Battery discharge under-voltage protection method, battery device and electric device

Abstract

The application discloses a battery discharge under-voltage protection method, a battery device and a power utilization device, and relates to the technical field of batteries. The battery discharge under-voltage protection method of an embodiment of the application comprises the following steps: obtaining a temperature value and a first voltage value of a battery; determining a discharge depth of the battery according to the temperature value; determining a first residual capacity ratio of the battery according to the first voltage value; and determining a second under-voltage threshold according to the first residual capacity ratio, the discharge depth and a first under-voltage threshold, so as to increase the discharge capacity ratio of the battery. The application determines the under-voltage threshold in different temperature intervals, selects different under-voltage thresholds at different temperatures, and thus realizes dynamic adjustment of the under-voltage threshold and increases the discharge capacity ratio of the battery at low temperatures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a battery discharge under-voltage protection method, a battery device and a power consumption device. BACKGROUND

[0002] At present, the under-voltage protection control of the battery usually adopts the method of setting a fixed under-voltage protection point, which is set in the range of 2.8V-3.0V, and the common protection points are: first under-voltage alarm: 3.0V, second under-voltage protection: 2.9V, and third under-voltage protection: 2.8V. However, when the battery is discharged under low temperature conditions, the discharge capacity ratio of the battery will decrease sharply, which cannot meet the capacity demand of the battery under low temperature. SUMMARY

[0003] In view of this, the present application provides a battery discharge under-voltage protection method, a battery device and a power consumption device, which can solve the problem of decrease of the discharge capacity ratio of the battery under low temperature.

[0004] The battery discharge under-voltage protection method of an embodiment of the present application comprises: obtaining a temperature value and a first voltage value of a battery; determining a discharge depth of the battery according to the temperature value; determining a first residual capacity ratio of the battery according to the first voltage value; determining a second under-voltage threshold value according to the first residual capacity ratio, the discharge depth and a first under-voltage threshold value, so as to increase the discharge capacity ratio of the battery; wherein the first under-voltage threshold value is a preset under-voltage threshold value, and the second under-voltage threshold value is a dynamically adjusted under-voltage threshold value.

[0005] In one of the embodiments, the determination of the discharge depth of the battery according to the temperature value comprises: determining a temperature interval corresponding to the temperature value; and determining the discharge depth corresponding to the temperature interval according to the temperature interval.

[0006] In another embodiment, the determination of the first residual capacity ratio of the battery according to the first voltage value comprises: determining the first residual capacity ratio corresponding to the first voltage value according to a parameter correspondence relationship of the battery; wherein the parameter correspondence relationship refers to the correspondence relationship between the residual capacity ratio and the open circuit voltage.

[0007] In another embodiment, the determination of the second under-voltage threshold value according to the first residual capacity ratio, the discharge depth and the first under-voltage threshold value comprises: determining a second residual capacity ratio of the battery according to the first residual capacity ratio and the discharge depth; determining a second voltage value corresponding to the second residual capacity ratio according to the parameter correspondence relationship; determining a change amount of the voltage value of the battery according to the second voltage value and the first voltage value; and determining the second under-voltage threshold value according to the change amount of the voltage value and the first under-voltage threshold value.

[0008] In another embodiment, after determining the second under-voltage threshold according to the first remaining capacity ratio, the discharge depth and the first under-voltage threshold, the method further comprises: obtaining a third voltage value of the battery after cutoff discharge; and determining whether to perform under-voltage protection on the battery according to the second under-voltage threshold and the third voltage value.

[0009] In another embodiment, determining whether to perform under-voltage protection on the battery according to the second under-voltage threshold and the third voltage value comprises: determining a fourth voltage value according to the third voltage value; and determining to perform under-voltage protection on the battery if the fourth voltage value is less than the second under-voltage threshold.

[0010] In another embodiment, before determining the first remaining capacity ratio corresponding to the first voltage value according to the parameter correspondence of the battery, the method further comprises: charging the battery until the capacity of the battery reaches a full-charge capacity; obtaining a full-charge voltage corresponding to the full-charge capacity; discharging the battery until the voltage of the battery reaches a cutoff voltage of discharge; obtaining a voltage value of the battery during discharge and a state of charge corresponding to the voltage value; and determining the parameter correspondence according to the voltage value and the state of charge corresponding to the voltage value.

[0011] In another embodiment, determining the second remaining capacity ratio of the battery according to the first remaining capacity ratio and the discharge depth comprises: determining a first discharge capacity ratio of the battery according to the first remaining capacity ratio; and determining the second remaining capacity ratio according to the first discharge capacity ratio and the discharge depth.

[0012] A battery device according to another embodiment of the present application comprises a battery, a processor and a memory, wherein the memory stores a computer program which, when executed by the processor, implements the battery discharge under-voltage protection method according to an embodiment of the present application.

[0013] A power consumption device according to another embodiment of the present application comprises a load and a battery device according to an embodiment of the present application, wherein the battery device is configured to provide power for the load.

[0014] In one embodiment, the power consumption device comprises any one of a drone, an electric vehicle, an electric tool and an energy storage product.

[0015] The embodiment of the present application determines the second under-voltage threshold value through the temperature value of the battery, the first voltage value and the first under-voltage threshold value, and then determines the under-voltage threshold value in different temperature intervals, so as to select different under-voltage threshold values in different temperature intervals, thereby realizing dynamic adjustment of the under-voltage threshold value and increasing the discharge capacity ratio of the battery at low temperature. Moreover, the embodiment of the present application determines whether to perform under-voltage protection on the battery according to the third voltage of the battery after cut-off discharge and the second under-voltage threshold value, which can avoid early under-voltage protection of the battery and ensure the discharge capacity ratio of the battery at low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a curve diagram of the voltage and discharge capacity ratio of the battery at different temperatures.

[0017] Figure 2 is a block diagram of the battery device of an embodiment of the present application.

[0018] Figure 3 is a flowchart of the battery discharge under-voltage protection method of an embodiment of the present application.

[0019] Figure 4 is a flowchart of the battery discharge under-voltage protection method of another embodiment of the present application.

[0020] Figure 5 is a flowchart of the battery discharge under-voltage protection method of another embodiment of the present application.

[0021] Figure 6 is a flowchart of the battery discharge under-voltage protection method of another embodiment of the present application.

[0022] Figure 7 is a flowchart of the battery discharge under-voltage protection method of another embodiment of the present application.

[0023] Figure 8 is an open-circuit voltage curve of the battery in different working states.

[0024] Figure 9 is an open-circuit voltage curve of the battery at different temperatures after cut-off discharge.

[0025] MAIN ELEMENT SYMBOL EXPLANATION

[0026] 10 power consuming device

[0027] 11 load

[0028] 20 battery device

[0029] 21 memory

[0030] 22 processor

[0031] 23 battery

[0032] 24 sensor DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. In the following description, a large number of specific details are described in order to facilitate a full understanding of the present application, and the described embodiments are only a part of the embodiments of the present application, but not all the embodiments.

[0034] It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in an order different from that in the flowchart. The method disclosed in the embodiments of the present application includes one or more steps or actions for implementing the method. The method steps and / or actions can be interchanged with each other without departing from the scope of the claims. In other words, unless the specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0035] Figure 1 A graph of the voltage to discharge capacity ratio of the battery at different temperatures. Among them, S11 is the voltage to discharge capacity ratio at 0.3C discharge rate and 45℃. S12 is the voltage to discharge capacity ratio at 0.3C discharge rate and 25℃. S13 is the voltage to discharge capacity ratio at 0.3C discharge rate and 15℃. S14 is the voltage to discharge capacity ratio at 0.3C discharge rate and 0℃. S15 is the voltage to discharge capacity ratio at 0.3C discharge rate and -10℃. S16 is the voltage to discharge capacity ratio at 0.3C discharge rate and -20℃.

[0036] As shown in Figure 1 At the same discharge rate (for example, 0.3C), the discharge capacity ratio of the battery at different temperatures is different. As the temperature decreases, the discharge capacity ratio of the battery will decrease sharply.

[0037] In the embodiments of the present application, the temperature refers to the ambient temperature, and the battery at different temperatures refers to the battery being at different ambient temperatures.

[0038] In the embodiments of the present application, the voltage refers to the open circuit voltage (OCV) of the battery, i.e. the terminal voltage of the battery in the open circuit state.

[0039] In the embodiments of the present application, the discharge capacity ratio refers to the percentage of the capacity discharged by the battery to the rated capacity.

[0040] Table 1 is the discharge capacity ratio of the battery at different temperatures. Please refer to Table 1 Figure 1 As shown in Table 1, first, the battery is charged at the same temperature (for example, 25℃) and the same charge rate (for example, 0.3C). Then, the battery is discharged at the same discharge rate (for example, 0.3C) and different temperatures until the voltage of the battery reaches the discharge cut-off voltage (for example, 2.5V). Finally, the discharge capacity ratio of the battery is determined. As shown in Table 1, the discharge capacity ratio of the battery will decrease sharply as the temperature decreases.

[0041] Table 1 is the discharge capacity ratio of the battery at different temperatures. Please refer to Table 1

[0042]

[0043] Since the discharge capacity ratio of the battery at low temperature decreases sharply, the discharge capacity of the battery at low temperature cannot meet the demand.

[0044] Therefore, the present application provides a battery discharge under-voltage protection method, a battery device and a power utilization device, which can increase the discharge capacity ratio of the battery at low temperature.

[0045] Figure 2 Figure 1 is a block diagram of a battery device 20. As shown in Figure 1, the battery device 20 includes a memory 21, a processor 22, a battery 23 and a sensor 24. The above-mentioned elements can be connected through a bus or directly connected. Figure 2

[0046] The memory 21 is used to store program codes and various data, and to complete the access of programs or data during the operation of the battery device 20. The memory 21 can be an internal memory of the battery device 20, i.e., a memory built-in the battery device 20. In other embodiments, the memory 21 can also be an external memory of the battery device 20, i.e., a memory connected to the battery device 20.

[0047] The memory 21 includes volatile or non-volatile memory devices, such as digital versatile discs (DVD) or other optical discs, magnetic discs, hard discs, smart media cards (SMC), secure digital (SD) cards, flash cards, etc.

[0048] ​The processor 22 includes a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like.

[0049] In one embodiment, the battery 23 is a rechargeable battery for providing power to the battery device 20. For example, the battery 23 can be a lead-acid battery, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-ion battery, a lithium polymer battery, a lithium-iron-phosphate battery, or the like. The battery 23 includes a battery cell. The sensor 24 can be disposed on a surface of the battery cell to measure the temperature of the surface of the battery cell to obtain the ambient temperature. In one embodiment, the sensor 24 is a Negative Temperature Coefficient (NTC) thermistor. It is understood that the battery device 20 can also include other sensors, such as a voltage sensor, a current sensor, a light sensor, a gyroscope, a hygrometer, an infrared sensor, or the like.

[0050] It is understood that the battery device 20 can include more or fewer elements, or have a different configuration of elements. The battery device 20 can be applied to the powered device 10, which includes, but is not limited to, a drone, an electric vehicle, a power tool, an energy storage product, or the like. The power tool includes, but is not limited to, a power screwdriver, a power drill, a power wrench, an angle grinder, a steel machine, an electric grab, an electric hammer, a stone machine, a jigsaw, or the like. The energy storage product includes, but is not limited to, a mobile phone, a tablet computer, an e-book reader, a computer, a workstation, a server, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a mobile medical device, a camera, a wearable device, a photovoltaic inverter, a wind power converter, an energy storage system, a new energy vehicle driving system, a photovoltaic device, or the like.

[0051] In one embodiment, the powered device 10 includes the battery device 20 and a load 11, and the battery device 20 is configured to provide power to the load 11.

[0052] The load 11 includes, but is not limited to, a refrigerator, a cooler, an air conditioner, an electric fan, a ventilation fan, a cool and hot air blower, an air dehumidifier, a washing machine, a clothes dryer, an electric iron, a vacuum cleaner, a floor polisher, a microwave oven, an electromagnetic cooker, an electric oven, an electric rice cooker, a dish washer, an electric water heater, an electric blanket, an electric quilt, an electric clothing, a space heater, an electric shaver, an electric hair dryer, a hair straightener, an ultrasonic facial cleanser, an electric massager, a micro projector, a television, a radio, a tape recorder, a video recorder, a camera, a combination sound system, a fire alarm, an electric bell, an electric lamp, a computer, and the like.

[0053] In one embodiment, the battery device 20 further comprises a battery management system (BMS). The battery 23 is connected to the processor 22 through the battery management system, so that the battery management system can realize functions such as charging, discharging, and power consumption management. The battery management system can be communicatively connected to a power conversion system (PCS).

[0054] Figure 3 A flowchart of a battery discharge undervoltage protection method according to one embodiment. The battery discharge undervoltage protection method comprises the following steps:

[0055] S31, obtaining a temperature value and a first voltage value U1 of the battery 23.

[0056] In this embodiment, the temperature value of the battery 23 refers to the temperature value of the environment in which the battery 23 is located. When the battery 23 is in a static state, the temperature value and the first voltage value U1 of the battery 23 are collected. The static state refers to a state in which the charging or discharging current of the battery 23 tends to be 0A. In one embodiment, the state in which the charging or discharging current of the battery 23 is less than 0.5A is defined as the static state.

[0057] Specifically, the battery device 20 obtains the temperature value (for example, any temperature value in the range of -20℃ to 50℃) of the battery 23 through the sensor 24. The battery device 20 obtains the first voltage value U1 (for example, any voltage value in the range of 2.0V to 3.6V) of the battery 23 through the battery management system.

[0058] In this embodiment, the battery device 20 can obtain the temperature value and the first voltage value U1 of the battery 23 in real time, or obtain the temperature value and the first voltage value U1 of the battery 23 at a preset time interval (for example, 1s or 2s, etc.). The preset time interval can be determined according to specific requirements.

[0059] S32, determining the depth of discharge (DOD) of the battery 23 according to the temperature value.

[0060] In the embodiment, the depth of discharge (DOD) refers to the percentage of the discharged capacity of the battery 23 to the rated capacity. It can be understood that the value of the depth of discharge of the battery 23 is equal to the value of the discharge capacity ratio in the embodiment.

[0061] In one embodiment, the battery device 20 determines the temperature interval corresponding to the temperature value according to the collected temperature value. It can be understood that the depth of discharge has a certain corresponding relationship with the temperature interval. When the battery 23 is in different temperature intervals, the depth of discharge is also different. When the temperature interval is determined, the depth of discharge is also determined. For example, when the temperature interval is 15℃-45℃, the depth of discharge is 95%. When the temperature interval is -20℃- -10℃, the depth of discharge is 70%.

[0062] It can be understood that the corresponding relationship between the depth of discharge and the temperature interval can be determined according to the design requirements of the battery 23. For example, the depth of discharge of the battery 23 at different temperature intervals can be preset at the beginning of the design of the battery 23.

[0063] S33, according to the first voltage value U1, determining the first remaining capacity ratio Q1 of the battery 23.

[0064] In the embodiment, the remaining capacity ratio Q of the battery 23 has a certain corresponding relationship with the open circuit voltage U. When the value of the open circuit voltage U is determined, the value of the remaining capacity ratio Q is also determined. For example, when the open circuit voltage U is 3.6V, the remaining capacity ratio Q is 100%. When the open circuit voltage U is 3.3V, the remaining capacity ratio Q is 80%.

[0065] In the embodiment, the remaining capacity ratio Q refers to the percentage of the remaining capacity of the battery 23 to the rated capacity. It can be understood that the value of the remaining capacity ratio Q of the battery 23 and the value of the discharge capacity ratio are 100% in the embodiment.

[0066] It can be understood that the corresponding relationship between the remaining capacity ratio Q and the open circuit voltage U can be determined according to the design requirements of the battery 23. For example, the corresponding relationship between the remaining capacity ratio Q and the open circuit voltage U can be preset at the beginning of the design of the battery 23. In one embodiment, the corresponding relationship between the remaining capacity ratio Q and the open circuit voltage U is a positive correlation.

[0067] In one embodiment, the battery device 20 determines the first remaining capacity ratio Q1 corresponding to the first voltage value U1 according to the parameter corresponding relationship of the battery 23. The parameter corresponding relationship refers to the corresponding relationship between the remaining capacity ratio Q and the open circuit voltage U.

[0068] In the embodiments of the present application, the first voltage value U1, the second voltage value U2, the third voltage value U3 and the fourth voltage value U4 described below are all open circuit voltage values of the battery 23.

[0069] In one embodiment, please refer to Figure 4 Before step S33, the battery discharge under-voltage protection method can further include the following steps:

[0070] S41, charge the battery 23 until the capacity of the battery 23 reaches the full charge capacity.

[0071] In the embodiments of the present application, the full charge capacity refers to the state of charge (SOC) of the battery 23 being 100%.

[0072] In the embodiments of the present application, the battery device 20 can charge the battery 23 in a constant-current charging (CC) mode, a constant-voltage charging (CV) mode or a constant-current constant-voltage charging (CC-CV) mode. It can be understood that the present application does not limit the charging mode of the battery 23.

[0073] S42, obtain the full charge voltage corresponding to the full charge capacity.

[0074] In the embodiments of the present application, when the charging current does not exceed a preset charging rate (for example, 0.05C) and the capacity of the battery 23 reaches the full charge capacity, the battery device 20 collects the voltage value of the battery 23, which is the full charge voltage value.

[0075] S43, discharge the battery 23 until the voltage of the battery 23 reaches the discharge cut-off voltage.

[0076] In the embodiments of the present application, the discharge cut-off voltage refers to the voltage at which the battery 23 stops discharging to prevent the battery 23 from being discharged excessively.

[0077] It can be understood that the discharge cut-off voltage can be determined according to the design requirements of the battery 23. For example, when the temperature range is 15℃-45℃, the preset discharge cut-off voltage is 2.8V. When the temperature range is -20℃--10℃, the preset discharge cut-off voltage is 2.1V.

[0078] In the embodiment, the battery device 20 can discharge the battery 23 at a preset discharge rate (e.g., 0.3C, 0.5C, or 1.0C, etc.). It can be understood that the preset discharge rate is not limited in the present application.

[0079] S44, acquiring the voltage value of the battery 23 during the discharging process and the state of charge (SOC) corresponding to the voltage value.

[0080] In the embodiment, when discharging the battery 23, the battery device 20 can acquire the voltage value of the battery 23 and the state of charge (SOC) corresponding to the voltage value in real time through the battery management system. The value of the state of charge (SOC) is equal to the value of the remaining capacity ratio Q.

[0081] S45, determining the parameter corresponding relationship of the battery 23 according to the voltage value and the state of charge (SOC) corresponding to the voltage value.

[0082] In the embodiment, the parameter corresponding relationship refers to the corresponding relationship between the remaining capacity ratio Q and the open circuit voltage U.

[0083] In the embodiment, the battery device 20 can fit the characteristic curve of the open circuit voltage and the state of charge (OCV-SOC) of the battery 23 according to the voltage value of the battery 23 during the discharging process and the state of charge (SOC) corresponding to the voltage value.

[0084] It can be understood that the characteristic curve of the open circuit voltage U and the remaining capacity ratio Q of the battery 23 (i.e., the parameter corresponding relationship) is the same as the characteristic curve of the open circuit voltage and the state of charge (OCV-SOC).

[0085] It can be understood that the above steps S41-S45 are specific steps of an embodiment for obtaining the parameter corresponding relationship of the battery 23.

[0086] S34, determining a second undervoltage threshold U e .

[0087] In the embodiment, the first undervoltage threshold U0 is a preset undervoltage threshold (e.g., 2.8V, 2.9V, or 3.0V, etc.), and the second undervoltage threshold U e is a dynamically adjusted undervoltage threshold (e.g., 2.1V, 2.2V, or 2.4V, etc.).

[0088] In one embodiment, referring to Figure 5 , step S34 can include the following sub-steps:

[0089] S341, determining a second remaining capacity ratio Q2 of the battery 23 according to the first remaining capacity ratio Q1 and the discharge depth.

[0090] In this embodiment, the battery device 20 can determine the second remaining capacity ratio Q2 of the battery 23 according to the first remaining capacity ratio Q1 and the discharge depth.

[0091] In one embodiment, referring to Figure 6 , step S341 can include the following sub-steps:

[0092] S3411, determining a first discharge capacity ratio of the battery 23 according to the first remaining capacity ratio Q1.

[0093] In this embodiment, the sum of the first remaining capacity ratio Q1 and the first discharge capacity ratio is 100%. According to the first remaining capacity ratio Q1, the first discharge capacity ratio can be calculated as (100%-Q1).

[0094] S3412, determining the second remaining capacity ratio Q2 according to the first discharge capacity ratio and the discharge depth.

[0095] In this embodiment, the discharge depth is preset as DOD x When the first discharge capacity ratio is equal to the discharge depth (i.e. 100%-Q1=DOD x ), it means that the current temperature value does not affect the discharge capacity ratio of the battery 23, and the second remaining capacity ratio Q2 is equal to the first remaining capacity ratio Q1 (i.e. Q2=Q1). At this time, the first undervoltage threshold U0 does not need to be adjusted.

[0096] When the first discharge capacity ratio is less than the discharge depth (i.e. 100%-Q1<DOD x ), it means that the current temperature value makes the discharge capacity ratio of the battery 23 decrease, and the second remaining capacity ratio Q2=100%-DOD x At this time, the first undervoltage threshold U0 needs to be adjusted to the second undervoltage threshold U e to increase the discharge capacity ratio of the battery 23.

[0097] It can be understood that, due to the low temperature effect, the first discharge capacity ratio Q1 of the battery 23 is smaller than the preset discharge depth DOD x . That is, the battery 23 loses a part of the discharge capacity ratio at low temperature, i.e. DOD x-(100%-Q1). If the discharge capacity ratio of the battery 23 at low temperature is to be increased, the discharge capacity ratio lost by the battery 23 at low temperature needs to be compensated by adjusting the first undervoltage threshold U0 to be smaller.

[0098] It can be understood that when the first undervoltage threshold U0 (i.e. the discharge cutoff voltage) is adjusted to be smaller, the battery 23 can discharge more capacity.

[0099] S342, determining a second voltage value U2 corresponding to the second residual capacity ratio Q2 according to the parameter correspondence.

[0100] In this embodiment, the battery device 20 can determine the second voltage value U2 corresponding to the second residual capacity ratio Q2 according to the parameter correspondence of the battery 23.

[0101] It can be understood that when the first discharge capacity ratio is less than the discharge depth (i.e. 100%-Q1 x ), the first residual capacity ratio Q1 is greater than the second residual capacity ratio Q2 (i.e. Q1>Q2). Accordingly, the first voltage value U1 is greater than the second voltage value U2 (i.e. U1>U2).

[0102] S343, determining a voltage value change amount ΔU of the battery 23 according to the second voltage value U2 and the first voltage value U1.

[0103] In this embodiment, the voltage value change amount ΔU of the battery 23 is U1-U2. It can be understood that the voltage value change amount ΔU is caused by the influence of low temperature on the battery 23.

[0104] S344, determining a second undervoltage threshold U e according to the voltage value change amount ΔU and the first undervoltage threshold U0.

[0105] In this embodiment, to compensate for the discharge capacity ratio (i.e. DOD x -(100%-Q1) lost by the battery 23 at low temperature, the second undervoltage threshold U e =U0-ΔU.

[0106] It can be understood that when the first undervoltage threshold U0 is adjusted to the second undervoltage threshold U e =U0-ΔU, the dischargeable capacity ratio of the battery 23 is DOD x -(100%-Q1).

[0107] Please refer to Figure 7 , Figure 7A flow chart of the battery discharge undervoltage protection method of an embodiment. It is assumed that the discharge rate is 0.3C, the temperature value of the battery 23 is -10℃, the first voltage value is 3.25V, and the preset first undervoltage threshold is 2.8V.

[0108] It can be understood that when the value of the discharge rate is different, the value of the first undervoltage threshold should also be adjusted accordingly.

[0109] The battery discharge undervoltage protection method comprises the following steps:

[0110] S71, according to the preset correspondence between the temperature interval and the discharge depth, it is determined that the discharge depth corresponding to the temperature value -10℃ is 80%.

[0111] In this embodiment, according to the preset correspondence between the temperature interval and the discharge depth, the discharge depth corresponding to the temperature interval -10℃-0℃ is 80%.

[0112] S72, according to the preset correspondence between the open circuit voltage and the remaining capacity ratio, it is determined that the first remaining capacity ratio corresponding to the first voltage value 3.25V is 30%.

[0113] In this embodiment, the correspondence between the open circuit voltage and the remaining capacity ratio is a positive correlation. According to the preset characteristic curve of the open circuit voltage and the remaining capacity ratio, it is determined that the first remaining capacity ratio corresponding to the first voltage value 3.25V is 30%.

[0114] S73, according to the first remaining capacity ratio 30%, the first discharge capacity ratio is calculated to be 70%.

[0115] In this embodiment, the sum of the first remaining capacity ratio and the first discharge capacity ratio is 100%.

[0116] S74, according to the discharge depth 80% and the first discharge capacity ratio 70%, it is calculated that the discharge capacity ratio lost by the battery 23 at -10℃ low temperature is 10%.

[0117] It can be understood that the discharge capacity ratio of the battery 23 at low temperature is reduced. In this embodiment, the discharge capacity ratio of the battery 23 at -10℃ low temperature is reduced by 10%.

[0118] S75, according to the discharge depth 80%, the second remaining capacity ratio is calculated to be 20%.

[0119] In this embodiment, the sum of the discharge depth and the second remaining capacity ratio is 100%.

[0120] S76, according to the preset open-circuit voltage and remaining capacity ratio corresponding relationship, the second remaining capacity ratio 20% corresponding to the second voltage value is 3.15V.

[0121] In this embodiment, according to the preset open-circuit voltage and remaining capacity ratio characteristic curve, the second remaining capacity ratio 20% corresponding to the second voltage value is 3.15V.

[0122] S77, according to the first voltage value 3.25V and the second voltage value 3.15V, the change amount of the voltage value generated by the battery 23 at-10℃ low temperature is calculated as 0.1V.

[0123] It can be understood that the change amount of the voltage value generated by the battery 23 at-10℃ low temperature is 0.1V, which corresponds to the lost discharge capacity ratio 10%.

[0124] S78, according to the first undervoltage threshold 2.8V and the change amount of the voltage value generated by the battery 23 at-10℃ low temperature, the second undervoltage threshold is calculated as 2.7V.

[0125] It can be understood that when the first undervoltage threshold 2.8V is adjusted to the second undervoltage threshold 2.7V, the capacity ratio of the battery 23 that can continue to discharge is 10%, which can compensate for the lost discharge capacity ratio 10% of the battery 23 at-10℃ low temperature.

[0126] It can be understood that the above steps S71-S78 are specific steps of an embodiment for determining the undervoltage threshold required for the battery 23 at-10℃ low temperature. The parameter values in the above steps S71-S78 are exemplary values. That is, in other scenarios, with different preset parameter values, the measured parameter values and calculated parameter values of the battery device 20 will also be different accordingly. In other embodiments, the determination of the dynamically adjusted undervoltage threshold can be determined according to specific application scenarios.

[0127] Please refer to Figure 8 , Figure 8 is the open-circuit voltage curve of the battery 23 under different working states. The working states include static state, charging state and discharging state. According to the open-circuit voltage curve of the battery 23 in the charging state, the full charge voltage and the charging cutoff voltage can be determined. According to the open-circuit voltage curve of the battery 23 in the discharging state, the discharge cutoff voltage can be determined, which is the first undervoltage threshold U0 or the second undervoltage threshold U1. eThe open-circuit voltage curve of the battery 23 at rest shows the change of the discharge depth of the battery 23 from the full charge voltage to full discharge. The open-circuit voltage curve of the battery 23 at discharge shows the change of the discharge depth of the battery 23 from the charge cut-off voltage to the discharge cut-off voltage, and the voltage change after cut-off discharge. Obviously, by reducing the discharge cut-off voltage, the discharge depth of the battery 23 will increase accordingly, and the discharge capacity ratio of the battery 23 will also increase accordingly.

[0128] In one embodiment, the battery device 20 can preset the second under-voltage threshold U e to select different under-voltage thresholds at different temperature intervals, thereby achieving dynamic adjustment of the under-voltage threshold.

[0129] Table 2 shows the under-voltage threshold and discharge capacity ratio of the battery 23 at different temperature intervals. First, the battery 23 is charged at the same temperature (e.g. 25°C) and the same charge rate (e.g. 0.3C). Then, the battery 23 is discharged at the same discharge rate (e.g. 0.3C) and different temperatures until the voltage of the battery 23 reaches the discharge cut-off voltage. The temperature intervals are divided, for example, the first temperature interval is 15°C-45°C, the second temperature interval is 0°C-15°C, the third temperature interval is -10°C-0°C, and the fourth temperature interval is -20°C- -10°C. Finally, the discharge capacity ratio of the battery 23 at different temperature intervals and the first under-voltage threshold (e.g. 2.8V) is determined, and the discharge capacity ratio of the battery 23 at different temperature intervals and the second under-voltage threshold (e.g. 2.8V, 2.4V, 2.2V, 2.1V, etc.) is determined. As can be seen from Table 2, below 0°C, the discharge capacity ratio of the battery 23 at the second under-voltage threshold (i.e. the dynamically adjusted under-voltage threshold) is significantly increased compared to the discharge capacity ratio of the battery 23 at the first under-voltage threshold (i.e. the preset under-voltage threshold), indicating that adjusting the first under-voltage threshold to the second under-voltage threshold can significantly improve the discharge performance of the battery 23 at low temperature. For example, in the fourth temperature interval of -20°C to -10°C, after adjusting the first under-voltage threshold (i.e. 2.8V) to the second under-voltage threshold (i.e. 2.1V), the discharge capacity ratio of the battery 23 increases from 30% to 70%, greatly improving the discharge performance of the battery 23 at low temperature.

[0130] Table 2 shows the under-voltage threshold and discharge capacity ratio of the battery 23 at different temperature intervals.

[0131]

[0132] In one embodiment, after step S34, the battery discharge under-voltage protection method can further comprise the following steps:

[0133] S35, determining whether to perform under-voltage protection on the battery 23 according to the third voltage value U3 of the battery 23 after the battery 23 is cut off from discharging and the second under-voltage threshold U e .

[0134] It can be understood that the battery device 20 can collect the third voltage value U3 through the battery management system. After the battery 23 is cut off from discharging, there are two cases:

[0135] (1) The third voltage value U3 of the battery 23 is greater than the second under-voltage threshold U e (i.e. U3> U e ), that is, the third voltage value U3 does not reach the discharge cutoff voltage (i.e. the second under-voltage threshold U e ). At this time, the battery 23 can continue to discharge, and of course there is no need to perform under-voltage protection on the battery 23.

[0136] (2) The third voltage value U3 of the battery 23 is equal to the second under-voltage threshold U e (i.e. U3= U e ), that is, the third voltage value U3 reaches the discharge cutoff voltage (i.e. the second under-voltage threshold U e ). If the battery 23 continues to discharge, the capacity of the battery 23 can be irreversibly lost. At this time, under-voltage protection needs to be performed on the battery 23.

[0137] The following will describe step S35 in a specific application scenario.

[0138] Suppose the temperature value of the battery 23 is -10°C, and according to the preset first under-voltage threshold 2.8V, the adjusted second under-voltage threshold is 2.2V, that is, the discharge cutoff voltage is 2.2V.

[0139] After the battery 23 is cut off from discharging, when the third voltage value collected by the battery management system is 2.3V, the third voltage value 2.3V is greater than the discharge cutoff voltage 2.2V, which indicates that the voltage of the battery 23 has not reached the discharge cutoff voltage 2.2V, and the battery 23 can continue to discharge, that is, there is no need to perform under-voltage protection on the battery 23.

[0140] When the third voltage value collected by the battery management system is 2.2V, the third voltage value 2.2V is equal to the discharge cutoff voltage 2.2V, and if the battery 23 continues to discharge, the capacity of the battery 23 can be irreversibly lost. At this time, under-voltage protection needs to be performed on the battery 23.

[0141] It can be understood that the third voltage value U3 dynamically changes after the battery 23 is cut off from discharging, and the third voltage value U3 tends to be stable only after a period of time. In this embodiment, the third voltage value U3 tending to be stable means that the change rate of the third voltage value U3 approaches 0 within a preset time period. In this embodiment, the third voltage value U3 tending to be stable is defined as a fourth voltage value U4.

[0142] In one embodiment, whether to perform under-voltage protection on the battery 23 is determined according to the fourth voltage value U4 of the battery 23 after being cut off from discharging and the second under-voltage threshold U e .

[0143] Specifically, if the fourth voltage value U4 is greater than the second under-voltage threshold U e (i.e., U4>U e ), the battery 23 continues to be discharged. If the fourth voltage value U4 is less than the second under-voltage threshold U e (i.e., U4<U e ), it is determined to perform under-voltage protection on the battery 23.

[0144] Please refer to Figure 9 , Figure 9 for the open-circuit voltage curves of the battery 23 at different temperatures after being cut off from discharging. Among them, S91 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and 45°C. S92 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and 25°C. S93 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and 15°C. S94 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and 0°C. S95 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and -10°C. S96 is the curve of voltage to discharge capacity ratio at 0.3C discharge rate and -20°C. In the curves S93, S94, S95 and S96, after the voltage reaches the second under-voltage threshold U e , the dashed part shows the rebound trend of the voltage.

[0145] The battery 23 is discharged at the same discharge rate (for example, 0.3C) and different temperatures. Obviously, at the same discharge rate, the second under-voltage threshold U e corresponding to different temperature values is different. As the temperature decreases, the second under-voltage threshold U e correspondingly decreases. When the temperature changes, the second under-voltage threshold U e needs to be dynamically adjusted.

[0146] In one embodiment, the battery device 20 can automatically adjust the second under-voltage threshold U eFor example, when the temperature value decreases from -10°C to -20°C, the battery management system correspondingly adjusts the second undervoltage threshold U e from 2.2 V to 2.1 V.

[0147] The above embodiments of the present application are described in detail with reference to the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method of battery discharge undervoltage protection, characterized by, The method comprises: obtaining a temperature value and a first voltage value of a battery; determining a discharge depth of the battery according to the temperature value; determining a first remaining capacity ratio of the battery according to the first voltage value; determining a second remaining capacity ratio of the battery according to the first remaining capacity ratio and the discharge depth; determining a second undervoltage threshold for increasing a discharge capacity ratio of the battery according to the second remaining capacity ratio and a first undervoltage threshold, wherein the first undervoltage threshold is a preset undervoltage threshold, and the second undervoltage threshold is a dynamically adjusted undervoltage threshold.

2. The battery discharge undervoltage protection method of claim 1, wherein, The determination of the discharge depth of the battery according to the temperature value comprises: determining a temperature interval corresponding to the temperature value; determining the discharge depth corresponding to the temperature interval according to the temperature interval.

3. The battery discharge undervoltage protection method of claim 1, wherein, The determination of the first remaining capacity ratio of the battery according to the first voltage value comprises: determining the first remaining capacity ratio corresponding to the first voltage value according to a parameter correspondence relationship of the battery, wherein the parameter correspondence relationship refers to a correspondence relationship between a remaining capacity ratio and an open-circuit voltage.

4. The battery discharge undervoltage protection method of claim 3, wherein, The determination of the second undervoltage threshold according to the second remaining capacity ratio and the first undervoltage threshold comprises: determining a second voltage value corresponding to the second remaining capacity ratio according to the parameter correspondence relationship; determining a voltage value change of the battery according to the second voltage value and the first voltage value; determining the second undervoltage threshold according to the voltage value change and the first undervoltage threshold.

5. The battery discharge undervoltage protection method according to any one of claims 1 to 4, characterized by, After the determination of the second undervoltage threshold, the method further comprises: obtaining a third voltage value of the battery after cutoff discharge; determining whether to perform undervoltage protection on the battery according to the second undervoltage threshold and the third voltage value.

6. The battery discharge undervoltage protection method of claim 5, wherein, The determination of whether to perform undervoltage protection on the battery according to the second undervoltage threshold and the third voltage value comprises: determining a fourth voltage value according to the third voltage value; if the fourth voltage value is less than the second undervoltage threshold, determining to perform undervoltage protection on the battery.

7. The battery discharge undervoltage protection method of claim 3, wherein, Before the determination of the first remaining capacity ratio corresponding to the first voltage value according to the parameter correspondence relationship of the battery, the method further comprises: charging the battery until a capacity of the battery reaches a full-charge capacity; obtaining a full-charge voltage corresponding to the full-charge capacity; discharging the battery until a voltage of the battery reaches a cutoff voltage of discharge; obtaining a voltage value of the battery during the discharging process and a state of charge corresponding to the voltage value; determining the parameter correspondence relationship according to the voltage value and the state of charge corresponding to the voltage value.

8. The battery discharge undervoltage protection method of claim 1, wherein, The determination of the second remaining capacity ratio of the battery according to the first remaining capacity ratio and the discharge depth comprises: determining a first discharge capacity ratio of the battery according to the first remaining capacity ratio; determining the second remaining capacity ratio according to the first discharge capacity ratio and the discharge depth.

9. A battery device characterized by comprising: The battery device comprises a battery, a processor, and a memory, and the memory stores a computer program which, when executed by the processor, implements the battery discharge undervoltage protection method according to any one of claims 1 to 8.

10. An electrical device, characterized by The power utilization device includes a load and the battery device as claimed in claim 9, and the battery device is used to provide electric energy for the load.

11. The powered device of claim 10, wherein, The power utilization device includes any one of a drone, an electric vehicle, an electric tool, and an energy storage product.

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