Short circuit identification and protection method for sampling element of battery management system

Abstract

The invention provides a battery management system sampling element short circuit identification method, which is characterized in that a temperature sensor is arranged in a battery management system to monitor the temperature of a discharge tube, and comprises the following steps: obtaining the temperature of the discharge tube through the temperature sensor, and calculating the temperature difference value of the discharge tube in a preset time length; in response to determining that the temperature difference value is greater than a preset temperature difference threshold value, comparing the discharge current obtained by the sampling element with a preset current threshold value; and in response to determining that the discharge current is less than the preset current threshold, determining that the sampling element is short-circuited. In the embodiment of the application, the temperature change rate of the discharge tube in the BMS system is monitored by the temperature sensor, the short-circuit fault of only one sampling element can be found by combining the discharge current obtained by the sampling element, and the corresponding protection measure is taken, so that the BMS system operates safely and stably.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a method for identifying and protecting short circuits in sampling components of a battery management system. Background Art

[0002] The statements in this section are merely intended to provide background information related to the technical solution of the present application to aid understanding, and they do not necessarily constitute prior art with respect to the technical solution of the present application.

[0003] A battery management system (BMS) closely monitors, controls, and distributes the reliable charging and discharging of the entire battery system throughout its service life. BMSs typically monitor the operating current through sampling elements and take protective measures upon detecting anomalies. If a sampling element short-circuit fails (e.g., a sampling resistor, Hall effect current sensor, or other current sensor), the management system will receive erroneous operating current data, mistaking the anomaly for normal operation. This prevents the management system from promptly identifying potential hazards and implementing appropriate protective measures. Detecting sampling element short-circuit failures is a technical challenge that BMSs must address.

[0004] Existing solutions typically involve adding a second, identical current-sampling element. When the sampling data from the two elements conflict, the element is deemed faulty. However, this solution requires hardware redundancy, which not only prolongs development time but also increases production costs. Summary of the Invention

[0005] Therefore, the purpose of this application is to overcome the above-mentioned defects of the prior art and provide a method for identifying short circuits in sampling elements of a battery management system, wherein a temperature sensor is provided in the battery management system to monitor the temperature of the discharge tube, and the method comprises:

[0006] Obtain the temperature of the discharge tube via a temperature sensor and calculate the temperature difference of the discharge tube for a preset time period;

[0007] In response to determining that the temperature difference is greater than a preset temperature difference threshold, comparing the discharge current obtained via the sampling element with a preset current threshold;

[0008] In response to determining that the discharge current is less than the preset current threshold, it is determined that the sampling element is short-circuited.

[0009] According to one embodiment of the present invention, the temperature sensor is a thermistor.

[0010] According to one embodiment of the present invention, the sampling element is a sampling resistor or a Hall current sensor.

[0011] According to an embodiment of the present invention, the preset temperature difference threshold is 4 degrees Celsius or 8 degrees Celsius.

[0012] According to one embodiment of the present invention, the preset temperature difference threshold is 4 degrees Celsius, and the preset current threshold is 20 amperes or 10 amperes.

[0013] According to one embodiment of the present invention, the preset temperature difference threshold is 8 degrees Celsius, and the preset current threshold is 40 amperes, or 20 amperes, or 10 amperes.

[0014] According to an embodiment of the present invention, the preset duration is 10 seconds, or 20 seconds, or 30 seconds.

[0015] According to a second aspect of the present application, a method for protecting a battery management system sampling element from short circuit is provided, comprising: in response to any of the above-mentioned methods for identifying a short circuit in a battery management system sampling element identifying that the sampling element is short-circuited, circuit protection is performed by shutting down a discharge tube of the battery management system.

[0016] According to an embodiment of the second aspect of the present application, the circuit protection method also includes turning off the high-current charging tube, floating charge switch, protection charging switch of the battery management system, blowing the controllable fuse and entering sleep mode.

[0017] According to an embodiment of the second aspect of the present application, the method further includes: in response to determining that the discharge tube is closed and the temperature change rate is 0 degrees Celsius every 30 seconds and lasts for 30 minutes, opening the discharge tube.

[0018] In the embodiments of the present application, by using a temperature sensor to monitor the temperature change rate of the discharge tube in the BMS system, combined with the discharge current obtained by the sampling element, a short circuit fault of only one sampling element can be detected and corresponding protection measures can be taken, so that the BMS system can operate safely and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present application are further described below with reference to the accompanying drawings, wherein:

[0020] Figure 1 This is a schematic diagram of an example circuit of an existing BMS;

[0021] Figure 2 The temperature change rate diagram of the discharge tube at different discharge currents;

[0022] Figure 3 A simplified diagram of the BMS circuit with an added temperature sensor;

[0023] Figure 4 This is a schematic diagram of a workflow for protecting a BMS system after a sampling element short circuit according to one embodiment of the present application;

[0024] Figure 5This is a schematic diagram of a workflow for protecting a BMS system after a sampling element short circuit according to another embodiment of the present application; DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the following further describes this application in detail through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0026] From the above analysis, it can be seen that how to identify the short-circuit fault of the sampling element of the BMS with only one sampling element and take measures to protect the BMS system is a technical problem that needs to be solved at present.

[0027] According to device characteristics, the heat generated by a MOSFET or IGBT is positively correlated with the current flowing through it, which in turn is positively correlated with the rate of temperature rise. Therefore, the BMS discharge current is positively correlated with the rate of change of the discharge tube temperature. If the sampled discharge current and the rate of change of the discharge tube temperature do not correspond, it can be concluded that the sampling element has a short circuit fault. The details are as follows.

[0028] Figure 1 The figure shows a simplified circuit diagram of an existing BMS, including a battery 1, a controllable fuse 2, a sampling element 3, a discharge tube 4, a high-current charging tube 5, a protective charging hardware circuit and switch 6, and a floating charge hardware circuit and switch 7. The controllable fuse 2 is controlled by the microcontroller unit (MCU) within the BMS (not shown); the sampling element 3 is used to sample the BMS's charge and discharge currents; the discharge tube 4 is composed of a metal-oxide-semiconductor field-effect transistor (MOSFET) and its own anti-parallel diode, and its opening and closing are also controlled by the MCU; the high-current charging tube 5 is composed of a MOSFET and its own anti-parallel diode, and its opening and closing are also controlled by the MCU; when the protective charging switch 6 is turned on, the maximum charging current is limited to 2A (adjustable to other values ​​as needed); when the floating charge switch 7 is turned on, the maximum charging current is limited to 50mA (adjustable to other values ​​as needed). At the same time, only one of the high current charging tube 5, protection charging switch 6 and floating charge switch 7 can be turned on. Figure 1 The switch shown in Figure 1 is closed and current is flowing through the switch. Figure 1 In the figure, P+ is the positive electrode of BMS, and P- is the negative electrode of BMS. The discharge tube in the BMS system can be as follows: Figure 1The discharge tube 4 may be a single discharge tube or multiple discharge tubes connected in parallel. A heat sink (not shown) may be provided for the discharge tube to dissipate heat. To save space and cost, a heat sink may be omitted, or multiple discharge tubes may be placed on a single heat sink. Of course, depending on needs or space availability, a heat sink may be provided for each discharge tube.

[0029] Within the BMS's allowable discharge current range, the inventors measured the temperature of the discharge tube 4 at different discharge currents and calculated its temperature change rate. They found that different discharge currents corresponded to different temperature change rates of the discharge tube 4, and that the temperature change rate of the discharge tube 4 increased with increasing discharge current. Temperatures are expressed in degrees Celsius (°C).

[0030] Figure 2 The figure shows the relationship between the temperature change rate of the discharge tube 4 and time for discharge currents of 10A, 20A, 40A, and 60A. The horizontal axis represents time in seconds (s), with the starting point being 4 seconds before the temperature change of the discharge tube 4. The vertical axis represents the temperature change rate in degrees Celsius per 30 seconds, calculated by subtracting the temperature of the discharge tube 4 30 seconds ago from the current temperature of the discharge tube 4.

[0031] from Figure 2 As can be seen from the data, when the discharge current is 10A, the temperature change rate of discharge tube 4 is 0°C / 30S, meaning the temperature of discharge tube 4 remains unchanged. When the discharge current is 20A, the maximum temperature change rate is 1°C / 30S, meaning the temperature of discharge tube 4 rises by 1°C every 30S. When the discharge current is 40A, the maximum temperature change rate is 4°C / 30S, meaning the temperature of discharge tube 4 rises by 4°C every 30S. When the discharge current is 60A, the maximum temperature change rate reaches 8°C / 30S, meaning the temperature of discharge tube 4 rises by 8°C every 30S. From these data, we can conclude that the temperature change rate of discharge tube 4 is related to the discharge current. When the temperature change rate reaches a certain value, it inevitably corresponds to a larger discharge current. For example, a temperature change rate of 4°C / 30S corresponds to a discharge current of 40A. Therefore, if the detected temperature change rate of the discharge tube 4 is 4° C. / 30S, but the discharge current obtained by the sampling element is less than 40A, it means that the discharge current obtained by the sampling element is wrong, and it can be determined that the sampling element is short-circuited.

[0032] Therefore, the inventors propose a method for identifying a short circuit of a sampling element based on the temperature change rate of the discharge tube 4. Figure 3As shown, a temperature sensor 8 is provided in the BMS system to monitor temperature changes in the discharge tube 4. The temperature sensor 8 can be a thermocouple sensor, a thermistor sensor, a platinum resistance sensor, etc., preferably a thermistor sensor. The temperature sensor 8 can be placed in close proximity to the discharge tube 4, or in close proximity to the heat sink of the discharge tube. Typically, the temperature sensor is connected to the BMS microcontroller (MCU) (not shown) in a communicative manner. For example, the temperature sensor converts the collected temperature into a voltage and sends it to the analog-to-digital conversion (ADC) pin of the BMS microcontroller MCU. The MCU monitors the temperature changes of the discharge tube via this temperature sensor. A method for determining whether a sampling element is short-circuited is to use the temperature sensor 8 to obtain the discharge tube temperature in real time and calculate the difference ΔTemp between the current temperature and the temperature obtained a preset time T ago (the current temperature minus the temperature obtained a preset time T ago). When the difference ΔTemp is greater than a preset temperature difference threshold Temp, the discharge current currently obtained by the sampling element is compared with a preset current threshold I. If the discharge current currently obtained by the sampling element is less than the preset current threshold I, the sampling element is determined to be short-circuited. For example, from Figure 2 From the data, we can see that when the discharge current is 40A, the temperature of the discharge tube 4 increases by 4°C every 30S. If the temperature change within 30S is greater than or equal to 4°C, the corresponding discharge current is greater than or equal to 40A. If the sampled current value is less than 40A, for example, 20A or 10A, it can be determined that the sampling element is faulty.

[0033] Similarly, from Figure 2 From the data, we can see that when the discharge current is 60A, the temperature of the discharge tube 4 increases by 8°C every 30S. If the temperature change within 30S is greater than or equal to 8°C, the corresponding discharge current is greater than or equal to 60A. If the sampled current value is less than 60A, for example, 40A, 20A or 10A, it can be determined that the sampling element is faulty.

[0034] The values ​​of the preset time length T, the preset temperature difference threshold Temp, and the preset current threshold I are selected based on experimental data according to different product designs. The selection principle is to avoid misjudgment when the BMS is operating normally and to identify a short circuit in the sampling element. In one example, the preset time length T is 30S, the preset temperature difference threshold Temp is 4°C, and the preset current I can be set to 20A or 10A. In another example, the preset time length T can be set to 30S, the preset temperature difference threshold Temp is set to 8°C, and the preset current I can be set to 40A, 20A, or 10A.

[0035] There is no special limitation on the values ​​of the preset time length T, the preset temperature difference threshold Temp, and the preset current threshold I. For example, the preset time length can also be 10 seconds, 20 seconds, etc. The corresponding preset temperature difference threshold Temp and preset current threshold I are usually different. These can be selected based on experimental data according to different product designs, as long as it is ensured that no misjudgment occurs when the BMS is operating normally and a short circuit of the sampling element can be identified.

[0036] After a short circuit fault is detected in the sampling element, the BMS system needs to take measures to respond to avoid potential hidden dangers.

[0037] Figure 4 A flowchart of an embodiment of a BMS system protecting itself after a sampling element short circuit is provided. The BMS system monitors the temperature rise rate of the discharge tube 4 and the discharge current detected by the sampling element in real time. If the temperature of the discharge tube 4 rises by 4°C within 30 seconds and the discharge current detected by the sampling element is less than 20A, indicating a sampling element short circuit, the system then shuts down the discharge tube 4, the high-current charging tube 5, the float charge switch, the protective charging switch, blows the controllable fuse, and enters sleep mode. Otherwise, the discharge tube 4 remains open and monitors the temperature rise rate of the discharge tube 4 and the discharge current detected by the sampling element in real time. This embodiment treats a sampling element short circuit as the highest level of fault handling. In this case, the BMS shuts down all charging and discharging functions, blows the controllable fuse, and enters sleep mode. If a highest level of fault occurs, the BMS must be returned to the factory. According to another embodiment of the present invention, the system can also initiate the above protective measures if the temperature of the discharge tube 4 rises by 4°C within 30 seconds and the discharge current detected by the sampling element is less than 10A. According to some further embodiments of the present invention, the system may take the above protection measures when the temperature of the discharge tube 4 rises by 8° C. within 30 seconds and the discharge current obtained by the sampling element is less than 40A, 20A or 10A.

[0038] Figure 5A flow chart of another embodiment of a BMS system protecting itself after a sampling element short-circuit is provided. The BMS system monitors the temperature rise rate of the discharge tube 4 and the discharge current obtained by the sampling element in real time. If the temperature of the discharge tube 4 rises by 4°C within 30 seconds and the discharge current obtained by the sampling element is less than 20A, indicating a short circuit, the BMS system shuts down the discharge tube 4. Otherwise, the discharge tube 4 remains open and the temperature rise rate and discharge current obtained by the sampling element are monitored in real time. If the discharge tube 4 is closed and the temperature change rate is 0°C / 30s for 30 minutes, the discharge tube 4 is opened, allowing discharge to resume. According to another embodiment of the present invention, the system can also initiate the above protection measures if the temperature of the discharge tube 4 rises by 4°C within 30 seconds and the discharge current obtained by the sampling element is less than 10A. According to still other embodiments of the present invention, the system can also initiate the above protection measures if the temperature of the discharge tube 4 rises by 8°C within 30 seconds and the discharge current obtained by the sampling element is less than 40A, 20A, or 10A.

[0039] The above-mentioned scheme of closing the discharge tube 4, and opening the discharge tube 4 after the discharge tube 4 is closed and the temperature change rate is 0°C / 30S for 30 minutes, and allowing discharge again is to treat the sampling element short circuit as a lower level fault. The lower level fault can be recovered, and the BMS can continue to work after recovery.

[0040] Through the above-mentioned specific embodiments of the present application, it is possible to identify a short-circuit fault in a sampling element of a BMS with only one sampling element and take measures to protect the BMS system. By monitoring the temperature change rate of the discharge tube 4 with a temperature sensor and combining it with the discharge current obtained by the sampling element, it is possible to detect a short circuit in the sampling element and take protective measures such as shutting down the discharge tube 4. It should be understood that the sampling element in the method described above in conjunction with the drawings and embodiments may be a sampling resistor or a current sensor such as a Hall sensor. In addition, the above-mentioned method can also be applied to identifying a short circuit in an ADC (analog-to-digital converter) pin of an MCU of a microcontroller in a BMS system, which is used to collect sensor data, current, voltage, etc. It should be understood that the execution subject of the method described above in conjunction with the drawings and embodiments may be the microcontroller MCU of the BMS system, or may be other control modules or control components communicatively coupled to the MCU.

[0041] It should be noted that ideally, when the sampling element is short-circuited, the sampled current data should be zero. This is because the resistance of the short-circuited material is assumed to be zero. However, in engineering practice, the sampling results after a short circuit are not necessarily zero. This is because the resistance of the short-circuited material in practice usually has a certain value. Therefore, after a short circuit, the sampled current data will decrease but not necessarily decrease to zero.

[0042] Although the present application has been described through preferred embodiments, the present application is not limited to the embodiments described herein, and includes various changes and modifications that may be made without departing from the scope of the present application.

Claims

1. A method for identifying a short circuit in a sampling element of a battery management system, wherein a temperature sensor is provided in the battery management system to monitor the temperature of a discharge tube, the method comprising: Obtain the temperature of the discharge tube via a temperature sensor and calculate the temperature difference of the discharge tube for a preset time period; In response to determining that the temperature difference is greater than a preset temperature difference threshold, comparing the discharge current obtained via the sampling element with a preset current threshold; In response to determining that the discharge current is less than the preset current threshold, it is determined that the sampling element is short-circuited. 2 . The method for identifying short circuits in sampling components of a battery management system according to claim 1 , wherein the temperature sensor is a thermistor. 3 . The method for identifying short circuits in sampling elements of a battery management system according to claim 1 , wherein the sampling element is a sampling resistor or a Hall current sensor.

4. The method for identifying short circuits in sampling components of a battery management system according to claim 1, wherein the preset temperature difference threshold is 4 degrees Celsius or 8 degrees Celsius. 5 . The method for identifying short circuits in sampling components of a battery management system according to claim 1 , wherein the preset temperature difference threshold is 4 degrees Celsius, and the preset current threshold is 20 amperes or 10 amperes. 6 . The method for identifying short circuits in sampling components of a battery management system according to claim 1 , wherein the preset temperature difference threshold is 8 degrees Celsius, and the preset current threshold is 40 amperes, 20 amperes, or 10 amperes.

7. The method for identifying short circuits in sampling components of a battery management system according to any one of claims 1 to 6, wherein the preset time length is 10 seconds, 20 seconds, or 30 seconds.

8. A short-circuit protection method for a sampling element of a battery management system, comprising: In response to the method for identifying a short circuit of a sampling element in a battery management system according to any one of claims 1 to 7 identifying that the sampling element is short-circuited, circuit protection is performed by closing a discharge tube of the battery management system.

9. The method for short-circuit protection of a sampling element in a battery management system according to claim 8, wherein the circuit protection further comprises shutting down a high-current charging tube, a floating charge switch, a protective charging switch, blowing a controllable fuse, and entering a sleep mode of the battery management system.

10. The battery management system sampling element short circuit protection method according to claim 8, further comprising: In response to determining that the discharge tube is closed and the temperature change rate is 0 degrees Celsius every 30 seconds and lasts for 30 minutes, the discharge tube is opened.

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