Battery protection circuit based on voltage and current double verification, control method and storage medium

Abstract

The application discloses a battery protection circuit based on voltage and current double verification, a control method and a storage medium. When the protection circuit works, the BMS instruction branch relay is turned off, the instruction main circuit relay is turned on, the BMS converts the voltage drop value between the main circuit current detection resistor at both ends of the current flowing through the main circuit current detection resistor into a main circuit current value IA; the BMS instruction branch relay is turned on, the total current IB of the main circuit is calculated: the BMS calculates the error value Iε between IA and IB, and the error value Vε between VA and VB; when Iε exceeds the preset current error threshold value, and / or Vε exceeds the preset voltage error threshold value, the BMS starts the battery protection mechanism. The application can improve the reliability and efficiency of battery protection.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a battery protection circuit, control method, and storage medium based on dual verification of voltage and current. Background Art

[0002] In battery energy storage systems, collecting battery voltage and current data is crucial. Excessive errors in these data can affect battery state estimation and system protection mechanisms, leading to deviations in the SOC (State of Charge) and SOH (State of Health) estimates. Inaccurate SOC and SOH estimates can lead to users misjudging the remaining battery charge and health status when using battery devices, and the battery system protection mechanisms can become ineffective. Even when the battery is in overcharge, overdischarge, or overcurrent conditions, if the collected voltage and current data have significant errors, the battery protection system mechanism may be unable to initiate effective protection actions in a timely manner or even malfunction, potentially posing a safety hazard and potentially leading to fires and explosions, impacting battery life and user safety. Therefore, a circuit and control method are urgently needed to prevent battery accidents caused by errors in the single detection of battery voltage and current values. Summary of the Invention

[0003] In response to the above problems, the purpose of this application is to provide a battery protection circuit, control method and storage medium based on dual verification of voltage and current, which can effectively reduce the error of single-string acquisition through multi-channel and multi-dimensional data acquisition, and improve the accuracy and reliability of overall data acquisition.

[0004] According to one aspect of the present application, a battery protection circuit based on dual verification of voltage and current is provided, which is connected between the battery and the charging and discharging port, and includes a main circuit, a branch circuit and a BMS; the battery is composed of at least two single cells connected in series.

[0005] The main circuit is connected in series from the negative pole of the battery to the negative pole of the total voltage acquisition probe, the main circuit current detection resistor, the negative pole of the charge and discharge port, the positive pole of the charge and discharge port, the fuse, the main circuit relay, the positive pole of the total voltage acquisition probe, and finally to the positive pole of the battery.

[0006] One end of the branch is connected between the positive pole of the total voltage acquisition probe and the main circuit relay; the other end is connected in series with the branch relay and the branch current sensing resistor, and finally connected between the main circuit current sensing resistor and the negative pole of the charge and discharge port.

[0007] The BMS has a first end connected to each single cell, main circuit current sensing resistor, and branch current sensing resistor through a circuit data acquisition module, and is used to collect the temperature of the single cell, main circuit current sensing resistor, and branch current sensing resistor in real time, as well as the voltage of the single cell; a second end connected to the positive and negative poles of the total voltage acquisition probe; a third end connected to the main circuit current sensing resistor; a fourth end connected to the branch current sensing resistor; a fifth end connected to the main circuit relay; and a sixth end connected to the branch relay;

[0008] BMS settings are:

[0009] When the protection circuit is working, the BMS instructs the branch relay to turn off and the main circuit relay to turn on. The voltage of each single cell is obtained through the circuit data acquisition module, and the sum of the voltages of the single cells VA is calculated; the total voltage VB of the battery is detected through the total voltage acquisition probe;

[0010] The BMS converts the voltage drop across the main circuit current sensing resistor formed by the current flowing through the main circuit current sensing resistor into the main circuit current value IA;

[0011] The following formula is used to compensate and correct the resistance of the main circuit current sensing resistor and the branch current sensing resistor in real time:

[0012] ,

[0013] in, Temperature The actual resistance value of the resistor when is the factory nominal resistance of the resistor; α is the first-order temperature coefficient of the resistor; β is the second-order temperature coefficient of the resistor; is the currently detected resistance temperature; is the reference temperature;

[0014] The BMS instructs the branch relay to turn on, and the total current IB of the main circuit is calculated using the following formula:

[0015] IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation, and R2_t is the resistance value of the branch current-sense resistor after compensation;

[0016] Calculate the error value Iε between IA and IB, and the error value Vε between VA and VB;

[0017] When Iε exceeds a preset current error threshold, and / or Vε exceeds a preset voltage error threshold, the BMS activates the battery protection mechanism.

[0018] Preferably, in some embodiments of the present application, the battery protection mechanism includes instructing the main circuit relay to disconnect and issuing an external alarm.

[0019] Preferably, in some embodiments of the present application, the branch current sensing resistor performs branch current detection only when the battery is powered on or when the current acquisition value of the branch current sensing resistor needs to be calibrated.

[0020] Preferably, in some embodiments of the present application, the error value Iε is a relative error, which is calculated as: Iε=|IA-IB| / max (IA,IB), where max (IA,IB) represents the maximum value between IA and IB; the error value Vε is a relative error, which is calculated as: Vε=|VA-VB| / max (VA,VB), where max (VA,VB) represents the maximum value between VA and VB.

[0021] Preferably, in some embodiments of the present application, converting the voltage drop across the main circuit current-sense resistor formed by the current flowing through the main circuit current-sense resistor into the main circuit current value IA includes: selecting a 16-bit AD conversion module for conversion; and starting the following digital filtering algorithm to eliminate high-frequency interference:

[0022] ,

[0023] Among them, I A，fil is the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0024] According to another aspect of the present application, the present application further provides a battery protection circuit control method based on dual voltage and current verification, including the protection circuit of any of the above embodiments, the control method comprising:

[0025] When the protection circuit is working, the BMS instructs the branch relay to turn off and the main circuit relay to turn on. The voltage of each single cell is obtained through the circuit data acquisition module, and the sum of the voltages of the single cells VA is calculated; the total voltage VB of the battery is detected through the total voltage acquisition probe;

[0026] The BMS converts the voltage drop across the main circuit current sensing resistor formed by the current flowing through the main circuit current sensing resistor into the main circuit current value IA;

[0027] The following formula is used to compensate and correct the resistance of the main circuit current sensing resistor and the branch current sensing resistor in real time:

[0028] ,

[0029] in, Temperature The actual resistance value of the resistor when is the factory nominal resistance of the resistor; α is the first-order temperature coefficient of the resistor; β is the second-order temperature coefficient of the resistor; is the currently detected resistance temperature; is the reference temperature;

[0030] The BMS instructs the branch relay to turn on, and the total current IB of the main circuit is calculated using the following formula:

[0031] IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation, and R2_t is the resistance value of the branch current-sense resistor after compensation;

[0032] Calculate the error value Iε between IA and IB, and the error value Vε between VA and VB;

[0033] When Iε exceeds a preset current error threshold, and / or Vε exceeds a preset voltage error threshold, the BMS activates the battery protection mechanism.

[0034] Preferably, in some embodiments of the present application, the battery protection mechanism includes instructing the main circuit relay to disconnect and issuing an external alarm.

[0035] Preferably, in some embodiments of the present application, the branch current sensing resistor performs branch current detection only when the battery is powered on or when the current acquisition value of the branch current sensing resistor needs to be calibrated.

[0036] Preferably, in some embodiments of the present application, the error value Iε is a relative error, which is calculated as: Iε=|IA-IB| / max (IA,IB), where max (IA,IB) represents the maximum value between IA and IB; the error value Vε is a relative error, which is calculated as: Vε=|VA-VB| / max (VA,VB), where max (VA,VB) represents the maximum value between VA and VB.

[0037] Preferably, in some embodiments of the present application, the branch current sensing resistor performs branch current detection only when the battery is powered on or when the current acquisition value of the branch current sensing resistor needs to be calibrated.

[0038] Preferably, in some embodiments of the present application, converting the voltage drop across the main circuit current-sense resistor formed by the current flowing through the main circuit current-sense resistor into the main circuit current value IA includes: selecting a 16-bit AD conversion module for conversion; and starting the following digital filtering algorithm to eliminate high-frequency interference:

[0039] ,

[0040] Among them, I A，filis the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0041] According to another aspect of the present application, the present application further provides a computer-readable storage medium on which computer instructions are stored. When the computer instructions are executed by a processor, the control method of any one of the above embodiments can be implemented.

[0042] It should be understood that within the scope of this application, the above-mentioned technical features of this application and the technical features described in detail below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be listed here one by one.

[0043] Compared with the existing technology, this application has the following technical effects:

[0044] This application adopts a dual voltage and current detection strategy to avoid inaccurate voltage and current acquisition while optimizing the circuit structure, avoiding increased circuit power consumption due to increased functions, improving acquisition accuracy and reliability, and achieving comprehensive evaluation and active regulation of the battery system status, thereby improving battery safety, efficiency and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings.

[0046] Figure 1 A schematic diagram of a battery protection circuit based on voltage and current dual verification according to an embodiment of the present application is shown.

[0047] Figure 2 A flow chart of a battery protection circuit control method based on voltage and current dual verification according to an embodiment of the present application is shown.

[0048] Figure 1: Battery; 2: Charge and discharge port; 3: BMS; 4: Single cell; 5: Total voltage acquisition probe; 6: Main circuit current-sense resistor; 7: Fuse; 8: Main circuit relay; 9: Branch relay; 10: Branch current-sense resistor; 11: Circuit data acquisition module. DETAILED DESCRIPTION

[0049] To make the purpose, technical solutions, beneficial effects, and significant improvements of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, all the embodiments described are only some of the embodiments of this application, not all of them; based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0050] The present application will be further described below in conjunction with specific implementations. It should be understood that these embodiments are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0051] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment herein. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor does it limit mutually exclusive independent or alternative embodiments. Those skilled in the art will appreciate that an embodiment herein may be combined with other embodiments as long as no structural conflicts arise.

[0052] In the description herein, unless otherwise specified or limited, the technical terms "installed," "connected," and "connected" should be understood broadly, and may refer to a movable connection, a fixed connection or integration, or connection via a connector. Those skilled in the art will understand the specific meanings of these terms in the embodiments of this application based on the specific circumstances.

[0053] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to having a specific orientation, being installed or operated in a specific orientation, and should not be understood as limiting the embodiments in this document.

[0054] In the description herein, terms such as "first" and "second" are used only to distinguish different objects and should not be understood to indicate relative importance or to limit the quantity, specific order, or primary and secondary relationship of the described technical features. In the description herein, "plurality" means at least two.

[0055] Embodiments of the present application will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present application, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

[0056] Figure 1 FIG1 shows a schematic diagram of a battery protection circuit based on voltage and current dual verification according to an embodiment of the present application. Figure 1 As shown, the present application discloses a battery protection circuit based on dual voltage and current verification, connected between battery 1 and charging and discharging port 2, and including a main circuit, branch circuits, and BMS 3. BMS, or battery management system, is an indispensable and important component in a battery system and serves as the hub for managing and monitoring the battery. It is used to manage, maintain, and monitor various modules of the battery, and is responsible for preventing overcharging and overdischarging of the battery, extending its service life, and ensuring its normal operation.

[0057] The battery 1 is composed of at least two single cells 4 connected in series.

[0058] The main circuit is connected in series with the negative pole of battery 1, the negative pole of the total voltage acquisition probe 5, the main circuit current detection resistor 6, the negative pole of the charge and discharge port 2, the positive pole of the charge and discharge port 2, the fuse 7, the main circuit relay 8, the positive pole of the total voltage acquisition probe 5, and finally connected to the positive pole of battery 1.

[0059] One end of the branch is connected between the positive electrode of the total voltage acquisition probe 5 and the main circuit relay 8; the other end is connected in series with the branch relay 9 and the branch current-sense resistor 10, and finally connected between the main circuit current-sense resistor 6 and the negative electrode of the charge and discharge port 2. Specifically, in some embodiments of the present application, the branch relay 9 is pulsed, with an on-time of ≤100ms and an interval of ≥5s between two on-times, to reduce branch power consumption.

[0060] In a specific embodiment of the present application, the battery 1 consists of 12 lithium-ion battery cells 4 connected in series. The main circuit current-sense resistor 6 utilizes a 0.01Ω / 5W precision alloy resistor, while the branch circuit current-sense resistor 10 utilizes a 0.02Ω / 2W precision resistor to ensure that the current detection error does not exceed 0.5%. The total voltage acquisition probe 5 is a differential voltage sensor with a measurement range of 0-100V and an accuracy of ±0.2%. The circuit data acquisition module 11 features 12 independent acquisition channels, each with a 1kHz sampling rate. A 50x differential amplifier circuit suppresses common-mode interference, keeping the voltage acquisition error of the single cell 4 within 2mV. The main circuit relay 8 utilizes a DC24V normally open relay, while the branch circuit relay 9 utilizes a DC12V miniature relay. The branch circuit relay 9 supports pulsed conduction, significantly reducing standby power consumption and avoiding increased energy consumption due to functional expansion. This application further ensures the accuracy of detection data by selecting high-precision current-sense resistors, differential voltage sensors and multi-channel acquisition modules, providing a reliable basis for the precise triggering of the battery protection mechanism, thereby effectively preventing protection failure or malfunction under abnormal conditions such as battery overcharging, over-discharging, and overcurrent, which is beneficial to extending battery life and improving system safety.

[0061] BMS3, its first end is connected to each single cell 4 through the circuit data acquisition module 11, and is used to collect the temperature of each single cell 4, the main circuit current sensing resistor 6 and the branch current sensing resistor 10 in real time, and collect the voltage of each single cell 4 for calculating the sum VA of the voltage of each single cell 4. Specifically, the circuit data acquisition module 11 is provided with a plurality of battery acquisition chips corresponding to the number of single cells 4 of the battery 1, which are respectively connected to each single cell 4, for collecting the voltage value of each single cell 4 and transmitting it back to BMS3; its second end is connected to the positive and negative poles of the total voltage acquisition probe 5, and is used to detect the total voltage VB of the battery 1; its third end is connected to the main circuit current sensing resistor 6; its fourth end is connected to the branch current sensing resistor 10; its fifth end is connected to the main circuit relay 8; and its sixth end is connected to the branch relay 9.

[0062] BMS3 is set as follows: when the protection circuit is working, BMS3 instructs the branch relay 9 to turn off and instructs the main circuit relay 8 to turn on, obtains the voltage of each single battery cell 4 through the circuit data acquisition module 11, and calculates the sum VA of the voltages of all single battery cells 4; and detects the total voltage VB of the battery 1 through the total voltage acquisition probe 5.

[0063] The BMS3 converts the voltage drop across the main circuit current-sensing resistor 6 formed by the current flowing through the main circuit current-sensing resistor 6 into the main circuit current value IA; and performs real-time compensation correction on the resistance values ​​of the main circuit current-sensing resistor 6 and the branch current-sensing resistor 10 using the following formula:

[0064] ,

[0065] in, Temperature The actual resistance value of the resistor at that time is the resistance value after compensation correction; The resistance is the nominal resistance of the resistor at the factory, usually the nominal resistance at 25°C; α is the first-order temperature coefficient of the resistor, which is determined by the characteristics of the resistor material. For example, the α value of a precision alloy resistor is usually 10 -5 ~10 -6 β is the second-order temperature coefficient of the resistor, which is used to correct nonlinear errors. Most precision resistors can be ignored, that is, β = 0); The current detected resistance temperature can be acquired by the NTC sensor built into the circuit data acquisition module 11 to acquire the temperature of the main circuit current sensing resistor 6 and the branch current sensing resistor 10; It is the reference temperature, the default is 25℃.

[0066] As those skilled in the art will appreciate, the resistance values ​​measured at different temperatures can be corrected to equivalent resistance values ​​at the reference temperature through real-time compensation correction, thereby eliminating the effect of temperature drift on the current calculation accuracy.

[0067] BMS3 instructs branch relay 9 to turn on, and the total current IB of the main circuit is calculated using the following formula:

[0068] IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation and R2_t is the resistance value of the branch current-sense resistor after compensation and correction.

[0069] BMS3 calculates the error value Iε between IA and IB, and the error value Vε between VA and VB; when Iε exceeds a preset current error threshold and / or Vε exceeds a preset voltage error threshold, BMS3 activates the battery protection mechanism. Furthermore, to avoid false operation caused by transient interference, the battery protection mechanism can also be activated only when Iε or Vε exceeds its error threshold for n consecutive times, where n is a positive integer.

[0070] Preferably, in some embodiments of the present application, converting the voltage drop across the main circuit current-sense resistor formed by the current flowing through the main circuit current-sense resistor into the main circuit current value IA includes: selecting a 16-bit AD conversion module for conversion; and starting the following digital filtering algorithm to eliminate high-frequency interference:

[0071] ,

[0072] Among them, I A，fil is the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0073] In a specific embodiment of the present application, the BMS3 is further configured as follows: when the protection circuit enters the operating state, the BMS3 instructs the branch relay 9 to turn off and the main circuit relay 8 to turn on. The voltage of each single cell 4 is obtained through the circuit data acquisition module 11, and the sum of the voltages VA of all single cells 4 is calculated; the total voltage VB of the battery 1 is detected through the total voltage acquisition probe 5. The voltage drop across the main circuit current sense resistor 6 formed by the current flowing through the main circuit current sense resistor 6 is converted into the main circuit current value IA through the 16-bit AD conversion module, and the following digital filtering algorithm is activated to eliminate high-frequency interference:

[0074] ,

[0075] Among them, I A，filis the main circuit current value after filtering; N is the sliding window size set according to the actual working conditions. In one possible embodiment, a sliding window mean filter is selected to dynamically adjust the window size to 5-20 sampling points, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value IA obtained by the k-th sampling after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0076] The digital filtering algorithm described above takes the arithmetic mean of N consecutive sampled values ​​within the window, effectively suppressing high-frequency interference, such as pulse interference caused by charging and discharging transients. This effectively reduces the impact of current fluctuations on measurement accuracy, ensuring the stability of the main circuit current value IA. The window size N can be dynamically adjusted by the BMS3 based on the degree of current fluctuation in real-time sampling. For example, the initial sliding window size is 10. When the current fluctuation amplitude exceeds 10% of the rated value, N is automatically increased to 20; when the fluctuation amplitude is less than 3% of the rated value, N is reduced to 5. This effectively balances filtering effectiveness and response speed. This dynamic adjustment mechanism resolves the contradiction between fixed parameter filtering: "good steady-state filtering leads to slow dynamic response, while fast dynamic response leads to poor filtering effectiveness," achieving a balance of performance under different operating conditions.

[0077] Preferably, in some embodiments of the present application, the BMS3 is further provided with a self-calibration module: the self-calibration module automatically performs a full-scale parameter calibration every 24 hours or after 5 cumulative charge and discharge cycles, and stores the calibration parameters in a non-volatile memory to ensure the detection accuracy in long-term use. The control logic solves the problem of misjudgment and delayed response of the traditional single verification method under complex working conditions through multi-dimensional parameter fusion, dynamic threshold adjustment and hierarchical protection mechanism, and significantly improves the reliability and accuracy of battery protection.

[0078] This application sets up a dual detection structure for the main circuit and the branch circuit, and uses the main circuit current detection resistor and the branch current detection resistor in conjunction with the total voltage acquisition probe and the circuit data acquisition module to achieve dual verification of voltage (the sum of the single cell voltages VA and the total voltage VB) and current (main circuit current IA and branch calculated current IB), effectively reducing the error influence of a single detection channel and improving the accuracy and reliability of battery voltage and current acquisition.

[0079] Preferably, in some embodiments of the present application, the error value Iε is a relative error, which is calculated as follows: Iε = |IA - IB| / max (IA, IB); the error value Vε is a relative error, which is calculated as follows: Vε = |VA - VB| / max (VA, VB). Where max (IA, IB) represents the maximum value between IA and IB, and max (VA, VB) represents the maximum value between VA and VB.

[0080] Preferably, in some embodiments of the present application, the battery protection mechanism includes instructing the main circuit relay 8 to disconnect and issuing an external alarm.

[0081] Preferably, in some embodiments of the present application, the branch current detection resistor 10 performs branch current detection only when the battery is turned on or the current acquisition value of the branch current detection resistor 10 needs to be calibrated. By reducing the working time of the branch current detection resistor 10, the energy loss caused by long-term conduction of the branch can be significantly reduced, which is more suitable for the needs of low-power battery systems to extend battery life; at the same time, reducing the continuous current-carrying time can reduce the accuracy drift and aging speed of the resistor due to the accumulation of temperature rise, thereby ensuring the long-term stability of current detection; and only enabling branch detection in specific scenarios can avoid the load fluctuations of daily charging and discharging interfering with the calibration process, ensuring that the branch current acquisition value corrected by the reference signal is more accurate, and in addition, it can reduce the BMS's continuous monitoring computing load on the branch current, so that system resources can be more concentrated on the real-time protection control of the main circuit, thereby improving the overall response efficiency.

[0082] Preferably, in some embodiments of the present application, the current error threshold and the voltage error threshold preset by the BMS 3 are both configured as dynamically adjustable thresholds. The BMS 3 can adaptively and dynamically adjust the current error threshold and the voltage error threshold based on the battery operating status parameters (such as battery temperature, SOC, etc.) collected by the circuit data acquisition module 11, so that the error threshold can match the actual operating status of the battery, thereby optimizing the accuracy and reliability of battery protection:

[0083] The formula for dynamically adjusting the current error threshold based on temperature is: I th =I 0th ×k T , where I 0th is the original threshold of current error, I th is the adjusted current error threshold ;k T The formula for dynamically adjusting the voltage error threshold based on temperature and SOC is: V th =V 0th ×K SOC , where V 0th is the voltage error original threshold, V th is the adjusted voltage error threshold, K SOC k is the adjustment coefficient based on SOC. T and K SOC The value of is dynamically determined based on the actual battery temperature and the SOC range. When the threshold needs to be expanded, the adjustment coefficient is greater than 1; when the threshold needs to be reduced, the adjustment coefficient is less than 1.

[0084] In a specific embodiment of the present application, the BMS3 dynamically adjusts the current error threshold according to the battery temperature collected by the circuit data acquisition module 11: when the temperature is ≥45°C, the current error threshold is expanded to 1.5 times the original threshold, that is, k T Set to 1.5, BMS3 dynamically adjusts the voltage error threshold according to the battery's SOC (state of charge): when SOC ≤ 20% or SOC ≥ 80%, the voltage error threshold is reduced to 80% of the original threshold, that is, K SO Set to 0.8.

[0085] According to another aspect of the present application, the present application further provides a battery protection circuit control method based on dual voltage and current verification, including the protection circuit of any of the above embodiments, the control method comprising:

[0086] BMS3 is set as follows: when the protection circuit is working, BMS3 instructs the branch relay 9 to turn off and instructs the main circuit relay 8 to turn on, obtains the voltage of each single battery cell 4 through the circuit data acquisition module 11, and calculates the sum VA of the voltages of all single battery cells 4; and detects the total voltage VB of the battery 1 through the total voltage acquisition probe 5.

[0087] The BMS3 converts the voltage drop across the main circuit current-sensing resistor 6 formed by the current flowing through the main circuit current-sensing resistor 6 into the main circuit current value IA; and performs real-time compensation correction on the resistance values ​​of the main circuit current-sensing resistor 6 and the branch current-sensing resistor 10 using the following formula:

[0088] ,

[0089] in, Temperature The actual resistance value of the resistor at that time is the resistance value after compensation correction; The resistance is the nominal resistance of the resistor at the factory, usually the nominal resistance at 25°C; α is the first-order temperature coefficient of the resistor, which is determined by the characteristics of the resistor material. For example, the α value of a precision alloy resistor is usually 10 -5 ~10 -6 β is the second-order temperature coefficient of the resistor, which is used to correct nonlinear errors. Most precision resistors can be ignored, that is, β = 0); The current detected resistance temperature can be acquired by the NTC sensor built into the circuit data acquisition module 11 to acquire the temperature of the main circuit current sensing resistor 6 and the branch current sensing resistor 10; It is the reference temperature, the default is 25℃.

[0090] As those skilled in the art will appreciate, the resistance values ​​measured at different temperatures can be corrected to equivalent resistance values ​​at the reference temperature through real-time compensation correction, thereby eliminating the effect of temperature drift on the current calculation accuracy.

[0091] BMS3 instructs branch relay 9 to turn on, and the total current IB of the main circuit is calculated using the following formula:

[0092] IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation and R2_t is the resistance value of the branch current-sense resistor after compensation and correction.

[0093] BMS3 calculates the error value Iε between IA and IB, and the error value Vε between VA and VB; when Iε exceeds a preset current error threshold and / or Vε exceeds a preset voltage error threshold, BMS3 activates the battery protection mechanism. Furthermore, to avoid false operation caused by transient interference, the battery protection mechanism can also be activated only when Iε or Vε exceeds its error threshold for n consecutive times, where n is a positive integer.

[0094] Figure 2 The flowchart of a battery protection circuit control method based on voltage and current dual verification according to an embodiment of the present application is shown. Figure 2 As shown, in some embodiments of the present application, the battery system is turned on, the BMS3 is powered by the battery 1, and the protection circuit of the present application starts to work, wherein the branch relay 9 and the main circuit relay 8 are selected as normally open relays (the initial state is the off state). First, the BMS3 instructs the branch relay 9 to turn off, the main circuit relay 8 to turn on, and the main circuit is then turned on. The voltage of each single cell 4 is obtained through the circuit data acquisition module 11, and the sum VA of the voltages of all single cells 4 is calculated; the total voltage VB of the battery 1 is detected through the total voltage acquisition probe 5.

[0095] Detect the main circuit current value IA. Specifically, the BMS 3 converts the voltage drop across the main circuit current sensing resistor 6 formed by the current flowing through the main circuit current sensing resistor 6 into the main circuit current value IA; and performs real-time compensation correction on the resistance values ​​of the main circuit current sensing resistor 6 and the branch current sensing resistor 10 using the following formula:

[0096] ,

[0097] in, Temperature The actual resistance value of the resistor at that time is the resistance value after compensation correction; The resistance is the nominal resistance of the resistor at the factory, usually the nominal resistance at 25°C; α is the first-order temperature coefficient of the resistor, which is determined by the characteristics of the resistor material. For example, the α value of a precision alloy resistor is usually 10 -5 ~10 -6 β is the second-order temperature coefficient of the resistor, which is used to correct nonlinear errors. Most precision resistors can be ignored, that is, β = 0); The current detected resistance temperature can be acquired by the NTC sensor built into the circuit data acquisition module 11 to acquire the temperature of the main circuit current sensing resistor 6 and the branch current sensing resistor 10; It is the reference temperature, the default is 25℃.

[0098] After detecting the main circuit current value IA, BMS3 instructs branch relay 9 to turn on and calculates the total current IB of the main circuit using the following formula:

[0099] IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation and R2_t is the resistance value of the branch current-sense resistor after compensation and correction.

[0100] BMS3 calculates the error value Iε between IA and IB, and the error value Vε between VA and VB; when Iε exceeds a preset current error threshold and / or Vε exceeds a preset voltage error threshold, BMS3 activates the battery protection mechanism. Furthermore, to avoid false operation caused by transient interference, the battery protection mechanism can also be activated only when Iε or Vε exceeds its error threshold for n consecutive times, where n is a positive integer.

[0101] During the charge and discharge process of Battery 1, BMS3 will continuously collect the voltage and current data of Battery 1, and use the collected data to estimate the State of Charge and State of Health of Battery 1, and determine whether the voltage and charge and discharge current of Battery 1 have reached dangerous values. When the voltage of Battery 1 is too high or too low during the charge and discharge process, when the charge and discharge current is too large, or when the voltage is too low in the static state, the BMS3 will be triggered to activate the battery protection mechanism. The battery protection mechanism includes but is not limited to the BMS3 determining the battery's alarm status based on the collected voltage and current data to limit, prohibit, or force charge the battery and issue corresponding warnings through LED signal lights. When the collected voltage and current data is inaccurate, the battery system's protection mechanism will fail, and the BMS3 will be unable to collect the true status of the battery, which may even cause the battery to overcharge or over-discharge, affecting battery life and user safety.

[0102] Preferably, in some embodiments of the present application, converting the voltage drop across the main circuit current-sense resistor formed by the current flowing through the main circuit current-sense resistor into the main circuit current value IA includes: selecting a 16-bit AD conversion module for conversion; and starting the following digital filtering algorithm to eliminate high-frequency interference:

[0103] ,

[0104] Among them, I A，fil is the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，kis the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0105] In a specific embodiment of the present application, the BMS3 is further configured as follows: when the protection circuit enters the operating state, the BMS3 instructs the branch relay 9 to turn off and the main circuit relay 8 to turn on. The voltage of each single cell 4 is obtained through the circuit data acquisition module 11, and the sum of the voltages VA of all single cells 4 is calculated; the total voltage VB of the battery 1 is detected through the total voltage acquisition probe 5. The voltage drop across the main circuit current sense resistor 6 formed by the current flowing through the main circuit current sense resistor 6 is converted into the main circuit current value IA through the 16-bit AD conversion module, and the following digital filtering algorithm is activated to eliminate high-frequency interference:

[0106] ,

[0107] Among them, I A，fil is the main circuit current value after filtering; N is the sliding window size set according to the actual working conditions. In one possible embodiment, a sliding window mean filter is selected to dynamically adjust the window size to 5-20 sampling points, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value IA obtained by the k-th sampling after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

[0108] The digital filtering algorithm described above takes the arithmetic mean of N consecutive sampled values ​​within the window, effectively suppressing high-frequency interference, such as pulse interference caused by charging and discharging transients. This effectively reduces the impact of current fluctuations on measurement accuracy, ensuring the stability of the main circuit current value IA. The window size N can be dynamically adjusted by the BMS3 based on the degree of current fluctuation in real-time sampling. For example, the initial sliding window size is 10. When the current fluctuation amplitude exceeds 10% of the rated value, N is automatically increased to 20; when the fluctuation amplitude is less than 3% of the rated value, N is reduced to 5. This effectively balances filtering effectiveness and response speed. This dynamic adjustment mechanism resolves the contradiction between fixed parameter filtering: "good steady-state filtering leads to slow dynamic response, while fast dynamic response leads to poor filtering effectiveness," achieving a balance of performance under different operating conditions.

[0109] Preferably, in some embodiments of the present application, the BMS3 is further provided with a self-calibration module: the self-calibration module automatically performs a full-scale parameter calibration every 24 hours or after 5 cumulative charge and discharge cycles, and stores the calibration parameters in a non-volatile memory to ensure the detection accuracy in long-term use. The control logic solves the problem of misjudgment and delayed response of the traditional single verification method under complex working conditions through multi-dimensional parameter fusion, dynamic threshold adjustment and hierarchical protection mechanism, and significantly improves the reliability and accuracy of battery protection.

[0110] This application sets up a dual detection structure for the main circuit and the branch circuit, and uses the main circuit current detection resistor and the branch current detection resistor in conjunction with the total voltage acquisition probe and the circuit data acquisition module to achieve dual verification of voltage (the sum of the single cell voltages VA and the total voltage VB) and current (main circuit current IA and branch calculated current IB), effectively reducing the error influence of a single detection channel and improving the accuracy and reliability of battery voltage and current acquisition.

[0111] Preferably, in some embodiments of the present application, the error value Iε is a relative error, which is calculated as follows: Iε = |IA - IB| / max (IA, IB); the error value Vε is a relative error, which is calculated as follows: Vε = |VA - VB| / max (VA, VB). Where max (IA, IB) represents the maximum value between IA and IB, and max (VA, VB) represents the maximum value between VA and VB.

[0112] Preferably, in some embodiments of the present application, the battery protection mechanism includes instructing the main circuit relay 8 to disconnect and issuing an external alarm.

[0113] Preferably, in some embodiments of the present application, the branch current detection resistor 10 performs branch current detection only when the battery is turned on or the current acquisition value of the branch current detection resistor 10 needs to be calibrated. By reducing the working time of the branch current detection resistor 10, the energy loss caused by long-term conduction of the branch can be significantly reduced, which is more suitable for the needs of low-power battery systems to extend battery life; at the same time, reducing the continuous current-carrying time can reduce the accuracy drift and aging speed of the resistor due to the accumulation of temperature rise, thereby ensuring the long-term stability of current detection; and only enabling branch detection in specific scenarios can avoid the load fluctuations of daily charging and discharging interfering with the calibration process, ensuring that the branch current acquisition value corrected by the reference signal is more accurate, and in addition, it can reduce the BMS's continuous monitoring computing load on the branch current, so that system resources can be more concentrated on the real-time protection control of the main circuit, thereby improving the overall response efficiency.

[0114] Preferably, in some embodiments of the present application, the current error threshold and the voltage error threshold preset by the BMS 3 are both configured as dynamically adjustable thresholds. The BMS 3 can adaptively and dynamically adjust the current error threshold and the voltage error threshold based on the battery operating status parameters (such as battery temperature, SOC, etc.) collected by the circuit data acquisition module 11, so that the error threshold can match the actual operating status of the battery, thereby optimizing the accuracy and reliability of battery protection:

[0115] The formula for dynamically adjusting the current error threshold based on temperature is: I th =I 0th ×k T , where I 0th is the original threshold of current error, I th is the adjusted current error threshold ;k T The formula for dynamically adjusting the voltage error threshold based on temperature and SOC is: V th =V 0th ×K SOC , where V 0th is the voltage error original threshold, V th is the adjusted voltage error threshold, K SOC k is the adjustment coefficient based on SOC. T and K SOC The value of is dynamically determined based on the actual battery temperature and the SOC range. When the threshold needs to be expanded, the adjustment coefficient is greater than 1; when the threshold needs to be narrowed, the adjustment coefficient is less than 1.

[0116] In a specific embodiment of the present application, the BMS3 dynamically adjusts the current error threshold according to the battery temperature collected by the circuit data acquisition module 11: when the temperature is ≥45°C, the current error threshold is expanded to 1.5 times the original threshold, that is, k T Set to 1.5, BMS3 dynamically adjusts the voltage error threshold according to the battery's SOC (state of charge): when SOC ≤ 20% or SOC ≥ 80%, the voltage error threshold is reduced to 80% of the original threshold, that is, K SO Set to 0.8.

[0117] According to another aspect of the present application, the present application further provides a computer-readable storage medium on which computer instructions are stored. When the computer instructions are executed by a processor, the control method of any one of the above embodiments can be implemented.

[0118] According to another aspect of the present application, the present application further provides a computer-readable storage medium on which computer instructions are stored. When the computer instructions are executed by a processor, the control method of any one of the above embodiments can be implemented.

[0119] The present application discloses a battery protection circuit, control method, and storage medium based on dual verification of voltage and current. The structure is relatively simple and the cost is low. A total voltage detection and a controllable current detection are added to the original voltage and current detection. By comparing the two sets of detection values, it is easy to determine whether the voltage and current detection are accurate. Through multi-channel and multi-dimensional data acquisition, the error of single-point acquisition can be effectively reduced and the accuracy of overall battery data acquisition can be improved. Through dual monitoring of voltage and current, abnormal conditions in the battery pack, such as overvoltage, overcurrent, short circuit, etc., can be detected in time, thereby ensuring that the protection system can operate normally. It can further optimize the battery charging and discharging strategy, improve the estimation accuracy of SOC, reduce the prediction deviation of SOH, and improve the overall efficiency of the system.

[0120] The above describes the preferred embodiments of the present application. It should be understood that the present application is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-mentioned disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present application without departing from the scope of the technical solutions of the present application, or modify them into equivalent embodiments with equivalent changes, which does not affect the substantive content of the present application. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application that do not depart from the content of the technical solutions of the present application are still within the scope of protection of the technical solutions of the present application.

Claims

1. A battery protection circuit based on dual voltage and current verification, characterized in that: The protection circuit is connected between the battery and the charging and discharging port, and includes a main circuit, a branch circuit and a BMS; The battery is composed of at least two single cells connected in series; The main circuit is connected in series from the negative electrode of the battery to the negative electrode of the total voltage acquisition probe, the main circuit current detection resistor, the negative electrode of the charge and discharge port, the positive electrode of the charge and discharge port, the fuse, the main circuit relay, the positive electrode of the total voltage acquisition probe, and finally to the positive electrode of the battery; One end of the branch is connected between the positive electrode of the total voltage acquisition probe and the main circuit relay; the other end is connected in series with the branch relay and the branch current sensing resistor, and finally connected between the main circuit current sensing resistor and the negative electrode of the charge and discharge port; The BMS has a first end connected to each of the single cells, the main circuit current sensing resistor, and the branch current sensing resistor through a circuit data acquisition module, and is used to collect the temperature of the single cells, the main circuit current sensing resistor, and the branch current sensing resistor in real time, as well as the voltage of the single cells; a second end connected to the positive and negative electrodes of the total voltage acquisition probe; a third end connected to the main circuit current sensing resistor; and a fourth end connected to the branch current sensing resistor; The fifth end thereof is connected to the main circuit relay; The sixth end thereof is connected to the branch relay; The BMS settings are: When the protection circuit is working, the BMS instructs the branch relay to turn off and instructs the main circuit relay to turn on, obtains the voltage of each single cell through the circuit data acquisition module, and calculates the sum of the voltages VA of the single cells; and detects the total voltage VB of the battery through the total voltage acquisition probe; The BMS converts the voltage drop across the main circuit current sensing resistor formed by the current flowing through the main circuit current sensing resistor into a main circuit current value IA; The resistance values ​​of the main circuit current sensing resistor and the branch current sensing resistor are compensated and corrected in real time using the following formula: ， in, Temperature The actual resistance value of the resistor when is the factory nominal resistance of the resistor; α is the first-order temperature coefficient of the resistor; β is the second-order temperature coefficient of the resistor; is the currently detected resistance temperature; is the reference temperature; The BMS instructs the branch relay to turn on, and the total current IB of the main circuit is calculated using the following formula: IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation, and R2_t is the resistance value of the branch current-sense resistor after compensation; Calculating an error value Iε between the IA and the IB, and an error value Vε between the VA and the VB; When the Iε exceeds a preset current error threshold, and / or the Vε exceeds a preset voltage error threshold, the BMS activates a battery protection mechanism.

2. The protection circuit according to claim 1, wherein: The battery protection mechanism includes instructing the main circuit relay to disconnect and issuing an external alarm.

3. The protection circuit according to claim 1, wherein: The branch current detection resistor performs branch current detection only when the battery is powered on or when the current acquisition value of the branch current detection resistor needs to be calibrated.

4. The protection circuit according to claim 1, wherein: The error value Iε is a relative error, which is calculated as follows: Iε=|IA-IB| / max(IA,IB), where max(IA,IB) represents the maximum value between IA and IB. The error value Vε is a relative error, which is calculated as follows: Vε=|VA-VB| / max (VA, VB), where max (VA, VB) represents the maximum value of VA and VB.

5. The protection circuit according to claim 1, wherein: The step of converting the voltage drop across the main circuit current-sensing resistor formed by the current flowing through the main circuit current-sensing resistor into the main circuit current value IA includes: Use 16-bit AD conversion module for conversion; Enable the following digital filtering algorithms to eliminate high-frequency interference: ， Among them, I A，fil is the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

6. A battery protection circuit control method based on voltage and current dual verification, characterized in that: The protection circuit according to any one of claims 1 to 5, wherein the control method comprises: When the protection circuit is working, the BMS instructs the branch relay to turn off and instructs the main circuit relay to turn on, obtains the voltage of each single cell through the circuit data acquisition module, and calculates the sum of the voltages VA of the single cells; and detects the total voltage VB of the battery through the total voltage acquisition probe; The BMS converts the voltage drop across the main circuit current sensing resistor formed by the current flowing through the main circuit current sensing resistor into a main circuit current value IA; The resistance values ​​of the main circuit current sensing resistor and the branch current sensing resistor are compensated and corrected in real time using the following formula: ， in, Temperature The actual resistance value of the resistor when is the factory nominal resistance of the resistor; α is the first-order temperature coefficient of the resistor; β is the second-order temperature coefficient of the resistor; is the currently detected resistance temperature; is the reference temperature; The BMS instructs the branch relay to turn on, and the total current IB of the main circuit is calculated using the following formula: IB=VB / (R1_t+R2_t), where R1_t is the resistance value of the main circuit current-sense resistor after compensation, and R2_t is the resistance value of the branch current-sense resistor after compensation; Calculating an error value Iε between the IA and the IB, and an error value Vε between the VA and the VB; When the Iε exceeds a preset current error threshold, and / or the Vε exceeds a preset voltage error threshold, the BMS activates a battery protection mechanism.

7. The control method according to claim 6, characterized in that: The error value Iε is a relative error, which is calculated as follows: Iε=|IA-IB| / max(IA,IB), where max(IA,IB) represents the maximum value between IA and IB. The error value Vε is a relative error, which is calculated as follows: Vε=|VA-VB| / max (VA, VB), where max (VA, VB) represents the maximum value of VA and VB.

8. The control method according to claim 6, characterized in that: The branch current detection resistor performs branch current detection only when the battery is powered on or when the current acquisition value of the branch current detection resistor needs to be calibrated.

9. The control method according to claim 6, characterized in that: The step of converting the voltage drop across the main circuit current-sensing resistor formed by the current flowing through the main circuit current-sensing resistor into the main circuit current value IA includes: Use 16-bit AD conversion module for conversion; Enable the following digital filtering algorithms to eliminate high-frequency interference: ， Among them, I A，fil is the main circuit current value after filtering, N is the sliding window size set according to the actual working conditions, and N is a positive integer; I A，k is the original value of the main loop current obtained by the k-th sampling, that is, the main loop current value after conversion by the 16-bit AD conversion module; k is the sampling sequence number, 0≤k≤N−1, and k is a positive integer.

10. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by a processor, the control method according to any one of claims 6 to 9 is implemented.

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