Coulombmeter monitoring system and method for dynamically calibrating multiple strings of lithium battery packs

Abstract

The invention relates to the technical field of digital measurement, and discloses a coulombmeter monitoring system and a coulombmeter monitoring method for dynamic calibration of multiple strings of lithium battery packs, and the coulombmeter monitoring method for dynamic calibration of the multiple strings of lithium battery packs comprises the following steps: a dynamic calibration module carries out dynamic calibration on the multiple strings of lithium battery packs according to pre-stored calibration parameters; a single voltage signal and a charging and discharging current signal are accurately calibrated, the measurement error of the battery in the charging and discharging process and the gain error and noise interference in current measurement are eliminated, the single voltage and the charging and discharging current are accurately monitored and dynamically calibrated, and then the state parameters of the multi-string lithium battery pack are accurately calculated. Accurate control over the charging and discharging process is achieved, abnormal conditions such as over-charging and over-discharging of the batteries can be avoided, and the monitoring reliability of the multi-string lithium battery pack is improved.

Description

Technical Field

[0001] The present application relates to the field of digital measurement technology, and in particular to a coulomb meter monitoring system and method for dynamic calibration of a multi-string lithium battery pack. Background Art

[0002] With the continuous advancement of technology, lithium batteries have been widely used in many fields due to their advantages such as high energy density and long cycle life. In particular, multi-string lithium battery packs have become a core energy solution in electric vehicles, energy storage systems, and various portable electronic devices. However, multi-string lithium battery packs face many challenges in actual use. Their safe, stable, and efficient operation is crucial to the performance of the entire system, which also places higher demands on battery monitoring technology.

[0003] While existing multi-string lithium battery pack monitoring technologies already have systems capable of measuring battery voltage, current, and other parameters, some limitations remain. For one thing, when monitoring the voltage of individual cells, the accuracy of voltage measurement decreases due to factors such as temperature fluctuations and self-discharge during the charge and discharge process. Existing systems are unable to compensate for these factors, making it difficult to accurately reflect the battery's true state. On the other hand, accurate measurement of charge and discharge currents is equally critical for current monitoring. However, existing monitoring systems often fail to effectively perform gain calibration and noise filtering on current signals, resulting in errors in current measurement data and affecting the accurate assessment of the battery's charge and discharge status.

[0004] Furthermore, the traditional coulomb counter monitoring method's measurement accuracy decreases over time due to changes in battery characteristics and environmental factors, making it unable to meet the requirements for high-precision, high-reliability battery monitoring. Therefore, improving the reliability of multi-string lithium battery pack monitoring has become a pressing technical challenge. Summary of the Invention

[0005] The present application provides a coulomb counter monitoring system and method for dynamic calibration of a multi-string lithium battery pack to improve the reliability of monitoring of the multi-string lithium battery pack.

[0006] In a first aspect, the present application further provides a coulomb counter monitoring system for dynamic calibration of a multi-string lithium battery pack, the system comprising:

[0007] A voltage acquisition module is connected to each battery cell of a multi-string lithium battery pack and is used to acquire voltage signals of the multi-string lithium battery pack;

[0008] A coulomb counter module, connected to the voltage acquisition module, for acquiring charge and discharge current signals of the multiple strings of lithium battery packs;

[0009] A dynamic calibration module, connected to the voltage acquisition module and the coulomb counter module, for dynamically calibrating the voltage signal and the charge and discharge current signal;

[0010] a processor module connected to the dynamic calibration module, configured to receive the voltage signal and the charge and discharge current signal after dynamic calibration, and process the state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm; the processor module is also connected to the charge and discharge management module of the multi-string lithium battery pack, configured to control the charge and discharge process of the multi-string lithium battery pack;

[0011] A storage module, connected to the processor module, for storing historical status data, calibration parameters, and monitoring result data of the multiple strings of lithium battery packs;

[0012] A communication module is connected to the processor module and is used to transmit the historical status data, the calibration parameters and the monitoring result data of the multi-string lithium battery pack to an external device.

[0013] In a second aspect, the present application provides a coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack, the method comprising:

[0014] The voltage acquisition module collects the cell voltage signal of each battery cell connected in series in the multiple strings of lithium battery packs, and transmits each cell voltage signal to the dynamic calibration module; the coulomb counter module measures the charge and discharge current signal of the multiple strings of lithium battery packs, and transmits the charge and discharge current signal to the dynamic calibration module;

[0015] The dynamic calibration module dynamically calibrates the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters to obtain a calibrated voltage signal and a calibrated current signal;

[0016] The processor module receives the calibration voltage signal and the calibration current signal, calculates the state parameters of the multiple lithium battery strings according to a preset monitoring algorithm, generates a control signal according to the state parameters and a preset parameter threshold, and controls the charge and discharge circuits of the multiple lithium battery strings to perform corresponding charge and discharge operations through the control signal;

[0017] The state parameters are stored in the storage module through the processor module, and the relevant information is transmitted to the external device through the communication module.

[0018] The present application discloses a coulomb meter monitoring system and method for dynamic calibration of a multi-string lithium battery pack, the method comprising collecting a cell voltage signal of each series-connected battery cell in a multi-string lithium battery pack through a voltage acquisition module, and transmitting each of the cell voltage signals to a dynamic calibration module, measuring a charge and discharge current signal of the multi-string lithium battery pack through a coulomb meter module, and transmitting the charge and discharge current signal to the dynamic calibration module; dynamically calibrating the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters by the dynamic calibration module to obtain a calibrated calibration voltage signal and a calibrated current signal; receiving the calibrated voltage signal and the calibrated current signal through a processor module, calculating the state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm, generating a control signal according to the state parameters and a preset parameter threshold, and controlling the charge and discharge circuit of the multi-string lithium battery pack to perform corresponding charge and discharge operations through the control signal; storing the state parameters in a storage module through the processor module, and transmitting the relevant information to an external device through a communication module. Through the above method, the present application uses the dynamic calibration module to accurately calibrate the single cell voltage signal and the charge and discharge current signal according to the pre-stored calibration parameters, eliminates the measurement error of the battery during the charge and discharge process, as well as the gain error and noise interference in the current measurement, and accurately monitors and dynamically calibrates the single cell voltage and charge and discharge current, thereby accurately calculating the state parameters of the multi-string lithium battery pack, realizing precise control of the charge and discharge process, avoiding the occurrence of abnormal conditions such as battery overcharging and over-discharging, and improving the reliability of monitoring of multi-string lithium battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is a schematic block diagram of a coulomb counter monitoring system for dynamic calibration of a multi-string lithium battery pack provided by an embodiment of the present application;

[0021] Figure 2 This is a schematic flow chart of a coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part 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.

[0023] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined, or partially merged, so the actual execution order may vary depending on the actual situation.

[0024] It should be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It will also be understood that the term "and / or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0026] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0027] See also Figure 1 , Figure 1 This is a schematic block diagram of a coulomb counter monitoring system for dynamic calibration of a multi-string lithium battery pack provided in an embodiment of the present application.

[0028] like Figure 1 As shown in FIG, the coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs includes:

[0029] A voltage acquisition module is connected to each battery cell of a multi-string lithium battery pack and is used to acquire voltage signals of the multi-string lithium battery pack;

[0030] A coulomb counter module, connected to the voltage acquisition module, for acquiring charge and discharge current signals of the multiple strings of lithium battery packs;

[0031] A dynamic calibration module, connected to the voltage acquisition module and the coulomb counter module, for dynamically calibrating the voltage signal and the charge and discharge current signal;

[0032] a processor module, connected to the dynamic calibration module, configured to receive the voltage signal and the charge and discharge current signal after dynamic calibration, and process the state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm;

[0033] A charge and discharge management module, connected to the processor module, for controlling the charge and discharge process of the multi-string lithium battery pack;

[0034] A storage module, connected to the processor module, for storing historical status data, calibration parameters, and monitoring result data of the multiple strings of lithium battery packs;

[0035] A communication module is connected to the processor module and is used to transmit the historical status data, the calibration parameters and the monitoring result data of the multi-string lithium battery pack to an external device.

[0036] based on Figure 1 In the embodiment shown, in this embodiment, the voltage acquisition module includes at least one voltage sensor corresponding to each of the battery cells in the multiple strings of lithium battery packs;

[0037] The input end of each voltage sensor is connected to the positive and negative electrodes of the corresponding battery cell, and the output end is connected to the dynamic calibration module, so as to collect the voltage signal and transmit it to the dynamic calibration module.

[0038] based on Figure 1 In the embodiment shown, in this embodiment, the coulomb counter module includes a current sensor and a signal processing circuit connected to the current sensor;

[0039] The current sensor is connected in series in the charge and discharge circuit of the multi-string lithium battery pack to collect the charge and discharge current signal;

[0040] The signal processing circuit processes the charge and discharge current signal output by the current sensor and transmits the processed signal to the dynamic calibration module.

[0041] based on Figure 1 In the embodiment shown, in this embodiment, the dynamic calibration module includes a calibration parameter storage unit, and the calibration parameter storage unit is used to store the calibration parameters;

[0042] The dynamic calibration module further includes a calibration processing unit, which is used to perform calibration processing on the voltage signal and the charge and discharge current signal.

[0043] based on Figure 1In the embodiment shown, in this embodiment, the processor module includes a central processing unit, a memory, and a software program for running a monitoring algorithm. The central processing unit is used to read the voltage signal and the charge and discharge current signal after dynamic calibration, call the monitoring algorithm software program stored in the memory, and calculate the state parameters.

[0044] based on Figure 1 In the embodiment shown, in this embodiment, the communication module transmits the historical status data, the calibration parameters and the monitoring result data to the external device through a wired communication method and / or a wireless communication method.

[0045] Specifically, multiple voltage sensors of the voltage acquisition module are respectively connected to the positive and negative electrodes of each battery cell of the multi-string lithium battery pack to ensure that the connection is firm and reliable so as to accurately acquire the cell voltage signal.

[0046] The current sensor of the coulomb counter module is connected in series in the charge and discharge circuit of multiple lithium battery packs, and connected to the circuit of the voltage acquisition module to achieve accurate measurement of the charge and discharge current signals.

[0047] The dynamic calibration module is connected to the voltage acquisition module and the coulomb counter module, and stores the calibration parameters obtained in advance through calibration, such as the calibration curve of the voltage sensor, the zero point reference value, the gain coefficient of the current sensor, etc., to prepare for subsequent dynamic calibration processing.

[0048] The processor module is connected to the dynamic calibration module and internally stores preset monitoring algorithms, such as the SOC calculation algorithm based on the ampere-hour integration method, the SOH estimation algorithm based on the battery internal resistance and voltage, etc. It is also connected to the charge and discharge management module, storage module and communication module to ensure normal communication between the modules.

[0049] The charge and discharge management module is connected to the charge and discharge circuits of multiple lithium battery packs. According to the control signal sent by the processor module, it controls the on and off of the charging circuit and the discharging circuit to achieve precise control of the charging and discharging process of the battery pack.

[0050] The storage module is used to store historical status data of multiple lithium battery packs, such as past SOC and SOH values, as well as calibration parameters and monitoring results data, to provide data support for subsequent data analysis and battery management.

[0051] The communication module establishes a connection with external devices (such as monitoring computers, mobile phones, etc.) using wired or wireless communication methods such as RS-485, CAN bus, WiFi, Bluetooth, etc. to ensure the stability and reliability of data transmission.

[0052] During the operation of a multi-string lithium battery pack, the voltage acquisition module collects the voltage signals of each battery cell in real time. These signals are affected by factors such as temperature fluctuations and self-discharge, which can cause errors. Simultaneously, the coulomb counter module measures the charge and discharge current signals in real time, which are also affected by the gain error of the current sensor and external noise.

[0053] The collected voltage and current signals are transmitted to the dynamic calibration module, which dynamically calibrates these signals based on pre-stored calibration parameters. For voltage signals, a calibration curve is used to perform a linear fit correction on the collected voltage values ​​to eliminate nonlinear errors in the voltage sensor. When the battery pack is at rest with no charge or discharge current, the voltage of each single cell is measured as the zero-point reference value, and subsequently collected voltage signals are calibrated for zero-point deviation to eliminate measurement errors caused by zero-point drift. For current signals, a standard current source is used to input a known calibration current into the coulombmeter module. The measured current signal is compared with the calibration current, and the coulombmeter module's gain factor is adjusted to align the measured current with the calibration current. A digital filtering algorithm or analog filtering circuit is then used to filter the current signal to remove high-frequency noise and interference, thereby improving the stability of the current signal.

[0054] The dynamically calibrated voltage and current signals are transmitted to the processor module, which calculates the state parameters of the multi-string lithium battery pack, such as state of charge (SOC) and state of health (SOH), based on a preset monitoring algorithm. For example, the ampere-hour integration method calculates the current SOC value based on the calibrated current signal and the battery's initial SOC value; the battery's SOH value is estimated based on the battery's internal resistance changes and voltage characteristics.

[0055] The processor module compares the calculated state parameters with preset parameter thresholds. When the SOC value is low, a charge control signal is generated, which controls the charging circuit through the charge-discharge management module to charge the battery pack. When the SOC value is high or fully charged, a stop-charge control signal is generated to control the charging circuit to stop charging. If an abnormal condition such as over-discharge, overcharge, or overcurrent is detected, a corresponding protection control signal is generated to control the charge-discharge management module to disconnect the charge and discharge circuit to protect the safety of the battery pack.

[0056] At the same time, the processor module stores the calculated status parameters in the storage module, forming a historical data record to facilitate subsequent analysis and evaluation of battery pack performance changes. In addition, the communication module transmits these status parameters and related information to external devices. Users or managers can use external devices to monitor the battery pack's operating status in real time, promptly understanding the battery's health and remaining energy, and providing a basis for decision-making for battery maintenance and management.

[0057] See also Figure 2, Figure 2 This is a schematic flow chart of a coulomb meter monitoring method for dynamic calibration of a multi-string lithium battery pack provided in an embodiment of the present application. This coulomb meter monitoring method for dynamic calibration of a multi-string lithium battery pack can be applied to a server, and is used to accurately calibrate the single-cell voltage signal and the charge and discharge current signal based on pre-stored calibration parameters through a dynamic calibration module, thereby eliminating measurement errors of the battery during the charge and discharge process, as well as gain errors and noise interference in current measurement, accurately monitoring and dynamically calibrating the single-cell voltage and charge and discharge current, and then accurately calculating the state parameters of the multi-string lithium battery pack, achieving precise control of the charge and discharge process, avoiding abnormal conditions such as overcharging and over-discharging of the battery, and improving the reliability of monitoring the multi-string lithium battery pack.

[0058] like Figure 2 As shown, the coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack specifically includes steps S10 to S40.

[0059] Step S10: collecting cell voltage signals of each series-connected battery cell in a multi-string lithium battery pack through a voltage acquisition module, and transmitting each cell voltage signal to a dynamic calibration module; measuring charge and discharge current signals of the multi-string lithium battery pack through a coulomb counter module, and transmitting the charge and discharge current signals to the dynamic calibration module;

[0060] Specifically, before starting signal acquisition, first check whether the connection between the voltage acquisition module and each series-connected battery cell of the multi-string lithium battery pack is firm and reliable, and ensure that the positive and negative poles of each battery cell are correctly connected to the corresponding voltage sensor without looseness or poor contact. At the same time, check whether the power supply of the voltage acquisition module is normal to ensure its stable operation. Set the sampling frequency of the voltage acquisition module according to the characteristics and monitoring requirements of the multi-string lithium battery pack. Generally, for lithium battery packs, the sampling frequency can be adjusted according to the actual application scenario. For example, when the battery charging and discharging process is relatively stable, it can be set to collect once per second; when the battery charging and discharging current changes rapidly or when a rapid charge and discharge test is performed, the sampling frequency can be appropriately increased, such as collecting once every 0.1 seconds. Start the voltage acquisition function, and the voltage acquisition module begins to collect the voltage signals of each series-connected battery cell in real time.

[0061] In some cases, to improve the quality of the voltage signal, a simple filtering circuit can be built into the voltage acquisition module to perform preliminary filtering on the collected voltage signal and remove high-frequency noise interference. For example, an RC filtering circuit can be used to smooth the voltage signal, and the parameters of the filter capacitor and resistor are selected based on the actual signal spectrum and noise characteristics.

[0062] The preliminarily processed cell voltage signal is transmitted to the dynamic calibration module via a wired connection. During transmission, ensure signal stability to avoid distortion caused by line interference and other factors. For long transmission distances, consider using shielded cables or differential transmission to improve signal resistance.

[0063] Check the proper connection between the coulomb counter module and the charge and discharge circuits of the multi-string lithium battery pack. Ensure that the current sensor is connected in series with the circuit and that the connection is secure and reliable, preventing poor contact and other factors from affecting current measurement accuracy. Also, check the coulomb counter module's power supply to ensure proper operation. Set the coulomb counter module's range and sampling frequency based on the charge and discharge current range and monitoring accuracy requirements of the multi-string lithium battery pack. For example, for a battery pack with a rated charge and discharge current of approximately 10A, a current sensor with a range of 20A can be selected to ensure safe and accurate measurement. The sampling frequency is also set based on actual conditions and is typically consistent with the sampling frequency of the voltage acquisition module to facilitate subsequent data synchronization and analysis.

[0064] A filtering circuit can also be set up within the coulomb counter module to perform preliminary filtering on the collected charge and discharge current signals to remove high-frequency noise. Because the current signal may be subject to electromagnetic interference from devices such as motors and chargers during the charging and discharging process, filtering can effectively improve the quality of the current signal. Common filtering methods include low-pass filtering and band-pass filtering, and the specific parameters should be adjusted according to the actual interference situation.

[0065] The processed charge and discharge current signals are transmitted to the dynamic calibration module through a wired connection. Similar to the voltage signal, the stability of the current signal transmission must be ensured to avoid the increase of signal errors due to external interference.

[0066] Step S20: dynamically calibrating the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters by the dynamic calibration module to obtain calibrated voltage signals and current signals;

[0067] Specifically, before the system is put into use, the voltage acquisition module and coulomb counter module need to be pre-calibrated. For the voltage acquisition module, a high-precision calibration power supply or battery simulator is used to provide a known stable voltage to the multi-string lithium battery pack. The voltage values ​​collected by the voltage acquisition module are recorded. Through comparison and calculation, the calibration curve (including linear fitting parameters, nonlinear error compensation parameters, etc.) and zero-point reference value of each voltage sensor are obtained. For the coulomb counter module, a high-precision standard current source is used to provide a known calibration current to the charge and discharge circuit of the multi-string lithium battery pack. The current value measured by the coulomb counter module is recorded, and the gain coefficient of the current sensor is calculated. These calibration parameters (including the calibration curve parameters of the voltage sensor, the zero-point reference value, the gain coefficient of the current sensor, etc.) are pre-stored in the storage unit of the dynamic calibration module.

[0068] During system operation, calibration parameters can be updated regularly or irregularly based on actual conditions. For example, if changes in battery pack performance or increased measurement errors are detected, the voltage acquisition module and coulomb counter module can be recalibrated, and the calibration parameters in the dynamic calibration module can be updated to ensure calibration accuracy.

[0069] After receiving the cell voltage signal, the dynamic calibration module performs linear compensation on each battery cell's voltage signal based on a pre-stored voltage sensor calibration curve. Specifically, the collected voltage value is substituted into the calibration curve's mathematical model (e.g., a linear equation, polynomial equation, etc.) to calculate the linearly compensated voltage value. For example, if the calibration curve is a linear equation (V_calibrated = a × V_measured + b), where V_measured is the collected voltage value and a and b are the calibration curve parameters, then the compensated voltage value (V_calibrated) can be calculated by substituting these values.

[0070] When a multi-string lithium-ion battery pack is at rest (i.e., no charge or discharge current is flowing), the dynamic calibration module reads the voltage of each battery cell and stores it as the zero-point reference value. During the subsequent voltage signal calibration process, the corresponding zero-point reference value is subtracted from each collected voltage signal to eliminate measurement errors caused by zero-point drift. For example, if the zero-point reference voltage of a battery cell is V0 when at rest, and the currently collected voltage value is V1, the voltage value after zero-point correction is V1-V0.

[0071] Use the pre-stored current sensor gain factor to perform gain calibration on the collected charge and discharge current signals. Specifically, multiply the collected current value by the gain factor to obtain the calibrated current value. For example, if the collected current value is I_measured and the gain factor is k, then the calibrated current value I_calibrated = k × I_measured.

[0072] Use digital filtering algorithms (such as moving average filtering, Kalman filtering, etc.) or analog filtering circuits to filter the calibrated current signal to remove high-frequency noise and interference components in the signal and improve the stability of the current signal. For example, when using moving average filtering, the average of the most recent n current sampling values ​​is taken as the filtered current value at the current moment, thereby smoothing the current signal and reducing the impact of noise.

[0073] Step S30: receiving the calibration voltage signal and the calibration current signal through a processor module, calculating state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm, generating a control signal based on the state parameters and a preset parameter threshold, and controlling the charge and discharge circuits of the multi-string lithium battery pack to perform corresponding charge and discharge operations through the control signal;

[0074] Specifically, after receiving the calibrated voltage and current signals, the processor module calculates the state of charge (SOC) of the multi-string lithium battery pack based on a preset SOC monitoring algorithm. Common SOC calculation methods include the ampere-hour integration method and the open-circuit voltage method. In the ampere-hour integration method, the formula SOC(t) = SOC(t-Δt) + (I_charge × Δt) / Q is used, where SOC(t) is the current SOC value, SOC(t-Δt) is the previous SOC value, I_charge is the calibrated charge and discharge current (positive for charging, negative for discharging), Δt is the sampling interval, and Q is the rated capacity of the battery pack. During the calculation process, the SOC value is updated in real time based on the initial SOC value of the battery pack and changes in the charge and discharge current. To improve the accuracy of SOC calculation, the corresponding relationship between the battery's open-circuit voltage (OCV) and SOC can be used to correct the SOC by measuring the open-circuit voltage after the battery has been idle for a period of time.

[0075] The battery pack's state of health (SOH) is calculated using a preset SOH estimation algorithm based on parameters such as the battery pack's voltage, current, and temperature. Common SOH estimation methods include the internal resistance method and the capacity estimation method. For example, by measuring the change in the battery pack's internal resistance during charge and discharge, comparing it with the battery's initial internal resistance, and estimating the battery's SOH based on the proportion of the internal resistance increase. Alternatively, by performing regular capacity calibration tests on the battery pack, recording the actual capacity of the battery, and comparing it with the rated capacity, the SOH value is calculated. In practical applications, a combination of multiple methods can be used to estimate SOH to improve accuracy.

[0076] In addition to SOC and SOH, other status parameters can be calculated based on actual needs, such as the battery pack's state of power (SOP) and remaining useful life (RUL). For example, based on parameters such as the battery pack's voltage, current, and temperature, an internal battery model is established, and the battery's SOP is calculated using a model prediction algorithm to assess the battery's output power in its current state.

[0077] Preset thresholds for multi-string lithium battery pack status parameters in the processor module, including upper and lower SOC thresholds, as well as thresholds for abnormal conditions such as over-discharge, overcharge, and overcurrent. These thresholds can be appropriately set based on factors such as the battery specification, actual application scenario, and safety requirements. For example, for a certain lithium battery pack model, the upper SOC threshold is set to 95% (to prevent overcharging), the lower SOC threshold is set to 10% (to prevent over-discharge), and the overcurrent threshold is set to 20A (the maximum allowable charge and discharge current of the battery pack is 20A).

[0078] The processor module compares the calculated state parameters with the preset parameter thresholds in real time and generates corresponding control signals based on the comparison results. The specific control logic is as follows:

[0079] When the SOC value is lower than the SOC lower limit threshold, a charging control signal is generated, and the charging circuit is controlled by the charge and discharge management module to charge the battery pack until the SOC value reaches the set charging stop threshold (such as 90%);

[0080] When the SOC value reaches or exceeds the SOC upper limit threshold, a stop charging control signal is generated to control the charging circuit to stop charging to prevent the battery from overcharging.

[0081] When it is detected that the charge and discharge current exceeds the overcurrent threshold, an overcurrent protection signal is immediately generated to control the charge and discharge management module to cut off the charge and discharge circuit to protect the safety of the battery pack;

[0082] When it is detected that the voltage of a battery cell in the battery pack is lower than the over-discharge protection threshold (for example, the single cell over-discharge voltage set according to the battery characteristics is 2.5V), an over-discharge protection signal is generated to cut off the discharge circuit to prevent excessive discharge of the battery.

[0083] If the voltage of a battery cell reaches the overcharge protection threshold during charging (for example, the single cell overcharge voltage set according to battery characteristics is 4.3V), an overcharge protection signal is generated to control the charging circuit to stop charging to prevent battery overcharge damage.

[0084] After receiving control signals from the processor module, the charge-discharge management module performs the corresponding operations according to the control signals. For example, when receiving a charge control signal, the charge-discharge management module closes the relay or switch in the charging circuit, turning on the charging circuit and enabling the external charging power supply to charge the multi-string lithium battery pack. Simultaneously, based on the voltage and current feedback from the battery pack, the module controls the output voltage and current of the charging power supply, switching between constant-current charging and constant-voltage charging modes. When receiving a stop-charge control signal, the charge-discharge management module disconnects the relay or switch in the discharge circuit, severing the discharge circuit and disconnecting the load from the battery pack. In abnormal conditions such as overcurrent, overcharge, and over-discharge, the charge-discharge management module can quickly respond to the control signal and disconnect the charge-discharge circuit, ensuring the safe operation of the battery pack.

[0085] Step S40: The processor module stores the state parameters in the storage module, and transmits the relevant information to the external device through the communication module.

[0086] Specifically, the processor module stores the calculated state parameters of the multi-string lithium battery pack (such as SOC, SOH, SOP, RUL, etc.), historical charge and discharge data (including charge current, charge time, discharge current, discharge time, single cell voltage change curve, etc.), calibration parameters (such as voltage sensor calibration curve, current sensor gain coefficient, etc.), and monitoring results (such as abnormal alarm information, battery balancing status, etc.) in the storage module. This data can be organized in chronological order to form a complete battery pack operation history database, providing rich data support for subsequent data analysis, battery performance evaluation, and fault diagnosis.

[0087] The storage module can utilize a variety of storage media, selected based on actual storage capacity requirements and cost budget. For applications requiring high data reliability, a redundant storage strategy can be employed, storing data across multiple storage media simultaneously to prevent data loss due to a single storage device failure. Furthermore, to facilitate data management and query, a database management system can be used to manage stored data, establish data table structures, define data fields and indexes, and achieve efficient data storage, query, and update.

[0088] Before the system is operational, the communication module establishes a connection with external devices (such as monitoring computers, mobile phones, and cloud servers). The communication module supports a variety of communication methods, including wired communication (such as RS-485, CAN bus, and Ethernet) and wireless communication (such as WiFi, Bluetooth, and 4G / 5G). The appropriate communication method should be selected based on the application scenario and the communication interface of the external device. For example, in electric vehicles, CAN bus communication can be used to exchange data with the vehicle's control system; in energy storage systems, Ethernet communication can be used to connect to the monitoring server.

[0089] The processor module encapsulates the relevant information to be transmitted (such as status parameters, historical data, and alarm information) according to a predefined data transmission format and sends it to the external device through the communication module. This data transmission format can use a common protocol. For example, when transmitting data in JSON format, status parameters such as SOC and SOH, as well as data such as battery cell voltage and current, can be organized into a JSON object containing information such as parameter name, value, and unit.

[0090] The frequency of data transmission can be set according to actual needs. It can be scheduled transmission (such as once per second, once per minute, etc.) or event-triggered transmission (such as immediately transmitting an alarm message when the battery pack enters an abnormal state). For example, under normal operating conditions, the system transmits battery pack status parameters and operating data to external devices every 10 seconds. When it detects that the voltage of a single cell in the battery pack is lower than the over-discharge protection threshold, data transmission is immediately triggered, and the alarm message and related data are sent to the external device in real time so that timely measures can be taken.

[0091] After receiving the data sent by the communication module, the external device parses and processes the data. For example, a monitoring computer can display the received data in real time on a monitoring interface, visually demonstrating the battery pack's operating status in the form of charts and curves. The cloud server can perform big data analysis and storage on the received data, enabling advanced functions such as remote monitoring, fault diagnosis, and performance evaluation of the battery pack.

[0092] The present embodiment discloses a coulomb counter monitoring system and method for dynamic calibration of a multi-string lithium battery pack. The method includes collecting a cell voltage signal of each series-connected battery cell in the multi-string lithium battery pack through a voltage acquisition module, and transmitting each of the cell voltage signals to a dynamic calibration module; measuring the charge and discharge current signals of the multi-string lithium battery pack through a coulomb counter module, and transmitting the charge and discharge current signals to the dynamic calibration module; dynamically calibrating the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters by the dynamic calibration module to obtain a calibrated calibration voltage signal and a calibration current signal; receiving the calibration voltage signal and the calibration current signal through a processor module, calculating the state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm, generating a control signal based on the state parameters and a preset parameter threshold, and controlling the charge and discharge circuit of the multi-string lithium battery pack to perform corresponding charge and discharge operations through the control signal; storing the state parameters in a storage module through the processor module, and transmitting the relevant information to an external device through a communication module. Through the above method, the present application uses the dynamic calibration module to accurately calibrate the single cell voltage signal and the charge and discharge current signal according to the pre-stored calibration parameters, eliminates the measurement error of the battery during the charge and discharge process, as well as the gain error and noise interference in the current measurement, and accurately monitors and dynamically calibrates the single cell voltage and charge and discharge current, thereby accurately calculating the state parameters of the multi-string lithium battery pack, realizing precise control of the charge and discharge process, avoiding the occurrence of abnormal conditions such as battery overcharging and over-discharging, and improving the reliability of monitoring of multi-string lithium battery packs.

[0093] based on Figure 2 In the embodiment shown, in this embodiment, step S20 includes:

[0094] Linear compensation and zero point correction are performed on the cell voltage signal, and gain calibration and noise filtering are performed on the charge and discharge current signal.

[0095] In a specific embodiment, linear compensation and zero point correction are performed on the cell voltage signal, and gain calibration and noise filtering are performed on the charge and discharge current signal, including:

[0096] Obtaining a calibration curve of the voltage sensor, and performing linear fitting correction on the cell voltage signal according to the calibration curve;

[0097] Specifically, prepare a high-precision calibration power supply or battery simulator. Its output voltage range should cover the single-cell voltage range of the multi-string lithium battery pack, and it should have high precision and stability, and be able to provide a known stable voltage value as a calibration standard. Connect the calibration power supply to the battery simulation interface of the multi-string lithium battery pack or to the input end of the voltage acquisition module through an appropriate connection method to ensure that the connection is firm and reliable to ensure accurate transmission of the voltage signal during the calibration process.

[0098] Set the calibration power supply to output a series of known discrete voltage values. These voltage values ​​should be within the normal operating voltage range of the battery cells and evenly distributed. For example, set multiple calibration voltage points at regular intervals (such as 0.1V or other appropriate intervals) from the battery's lowest to highest operating voltage. At each set calibration voltage value, wait for the system to stabilize to ensure that the voltage value collected by the voltage acquisition module accurately reflects the current calibration voltage. Record each calibration voltage value and the corresponding actual voltage value collected by the voltage acquisition module to form a set of voltage data pairs (i.e., the corresponding relationship between the calibration voltage value and the collected voltage value).

[0099] The collected calibration voltage values ​​are aligned with the corresponding collected voltage values. A scatter plot is plotted with the calibration voltage values ​​as the horizontal axis and the collected voltage values ​​as the vertical axis. Based on the distribution of the scatter plot, an appropriate curve fitting method (such as linear fitting or polynomial fitting) is selected. If the voltage acquisition module ideally has a linear response, linear fitting is typically used. Using the software's fitting function, a fitted curve is generated that reflects the relationship between the collected voltage values ​​of the voltage acquisition module and the actual calibration voltage values. This is the calibration curve of the voltage sensor.

[0100] The calibration curve equation obtained by fitting is generally in the form of y=a+bX (for linear fitting), where y represents the collected voltage value, X represents the actual voltage value (calibration voltage value), a is the intercept of the fitting curve, and b is the slope.

[0101] Subsequent acquisition of the individual voltage signals (raw voltage values) is substituted into the calibration curve equation to calculate the voltage values ​​corrected by linear fitting. For example, if the raw voltage value is V_measured, the corrected voltage value is V_corrected = a + bV_measured. This method compensates for the nonlinear error of the voltage sensor and improves the accuracy of voltage measurement.

[0102] When the multi-string lithium battery pack is in a static state and the charge and discharge current signals are detected, the single cell voltage signal is used as a zero point reference value to perform zero point deviation calibration on the subsequently collected voltage signals;

[0103] Specifically, the charge and discharge current signals of multiple lithium battery packs are monitored. When the charge and discharge current is lower than a set threshold (such as milliampere level, which is determined according to the battery characteristics) for a period of time (such as 10 minutes or set according to actual conditions), and the battery management system or other relevant monitoring equipment confirms that there is no charger or load connected to the battery pack, the battery pack is determined to be in a static state.

[0104] After confirming that the battery pack is in a static state, the voltage acquisition module collects the voltage value of each battery cell and records these voltage values ​​as zero-point reference values. These values ​​are stored in the dynamic calibration module's memory unit and associated with the corresponding battery cell. During the subsequent voltage signal acquisition process, the pre-stored zero-point reference value for each battery cell is subtracted from the collected voltage signal in real time to obtain the zero-point-corrected voltage value. For example, if the currently collected battery cell voltage is V_current and the zero-point reference value is V_zero, the zero-point-corrected voltage value is V_current - V_zero. This method eliminates zero-point drift caused by factors such as self-discharge and temperature changes when the battery pack is in a static state, improving the accuracy and stability of voltage measurement.

[0105] Using a standard current source to input a preset calibration current into the coulomb counter module to obtain a test current signal, and comparing the test current signal with the preset calibration current to determine a gain coefficient of the coulomb counter module;

[0106] Specifically, prepare a high-precision standard current source, whose output current range should cover the charge and discharge current range of multiple lithium battery strings, and have high precision and stability, and can provide a known accurate calibration current as a calibration standard. Connect the standard current source in series with the charge and discharge circuit of the multiple lithium battery strings, and ensure that the current sensor of the coulomb meter module is also connected in series in the circuit. At the same time, connect the lines between the standard current source, the coulomb meter module and the battery pack to ensure that the current can flow normally and the current signal can be accurately transmitted to the coulomb meter module.

[0107] Set the standard current source to output a series of known discrete current values. These current values ​​should be within the normal charge and discharge current range of the battery pack and evenly distributed. For example, set multiple calibration current points at certain intervals (such as 0.5A or other appropriate intervals) from the minimum charge and discharge current to the maximum charge and discharge current of the battery pack.

[0108] At each set calibration current value, wait for the system to stabilize to ensure that the current value collected by the coulomb counter accurately reflects the current calibration current. Record each calibration current value and the corresponding actual current value collected by the coulomb counter to form a set of current data pairs (i.e., the corresponding relationship between the calibration current value and the collected current value).

[0109] Use data analysis software to collate the recorded calibration current values ​​and the corresponding collected current values. A scatter plot is plotted with the calibration current values ​​on the horizontal axis and the collected current values ​​on the vertical axis. Based on the distribution of the scatter plot, a linear fit is typically used to obtain a fitted line. Its equation is y = kx, where y represents the collected current value, x represents the calibration current value, and k is the slope of the fitted line, which is the gain factor of the coulomb counter module. By calculating the slope of the fitted line, the gain factor k is obtained and used to subsequently calibrate the gain of the current signal collected by the coulomb counter module.

[0110] The charge and discharge current signal is filtered using a digital filtering algorithm to remove high-frequency noise in the charge and discharge current signal.

[0111] Specifically, an appropriate digital filtering algorithm is selected based on the characteristics of the charge and discharge current signals and the frequency distribution of the interference noise. Common digital filtering algorithms include moving average filtering, Kalman filtering, and median filtering. For example, if the interference noise is primarily high-frequency and the signal is relatively stable, moving average filtering is a simple and effective option. If the current signal has certain dynamic characteristics, Kalman filtering can better track signal changes and filter out noise.

[0112] Determine the specific parameters of the filtering algorithm based on the actual sampling frequency and signal characteristics. For example, using a moving average filter, the filter window size—the number of sampling points used in the averaging calculation—must be determined. Choosing the window size should be a trade-off between noise characteristics and signal bandwidth. A window that is too large may cause signal lag and loss of detail, while a window that is too small may result in poor filtering effectiveness. This can generally be adjusted through experimentation and experience. For example, for a current signal with a sampling frequency of 10 Hz, a window size of 5 or 10 can be used for filtering.

[0113] Program the corresponding digital filtering algorithm in the processor module to perform real-time filtering on the collected charge and discharge current signals according to the set filtering parameters. For each new current sample, the selected filtering algorithm is used to calculate the filtered current signal value. For example, in a moving average filter, the average of the previous n samples (n is the filter window size) is used as the filtered current value for the current moment. In a Kalman filter, the Kalman filter's recursive formula uses the previous filter estimate and the current sample value to calculate the current filtered current value.

[0114] The filtered current signal is used as the basis for the subsequent processor module to perform state parameter calculations (such as SOC calculation, etc.), replacing the original collected current signal, thereby reducing the impact of high-frequency noise on current measurement and state parameter calculation, and improving the measurement accuracy and stability of the system.

[0115] based on Figure 2 In the embodiment shown, in this embodiment, step S30 includes:

[0116] When the SOC is less than a preset SOC threshold, controlling the charge and discharge circuit to charge the multiple strings of lithium battery packs;

[0117] When the SOC is greater than or equal to the preset SOC threshold, controlling the charge and discharge circuit to stop charging the multiple strings of lithium battery packs;

[0118] When the SOC is in an abnormal state, the charge and discharge circuit is controlled to be cut off.

[0119] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs, characterized in that: include: A voltage acquisition module is connected to each battery cell of a multi-string lithium battery pack and is used to acquire voltage signals of the multi-string lithium battery pack; A coulomb counter module, connected to the voltage acquisition module, for acquiring charge and discharge current signals of the multiple strings of lithium battery packs; A dynamic calibration module, connected to the voltage acquisition module and the coulomb counter module, for dynamically calibrating the voltage signal and the charge and discharge current signal; a processor module, connected to the dynamic calibration module, configured to receive the voltage signal and the charge and discharge current signal after dynamic calibration, and process the state parameters of the multi-string lithium battery pack according to a preset monitoring algorithm; A charge and discharge management module, connected to the processor module, for controlling the charge and discharge process of the multi-string lithium battery pack; A storage module, connected to the processor module, for storing historical status data, calibration parameters, and monitoring result data of the multiple strings of lithium battery packs; A communication module is connected to the processor module and is used to transmit the historical status data, the calibration parameters and the monitoring result data of the multiple strings of lithium battery packs to an external device.

2. The coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs according to claim 1, characterized in that: The voltage acquisition module includes at least one voltage sensor corresponding to each battery cell in the multi-string lithium battery pack; The input end of each voltage sensor is connected to the positive and negative electrodes of the corresponding battery cell, and the output end is connected to the dynamic calibration module, so as to collect the voltage signal and transmit it to the dynamic calibration module.

3. The coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs according to claim 1, characterized in that: The coulomb counter module includes a current sensor and a signal processing circuit connected to the current sensor; The current sensor is connected in series in the charge and discharge circuit of the multi-string lithium battery pack to collect the charge and discharge current signal; The signal processing circuit processes the charge and discharge current signal output by the current sensor and transmits the processed signal to the dynamic calibration module.

4. The coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs according to claim 1, characterized in that: The dynamic calibration module includes a calibration parameter storage unit, and the calibration parameter storage unit is used to store the calibration parameters; The dynamic calibration module further includes a calibration processing unit, which is used to perform calibration processing on the voltage signal and the charge and discharge current signal.

5. The coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs according to claim 1, characterized in that: The processor module includes a central processing unit, a memory, and a software program for running a monitoring algorithm. The central processing unit is used to read the voltage signal and the charge and discharge current signal after dynamic calibration, call the monitoring algorithm software program stored in the memory, and calculate the state parameters.

6. The coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs according to claim 1, characterized in that: The communication module transmits the historical status data, the calibration parameters, and the monitoring result data to the external device via a wired communication method and / or a wireless communication method.

7. A coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack, characterized in that: The coulomb counter monitoring method for dynamic calibration of multiple lithium battery packs is applied to a coulomb counter monitoring system for dynamic calibration of multiple lithium battery packs. The coulomb counter monitoring method for dynamic calibration of multiple lithium battery packs includes: The voltage acquisition module collects the cell voltage signal of each battery cell connected in series in the multiple strings of lithium battery packs, and transmits each cell voltage signal to the dynamic calibration module; the coulomb counter module measures the charge and discharge current signal of the multiple strings of lithium battery packs, and transmits the charge and discharge current signal to the dynamic calibration module; The dynamic calibration module dynamically calibrates the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters to obtain a calibrated voltage signal and a calibrated current signal; The processor module receives the calibration voltage signal and the calibration current signal, calculates the state parameters of the multiple lithium battery strings according to a preset monitoring algorithm, generates a control signal according to the state parameters and a preset parameter threshold, and controls the charge and discharge circuits of the multiple lithium battery strings to perform corresponding charge and discharge operations through the control signal; The state parameters are stored in the storage module through the processor module, and the relevant information is transmitted to the external device through the communication module.

8. The coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack according to claim 7, characterized in that: The dynamic calibration module dynamically calibrates the cell voltage signal and the charge and discharge current signal according to pre-stored calibration parameters, including: Linear compensation and zero point correction are performed on the cell voltage signal, and gain calibration and noise filtering are performed on the charge and discharge current signal.

9. The coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack according to claim 8, characterized in that: The voltage acquisition module includes at least one voltage sensor, and performs linear compensation and zero point correction on the cell voltage signal, and performs gain calibration and noise filtering on the charge and discharge current signal, including: Obtaining a calibration curve of the voltage sensor, and performing linear fitting correction on the cell voltage signal according to the calibration curve; When the multi-string lithium battery pack is in a static state and the charge and discharge current signals are detected, the single cell voltage signal is used as a zero point reference value to perform zero point deviation calibration on the subsequently collected voltage signals; Using a standard current source to input a preset calibration current into the coulomb counter module to obtain a test current signal, and comparing the test current signal with the preset calibration current to determine a gain coefficient of the coulomb counter module; The charge and discharge current signal is filtered using a digital filtering algorithm to remove high-frequency noise in the charge and discharge current signal.

10. The coulomb counter monitoring method for dynamic calibration of a multi-string lithium battery pack according to claim 7, characterized in that: The state parameter includes a state of charge parameter SOC, and the control signal is used to control the charge and discharge circuits of the multiple lithium battery packs to perform corresponding charge and discharge operations, including: When the SOC is less than a preset SOC threshold, controlling the charge and discharge circuit to charge the multiple strings of lithium battery packs; When the SOC is greater than or equal to the preset SOC threshold, controlling the charge and discharge circuit to stop charging the multiple strings of lithium battery packs; When the SOC is in an abnormal state, the charge and discharge circuit is controlled to be cut off.

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