system executes the program, the steps of the method according to any one of claims 1 to 7 are implemented.

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