An equalization maintenance device and method for online monitoring of lead-acid battery pack

Abstract

The application relates to the technical field of storage batteries, in particular to a kind of equalization maintenance device and method for online monitoring of lead-acid battery pack, which comprises a battery online monitoring module, which obtains the remaining capacity of the battery according to the charge-discharge current of the lead-acid battery pack; a battery equalization control module, which measures the voltage of the single battery of the lead-acid battery pack by using the voltage dividing resistor method, and outputs a pulse width modulation signal when the voltage difference between the highest voltage and the lowest voltage of the single battery of the lead-acid battery pack exceeds the preset voltage difference threshold or the difference in the remaining capacity of the different single batteries exceeds the preset power difference threshold; and a battery discharge control module, which regulates the equalization discharge power of the power resistor according to the pulse width modulation signal and the temperature value of the power resistor radiator, and controls the equalization discharge by the equalization discharge power. The application dynamically adjusts the duty cycle of the pulse width modulation signal and cooperatively controls the equalization discharge power of the power resistor by temperature, effectively ensuring the equalization discharge of the battery pack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of storage batteries, in particular to a balancing maintenance device and method for online monitoring of a lead-acid storage battery pack. BACKGROUND

[0002] As an important energy storage device, lead-acid storage battery packs are widely used in communication base stations, power systems, rail transit and other fields. In practical applications, in order to meet the voltage requirements of different devices, lead-acid storage batteries are usually used in a manner of multiple batteries connected in series to increase the output voltage of the entire battery pack.

[0003] However, under the existing technical conditions, the monitoring and maintenance of lead-acid storage battery packs face many technical difficulties. Due to the influence of factors such as manufacturing process differences and use environment, there is a common problem of voltage imbalance between single batteries in the battery pack during long-term operation. During the charging and discharging process of the battery pack, the imbalance of single battery voltage will further aggravate the aging degree of the battery, greatly shortening the service life of the battery pack. Specifically, voltage imbalance will cause some batteries to withstand excessive current or voltage during the charging and discharging process of the battery pack, accelerating the aging process, while the other part of the battery may not be able to fully exert its performance, thereby reducing the overall performance and life of the battery pack. At the same time, the temperature change of the battery during the charging and discharging process will also have a significant impact on the performance of the battery. However, the existing temperature measurement method has weak anti-interference ability and is difficult to accurately reflect the actual temperature condition of the battery, thereby affecting the comprehensive evaluation of the performance of the battery.

[0004] In summary, the existing monitoring technology of lead-acid storage battery packs cannot meet the demand for comprehensive and accurate evaluation of the performance of the battery pack, especially under complex working conditions. The existing technology cannot realize real-time and accurate monitoring of the state of the battery pack, and it is even more difficult to provide effective maintenance guidance. These problems directly affect the use efficiency and life of the lead-acid storage battery pack. Therefore, there is an urgent need for a device that can monitor the performance of the lead-acid storage battery pack in real time and accurately, so as to improve the performance and service life of the battery pack and reduce maintenance costs. SUMMARY

[0005] To solve the above technical problems, the present application provides a balancing maintenance device and method for online monitoring of a lead-acid storage battery pack.

[0006] In a first aspect, the present application provides a balancing maintenance device for online monitoring of a lead-acid storage battery pack, which comprises:

[0007] a battery online monitoring module for non-contact measurement of the charging and discharging current of the lead-acid storage battery pack using a Hall current sensor, and calculating the state of charge of the single battery and obtaining the remaining capacity of the battery according to the charging and discharging current of the lead-acid storage battery pack through Kalman filtering and ampere-hour integration method;

[0008] a battery equalization control module configured to measure the voltage of each single battery of the lead-acid battery pack by using a voltage dividing resistor method, and to generate a pulse width modulation signal according to a voltage difference between the highest voltage and the lowest voltage of the single batteries and a difference in the remaining capacity of the single batteries when a voltage difference between the highest voltage and the lowest voltage of the single batteries of the lead-acid battery pack exceeds a preset voltage difference threshold or a difference in the remaining capacity of the single batteries exceeds a preset capacity difference threshold;

[0009] a battery discharge control module configured to control the equalization discharge power of the power resistor according to the pulse width modulation signal and a pre-acquired temperature value of the power resistor radiator during the charging and discharging process of the lead-acid battery pack, and to control the equalization discharge of the single batteries of the lead-acid battery pack by the equalization discharge power, so that the equalization end time of all the single batteries of the lead-acid battery pack is consistent.

[0010] In further embodiments, the process of obtaining the pulse width modulation signal is specifically as follows:

[0011] During the charging and discharging process of the lead-acid battery pack, the battery voltage signals of each single battery in the lead-acid battery pack are collected in real time;

[0012] If the battery voltage signal is greater than the preset highest battery voltage, the battery voltage signal is processed by a voltage dividing resistor network based on the voltage dividing principle to obtain an initial voltage signal;

[0013] The initial voltage signal is converted into an analog-to-digital signal to obtain the voltage measurement value of each single battery, and the voltage difference between the highest voltage and the lowest voltage of each single battery is calculated according to the voltage measurement value;

[0014] The voltage difference is compared with the preset voltage difference threshold, and when the voltage difference exceeds the preset voltage difference threshold, the duty cycle of the voltage difference is calculated according to the proportional relationship between the difference between the voltage difference and the preset voltage difference threshold and the preset voltage difference threshold;

[0015] The difference in the remaining capacity of the single batteries is compared with the preset capacity difference threshold, and when the difference in the remaining capacity of the single batteries exceeds the preset capacity difference threshold, the duty cycle of the capacity difference is calculated according to the proportional relationship between the difference between the difference in the remaining capacity of the single batteries and the preset capacity difference threshold and the preset capacity difference threshold;

[0016] The maximum value of the duty cycle of the voltage difference and the duty cycle of the capacity difference is taken as the actual optimal duty cycle, and the pulse width modulation signal corresponding to the pulse width is generated according to the actual optimal duty cycle.

[0017] In further embodiments, both the differential pressure duty cycle and the differential electric quantity duty cycle should be between a preset minimum duty cycle threshold and a preset maximum duty cycle threshold.

[0018] In further embodiments, if the differential pressure duty cycle or the differential electric quantity duty cycle is less than the minimum duty cycle threshold, the minimum duty cycle threshold is used for equalization control, the differential pressure duty cycle is set to the minimum duty cycle threshold or the differential electric quantity duty cycle is set to the minimum duty cycle threshold, until the voltage differential is less than the preset differential pressure threshold and the battery residual capacity differential value is less than the preset differential electric quantity threshold, the corresponding pulse width modulation signal is stopped to terminate the equalization discharge operation.

[0019] In further embodiments, the process of obtaining the equalization discharge power is specifically:

[0020] In the process of equalization discharging the lead-acid battery group by using the pulse width modulation signal, the temperature value of the power resistor radiator in the battery discharge control module is collected in real time;

[0021] The temperature value of the power resistor radiator is compared with a preset temperature threshold, and when the temperature value of the power resistor radiator exceeds the preset temperature threshold, a duty cycle adjustment trigger signal is generated;

[0022] In response to the duty cycle adjustment trigger signal, a duty cycle adjustment coefficient is obtained according to the proportional relationship between the difference between the temperature value of the power resistor radiator and the preset temperature threshold and the preset temperature threshold;

[0023] The duty cycle of the pulse width modulation signal is dynamically adjusted according to the duty cycle adjustment coefficient to obtain an adjusted pulse width modulation signal duty cycle;

[0024] According to the adjusted pulse width modulation signal duty cycle and the battery voltage signal of the single battery, an equivalent voltage value across the power resistor is calculated;

[0025] According to the equivalent voltage value and the resistance value of the power resistor, the current flowing through the power resistor is calculated, and according to the current flowing through the power resistor and the resistance value of the power resistor, the equalization discharge power of the power resistor in the current state is calculated.

[0026] In further embodiments, the process of obtaining the temperature value of the power resistor radiator is specifically:

[0027] A negative temperature coefficient thermistor is mounted on the surface of the power resistor radiator, and the thermistor is connected to a multi-resonance oscillation circuit composed of a timer, so that the oscillation frequency of the multi-resonance oscillation circuit changes with the resistance value of the thermistor;

[0028] The resistance change of the thermistor is converted into the frequency change of the square wave output by the timer, and the square wave signal output by the multi-vibrator is collected at a preset counting frequency;

[0029] The square wave period is obtained by continuously capturing the time difference between the two falling edges of the square wave signal, and the square wave frequency output by the multi-vibrator is calculated according to the square wave period;

[0030] According to the square wave frequency, the real-time resistance value of the thermistor is inversely deduced by using the relationship model between the square wave frequency and the resistance value of the thermistor;

[0031] The real-time resistance value of the thermistor is converted into the corresponding ambient temperature value by using the resistance-temperature characteristic relationship model of the thermistor, and the temperature value of the power resistor radiator is obtained.

[0032] In further embodiments, the voltage division resistance network is composed of two voltage division resistors, and the ratio of the resistance values of the two voltage division resistors is two times.

[0033] In further embodiments, each battery discharge control module includes a field effect transistor, a power resistor and a current limiting resistor.

[0034] The power resistor is connected between the drain of the field effect transistor and the positive electrode of the single battery, and the power resistor is used to consume the energy of the single battery during the equalization discharge process to control the equalization of the battery voltage.

[0035] The source of the field effect transistor is connected to the negative electrode of the single battery, and the gate of the field effect transistor is connected to the pulse width modulation signal output end of the battery equalization control module through the current limiting resistor; the field effect transistor is used to control the on-off of the current between the single battery and the power resistor according to the pulse width modulation signal.

[0036] The current limiting resistor is used to limit the current flowing into the gate of the field effect transistor.

[0037] In further embodiments, the process of controlling the on-off of the current between the single battery and the power resistor according to the pulse width modulation signal is specifically:

[0038] When the pulse width modulation signal is high, the field effect transistor is controlled to be turned on to form a discharge circuit from the positive electrode of the single battery to the negative electrode of the single battery through the power resistor and the field effect transistor, so that the single battery connected with the field effect transistor is discharged through the power resistor, and the voltage of the single battery connected with the field effect transistor gradually decreases during the equalization discharge process; when the voltage difference is less than the preset voltage difference threshold and the battery residual capacity difference is less than the preset electric quantity difference threshold, the battery equalization control module is controlled to stop outputting the corresponding pulse width modulation signal, and the field effect transistor is controlled to remain in an off state, and the equalization discharge process ends.

[0039] When the pulse width modulation signal is low, the field effect transistor is controlled to be turned off to disconnect the discharge circuit, so that the single battery connected with the field effect transistor stops discharging through the power resistor.

[0040] In a second aspect, the present application provides a method for equalization and maintenance of online monitoring of lead-acid battery pack, which comprises the following steps:

[0041] The charging and discharging current of the lead-acid battery pack is measured non-contact, and the state of charge of the single battery is calculated by Kalman filtering and ampere-hour integration method according to the charging and discharging current of the lead-acid battery pack, so as to obtain the battery residual capacity.

[0042] The voltage of the single battery of the lead-acid battery pack is measured by using the voltage dividing resistor method, and when the voltage difference between the highest voltage and the lowest voltage of the single battery of the lead-acid battery pack is greater than the preset voltage difference threshold or the battery residual capacity difference between different single batteries is greater than the preset electric quantity difference threshold, the pulse width modulation signal is modulated and output according to the voltage difference and the battery residual capacity difference;

[0043] During the charging and discharging process of the lead-acid battery pack, the equalization discharge power of the power resistor is regulated according to the pulse width modulation signal and the pre-acquired power resistor heat sink temperature value;

[0044] The single battery of the lead-acid battery pack is controlled to be discharged through the equalization discharge power, so that the equalization end time of all single batteries of the lead-acid battery pack is consistent.

[0045] The application provides a kind of equalization maintenance device and method of lead-acid battery pack online monitoring, the device is measured by battery online monitoring module to lead-acid battery pack charge-discharge current Non-contact, and according to the charge-discharge current of lead-acid battery pack, the state of charge of single battery is calculated by Kalman filtering and ampere-hour integration method, and the remaining capacity of battery is obtained;Battery equalization control module utilizes the method of voltage dividing resistor to measure the voltage of lead-acid battery pack single battery, and when the voltage difference between the highest voltage and the lowest voltage of lead-acid battery pack single battery is monitored to exceed the preset voltage difference threshold or the difference of battery remaining capacity between different single batteries exceeds the preset power difference threshold, the pulse width modulation signal is modulated according to the voltage difference and the difference of battery remaining capacity;The equalization discharge power of power resistor is regulated according to the pulse width modulation signal and the temperature value of power resistor radiator obtained in advance by battery discharge control module during the charge-discharge process of lead-acid battery pack, and the equalization discharge control of lead-acid battery pack single battery is carried out by equalization discharge power, so that all lead-acid battery pack single battery equalization end time is consistent.Compared with prior art, the device dynamically adjusts the duty cycle of pulse width modulation signal and temperature to control the equalization discharge power of power resistor, effectively ensures the equalization discharge of battery pack, prolongs the service life of battery pack, prevents the overall performance of battery pack from being reduced due to the difference of single battery, and ensures the stable, efficient and safe operation of lead-acid battery pack. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is the block diagram of equalization maintenance device of lead-acid battery pack online monitoring provided by the embodiment of the application;

[0047] Figure 2 It is the schematic diagram of voltage dividing resistor network structure provided by the embodiment of the application;

[0048] Figure 3 It is the schematic diagram of resistance equalization process provided by the embodiment of the application;

[0049] Figure 4 It is the schematic diagram of battery discharge control module provided by the embodiment of the application;

[0050] Figure 5 It is the principle block diagram of equalization maintenance device provided by the embodiment of the application;

[0051] Figure 6 It is the schematic diagram of temperature measurement module structure provided by the embodiment of the application;

[0052] Figure 7 It is the schematic diagram of temperature acquisition process provided by the embodiment of the application;

[0053] Figure 8 It is the schematic diagram of battery discharge voltage change curve provided by the embodiment of the application;

[0054] Figure 9 This is a schematic diagram of the battery charging voltage change curve provided in an embodiment of the present invention;

[0055] Figure 10 This is a schematic diagram of the online monitoring and equalization maintenance method for lead-acid battery packs provided in an embodiment of the present invention.

[0056] Explanation of reference numerals in the attached diagram: 101, Battery online monitoring module; 102, Battery equalization control module; 103, Battery discharge control module; 104, Temperature measurement module. Detailed Implementation

[0057] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0058] Lead-acid battery packs typically consist of multiple cells connected in series. During charging, charging stops when any single cell in the pack reaches its upper voltage limit; otherwise, the cell with the highest voltage will be overcharged. Similarly, during discharging, discharging stops when any single cell in the pack reaches its lower voltage limit; otherwise, the cell with the lowest voltage will be over-discharged, thus reducing battery life. To address this issue, refer to... Figure 1 This invention provides an online monitoring and equalization maintenance device for lead-acid battery packs, such as... Figure 1 As shown, the device includes a battery online monitoring module 101, a battery equalization control module 102, and a battery discharge control module 103. In this embodiment, when the difference between the highest and lowest voltage of a single cell in the battery pack is detected to be greater than 150mV, the device will automatically start the equalization discharge program. During this process, this embodiment uses a power resistor to equalize the discharge of the single cell. To improve the equalization efficiency and reduce the heat generated by the power resistor during the discharge process, this embodiment uses the single cell with the lowest voltage in the battery pack as a reference and equalizes the discharge by controlling the duty cycle of the power resistor. This adjustment mechanism ensures that the higher voltage battery discharges with a larger discharge resistor power, while the lower voltage battery discharges with a smaller discharge resistor power. The discharge resistor power is controlled by voltage. By controlling the duty cycle of the power resistor's working voltage, its power can be adjusted, making the equalization end time of all single cells consistent, thereby significantly improving the equalization efficiency of the entire battery pack and extending the service life of the battery pack.

[0059] In some embodiments, the battery online monitoring module is used to non-contact measure the charging and discharging current of the lead-acid battery pack by using a Hall current sensor, and calculate the state of charge of the single battery by Kalman filtering and ampere-hour integration method according to the charging and discharging current of the lead-acid battery pack, to obtain the remaining capacity of the battery.

[0060] In the present embodiment, the battery online monitoring module measures the current based on the magnetic balance type Hall principle of the Hall current sensor. The working principle of the Hall current sensor is based on the magnetic balance type Hall principle and the Hall effect principle. Specifically, when a current is passed through the control current end of the Hall element , and a magnetic field with a magnetic induction strength B is applied in the normal direction of the plane of the Hall element, an electric potential will be generated in the direction perpendicular to the current and the magnetic field (i.e. between the Hall output ends) based on the Hall effect. By accurately measuring the voltage , and using the related characteristics of the Hall effect, the corresponding current can be accurately back calculated, thereby realizing non-contact measurement of the current. This non-contact current measurement does not produce additional interference to the measured circuit, and can safely and reliably obtain the current information, thereby providing accurate current data support for the online monitoring of the lead-acid battery pack. Before starting to calculate the state of charge (SOC) of the single battery, the present embodiment needs to perform an initialization operation on the battery pack to record the full charge capacity and the current remaining capacity of the battery pack in the initial state. When the battery pack is fully charged, the current remaining capacity is equal to the full charge capacity. When the battery pack starts to discharge, the current remaining capacity is the full charge capacity minus the discharged capacity. During the charging and discharging process of the battery pack, the battery online monitoring module samples the charging and discharging current of the lead-acid battery pack measured by the Hall current sensor at a preset time interval, multiplies the sampled current value by the time interval to obtain the amount of electricity discharged or charged by the battery pack in the time interval, and then calculates the remaining capacity of the battery pack in real time based on the ampere-hour integration method. Specifically, the initial current remaining capacity changes during the charging and discharging process as follows: for the discharging process, the present embodiment takes the difference between the current remaining capacity and the accumulated change in the amount of electricity during the charging and discharging process as the updated remaining capacity; for the charging process, the present embodiment takes the sum of the current remaining capacity and the accumulated change in the amount of electricity during the charging and discharging process as the updated remaining capacity. By updating the remaining capacity in real time, the change curve of the remaining capacity of the battery pack during the charging and discharging process can be obtained.

[0061] In order to improve the accuracy of the state of charge calculation, the Kalman filter algorithm is introduced to optimize the result of the ampere-hour integration method in the embodiment. The Kalman filter is a recursive algorithm based on a state-space model, which can estimate the measurement data containing noise. In the embodiment, the remaining capacity of the battery pack is taken as the state variable, and the current measured by the Hall current sensor is taken as the input variable. The remaining capacity calculated by the ampere-hour integration method is corrected in real time by the Kalman filter algorithm, which effectively reduces the influence of current measurement error and model error on the calculation result of the state of charge, and improves the accuracy of the state of charge estimation. For the single batteries in the battery pack, it is assumed that the current distribution ratio of each single battery remains constant during the charging or discharging process of the battery pack. Based on this assumption, the initial capacity ratio of each single battery can be estimated based on the total remaining capacity of the battery pack and the initial capacity ratio of each single battery. The ratio of the remaining capacity of the single battery to its full charge capacity is defined as the state of charge of the single battery, thereby realizing real-time and accurate estimation of the state of charge of the single battery. Therefore, the battery online monitoring module measures the charging and discharging current of the lead-acid battery pack by using the Hall current sensor for non-contact measurement, obtains accurate current data, then calculates the basic value of SOC by using the ampere-hour integration method, and optimizes the SOC estimation value by using the Kalman filter algorithm to overcome the cumulative error of the ampere-hour integration method. Finally, the remaining capacity of the battery is obtained based on the calculated SOC value and the rated capacity of the battery, which provides an important basis for the online monitoring and balancing maintenance of the lead-acid battery pack.

[0062] In some embodiments, the battery equalization control module is configured to measure the voltage of the single battery of the lead-acid battery pack by using the voltage dividing resistor method, and when it is detected that the voltage difference between the highest voltage and the lowest voltage of the single battery of the lead-acid battery pack exceeds a preset voltage difference threshold or the difference in the remaining capacity of the battery between different single batteries exceeds a preset capacity difference threshold, modulate a pulse width modulation signal according to the voltage difference and the difference in the remaining capacity of the battery. In the embodiment, the process of obtaining the pulse width modulation signal is specifically as follows:

[0063] During the charging and discharging process of the lead-acid battery pack, the battery voltage signals of each single battery in the lead-acid battery pack are collected in real time.

[0064] If it is detected that the battery voltage signal is greater than the preset highest battery voltage, the battery voltage signal is processed by using the voltage dividing resistor network based on the voltage dividing principle to obtain an initial voltage signal.

[0065] The initial voltage signal is subjected to analog-to-digital conversion to obtain the voltage measurement value of each single battery, and the voltage difference between the highest voltage and the lowest voltage of each single battery is calculated according to the voltage measurement value.

[0066] The voltage difference is compared with a preset pressure difference threshold, and when the voltage difference exceeds the preset pressure difference threshold, a pressure difference duty cycle is calculated according to a proportional relationship between a difference value between the voltage difference and the preset pressure difference threshold and the preset pressure difference threshold relative to the preset pressure difference threshold.

[0067] The battery remaining capacity difference value is compared with a preset power difference threshold, and when the battery remaining capacity difference value exceeds the preset power difference threshold, a power difference duty cycle is calculated according to a proportional relationship between a difference value between the battery remaining capacity difference value and the preset power difference threshold and the preset power difference threshold relative to the preset power difference threshold.

[0068] The maximum value of the pressure difference duty cycle and the power difference duty cycle is taken as an actual optimal duty cycle, and a pulse width modulation signal corresponding to a pulse width is generated according to the actual optimal duty cycle.

[0069] The upper limit of the voltage that can be collected by the traditional battery voltage collection circuit is usually 5V for a single battery, but the voltage range of a single battery of a lead-acid battery pack is generally between 12V and 15V. Therefore, the traditional battery voltage collection circuit cannot directly adapt to the single battery voltage collection of the lead-acid battery pack. To this end, a level conversion circuit is designed at the front end of the traditional battery voltage collection circuit in the embodiment, which raises the upper limit of the collectable battery voltage to 15V to adapt to the lead-acid battery, and the measurement error is as low as 1.2mV, greatly improving the accuracy and applicability of voltage collection. In the specific implementation process, the battery equalization control module adopts an LTC6804 chip, which can only realize accurate measurement and equalization control of lithium batteries below 5V. There is no effective solution for accurate measurement and passive equalization control of the single battery voltage of the lead-acid battery pack with a single battery voltage range of 12V to 15V. To solve this problem, the embodiment combines the LTC6804 chip with the voltage division resistance method, effectively solving the problem of accurate measurement of the single battery voltage of the 12V lead-acid battery pack, and the battery voltage measurement accuracy reaches the millivolt level. At the same time, combined with the accurate control of the discharge power of the high-power resistor, the passive equalization control problem between the single batteries of the lead-acid battery pack is effectively solved, ensuring that the voltage difference between the single batteries of the battery pack is less than 10mV, and the performance and stability of the battery pack are significantly improved.

[0070] When the input voltage signal reaches or exceeds 5V, the embodiment automatically triggers voltage division conversion, such as Figure 2As shown, DC48 corresponds to the positive terminal of a lead-acid battery. In this embodiment, after the battery voltage signal is input, it is sequentially processed by a voltage divider network. The voltage divider network consists of two voltage divider resistors: a first voltage divider resistor R17 and a second voltage divider resistor R22. The first voltage divider resistor R17 is a 20kΩ precision resistor and is connected to the positive terminal of each individual battery cell. The second voltage divider resistor R22 is a 10kΩ precision resistor and is connected between the first voltage divider resistor R17 and ground (GND). The resistance ratio of the two voltage divider resistors is twice that of the first voltage divider resistor. Specifically, the voltage divider network uses 20K and 10K precision resistors to construct a 3:1 voltage divider circuit. In this embodiment, the input battery voltage signal is sequentially divided by 20K and 10K precision resistors in a 3:1 ratio. By using a 3:1 voltage division ratio, the input voltage signal is linearly reduced to one-third of its original value. For example, a 15V input voltage signal is reduced to one-third of its original value. The input voltage is converted into a low voltage signal within the 5V range, thereby proportionally reducing the high voltage signal to the measurable range of the LTC6804 chip. In this embodiment, a ground filter capacitor C7 is connected in parallel at the output of the voltage divider network. The ground filter capacitor is used to suppress high-frequency interference signals. The voltage-divided signal is then regulated and filtered by the ground filter capacitor, which can effectively eliminate high-frequency noise and interference in the signal and ensure the stability of the voltage signal. Then, in this embodiment, an impedance matching resistor R23 is connected in series between the output of the voltage divider network and the input pin of the LTC6804 to reduce the output impedance of the signal source and avoid signal attenuation or reflection caused by impedance mismatch. Therefore, the voltage signal is input to the sampling input terminal of the LTC6804 chip after impedance matching by the 100Ω impedance matching resistor R23. The LTC6804 chip uses its built-in analog-to-digital converter to realize accurate acquisition of battery voltage. By performing analog-to-digital conversion on the initial voltage signal, the voltage measurement value of each individual battery cell is obtained.

[0071] After calculating the voltage measurement values ​​of each individual cell, such as Figure 3 As shown, this embodiment assumes that the voltage of a single battery cell is U, and the preset voltage difference threshold is... The voltage difference between the highest and lowest voltages of a single cell is b. When the voltage difference b exceeds the voltage difference threshold... In this embodiment, the pulse width modulation (PWM) duty cycle is calculated based on the voltage difference to obtain the voltage difference duty cycle D1. The specific calculation formula is as follows:

[0072]

[0073] In the formula, b is the voltage difference between the highest and lowest voltages of a single cell; is a preset pressure difference threshold; D1 is a pressure difference duty cycle, in the embodiment, the pressure difference duty cycle should be between a preset minimum duty cycle threshold and a preset maximum duty cycle threshold, for example, the embodiment can set It should be noted that if the pressure difference duty cycle is less than the minimum duty cycle threshold, the minimum duty cycle threshold is used for equalization control, the pressure difference duty cycle is set to the minimum duty cycle threshold, and the equalization discharge operation is terminated when the voltage difference is less than the preset pressure difference threshold and the battery remaining capacity difference is less than the preset power difference threshold, and the corresponding pulse width modulation signal is stopped outputting. For example, when , the embodiment sets the duty cycle to 20%, and the PWM signal is stopped outputting when the voltage difference b is less than the pressure difference threshold a.

[0074] Similarly, the embodiment assumes that the power difference threshold is c, and the current battery remaining capacity difference is d. When the battery remaining capacity difference d exceeds the power difference threshold c, the embodiment calculates the corresponding PWM duty cycle according to the battery remaining capacity difference to obtain the power difference duty cycle D2, and the specific calculation formula is:

[0075]

[0076] In the formula, c is the power difference threshold; d is the battery remaining capacity difference; D2 is the power difference duty cycle, in the embodiment, the power difference duty cycle should be between a preset minimum duty cycle threshold and a preset maximum duty cycle threshold, for example, the embodiment can set It should be noted that if the power difference duty cycle is less than the minimum duty cycle threshold, the minimum duty cycle threshold is used for equalization control, the power difference duty cycle is set to the minimum duty cycle threshold, and the equalization discharge operation is terminated when the voltage difference is less than the preset pressure difference threshold and the battery remaining capacity difference is less than the preset power difference threshold, and the corresponding pulse width modulation signal is stopped outputting. For example, when , the embodiment sets the duty cycle to 20%, and the PWM signal is stopped outputting when the battery remaining capacity difference d is less than the power difference threshold c.

[0077] Finally, the embodiment comprehensively considers the pressure difference and power difference factors to determine the actual optimal duty cycle of the pulse width modulation signal. Specifically, the embodiment takes the maximum value of the pressure difference duty cycle and the power difference duty cycle as the actual optimal duty cycle, and generates a pulse width modulation signal with a corresponding pulse width according to the actual optimal duty cycle, so as to control the power of the equalization resistor by adjusting the PWM duty cycle, and realize accurate battery equalization discharge.

[0078] It should be noted that traditional passive resistor equalization uses a simple switch to control resistor discharge, which is equivalent to outputting a pulse signal with a 100% duty cycle. This results in uniform equalization discharge efficiency for each battery. However, this embodiment employs a control method based on voltage difference to adjust the duty cycle, allowing the discharge power of each battery to be dynamically adjusted according to the voltage difference. Specifically, this embodiment modulates pulse signals with different duty cycles to control the resistors for equalization discharge based on the differences in battery voltage and charge. Because the voltage differences between batteries are different, the pulse duty cycles are also different, leading to different battery discharge power. Compared to traditional passive equalization, this design can more accurately control the power of the equalizing resistors, making the equalization time of each battery more consistent and improving equalization efficiency. Furthermore, in traditional passive resistor equalization, the resistors continuously discharge at maximum power, resulting in significant heat generation. In this embodiment, by adjusting the pulse duty cycle to control resistor discharge, the heat generation of the resistors is significantly reduced compared to traditional methods. Reduced heat generation means a smaller temperature rise in the battery pack, effectively reducing safety hazards caused by overheating and improving the safety and reliability of the battery pack.

[0079] In some implementations, such as Figure 4 As shown, each battery discharge control module includes a field-effect transistor (FET) Q1, a power resistor R1, and a current-limiting resistor R5. The power resistor R1 has a resistance of 2200Ω and a power capacity of 2W. The power resistor is connected between the drain of the FET and the positive terminal DC48 of the individual battery. Each battery has an independent power resistor. The power resistor is used to dissipate the energy of the individual battery during equalization discharge, controlling the battery voltage balance and achieving controllable discharge. In this embodiment, each FET corresponds to one individual battery. The FET is an N-channel metal-oxide-semiconductor field-effect transistor. The source of the field-effect transistor (FET) is connected to the negative terminal DC36 of the single-cell battery, and the gate of the FET is connected to the pulse width modulation (PWM) signal output terminal of the battery equalization control module through the current-limiting resistor. The FET is used to control the current flow between the single-cell battery and the power resistor according to the PWM signal. The current-limiting resistor has a resistance value of 100Ω and is used to limit the current flowing into the gate of the FET to prevent the MOSFET from being damaged due to overcurrent, while also suppressing high-frequency oscillation. In this embodiment, the process of controlling the current flow between the single-cell battery and the power resistor according to the PWM signal is as follows:

[0080] When the pulse width modulation signal is high, the field effect transistor is controlled to be turned on, forming a discharge circuit from the positive electrode of a single battery to the negative electrode of the single battery via a power resistor and the field effect transistor, so that the single battery connected to the field effect transistor is discharged through the power resistor, and the voltage of the single battery connected to the field effect transistor gradually decreases during the equalization discharge process. When the voltage difference is less than the preset voltage difference threshold and the battery remaining capacity difference is less than the preset battery capacity difference threshold, the battery equalization control module is controlled to stop outputting the corresponding pulse width modulation signal, and the field effect transistor is controlled to remain in an off state, and the equalization discharge process ends.

[0081] When the pulse width modulation signal is low, the field effect transistor is controlled to be turned off, so that the discharge circuit is disconnected, and the single battery connected to the field effect transistor stops discharging through the power resistor.

[0082] In some embodiments, the battery discharge control module is used to regulate the equalization discharge power of the power resistor during the charging and discharging process of the lead-acid battery pack according to the pulse width modulation signal and the pre-acquired power resistor heat sink temperature value, and to control the equalization discharge of the single battery of the lead-acid battery pack through the equalization discharge power, so that the equalization end time of all single batteries of the lead-acid battery pack is consistent. In this embodiment, the equalization discharge power is obtained by:

[0083] During the equalization discharge process of the lead-acid battery pack using the pulse width modulation signal, the power resistor heat sink temperature value in the battery discharge control module is collected in real time.

[0084] The power resistor heat sink temperature value is compared with the preset temperature threshold value, and when the power resistor heat sink temperature value exceeds the preset temperature threshold value, a duty cycle adjustment trigger signal is generated.

[0085] In response to the duty cycle adjustment trigger signal, a duty cycle adjustment coefficient is obtained according to the proportional relationship between the difference between the power resistor heat sink temperature value and the preset temperature threshold value and the preset temperature threshold value.

[0086] The duty cycle of the pulse width modulation signal is dynamically adjusted according to the duty cycle adjustment coefficient to obtain an adjusted pulse width modulation signal duty cycle.

[0087] According to the adjusted pulse width modulation signal duty cycle and the battery voltage signal of the single battery, an equivalent voltage value across the power resistor is calculated.

[0088] According to the equivalent voltage value and the resistance value of the power resistor, the current flowing through the power resistor is calculated, and according to the current flowing through the power resistor and the resistance value of the power resistor, the equalization discharge power of the power resistor in the current state is calculated.

[0089] In the maintenance process of the lead-acid battery, in order to ensure the safety and effectiveness of the discharge process, the embodiment adopts a power regulation mechanism based on temperature feedback. Specifically, in the initial stage of discharge, the PWM duty cycle of the discharge resistor is set to 100%, that is, the discharge resistor discharges at maximum power. As the discharge process continues, the resistor generates heat during operation, causing the temperature of the resistor radiator to gradually rise. In the process of balancing discharge of the lead-acid battery using a pulse width modulation signal, the power resistor radiator temperature value in the battery discharge control module is collected in real time by a temperature sensor. The power resistor radiator temperature value is converted into an anti-interference frequency signal by a multi-resonance circuit composed of a thermistor (NTC10K) and a 555 timer (NE555 chip). After capturing the frequency signal, the actual power resistor radiator temperature value T1 is back calculated. The power resistor radiator temperature value T1 is compared with the preset temperature threshold T. If the power resistor radiator temperature value T1 is greater than the preset temperature threshold T, the power regulation strategy is started, the duty cycle adjustment trigger signal is generated, and the duty cycle adjustment coefficient is calculated according to the characteristic of linear attenuation of the duty cycle according to the ratio of the over-temperature part to the threshold value. The duty cycle of the pulse width modulation signal is dynamically adjusted according to the duty cycle adjustment coefficient to obtain the adjusted pulse width modulation signal duty cycle. By reducing the PWM duty cycle, the power of the discharge resistor is reduced, thereby reducing the heat generated by the resistor and the radiator, effectively controlling the temperature of the resistor and the radiator, avoiding safety hazards such as fire caused by overheating, and ensuring the safe and stable performance of the lead-acid battery during the verification discharge process. In the embodiment, the calculation formula of the adjusted pulse width modulation signal duty cycle is:

[0090]

[0091]

[0092] wherein, is the adjusted pulse width modulation signal duty cycle; is the pulse width modulation signal duty cycle before temperature adjustment; is the duty cycle adjustment coefficient; is the power resistor radiator temperature value; and T is the preset temperature threshold.

[0093] Therefore, the balancing discharge power calculation formula of the power resistor in the current state is:

[0094]

[0095] wherein, is the equalization discharge power of the power resistor in the current state, U is the voltage of the single battery, wherein the product of the adjusted pulse width modulation signal duty ratio and the battery voltage signal of the single battery is the equivalent voltage value across the power resistor, and the ratio between the equivalent voltage value and the resistance value of the power resistor is the current value flowing through the power resistor; is the resistance value of the power resistor.

[0096] In some embodiments, the process of obtaining the power resistor heat sink temperature value is specifically:

[0097] A negative temperature coefficient thermistor is mounted on the surface of the power resistor heat sink, and the thermistor is connected to a multi-resonance oscillation circuit composed of a timer, so that the oscillation frequency of the multi-resonance oscillation circuit changes with the resistance value of the thermistor;

[0098] The resistance value change of the thermistor is converted into the frequency change of the square wave output by the oscillation circuit through the timer, and the square wave signal output by the multi-resonance oscillation circuit is collected at a preset counting frequency;

[0099] The square wave period is obtained by continuously capturing the time difference between the two falling edges of the square wave signal, and the square wave frequency output by the multi-resonance oscillator is calculated according to the square wave period;

[0100] According to the square wave frequency, the real-time resistance value of the thermistor is inversely deduced by using the relationship model between the square wave frequency and the resistance value of the thermistor;

[0101] The real-time resistance value of the thermistor is converted into the corresponding ambient temperature value by using the resistance-temperature characteristic relationship model of the thermistor, so as to obtain the power resistor heat sink temperature value.

[0102] Specifically, as shown in Figure 5 The temperature measurement module 104 is used to monitor the power resistor heat sink temperature value, as shown in Figure 6As shown, the temperature measurement module includes a thermistor NTC1, an NE555 chip (i.e. NE555 timer), a resistor R5, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R14, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C15, a triode Q2, and an optical coupler OC2. In this embodiment, the thermistor NTC1 is an NTC10K thermistor. The thermistor NTC1 includes a ground pin 1, a trigger pin 2, an output pin 3, a reset pin 4, a control pin 5, a threshold pin 6, a discharge pin 7, and a power pin 8. Two pins of the thermistor NTC1 are connected to the trigger pin 2 and the threshold pin 6 of the NE555 timer, respectively. The resistance of the thermistor decreases with the increase of temperature, and the thermistor is used to modulate the oscillation frequency. The power pin 8 of the NE555 timer is connected to a 5V power supply (VCC5), the ground pin 1 of the NE555 timer is connected to the ground, the output pin 3 of the NE555 timer is connected to the resistor R9, the resistance of the resistor R9 is 4.7 , the resistor R9 is used for current limiting, protecting the base of the triode Q2, and preventing excessive current from damaging the triode; the discharge pin 7 of the NE555 timer is connected to the resistor R8, one end of the resistor R8 is connected to the power supply VCC5, the other end of the resistor R8 is connected to the power pin 8 of the NE555 timer, and the resistance of the resistor R8 is 10 , the resistor R8 provides a pull-up resistor for the NE555 timer, ensuring the normal operation of the chip; the reset pin 4 of the NE555 timer is enabled by default, and the thermistor and the NE555 timer in this embodiment constitute a multi-resonant oscillator, converting the resistance value change of the thermistor into a square wave frequency change.

[0103] In the embodiment, the capacitor C12 is used to filter the high-frequency noise introduced by the thermistor lead, stabilize the oscillation signal, and the capacitor C12 is set to 0.047 μF, and the capacitance values of the capacitors C13, C14 and C15 are all set to 0.01 μF; the capacitors C13, C14 and C15 are connected in parallel between the VCC pin of the NE555 timer and the ground, and are used to suppress the power supply ripple and ensure the stable operation of the NE555 timer; the base of the transistor Q2 is connected to the output pin of the NE555 timer through the resistor R9, the emitter is grounded, and the collector is connected to the input end (anode of the light-emitting diode) of the optocoupler OC2; the transistor Q2 is used to amplify the square wave signal output by the NE555 timer and drive the optocoupler to work, specifically, the transistor Q2 acts as a switch tube, when the NE555 timer outputs a high level, the transistor Q2 is turned on, and the square wave signal is transmitted to the input end of the optocoupler OC2 through the resistor R9; when the NE555 timer outputs a low level, the transistor Q2 is cut off, and the square wave signal stops transmitting; the optocoupler OC2 uses a chip with the model number TIP521, the anode of the light-emitting diode of the input end of the optocoupler OC2 is connected to the collector of the transistor Q2, the cathode of the light-emitting diode is connected to the 5V power supply VCC5 through the resistor R7, the collector of the photosensitive transistor of the output end of the optocoupler OC2 is connected to the battery discharge control module through the resistor R14, and the collector of the photosensitive transistor of the output end of the optocoupler OC2 is also grounded through the resistor R10, the emitter of the photosensitive transistor is connected to the 3V power supply VCC3V3, and the optocoupler OC2 realizes electrical isolation and transmits the frequency signal to the battery discharge control module; the resistor R7 is used to limit the working current of the optocoupler light-emitting diode to prevent overcurrent damage; the resistor R14 is a pull-up resistor that ensures that the output signal level of the optocoupler is adapted to the battery discharge control module, in the embodiment, the square wave signal output by the NE555 timer drives the transistor Q2 to turn on after current limiting by the resistor R9, the transistor Q2 amplifies the square wave signal output by the NE555 timer, at this time the optocoupler light-emitting diode is lit, the output end of the optocoupler generates an isolated square wave signal, and transmits it to the battery discharge control module after being pulled up by the resistor R14, and the battery discharge control module measures the square wave period through the input capture function and inversely calculates the frequency value, thereby converting it into a temperature value.

[0104] As Figure 7As shown, the embodiment is in power resistance radiator surface mounted NTC 10K, its resistance value decreases with temperature rise, and the thermistor is connected to the multi-vibrator circuit composed of 555 timer (NE555), the multi-vibrator circuit outputs square wave signal, the frequency is inversely proportional to the resistance value of the thermistor, the frequency increases when the temperature rises, in the embodiment, the square wave signal is driven by the triode amplification circuit to the input end of the optical coupler OC2, the optical coupler OC2 plays the role of electrical isolation, the timer works at a count frequency of 1MHz, continuously captures the time stamp of the falling edge of the square wave signal twice, then calculates the time interval of the falling edge twice, obtains the square wave period, and further calculates the square wave frequency output by the multi-vibrator, the embodiment inversely deduces the real-time resistance value of the thermistor according to the square wave frequency output by the multi-vibrator, the relationship model between the square wave frequency and the resistance value of the thermistor can be obtained by using the regression model, the relationship model between the square wave frequency and the resistance value of the thermistor in the embodiment can be expressed as:

[0105]

[0106] In the formula, The square wave frequency output by the multi-vibrator is f; The preset count frequency is f0; The time difference between the two falling edges is Δt; and R is the real-time resistance value of the thermistor. The resistance value of the resistor R8 is R8; The resistance value of the resistor R10 is R10; The capacitance value of the capacitor C12 is C12; The capacitance value of the capacitor C13 is C13; The capacitance value of the capacitor C14 is C14, in the embodiment, the value 1.443 is the characteristic constant of the multi-vibrator composed of the NE555 timer, and the value 2000 is the calibration offset in the circuit, which can be determined by the person skilled in the art according to the specific implementation, and is not limited to the embodiment of the application.

[0107] The embodiment converts the real-time resistance value of the thermistor into the corresponding ambient temperature value by using the resistance-temperature characteristic relationship model of the thermistor, obtains the temperature value of the power resistance radiator, thereby realizes the conversion of the temperature signal into the frequency signal with strong anti-interference ability, and ensures the accuracy and reliability of the temperature measurement, it should be noted that the resistance-temperature characteristic relationship model of the thermistor can adopt the thermistor temperature-to-resistance equation (Steinhart-Hart equation), and the resistance-temperature characteristic relationship model of the thermistor can be expressed as:

[0108]

[0109] In the formula, t is the ambient temperature value. is a logarithm function with base 10; is a nominal resistance value of the thermistor at a reference temperature, and the nominal resistance value at 25℃ is 10kΩ; B is a material constant of the thermistor, and in the embodiment, the material constant of the thermistor is set to 3950K; is an absolute temperature scale corresponding to the reference temperature; is a conversion constant of the absolute temperature scale and the ambient temperature (Celsius temperature scale), that is, a conversion constant of Kelvin and Celsius.

[0110] In the embodiment, the thermistor and the timer are used to construct an oscillation circuit, the thermal signal is converted into an anti-interference frequency signal, and precise temperature measurement is realized. In the aspect of battery equalization, the embodiment discards the traditional passive equalization mode of the resistor, and instead uses the PWM wave to match the MOS tube to control the resistor discharge equalization. According to the SOC difference of each battery, the discharge power of the resistor is finely controlled by adjusting the PWM duty cycle, so as to ensure that the equalization time of each battery is synchronized. Compared with the traditional passive equalization of the resistor, the embodiment significantly reduces the discharge resistor power and the heat generation, greatly improves the equalization efficiency, and provides more accurate and efficient equalization management strategy for the battery pack.

[0111] In some embodiments, the equalization maintenance device for online monitoring of the lead-acid battery pack provided by the embodiment further includes a power module, which provides reliable power support for stable operation of the entire system. The power module adopts a hierarchical step-down design, and includes a 48VDC-to-5VDC unit and a 5VDC-to-3VDC unit. In the embodiment, the 48VDC-to-5VDC unit selects a URB4805YMD10W isolation power converter, which has high voltage conversion capability and good isolation performance, and can convert the input 48V DC voltage into 5V DC voltage to provide stable power supply for the subsequent circuit. At the same time, its isolation characteristic can effectively reduce the interference between different circuits and ensure the electrical safety of the system. The 5VDC-to-3VDC unit adopts an AMS-1117 power converter, which has the advantages of low noise and high precision, and can further convert the 5V DC voltage into 3V DC voltage to meet the needs of some chips and circuits in the device that require lower voltage, so as to ensure that each module of the entire device can work normally in a suitable voltage environment.

[0112] In some embodiments, the battery equalization control module is also used to monitor the voltage change in the charging and discharging process of the single battery, and draw the voltage-time curve. For the monitoring requirement of 12V voltage of lead-acid battery, the voltage conversion circuit is added before voltage collection in this embodiment, and the upper limit of collected voltage is raised to 15V, which effectively solves the problem that the conventional battery voltage collection circuit (upper limit 5V) cannot adapt to lead-acid battery. Then, this embodiment measures the voltage and current of the single battery in the charging and discharging process of the lead-acid battery, calculates the internal resistance of the single battery by Ohm's law, and draws the internal resistance-time curve. At the same time, this embodiment calculates the state of charge SOC of the battery by combining Kalman filtering and ampere-hour integration method, and draws the SOC-time curve. Compared with the traditional technology which only uses a single judgment method, this embodiment performs triple comprehensive evaluation on the battery performance based on the voltage-time curve change characteristics, the internal resistance-time curve change characteristics and the SOC-time curve change characteristics. When detecting that the voltage-time curve change is inconsistent in the charging and discharging process of the lead-acid battery, combined with the internal resistance-time curve and the SOC-time curve, the lead-acid battery with the fastest voltage-time curve drop, the largest internal resistance and the abnormal SOC change can be accurately determined as the worst performance, and timely maintenance is recommended.

[0113] In the discharging process, in order to prevent the discharge power resistor from overheating and causing safety hazards, this embodiment sets a temperature monitoring and protection mechanism. When the temperature of the discharge power resistor heat sink exceeds the set temperature, the fan control circuit starts immediately to control the fan to perform forced exhaust heat dissipation, ensuring the safe operation of the equipment. In the specific implementation process, Figure 8 For the battery discharge voltage change curve in the battery verification discharge process, by comparing the curves of battery 11 and battery 22, it can be seen that the voltage of battery 22 drops faster in the discharging process. Battery 11 ends discharging after 7 hours, while battery 22 ends discharging after 4 hours, and the final voltage is less than 10.8V (usually, the discharge end voltage of a battery with normal performance is 0.9 times the rated voltage, i.e. 10.8V). Therefore, it can be judged that the performance of battery 22 is poor, and maintenance is recommended. Similarly, as shown in Figure 9 In the battery charging process, the voltage curve of battery 22 changes quickly and ends charging after 3 hours, while the voltage curve of the other battery changes slowly and completes charging after 7 hours. According to this situation, it can also be judged that the performance of battery 22 is poor, and maintenance is recommended.

[0114] The embodiment of the present application provides a kind of equalization maintenance device of lead-acid battery pack online monitoring, the device is measured by battery online monitoring module to lead-acid battery pack charge-discharge current non-contact, and according to the charge-discharge current of lead-acid battery pack, the state of charge of single battery is calculated by Kalman filtering and ampere-hour integration method, and the remaining capacity of battery is obtained;Battery equalization control module utilizes the method of voltage dividing resistor to measure the voltage of lead-acid battery pack single battery, and when the voltage difference between the highest voltage and the lowest voltage of lead-acid battery pack single battery is monitored to exceed the preset pressure difference threshold or the difference of the remaining capacity of battery between different single batteries exceeds the preset power difference threshold, the output pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of battery;Battery discharge control module, during the charge-discharge process of lead-acid battery pack, the equalization discharge power of power resistor is regulated according to the pulse width modulation signal and the temperature value of power resistor radiator obtained in advance, and the equalization discharge control of lead-acid battery pack single battery is carried out by equalization discharge power, so that all lead-acid battery pack single battery equalization end time is consistent.Compared with prior art, the device cooperatively controls the equalization discharge power of power resistor by dynamically adjusting the duty cycle of pulse width modulation signal and temperature, effectively ensures the equalization discharge of battery pack, prolongs the service life of battery pack, prevents the overall performance of battery pack from being reduced due to the difference of single battery, and guarantees the stable, efficient and safe operation of lead-acid battery pack.

[0115] It should be noted that the size of the serial number of the above processes does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0116] In one embodiment, as shown in Figure 10 The embodiment of the present application provides an equalization maintenance method of lead-acid battery pack online monitoring, which comprises the following steps:

[0117] S1. non-contact measurement of the charge-discharge current of lead-acid battery pack, and calculating the state of charge of single battery by Kalman filtering and ampere-hour integration method according to the charge-discharge current of lead-acid battery pack, to obtain the remaining capacity of battery;

[0118] S2. the voltage of lead-acid battery pack single battery is measured by using the method of voltage dividing resistor, and when the voltage difference between the highest voltage and the lowest voltage of lead-acid battery pack single battery is monitored to exceed the preset pressure difference threshold or the difference of the remaining capacity of battery between different single batteries exceeds the preset power difference threshold, the output pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of battery;

[0119] S3. during the charge-discharge process of lead-acid battery pack, the equalization discharge power of power resistor is regulated according to the pulse width modulation signal and the temperature value of power resistor radiator obtained in advance.

[0120] S4. Controlling the equalization discharge of the lead-acid battery monomer cells by the equalization discharge power, so that the equalization end time of all the lead-acid battery monomer cells is consistent.

[0121] The specific limitations of the equalization maintenance method for the online monitoring of the lead-acid battery can be seen from the above limitations of the equalization maintenance device for the online monitoring of the lead-acid battery, which will not be repeated here. Those skilled in the art can realize that the various modules and steps described in combination with the embodiments disclosed in the present application can be realized in hardware, software or a combination of both. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0122] The embodiment of the present application provides an equalization maintenance method for the online monitoring of a lead-acid battery, which comprises non-contact measurement of the charge and discharge current of the lead-acid battery, and calculating the state of charge of the monomer cell by Kalman filtering and ampere-hour integration method according to the charge and discharge current of the lead-acid battery to obtain the remaining capacity of the battery; the voltage of the lead-acid battery monomer cell is measured by using the voltage dividing resistor method, and when the voltage difference between the highest voltage and the lowest voltage of the lead-acid battery monomer cell is monitored to exceed the preset voltage difference threshold or the difference in the remaining capacity of the battery between different monomer cells exceeds the preset power difference threshold, the pulse width modulation signal is modulated according to the voltage difference and the difference in the remaining capacity of the battery; during the charge and discharge process of the lead-acid battery, the equalization discharge power of the power resistor is regulated according to the pulse width modulation signal and the pre-acquired temperature value of the power resistor radiator, and the equalization discharge of the lead-acid battery monomer cell is controlled by the equalization discharge power, so that the equalization end time of all the lead-acid battery monomer cells is consistent. Compared with the prior art, the method dynamically adjusts the duty cycle of the pulse width modulation signal and cooperatively controls the equalization discharge power of the power resistor according to the temperature, effectively ensures the equalization discharge of the battery pack, prolongs the service life of the battery pack, prevents the overall performance of the battery pack from being reduced due to the difference between the monomer cells, and ensures the stable, efficient and safe operation of the lead-acid battery pack.

[0123] The above embodiments only express several preferred embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled persons in the technical field, several improvements and replacements can be made without departing from the technical principles of the present application, and these improvements and replacements should be considered as the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the protection scope of the claims.

Claims

1. An equalizing maintenance device for on-line monitoring of a lead-acid battery pack, characterized in that, The application relates to a battery equalization control method and device. The battery online monitoring module is used for non-contact measurement of the charging and discharging current of a lead-acid battery pack by adopting a Hall current sensor, and the state of charge of a single battery is calculated by a Kalman filter and an ampere-hour integration method according to the charging and discharging current of the lead-acid battery pack, so as to obtain the residual capacity of the battery. The battery equalization control module is used for measurement of the voltage of the single battery of the lead-acid battery pack by utilizing a voltage dividing resistor method, and when the voltage difference between the highest voltage and the lowest voltage of the single battery of the lead-acid battery pack is monitored to exceed a preset voltage difference threshold value or the residual capacity difference between different single batteries exceeds a preset electric quantity difference threshold value, a pulse width modulation signal is generated according to the voltage difference and the residual capacity difference. The battery discharging control module is used for regulating the equalization discharging power of a power resistor according to the pulse width modulation signal and a pre-acquired power resistor radiator temperature value during the charging and discharging process of the lead-acid battery pack, and the single battery of the lead-acid battery pack is controlled to be equalized and discharged by the equalization discharging power, so that the equalization ending time of all the single batteries of the lead-acid battery pack is consistent. The acquisition process of the pulse width modulation signal is specifically as follows: During the charging and discharging process of the lead-acid battery pack, the battery voltage signals of all the single batteries in the lead-acid battery pack are collected in real time. If the battery voltage signal is greater than a preset highest battery voltage, the battery voltage signal is processed by voltage dividing by utilizing a voltage dividing resistor network based on the voltage dividing principle, so as to obtain an initial voltage signal. The initial voltage signal is converted into a voltage measurement value of each single battery by an analog-digital conversion, and the voltage difference between the highest voltage and the lowest voltage of each single battery is calculated according to the voltage measurement value. The voltage difference is compared with the preset voltage difference threshold value, and when the voltage difference exceeds the preset voltage difference threshold value, a voltage difference duty cycle is calculated according to the proportional relationship between the difference between the voltage difference and the preset voltage difference threshold value and the preset voltage difference threshold value. The residual capacity difference is compared with the preset electric quantity difference threshold value, and when the residual capacity difference exceeds the preset electric quantity difference threshold value, an electric quantity difference duty cycle is calculated according to the proportional relationship between the difference between the residual capacity difference and the preset electric quantity difference threshold value and the preset electric quantity difference threshold value. The maximum value of the voltage difference duty cycle and the electric quantity difference duty cycle is taken as an actual optimal duty cycle, and a pulse width modulation signal corresponding to the pulse width is generated according to the actual optimal duty cycle.

2. An equalizing maintenance device for on-line monitoring of a lead-acid battery pack according to claim 1, characterized in that: The voltage difference duty cycle and the electric quantity difference duty cycle should be between a preset lowest duty cycle threshold value and a preset highest duty cycle threshold value.

3. An on-line monitoring and equalizing maintenance device for a lead-acid battery bank as claimed in claim 2, characterized in that: If the voltage difference duty cycle or the electric quantity difference duty cycle is monitored to be less than the lowest duty cycle threshold value, the lowest duty cycle threshold value is adopted for equalization control, the voltage difference duty cycle is set to be constant at the lowest duty cycle threshold value or the electric quantity difference duty cycle is set to be constant at the lowest duty cycle threshold value, until the voltage difference is less than the preset voltage difference threshold value and the residual capacity difference is less than the preset electric quantity difference threshold value, the corresponding pulse width modulation signal is stopped from being outputted, and the equalization discharging operation is terminated.

4. An on-line monitoring and equalizing maintenance device for lead-acid battery banks as claimed in claim 1, characterized in that, The equalization discharge power acquisition process is specifically as follows: In the equalization discharge process of the lead-acid battery group by using the pulse width modulation signal, the power resistor radiator temperature value in the battery discharge control module is collected in real time; The power resistor radiator temperature value is compared with the preset temperature threshold value, and when the power resistor radiator temperature value exceeds the preset temperature threshold value, a duty cycle adjustment trigger signal is generated; In response to the duty cycle adjustment trigger signal, a duty cycle adjustment coefficient is obtained according to the proportional relationship between the difference between the power resistor radiator temperature value and the preset temperature threshold value and the preset temperature threshold value; The duty cycle of the pulse width modulation signal is dynamically adjusted according to the duty cycle adjustment coefficient to obtain an adjusted pulse width modulation signal duty cycle; According to the adjusted pulse width modulation signal duty cycle and the battery voltage signal of the single battery, an equivalent voltage value across the power resistor is calculated; According to the equivalent voltage value and the resistance value of the power resistor, the current flowing through the power resistor is calculated, and the equalization discharge power of the power resistor in the current state is calculated according to the current flowing through the power resistor and the resistance value of the power resistor.

5. An on-line monitoring and equalizing maintenance device for a lead-acid battery pack as claimed in claim 4, characterized in that, The power resistor radiator temperature value acquisition process is specifically as follows: A negative temperature coefficient thermistor is mounted on the surface of the power resistor radiator, and the thermistor is connected to a multi-resonance oscillation circuit composed of a timer, so that the oscillation frequency of the multi-resonance oscillation circuit changes with the resistance value of the thermistor; The resistance value change of the thermistor is converted into the frequency change of the square wave output by the oscillation circuit by the timer, and the square wave signal output by the multi-resonance oscillation circuit is collected at a preset counting frequency; The square wave period is obtained by continuously capturing the time difference between the two falling edges of the square wave signal, and the square wave frequency output by the multi-resonance oscillator is calculated according to the square wave period; According to the square wave frequency, the real-time resistance value of the thermistor is inversely deduced by using the relationship model between the square wave frequency and the resistance value of the thermistor; The real-time resistance value of the thermistor is converted into the corresponding ambient temperature value by using the resistance-temperature characteristic relationship model of the thermistor to obtain the power resistor radiator temperature value.

6. An on-line monitoring and equalizing maintenance device for lead acid battery banks as claimed in claim 1, characterized in that: The voltage dividing resistor network is composed of two voltage dividing resistors, and the ratio of the resistance values of the two voltage dividing resistors is two times.

7. An on-line monitoring and equalizing maintenance device for lead-acid battery banks as claimed in claim 1, characterized in that: Each battery discharge control module includes a field effect transistor, a power resistor, and a current limiting resistor; The power resistor is connected between the drain of the field effect transistor and the positive electrode of the single battery, and is used to consume the energy of the single battery and control the equalization of the battery voltage during the equalization discharge process; The source of the field effect transistor is connected to the negative electrode of the single battery, and the gate of the field effect transistor is connected to the pulse width modulation signal output end of the battery equalization control module through the current limiting resistor; the field effect transistor is used to control the on-off of the current between the single battery and the power resistor according to the pulse width modulation signal; The current limiting resistor is used to limit the current flowing into the gate of the field effect transistor.

8. A balancing maintenance device for on-line monitoring of a lead-acid battery pack as claimed in claim 7, characterized in that The process of controlling the on-off of the current between the single battery and the power resistor according to the pulse width modulation signal is specifically as follows: When the pulse width modulation signal is high, the field effect transistor is controlled to be turned on, forming a discharge circuit from the positive electrode of a single battery to the negative electrode of the single battery through a power resistor and the field effect transistor, so that the single battery connected with the field effect transistor is discharged through the power resistor for equalization, and in the process of equalization discharge, the voltage of the single battery connected with the field effect transistor gradually decreases, and when the voltage difference is less than the preset voltage difference threshold and the battery residual capacity difference is less than the preset electric quantity difference threshold, the battery equalization control module is controlled to stop outputting the corresponding pulse width modulation signal, and the field effect transistor is controlled to remain in an off state, and the equalization discharge process ends; When the pulse width modulation signal is low, the field effect transistor is controlled to be turned off, so that the discharge circuit is disconnected, and the single battery connected with the field effect transistor stops discharging through the power resistor for equalization.

9. A method of equalization maintenance of lead-acid battery packs for online monitoring, characterized in that, The method comprises the following steps: The charge and discharge current of the lead-acid battery pack is measured non-contact, and the state of charge of the single battery is calculated by Kalman filtering and ampere-hour integration method according to the charge and discharge current of the lead-acid battery pack, so as to obtain the battery residual capacity; The voltage of the single battery of the lead-acid battery pack is measured by using the voltage dividing resistor method, and when the voltage difference between the highest voltage and the lowest voltage of the single battery of the lead-acid battery pack is monitored to exceed the preset voltage difference threshold or the battery residual capacity difference between different single batteries exceeds the preset electric quantity difference threshold, the pulse width modulation signal is modulated and output according to the voltage difference and the battery residual capacity difference; During the charging and discharging process of the lead-acid battery pack, the equalization discharge power of the power resistor is regulated according to the pulse width modulation signal and the pre-acquired power resistor heat sink temperature value; The single battery of the lead-acid battery pack is controlled to be discharged for equalization by the equalization discharge power, so that the equalization end time of all single batteries of the lead-acid battery pack is consistent; The acquisition process of the pulse width modulation signal is specifically as follows: During the charging and discharging process of the lead-acid battery pack, the battery voltage signals of each single battery in the lead-acid battery pack are collected in real time; If it is detected that the battery voltage signal is greater than the preset highest battery voltage, the battery voltage signal is processed by voltage dividing by using a voltage dividing resistor network based on the voltage dividing principle, to obtain an initial voltage signal; The initial voltage signal is converted into digital, to obtain the voltage measurement value of each single battery, and the voltage difference between the highest voltage and the lowest voltage of each single battery is calculated according to the voltage measurement value; The voltage difference is compared with the preset voltage difference threshold, and when the voltage difference exceeds the preset voltage difference threshold, the duty cycle of the voltage difference is calculated according to the proportional relationship between the difference between the voltage difference and the preset voltage difference threshold and the preset voltage difference threshold; The battery residual capacity difference is compared with the preset electric quantity difference threshold, and when the battery residual capacity difference exceeds the preset electric quantity difference threshold, the duty cycle of the electric quantity difference is calculated according to the proportional relationship between the difference between the battery residual capacity difference and the preset electric quantity difference threshold and the preset electric quantity difference threshold. The maximum value of the differential pressure duty cycle and the electric quantity differential duty cycle is taken as an actual optimal duty cycle, and a pulse width modulation signal corresponding to a pulse width is generated according to the actual optimal duty cycle. The maximum value of the differential pressure duty cycle and the electric quantity differential duty cycle is taken as an actual optimal duty cycle, and a pulse width modulation signal corresponding to a pulse width is generated according to the actual optimal duty cycle.

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