Battery overcurrent detection method, battery management system, battery pack and electric device

Abstract

The application discloses a battery overcurrent detection method, a battery management system, a battery pack and a power utilization device. The battery overcurrent detection method comprises the following steps: acquiring a discharge current of a battery and a target parameter, wherein the target parameter comprises at least two of the following parameters: an ambient temperature of the battery, a health state value of the battery and a temperature of a switch tube arranged on a discharge path of the battery; when the discharge current is greater than or equal to a first current threshold, the following steps are executed: determining an integral threshold according to the target parameter; determining a discharge capacity of the battery within a first preset time length according to the discharge current; and determining that an overcurrent fault occurs in the battery when the discharge capacity is greater than or equal to the integral threshold. In the foregoing manner, the detection accuracy can be improved, and the method is suitable for different working conditions.

Description

Battery overcurrent detection methods, battery management systems, battery packs and electrical devices Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a battery overcurrent detection method, a battery management system, a battery pack, and electrical equipment. Background Technology

[0002] Currently, the overcurrent detection process during battery discharge is as follows: a fixed overcurrent threshold and a fixed delay time are set. When the battery discharge current is detected to exceed the overcurrent threshold, the delay begins. If the discharge current still exceeds the overcurrent threshold after the fixed delay time, an overcurrent fault is confirmed. However, this detection method has poor accuracy. Summary of the Invention

[0003] This application provides a battery overcurrent detection method, a battery management system, a battery pack, and electrical equipment, which can improve detection accuracy and is applicable to different working conditions.

[0004] In a first aspect, embodiments of this application provide a battery overcurrent detection method, comprising: acquiring the battery's discharge current and target parameters, wherein the target parameters include at least two of the following parameters: the battery's ambient temperature, the battery's health status value, and the temperature of a switching transistor located on the battery's discharge path; when the discharge current is greater than or equal to a first current threshold, performing the following steps: determining an integral threshold based on the target parameters; determining the battery's discharge capacity within a first preset time period based on the discharge current; and determining that the battery has experienced an overcurrent fault when the discharge capacity is greater than or equal to the integral threshold.

[0005] In one or more embodiments, the method further includes: when the discharge capacity is less than an integral threshold and the discharge current is greater than or equal to a first current threshold, updating the first preset duration to the duration when the discharge current is greater than or equal to the first current threshold, and returning to execute the step of determining the discharge capacity of the battery within the first preset duration based on the discharge current and subsequent steps.

[0006] In one or more embodiments, the method further includes: when the discharge capacity is less than an integral threshold and the discharge current is less than a first current threshold, or when the discharge current is less than the first current threshold, performing the following steps: determining historical capacity based on the discharge capacity, wherein the historical capacity is less than the discharge capacity; delaying for a second preset duration; at the end of the second preset duration, if the discharge current is greater than or equal to the first current threshold, performing the following steps: determining the battery's discharge capacity within the first preset duration based on the discharge current; updating the discharge capacity to the sum of the discharge capacity and the historical capacity; when the discharge capacity is greater than or equal to the integral threshold, determining that the battery has experienced an overcurrent fault; when the discharge capacity is less than the integral threshold, returning to the step of determining historical capacity based on the discharge capacity and its subsequent steps; at the end of the second preset duration, if the discharge current is less than the first current threshold, returning to the step of obtaining the battery's discharge current and target parameters and its subsequent steps.

[0007] In one or more embodiments, determining the historical energy level based on the discharge capacity includes: determining the historical energy level using the following formula: Where Q_OLD is the historical power level, Q_DIS is the discharge power level, Δt is the second preset duration, and τ is the decay time constant.

[0008] In one or more embodiments, determining the integration threshold based on the target parameters includes: determining a first reference parameter corresponding to the ambient temperature based on a first temperature range in which the ambient temperature is located; determining a second reference parameter based on a health status value; determining a third reference parameter corresponding to the temperature of the switching transistor based on a second temperature range in which the temperature of the switching transistor is located; and determining the integration threshold based on the product of the reference parameters corresponding to each parameter in the target parameters.

[0009] In one or more embodiments, determining a first reference parameter corresponding to the ambient temperature based on a first temperature range in which the ambient temperature is located includes: determining the first reference parameter based on the product of the square of the reference current corresponding to the first temperature range in which the ambient temperature is located and the corresponding reference time.

[0010] In one or more embodiments, a third reference parameter corresponding to the temperature of the switching transistor is determined based on the second temperature range in which the temperature of the switching transistor is located, including: when the second temperature range is a range less than a first preset temperature, the third reference parameter is kept at 1; when the second temperature range is a range greater than or equal to the first preset temperature, the third reference parameter is negatively correlated with the temperature of the switching transistor.

[0011] In a second aspect, embodiments of this application provide a battery management system, including: at least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the battery overcurrent detection method in the first aspect.

[0012] Thirdly, embodiments of this application provide a battery pack, including a battery and a battery management system as described in the second aspect.

[0013] Fourthly, embodiments of this application provide an electrical device, including a load and a battery pack as described in the third aspect, the battery pack being used to supply power to the load.

[0014] The beneficial effects of this application are as follows: The battery overcurrent detection method of this application first combines at least two of the following three parameters to dynamically determine the integration threshold: the ambient temperature of the battery, the health status value of the battery, and the temperature of the switching transistor located on the discharge path of the battery. Then, the battery is determined to have an overcurrent fault only when the actual discharge capacity determined by the discharge current is greater than the integration threshold dynamically determined by the target parameters. This realizes the automatic adjustment of the overcurrent detection strategy according to battery aging and environmental changes, which can improve the detection accuracy and is beneficial to be applicable to different working conditions. Attached Figure Description

[0015] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.

[0016] Figure 1 is a flowchart of a battery overcurrent detection method provided in an embodiment of this application;

[0017] Figure 2 is a flowchart of the battery overcurrent detection method provided in the embodiment of this application;

[0018] Figure 3 is a flowchart of the battery overcurrent detection method provided in the embodiment of this application;

[0019] Figure 4 is a flowchart of the battery overcurrent detection method provided in the embodiment of this application;

[0020] Figure 5 is a flowchart of the battery overcurrent detection method provided in the embodiment of this application;

[0021] Figure 6 is a flowchart of the battery overcurrent detection method provided in the embodiment of this application;

[0022] Figure 7 is a schematic diagram of the battery management system provided in an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. 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.

[0024] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.

[0025] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0026] Please refer to Figure 1, which is a flowchart of a battery overcurrent detection method provided in an embodiment of this application. As shown in Figure 1, the battery overcurrent detection method includes the following steps S110 to S140.

[0027] Step S110: Obtain the battery discharge current and target parameters, wherein the target parameters include at least two of the following parameters: the ambient temperature of the battery, the battery health status value, and the temperature of the switch transistor located on the battery discharge path.

[0028] The battery discharge current is the current flowing from the positive terminal of the battery, through the load, and back to the negative terminal during the battery's power supply (i.e., discharge). The battery ambient temperature is the temperature of the external space surrounding the battery, i.e., the temperature of the air or medium surrounding the battery. In some embodiments, a temperature sensor (such as a thermistor) can be used to detect the battery's ambient temperature. The battery's State of Health (SOH) value represents the percentage of the battery's current maximum usable capacity (or power capability) relative to its factory-rated value, reflecting the degree of battery aging. The temperature of the switching transistor located in the battery's discharge path is the real-time junction temperature (i.e., the actual temperature of the PN junction inside the semiconductor chip) or case temperature (i.e., the temperature of the device package surface) of the power semiconductor device (such as a MOSFET or IGBT) installed in the battery discharge circuit to perform functions such as on / off control or current limiting.

[0029] When the discharge current is greater than or equal to the first current threshold, the following steps S120 to S140 are executed.

[0030] The first current threshold is a preset current threshold that can be set according to the actual application scenario. Only when the discharge current is greater than or equal to the first current threshold does it indicate a risk of overcurrent, meaning that subsequent steps S120 to S140 are required to further determine whether battery overcurrent has occurred.

[0031] Step S120: Determine the integration threshold based on the target parameters.

[0032] When the discharge current is greater than or equal to the first current threshold, the corresponding integral threshold is first determined based on the target parameters of the current scenario to accurately determine whether there is an overcurrent under the current operating conditions.

[0033] In some embodiments, as shown in FIG2, the specific implementation process of step S120 includes the following steps S210 to S240.

[0034] Step S210: Determine the first reference parameter corresponding to the ambient temperature based on the first temperature range in which the ambient temperature is located.

[0035] The first temperature range is a pre-set range that can be set based on the actual application scenario. Specifically, at least two temperature ranges are first determined. For example, in a specific embodiment, the temperature range greater than or equal to 0°C is defined as the first ambient temperature range, and the temperature range less than 0°C is defined as the second ambient temperature range. Therefore, when the ambient temperature is greater than or equal to 0°C, the first temperature range in which the ambient temperature falls is the first ambient temperature range; when the ambient temperature is less than 0°C, the first temperature range in which the ambient temperature falls is the second ambient temperature range. Next, based on the first reference parameter corresponding to the first temperature range in which the ambient temperature falls, the first reference parameter corresponding to the ambient temperature can be determined.

[0036] In some embodiments, as shown in FIG3, the specific implementation process of step S210 includes the following step S310.

[0037] Step S310: Determine the first reference parameter based on the product of the square of the reference current corresponding to the first temperature range of the ambient temperature and the corresponding reference time.

[0038] Specifically, when at least two temperature ranges are determined, the reference current and reference time corresponding to each temperature range are determined. For example, taking the first and second ambient temperature ranges mentioned above as examples, the reference current and reference time corresponding to the first ambient temperature range are denoted as IB1 and TB1, respectively, and the reference current and reference time corresponding to the second ambient temperature range are denoted as IB2 and TB2, respectively. IB1 = IB2, and TB1 > TB2. Therefore, the first reference parameter IB1 corresponding to the first ambient temperature range is... 2*TB1, the first reference parameter corresponding to the second ambient temperature range is IB2. 2 *TB2, thus enabling the integration threshold at low temperatures to be greater than that at normal temperatures.

[0039] On the one hand, it can ensure that false overcurrent is avoided in low-temperature environments based on a larger integral threshold. For example, when the battery is used in electrical equipment (such as electric vehicles), the internal resistance of the battery increases in low-temperature environments, and the start-up time of the electrical equipment increases. In this case, long-term high current should be allowed (by setting a larger integral threshold) to ensure that the electrical equipment can start successfully.

[0040] On the other hand, it can ensure that overcurrent can be detected quickly at room temperature based on a smaller integral threshold, that is, to realize overcurrent protection in a timely manner. For example, when the battery is used in electrical equipment, the battery's thermal tolerance deteriorates at room temperature. If the electrical equipment experiences a long-term high current, it is prone to thermal runaway, which can damage the battery and other devices. In this case, the response speed of overcurrent detection should be accelerated (by setting a smaller integral threshold) to effectively curb the temperature rise of the battery and power devices and prevent thermal runaway.

[0041] It is understood that in the above embodiments, two temperature ranges are defined as an example. However, in other embodiments, more temperature ranges can be defined. For example, in a specific embodiment, the temperature range greater than or equal to 40°C is defined as the first ambient temperature range, the temperature range greater than or equal to 0°C and less than 40°C is defined as the second ambient temperature range, and the temperature range less than 0°C is defined as the third ambient temperature range. Then, when the ambient temperature is greater than or equal to 40°C, the first temperature range in which the ambient temperature falls is the first ambient temperature range; when the ambient temperature is greater than or equal to 0°C and less than 40°C, the first temperature range in which the ambient temperature falls is the second ambient temperature range; and when the ambient temperature is less than 0°C, the first temperature range in which the ambient temperature falls is the third ambient temperature range. The reference current and reference time corresponding to the first ambient temperature range are denoted as IC1 and TC1, respectively; the reference current and reference time corresponding to the second ambient temperature range are denoted as IC2 and TC2, respectively; and the reference current and reference time corresponding to the third ambient temperature range are denoted as IC3 and TC3, respectively. IC1=IC2=IC3, and TC1>TC2>TC3 are set. Thus, the first reference parameter IC1 corresponding to the first ambient temperature range is... 2 *TC1, the first reference parameter corresponding to the second ambient temperature range is IC2. 2 *TC2, the first reference parameter corresponding to the third ambient temperature range is IC3. 2*TC3 ensures that the integral threshold at low temperatures is greater than that at room temperature, which in turn is greater than that at high temperatures. This allows for several advantages: firstly, a larger integral threshold at low temperatures prevents false overcurrent detection and ensures successful startup of electrical equipment; secondly, a normal integral threshold at room temperature meets standard overcurrent detection requirements; and thirdly, a smaller integral threshold at high temperatures enables rapid overcurrent detection, preventing thermal runaway.

[0042] Step S220: Determine the second baseline parameter based on the health status value.

[0043] Specifically, in some embodiments, the health status value can be directly used as the second reference parameter. In other embodiments, a parameter that corresponds to the health status value can also be used as the second reference parameter. For example, if the parameter that corresponds to the health status value is the DC internal resistance of the battery, then the DC internal resistance of the battery can be used as the second reference parameter.

[0044] Introducing a second baseline parameter related to the state of health makes the protection strategy more conservative as the battery ages. This means that aging batteries are protected more quickly, avoiding accelerated degradation under overcurrent conditions, thus significantly extending the overall lifespan of the battery system.

[0045] Step S230: Determine the third reference parameter corresponding to the temperature of the switching transistor based on the second temperature range in which the temperature of the switching transistor is located.

[0046] The second temperature range is a pre-set range that can be configured based on the actual application scenario. Specifically, at least two temperature ranges are first determined. For example, in a specific embodiment, the temperature range greater than or equal to a first preset temperature (e.g., 100°C) is defined as the first switching temperature range, and the temperature range less than the first preset temperature is defined as the second switching temperature range. Therefore, when the temperature of the switching transistor is greater than or equal to the first preset temperature, the second temperature range in which the switching transistor's temperature falls is the first switching temperature range; when the temperature of the switching transistor is less than the first preset temperature, the second temperature range in which the switching transistor's temperature falls is the second switching temperature range. Next, based on the third reference parameter corresponding to the second temperature range in which the switching transistor's temperature falls, the third reference parameter corresponding to the switching transistor's temperature can be determined.

[0047] In some embodiments, as shown in FIG4, the specific implementation process of step S230 includes the following steps S410 to S420.

[0048] Step S410: When the second temperature range is less than the first preset temperature range, the third reference parameter remains at 1.

[0049] Step S420: When the second temperature range is greater than or equal to the first preset temperature range, the third reference parameter is negatively correlated with the temperature of the switching transistor.

[0050] The first preset temperature is a pre-set temperature value, which can be set based on the actual application scenario. This application embodiment does not impose specific restrictions on this.

[0051] Specifically, the second temperature range is greater than or equal to the first preset temperature, meaning the switching transistor's temperature is too high. In this case, the system prioritizes protecting the switching transistor by decreasing the third reference parameter as the temperature rises (because the third reference parameter has a negative correlation with the switching transistor's temperature) to reduce the integral threshold, thus quickly identifying battery overcurrent and protecting the switching transistor in a timely manner to prevent damage due to overheating. If the second temperature range is less than the first preset temperature, it means the switching transistor's temperature is within the normal range, and the risk of damage due to overheating is low. In this case, the third reference parameter remains at 1, having no impact on the integral threshold.

[0052] The negative correlation between the third reference parameter and the temperature of the switching transistor can be achieved in different ways. For example, in a specific embodiment, the third reference parameter is configured as: K_MOS=max(0.5, 0.01*(T_MOS-100)), where K_MOS is the third reference parameter, max() means taking the maximum value, and T_MOS represents the temperature of the switching transistor.

[0053] Step S240: Determine the integration threshold based on the product of the baseline parameters corresponding to each parameter in the target parameters.

[0054] Specifically, if the target parameters include the battery's ambient temperature and the battery's state of health, the integration threshold is determined based on the product of the first and second reference parameters; if the target parameters include the battery's ambient temperature and the switching transistor's temperature, the integration threshold is determined based on the product of the first and third reference parameters; if the target parameters include the battery's state of health and the switching transistor's temperature, the integration threshold is determined based on the product of the second and third reference parameters; if the target parameters include the battery's ambient temperature, the battery's state of health, and the switching transistor's temperature, the integration threshold is determined based on the product of the first, second, and third reference parameters.

[0055] Step S130: Determine the battery discharge capacity within the first preset time period based on the discharge current.

[0056] Specifically, the battery's discharge capacity within the first preset time period is obtained by integrating the square of the discharge current over that first preset time period. The first preset time period can be set based on the actual application scenario.

[0057] Step S140: When the discharge capacity is greater than or equal to the integral threshold, it is determined that the battery has an overcurrent fault.

[0058] As can be seen from the foregoing, the integration threshold is adaptively adjusted according to the ambient temperature of the battery, the battery's health status value, and the temperature of the switching transistor located on the battery's discharge path. Thus, when the discharge capacity is greater than or equal to the integration threshold, an overcurrent fault is determined to have occurred in the battery. This allows for automatic adjustment of the overcurrent detection strategy based on battery aging and environmental changes, thereby improving detection accuracy and making it suitable for different operating conditions.

[0059] In some embodiments, as shown in FIG5, after step S130 is executed, if the discharge capacity is less than the integral threshold and the discharge current is greater than or equal to the first current threshold, then step S510 is executed, and the execution of step S130 and subsequent steps is returned.

[0060] Step S510: Update the first preset duration to the duration when the discharge current is greater than or equal to the first current threshold.

[0061] Specifically, after executing step S130, although the detected discharge current is less than the integration threshold, the discharge current is still greater than or equal to the first current threshold. This means that the discharge current is still relatively large, posing a significant safety hazard. The discharge current is only less than the integration threshold because the first preset duration is set too short. In this case, the first preset duration should be updated according to the duration during which the discharge current is greater than or equal to the first current threshold to determine the discharge capacity during the high current period (i.e., the period during which the discharge current is greater than or equal to the first current threshold). Based on the relationship between this discharge capacity and the integration threshold, it can be accurately determined whether the battery has experienced an overcurrent fault.

[0062] In some embodiments, as shown in FIG6, after step S130 is executed, if the discharge capacity is less than the integral threshold and the discharge current is less than the first current threshold, then step S610 and subsequent steps are executed.

[0063] Step S610: Determine the historical energy level based on the discharge energy level, wherein the historical energy level is less than the discharge energy level.

[0064] Step S620: Delay for the second preset duration.

[0065] If the discharge current is greater than or equal to the first current threshold at the end of the second preset time, then the following steps S630 and subsequent steps are executed.

[0066] Step S630: Determine the battery discharge capacity within the first preset time period based on the discharge current.

[0067] Step S640: Update the discharge capacity to the sum of the discharge capacity and the historical capacity.

[0068] After completing step S640, the following steps are performed: if the discharge capacity is greater than or equal to the integral threshold, an overcurrent fault is determined to have occurred in the battery; if the discharge capacity is less than the integral threshold, the process returns to step S610 and subsequent steps.

[0069] If the discharge current is less than the first current threshold when the second preset time ends, then return to step S110 and its subsequent steps.

[0070] Specifically, when the discharge charge is less than the integration threshold and the discharge current is less than the first current threshold, the discharge charge obtained by integration is not immediately cleared to zero. Instead, it enters a pre-set thermal memory model, which is step S610 and its subsequent steps.

[0071] First, the historical charge is determined based on the discharge charge. The historical charge represents the thermal effect corresponding to the current high current. In a specific embodiment, the historical charge is determined using the following formula: Where Q_OLD represents the historical battery level, Q_DIS represents the discharged battery level, Δt represents the second preset duration, and τ represents the decay time constant. The second preset duration is a pre-set duration that can be adjusted based on the actual application scenario.

[0072] Then, a second preset time is applied to determine whether the discharge current will again exceed the first current threshold within a short period (i.e., the second preset time). If, at the end of the second preset time, the discharge current exceeds the first current threshold again, the current discharge capacity is first determined, i.e., based on the discharge current, the battery's discharge capacity within the first preset time is determined. For details, refer to the description of step S130; it will not be repeated here. The discharge capacity is then updated to the sum of the discharge capacity and the historical capacity, at which point the historical capacity has been accumulated once. The discharge capacity is again checked to see if it exceeds the integral threshold. If yes, an overcurrent fault is determined in the battery; otherwise, the process returns to step S610 and subsequent steps.

[0073] Assuming the discharge capacity is less than the integration threshold and the discharge current is less than the first current threshold, the discharge capacity is Q_DIS1, and the historical capacity is Q_OLD1. After a second delay, if the discharge current is again greater than or equal to the first current threshold, the current discharge capacity is determined to be Q_DIS2, and the updated discharge capacity is Q_DIS3, where Q_DIS3 = Q_DIS2 + Q_OLD1. The integration threshold is set to Q_threshold, and Q_DIS3 < Q_threshold, confirming no overcurrent fault has occurred. The historical capacity Q_OLD2 is then obtained again based on Q_DIS3. After another second delay, if the discharge current is again greater than or equal to the first current threshold, the current discharge capacity is determined to be Q_DIS4, and the updated discharge capacity is Q_DIS5, where Q_DIS5 = Q_DIS4 + Q_OLD3. If Q_DIS5 < Q_threshold, it is determined that no overcurrent fault has occurred, and the above process is repeated until the discharge charge is greater than or equal to the integral threshold, indicating an overcurrent fault has occurred, or the discharge current drops below the first current threshold. If the discharge charge is greater than or equal to the integral threshold, indicating an overcurrent fault has occurred (i.e., Q_DIS5 is greater than or equal to Q_threshold), an overcurrent fault is confirmed. If the discharge current decreases and falls below the first current threshold, the process directly returns to step S110.

[0074] Understandably, in some applications, such as frequent start-stop cycles of electrical equipment using this battery, even if not identified as an overcurrent fault, each short-term high current (i.e., a short-term discharge current greater than or equal to the first current threshold) can generate thermal effects. The cumulative effect of these repeated thermal events can damage the battery and even the electrical equipment. Therefore, by setting a thermal memory model, the thermal effects of multiple short-term overcurrent events can be better accumulated, preventing protection delays caused by zero discharge capacity, more accurately reflecting the battery's cumulative thermal load, and improving the reliability of the protection.

[0075] Please refer to Figure 6. In some embodiments, when the discharge current is less than a first current threshold, the following steps S610 and subsequent steps are performed.

[0076] Step S610: Determine the historical energy level based on the discharge energy level, wherein the historical energy level is less than the discharge energy level.

[0077] Step S620: Delay for the second preset duration.

[0078] If the discharge current is greater than or equal to the first current threshold at the end of the second preset time, then the following steps S630 and subsequent steps are executed.

[0079] Step S630: Determine the battery discharge capacity within the first preset time period based on the discharge current.

[0080] Step S640: Update the discharge capacity to the sum of the discharge capacity and the historical capacity.

[0081] After completing step S640, the following steps are performed: if the discharge capacity is greater than or equal to the integral threshold, an overcurrent fault is determined to have occurred in the battery; if the discharge capacity is less than the integral threshold, the process returns to step S610 and subsequent steps.

[0082] If the discharge current is less than the first current threshold when the second preset time ends, then return to step S110 and its subsequent steps.

[0083] For details on the implementation process, please refer to the description of the foregoing embodiments, which will not be repeated here.

[0084] The following will use the example of the integral threshold Q_threshold being determined by the product of a first reference parameter (denoted as Q_BASE), a second reference parameter (denoted as F_SOH), and a third reference parameter (denoted as K_MOS) to illustrate the embodiments of this application in a practical application scenario (the battery is used in various operating conditions in a vehicle). The first current threshold is set to 200A, and τ=60s.

[0085] In one specific embodiment, the vehicle is started in an environment of -15°C (a scenario applicable to low-temperature vehicle starting). When the vehicle starts, the battery discharges at a current of 550A.

[0086] The temperature range greater than or equal to 0℃ is defined as the first ambient temperature range, with a corresponding reference current and reference time of 500A and 5s, respectively; and the temperature range less than 0℃ is defined as the second ambient temperature range, with a corresponding reference current and reference time of 500A and 8s, respectively. Then the first reference parameter Q_BASE = 500² × 8 = 2000000A²·s.

[0087] SOH=90%, second reference parameter F_SOH=0.9.

[0088] When the temperature of the switching transistor falls within the second temperature range that is lower than the first preset temperature range, the third reference parameter K_MOS remains at 1.

[0089] The integration threshold Q_threshold = Q_BASE * F_SOH * K_MOS = 1800000A²·s. Based on the update process of the first preset duration in step S510 above, the first preset duration can be obtained as Q_threshold / I² = 1800000 / (550). 2 =1800000 / 302500≈5.95s.

[0090] In summary, once the discharge current is detected to be greater than or equal to the first current threshold, the discharge capacity is calculated in real time. If the discharge current remains constant, it will take approximately 5.95 seconds to detect an overcurrent fault and trigger overcurrent protection. This process provides a buffer time of approximately 6 seconds for vehicle startup, which is relatively long and effectively avoids false triggering of overcurrent protection due to excessively long vehicle startup time, thus helping to ensure a smooth vehicle startup.

[0091] In one specific embodiment, the vehicle is started in an environment of 45°C (a scenario applicable to high-temperature vehicle startup). When the vehicle starts, the battery discharges at a current of 600A.

[0092] The temperature range greater than or equal to 0℃ is defined as the first ambient temperature range, with a corresponding reference current and reference time of 500A and 5s, respectively; and the temperature range less than 0℃ is defined as the second ambient temperature range, with a corresponding reference current and reference time of 500A and 8s, respectively. Then the first reference parameter Q_BASE = 500² × 5 = 1250000A²·s.

[0093] SOH=90%, second reference parameter F_SOH=0.9.

[0094] When the temperature of the switching transistor falls within the second temperature range that is greater than or equal to the first preset temperature range, the third reference parameter K_MOS is set to K_MOS=max(0.5, 0.01*(T_MOS-100))=max(0.5, 0.95)=0.95.

[0095] The integration threshold Q_threshold = Q_BASE * F_SOH * K_MOS = 1068750A²·s. Based on the update process of the first preset duration in step S510 above, the first preset duration can be obtained as Q_threshold / I² = 1068750 / (600). 2 =1068750 / 360000≈2.97s.

[0096] In summary, after detecting a discharge current greater than or equal to the first current threshold, the discharge capacity is calculated in real time. If the discharge current remains constant, an overcurrent fault is detected in approximately 2.97 seconds, triggering overcurrent protection. This process, through the combined effect of the first and second reference parameters, significantly reduces the integral threshold under high-temperature environments and high switching transistor temperatures, resulting in a faster response, effectively curbing the temperature rise of the battery and power devices, and preventing thermal runaway.

[0097] In a specific embodiment, a vehicle with battery aging (SOH = 80%) frequently starts and stops in a congested section, and short-term large currents (a discharge current of 300 A for 2 s) occur multiple times, and the interval between two occurrences of short-term large currents is 10 s.

[0098] The temperature range greater than or equal to 0 °C is determined as the first ambient temperature range, and the corresponding reference current and reference time are 500 A and 5 s respectively; and the temperature range less than 0 °C is determined as the second ambient temperature range, and the corresponding reference current and reference time are 500 A and 8 s respectively. Then the first reference parameter Q_BASE = 500² × 5 = 1250000 A²·s.

[0099] SOH = 80%, and the second reference parameter F_SOH = 0.8.

[0100] When the second temperature range in which the temperature of the switching tube is located is the range less than the first preset temperature, the third reference parameter K_MOS remains 1.

[0101] The integration threshold Q_threshold = Q_BASE * F_SOH * K_MOS = 1000000 A²·s.

[0102] Discharge capacity , and no overcurrent fault is detected.

[0103] Historical capacity .

[0104] After the second preset duration (denoted as 10 s), if the discharge current (still 300 A) is greater than the first current threshold again, then according to the integration formula, the discharge capacity Q_DIS2 = 180000 A²·s, and the updated discharge capacity is Q_DIS3 = Q_DIS2 + Q_DIS1 = 332280 A²·s <1000000> A²·s, and no overcurrent fault is detected.

[0105] Calculate the historical capacity again, and continuously repeat the above process. The updated discharge capacity continuously increases and will eventually be greater than the integration threshold, determining that an overcurrent fault has occurred and triggering overcurrent protection.

[0106] It can be understood that in the related art, when no overcurrent fault is detected, the discharge circuit will be directly cleared, and the discharge capacity will be recalculated according to the above integration formula next time. Then the thermal stress cannot be accumulated, and the overcurrent protection is not triggered, which will cause the battery to continuously bear the thermal stress, and the risk of damage to the battery or even the vehicle is relatively high.

[0107] In this application, by setting a thermal memory model, the thermal effects of multiple short-term overcurrents can be accumulated more effectively, preventing protection delays caused by the discharge charge being cleared, more realistically reflecting the battery's accumulated thermal load, and improving the reliability of protection.

[0108] Please refer to Figure 7, which is a schematic diagram of the battery management system provided in an embodiment of this application. As shown in Figure 7, the battery management system 700 includes at least one processor 710 and a memory 720. The memory 720 can be built into the battery management system 700 or externally located outside the battery management system 700. The memory 720 can also be a remotely configured memory connected to the battery management system 700 via a network.

[0109] Memory 720, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. Memory 720 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on terminal usage, etc. Furthermore, memory 720 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 720 may optionally include memory remotely located relative to processor 710, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0110] The processor 710 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 720 and calling data stored in the memory 720, thereby performing overall monitoring of the terminal, such as implementing the battery overcurrent detection method described in any embodiment of this application.

[0111] There can be one or more processors 710; Figure 7 shows an example of one processor 710. The processor 710 and memory 720 can be connected via a bus or other means. The processor 710 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field-programmable gate array (FPGA) device, etc. The processor 710 can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0112] This application also provides a battery pack, which includes a battery and a battery management system as described in any embodiment of this application.

[0113] This application also provides an electrical device, which includes a load and a battery pack as described in any embodiment of this application, wherein the battery pack is used to supply power to the load.

[0114] Loads include electrical components on electrical equipment such as motors, lights, horns, and instruments. Electrical equipment refers to devices that require battery pack power. Examples of electrical equipment include: unmanned aerial vehicles, energy storage products, power tools, and electric vehicles (electric two-wheelers, electric tricycles), etc.

[0115] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0116] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery overcurrent detection method, characterized in that, include: The discharge current and target parameters of the battery are obtained, wherein the target parameters include at least two of the following parameters: the ambient temperature of the battery, the health status value of the battery, and the temperature of the switching transistor located on the discharge path of the battery; when the discharge current is greater than or equal to a first current threshold, the following steps are performed: determining an integration threshold based on the target parameters; determining the discharge capacity of the battery within a first preset time period based on the discharge current; determining that the battery has an overcurrent fault when the discharge capacity is greater than or equal to the integration threshold; the step of determining the integration threshold based on the target parameters includes: determining a first reference parameter based on the product of the square of the reference current corresponding to the first temperature range of the ambient temperature and the corresponding reference time; using the health status value as a second reference parameter, or using a parameter that has a corresponding relationship with the health status value as the second reference parameter; when the temperature of the switching transistor is in a second temperature range that is less than the first preset temperature range, a third reference parameter is kept at 1; when the second temperature range is greater than or equal to the first preset temperature range, the third reference parameter and the temperature of the switching transistor show a negative correlation; determining the integration threshold based on the product of the reference parameters corresponding to each parameter in the target parameters.

2. The battery overcurrent detection method according to claim 1, characterized in that, The method further includes: when the discharge capacity is less than the integral threshold and the discharge current is greater than or equal to the first current threshold, updating the first preset duration to the duration when the discharge current is greater than or equal to the first current threshold, and returning to execute the step of determining the discharge capacity of the battery within the first preset duration based on the discharge current and subsequent steps.

3. The battery overcurrent detection method according to claim 1, characterized in that, The method further includes: when the discharge capacity is less than the integral threshold and the discharge current is less than the first current threshold, or when the discharge current is less than the first current threshold, performing the following steps: determining the historical capacity based on the discharge capacity, wherein the historical capacity is less than the discharge capacity; delaying for a second preset duration; at the end of the second preset duration, if the discharge current is greater than or equal to the first current threshold, performing the following steps: determining the battery's discharge capacity within a first preset duration based on the discharge current; updating the discharge capacity to the sum of the discharge capacity and the historical capacity; when the discharge capacity is greater than or equal to the integral threshold, determining that the battery has experienced an overcurrent fault; when the discharge capacity is less than the integral threshold, returning to the step of determining the historical capacity based on the discharge capacity and its subsequent steps; at the end of the second preset duration, if the discharge current is less than the first current threshold, returning to the step of obtaining the battery's discharge current and target parameters and its subsequent steps.

4. The battery overcurrent detection method according to claim 3, characterized in that, Determining the historical energy level based on the discharged energy level includes: determining the historical energy level using the following formula: Where Q_OLD is the historical power level, Q_DIS is the discharge power level, Δt is the second preset duration, and τ is the decay time constant.

5. A battery management system, characterized in that, include: At least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the battery overcurrent detection method according to any one of claims 1-4.

6. A battery pack, characterized in that, Includes a battery and a battery management system as described in claim 5.

7. An electrical appliance, characterized in that, It includes a load and a battery pack as described in claim 6, the battery pack being used to power the load.

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