Balanced maintenance device and method for online monitoring of lead-acid storage battery pack

Abstract

The invention relates to the technical field of storage batteries, in particular to a balanced maintenance device and method for online monitoring of a lead-acid storage battery pack, and the method comprises the steps: a battery online monitoring module obtains the residual capacity of a battery according to the charging and discharging current of the lead-acid storage battery pack; the battery equalization control module measures the voltage of the single batteries of the lead-acid storage battery pack by using a divider resistance method; when it is monitored that the voltage difference between the highest voltage and the lowest voltage of the single batteries of the lead-acid storage battery pack exceeds a preset voltage difference threshold value or the difference value of the residual capacities of the different single batteries exceeds a preset electric quantity difference threshold value, a pulse width modulation signal is output; and the battery discharge control module regulates and controls the balanced discharge power of the power resistor according to the pulse width modulation signal and the temperature value of the power resistor radiator, and carries out balanced discharge control through the balanced discharge power. According to the invention, the balanced discharge power of the power resistor is cooperatively controlled by dynamically adjusting the duty ratio of the pulse width modulation signal and the temperature, so that balanced discharge of the battery pack is effectively ensured.

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 the voltage of the single batteries 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: 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; a battery equalization control module configured to measure voltages of the individual batteries of the lead-acid battery pack using a voltage dividing resistor method, and to generate a pulse width modulation signal according to a voltage difference between a highest voltage and a lowest voltage of the individual batteries of the lead-acid battery pack and a battery capacity difference between the individual batteries of the lead-acid battery pack when the voltage difference exceeds a preset voltage difference threshold or the battery capacity difference exceeds a preset capacity difference threshold; a battery discharge control module configured to control equalization discharge power of the power resistor according to the pulse width modulation signal and a pre-acquired temperature value of the power resistor heat sink, and to control equalization discharge of the individual batteries of the lead-acid battery pack by the equalization discharge power, so that all the individual batteries of the lead-acid battery pack have a same equalization end time.

[0007] In further embodiments, the pulse width modulation signal is generated according to the following process: In the charging and discharging process of the lead-acid battery pack, battery voltage signals of the individual batteries of 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 a voltage dividing resistor network based on a voltage dividing principle to obtain an initial voltage signal; The initial voltage signal is converted into an analog-to-digital signal to obtain voltage measurement values of the individual batteries, and a voltage difference between a highest voltage and a lowest voltage of the individual batteries is calculated according to the voltage measurement values; The voltage difference is compared with the preset voltage difference threshold, and when the voltage difference exceeds the preset voltage difference threshold, a voltage difference duty cycle is calculated according to a proportional relationship between a difference between the voltage difference and the preset voltage difference threshold and the preset voltage difference threshold; The battery capacity difference is compared with the preset capacity difference threshold, and when the battery capacity difference exceeds the preset capacity difference threshold, a capacity difference duty cycle is calculated according to a proportional relationship between a difference between the battery capacity difference and the preset capacity difference threshold and the preset capacity difference threshold; The maximum value of the voltage difference duty cycle and the capacity 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.

[0008] In further embodiments, the voltage difference duty cycle and the capacity difference duty cycle should be between a preset minimum duty cycle threshold and a preset maximum duty cycle threshold.

[0009] In a further embodiment, if it is monitored that the voltage difference duty cycle or the charge difference duty cycle is less than the minimum duty cycle threshold, the minimum duty cycle threshold is used for balancing control, and the voltage difference duty cycle is constantly set to the minimum duty cycle threshold or the charge difference duty cycle is constantly set to the minimum duty cycle threshold until the voltage difference is less than the preset voltage difference threshold and the battery remaining capacity difference is less than the preset charge difference threshold, and the corresponding pulse width modulation signal is stopped from being output to terminate the balancing discharge operation.

[0010] In a further embodiment, the process of obtaining the balanced discharge power is specifically as follows: In the process of performing balanced discharge on the lead-acid battery pack 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; Comparing the temperature value of the power resistor heat sink with a preset temperature threshold, and generating a duty cycle adjustment trigger signal when the temperature value of the power resistor heat sink exceeds the preset temperature threshold; In response to the duty cycle adjustment trigger signal, obtaining a duty cycle adjustment coefficient according to a proportional relationship between a difference between a temperature value of the power resistor heat sink and the preset temperature threshold and the preset temperature threshold; Dynamically adjusting the duty cycle of the pulse width modulation signal according to the duty cycle adjustment coefficient to obtain an adjusted duty cycle of the pulse width modulation signal; The equivalent voltage value across the power resistor is calculated based on the adjusted duty cycle of the pulse width modulation signal and the battery voltage signal of the single battery; The current value flowing through the power resistor is calculated according to the equivalent voltage value and the resistance value of the power resistor, and the balanced discharge power of the power resistor in the current state is calculated according to the current value flowing through the power resistor and the resistance value of the power resistor.

[0011] In a further embodiment, the process of obtaining the temperature value of the power resistor radiator is specifically as follows: A thermistor with a negative temperature coefficient is mounted on the surface of a power resistor heat sink, and the thermistor is connected to a multivibrator circuit formed by a timer, so that the oscillation frequency of the multivibrator circuit changes with the resistance value of the thermistor; The timer converts the resistance change of the thermistor into the frequency change of the square wave output by the oscillation circuit, and collects the square wave signal output by the multivibrator circuit at a preset counting frequency; By continuously capturing the time difference between two falling edges of the square wave signal, the square wave period is obtained, and the square wave frequency output by the multivibrator is calculated based on the square wave period; According to the square wave frequency, the real-time resistance value of the thermistor is inversely deduced by using a model of the relationship between the square wave frequency and the resistance value of the thermistor. The real-time resistance value of the thermistor is converted into a corresponding ambient temperature value by using a model of the relationship between the resistance value and the temperature of the thermistor, so as to obtain the temperature value of the power resistor radiator.

[0012] In a further embodiment, 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.

[0013] In a further embodiment, each of the battery discharge control modules comprises 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 the power resistor is used to consume the energy of the single battery during the equalization discharge process and control the equalization of the battery voltage. 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.

[0014] In a further embodiment, 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 at a high level, the field effect transistor is controlled to be turned on to form a discharge loop from the positive electrode of the single battery, through the power resistor and the field effect transistor, to the negative electrode of the single battery, so that the single battery connected to the field effect transistor is discharged through the power resistor for equalization, and in the equalization discharge process, the voltage of the single battery connected to the field effect transistor gradually decreases; when the voltage difference is less than the preset voltage difference threshold and the residual capacity difference of the battery is less than the preset 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. When the pulse width modulation signal is at a low level, the field effect transistor is controlled to be turned off to disconnect the discharge loop, so that the single battery connected to the field effect transistor stops discharging through the power resistor for equalization.

[0015] In a second aspect, the present application provides a balancing maintenance method for online monitoring of a lead-acid battery pack, which comprises the following steps: The charging and discharging current of the lead-acid storage battery 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 storage battery, so as to obtain the remaining capacity of the battery; The voltage of the single battery of the lead-acid storage battery is measured by using 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 storage battery is monitored to exceed a preset voltage difference threshold or the difference of the remaining capacity of the battery between different single batteries exceeds a preset electric quantity difference threshold, a pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of the battery; During the charging and discharging process of the lead-acid storage battery, the equalizing discharging 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. The equalizing discharging control of the single battery of the lead-acid storage battery is performed by the equalizing discharging power, so that the equalizing end time of all the single batteries of the lead-acid storage battery is consistent.

[0016] The present application provides an equalizing maintenance device and method for online monitoring of a lead-acid storage battery. The device measures the charging and discharging current of the lead-acid storage battery non-contact through a battery online monitoring module, and calculates 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 storage battery, so as to obtain the remaining capacity of the battery. The battery equalizing control module measures the voltage of the single battery of the lead-acid storage battery by using 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 storage battery is monitored to exceed a preset voltage difference threshold or the difference of the remaining capacity of the battery between different single batteries exceeds a preset electric quantity difference threshold, a pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of the battery. The battery discharging control module regulates the equalizing discharging power of the power resistor according to the pulse width modulation signal and the pre-acquired temperature value of the power resistor radiator during the charging and discharging process of the lead-acid storage battery, and performs the equalizing discharging control of the single battery of the lead-acid storage battery by the equalizing discharging power, so that the equalizing end time of all the single batteries of the lead-acid storage battery is consistent. Compared with the prior art, the device dynamically adjusts the duty cycle of the pulse width modulation signal and cooperatively controls the equalizing discharging power of the power resistor by temperature, effectively ensures the equalizing discharging 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 of the single batteries, and ensures the stable, efficient and safe operation of the lead-acid storage battery. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a block diagram of the equalizing maintenance device for online monitoring of a lead-acid storage battery provided by the embodiment of the present application; Figure 2 It is a schematic diagram of a voltage dividing resistor network structure provided by the embodiment of the present application; Figure 3is a resistance equalization process schematic diagram provided by the embodiment of the present application; Figure 4 is a battery discharge control module schematic diagram provided by the embodiment of the present application; Figure 5 is a principle block diagram of the equalization maintenance device provided by the embodiment of the present application; Figure 6 is a temperature measurement module structure schematic diagram provided by the embodiment of the present application; Figure 7 is a temperature acquisition process schematic diagram provided by the embodiment of the present application; Figure 8 is a battery discharge voltage change curve schematic diagram provided by the embodiment of the present application; Figure 9 is a battery charging voltage change curve schematic diagram provided by the embodiment of the present application; Figure 10 is a flowchart of the equalization maintenance method of the lead-acid battery pack online monitoring provided by the embodiment of the present application.

[0018] Mark explanation: 101, battery online monitoring module; 102, battery equalization control module; 103, battery discharge control module; 104, temperature measurement module. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments are given only for the purpose of illustration and cannot be understood as limiting the present application. The accompanying drawings are only for reference and illustration and do not constitute a limitation on the scope of protection of the present application, because many changes can be made to the present application without departing from the spirit and scope of the present application.

[0020] The lead-acid battery pack is usually composed of multiple batteries in series. During the charging process, when the voltage of any single battery in the battery pack reaches the upper limit, the charging is stopped, otherwise the battery with the highest single battery voltage will be overcharged. During the discharging process, when the voltage of any single battery in the battery pack reaches the lower limit, the discharging is stopped, otherwise the battery with the lowest single battery voltage will be over-discharged, thereby reducing the service life of the battery. To solve this problem, reference Figure 1 The embodiment of the present application provides an equalization maintenance device for lead-acid battery pack online monitoring, as shown in Figure 1As 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 voltage and the lowest voltage of the single batteries in the battery pack is greater than 150mV, the device will automatically start the equalization discharge program. In this process, this embodiment uses a power resistor to discharge the single batteries for equalization. In order to improve the equalization efficiency and reduce the heat generated by the power resistor during discharge, this embodiment takes the single battery with the lowest voltage in the battery pack as the reference, and discharges the battery by controlling the duty cycle of the power resistor. This adjustment mechanism ensures that the higher voltage battery is discharged with a larger power resistor, and the lower voltage battery is discharged with a smaller power resistor. The size of the discharge resistor power is controlled by the voltage, and by controlling the duty cycle of the power resistor operating voltage, the power can be adjusted, so that all single batteries have the same equalization end time, thereby significantly improving the equalization efficiency of the entire battery pack and prolonging the service life of the battery pack.

[0021] In some embodiments, the battery online monitoring module is used to measure the charging and discharging current of the lead-acid battery pack using a Hall current sensor, and calculate the state of charge of the single battery based on the charging and discharging current of the lead-acid battery pack by Kalman filtering and ampere-hour integration method to obtain the remaining capacity of the battery.

[0022] In this 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 of B is applied in the normal direction of the Hall element plane, based on the Hall effect, an electric potential will be generated in the direction perpendicular to the current and the magnetic field (i.e. between the Hall output ends). By accurately measuring this voltage and using the related characteristics of the Hall effect, the corresponding current can be accurately deduced, 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 current information, providing accurate current data support for online monitoring of lead-acid battery packs. Before starting to calculate the state of charge (SOC) of the single battery, the battery pack needs to be initialized to record the full charge capacity , when the battery pack is fully charged, the current remaining capacity is equal to the full charge capacity; when the battery pack starts discharging, 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 lead-acid battery pack charging and discharging current 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, then, based on the ampere-hour integration method, the remaining capacity of the battery pack is calculated in real time, in particular, the initial current remaining capacity The change in the charging and discharging process is as follows: for the discharging process, the difference between the current remaining capacity and the cumulative change in the amount of electricity in the charging and discharging process is taken as the updated remaining capacity; for the charging process, the sum of the current remaining capacity and the cumulative change in the amount of electricity in the charging and discharging process is taken as the updated remaining capacity, by updating the remaining capacity in real time, the remaining capacity change curve of the battery pack in the charging and discharging process can be obtained.

[0023] In order to improve the accuracy of the state of charge calculation, the Kalman filter algorithm is introduced to optimize the results of the ampere-hour integration method, the Kalman filter is a recursive algorithm based on state space model, which can estimate the measurement data containing noise, in this 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 results of the state of charge, and improves the accuracy of the state of charge estimation. For the single battery 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 and the total remaining capacity of the battery pack can be estimated, and 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 uses the Hall current sensor to measure the charging and discharging current of the lead-acid battery pack non-contact, obtains accurate current data, then calculates the basic value of SOC using the ampere-hour integration method, and optimizes the SOC estimation value by combining the Kalman filter algorithm to overcome the cumulative error of the ampere-hour integration method, finally, according to the calculated SOC value and the rated capacity of the battery, the remaining capacity of the battery is obtained, which provides an important basis for the online monitoring and equalization maintenance of the lead-acid battery pack.

[0024] In some embodiments, the battery equalization control module is configured to measure the voltage of each single battery of the lead-acid battery pack by using a voltage dividing resistor method, and when the voltage difference between the highest voltage and the lowest voltage of the single batteries of the lead-acid battery pack is detected to exceed a preset voltage difference threshold or the difference in the remaining capacity of the batteries 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 batteries, and in this embodiment, the process of obtaining 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 the battery voltage signal is detected to be greater than a preset highest battery voltage, the battery voltage signal is processed by using a voltage dividing resistor network based on the principle of voltage division to obtain an initial voltage signal. 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. The voltage difference is compared with a 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 difference in the remaining capacity of the batteries is compared with a preset capacity difference threshold, and when the difference in the remaining capacity of the batteries exceeds the preset capacity difference threshold, the duty cycle of the difference in the remaining capacity of the batteries is calculated according to the proportional relationship between the difference between the difference in the remaining capacity of the batteries and the preset capacity difference threshold and the preset capacity difference threshold. The maximum value of the duty cycle of the voltage difference and the duty cycle of the difference in the remaining capacity of the batteries is taken as the actual optimal duty cycle, and a pulse width modulation signal corresponding to the pulse width is generated according to the actual optimal duty cycle.

[0025] The upper limit of the voltage of the traditional battery voltage acquisition circuit is usually 5V for single battery, however, the voltage range of the single battery of the lead-acid storage battery is generally between 12V and 15V, therefore, the traditional battery voltage acquisition circuit cannot be directly adapted to the single battery voltage acquisition of the lead-acid storage battery, for this reason, the embodiment designs a level conversion circuit in front of the traditional battery voltage acquisition circuit, the upper limit of the collectable battery voltage is raised to 15V through the level conversion circuit, so as to adapt to the lead-acid storage battery, and the measurement error is as low as 1.2mV, which greatly improves the accuracy and applicability of the voltage acquisition, in the specific implementation process, the battery equalization control module adopts the LTC6804 chip, the LTC6804 chip itself can only realize the accurate measurement and equalization control of the lithium battery voltage below 5V, and there is no effective solution for the accurate measurement and passive equalization control of the single battery voltage of the lead-acid storage battery with the single battery voltage range between 12V and 15V, for this problem, the embodiment combines the LTC6804 chip with the voltage division resistance method, effectively solves the problem of accurate measurement of the single battery voltage of the 12V lead-acid storage battery, and makes the battery voltage measurement accuracy reach the millivolt level, at the same time, combined with the accurate control of the discharge power of the high-power resistance, the passive equalization control problem between the single batteries of the lead-acid storage battery is effectively solved, and the voltage difference between the single batteries of the battery pack is ensured to be less than 10mV, which significantly improves the performance and stability of the battery pack.

[0026] 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 the lead-acid battery. In this embodiment, after the battery voltage signal is connected, it is sequentially divided by a voltage-dividing resistor network. The voltage-dividing resistor network is composed of two voltage-dividing resistors, namely a first voltage-dividing resistor R17 and a second voltage-dividing resistor R22. The first voltage-dividing resistor R17 adopts a 20kΩ precision resistor. The first voltage-dividing resistor R17 is connected to the positive electrode of each single battery. The second voltage-dividing resistor R22 adopts a 10kΩ precision resistor. The second voltage-dividing resistor R22 is connected between the first voltage-dividing resistor R17 and the ground GND. The resistance ratio of the two voltage-dividing resistors is twice. Specifically, the voltage-dividing resistor network adopts 20K and 10K precision resistors to construct a 3:1 voltage-dividing circuit. In this embodiment, the connected battery voltage signal is sequentially divided by 20K and 10K precision resistors for a 3:1 voltage-dividing process. The input voltage signal is linearly reduced to one-third of the original value through the proportional relationship of the voltage-dividing ratio of 3:1. For example, a 15V input The input voltage is converted into a low-voltage signal within the 5V range, thereby proportionally reducing the high-voltage signal to a range that can be measured by the LTC6804 chip. In this embodiment, a ground filter capacitor C7 is connected in parallel to the output end of the voltage divider network. The ground filter capacitor is used to suppress high-frequency interference signals. The divided signal is then stabilized 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 end 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 due to impedance mismatch. Therefore, the voltage signal is impedance matched by the 100Ω impedance matching resistor R23 and then input to the sampling input end of the LTC6804 chip. The LTC6804 chip uses its built-in analog-to-digital converter to accurately collect the battery voltage and obtain the voltage measurement value of each single battery by performing analog-to-digital conversion on the initial voltage signal.

[0027] After calculating the voltage measurement value of each single battery, Figure 3 As shown, in this embodiment, it is assumed that the voltage of the single battery is U and the preset voltage difference threshold is The voltage difference between the highest voltage and the lowest voltage of the single battery is b. When the voltage difference b exceeds the voltage difference threshold When , this embodiment calculates the pulse width modulation (PWM) duty cycle according to the voltage difference to obtain the voltage difference duty cycle D1. The specific calculation formula is: Where b is the voltage difference between the highest voltage and the lowest voltage of the single cell; is the preset pressure difference threshold; D1 is the pressure difference duty cycle. In this embodiment, the pressure difference duty cycle should be between the preset minimum duty cycle threshold and the preset maximum duty cycle threshold. For example, this embodiment can be 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, and the pressure difference duty cycle is set to the minimum duty cycle threshold, until 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, the corresponding pulse width modulation signal is stopped to terminate the equalization discharge operation, for example, when The duty cycle is constant at 20%, and the voltage difference b is less than the pressure difference threshold a, at which time the PWM signal is stopped.

[0028] Similarly, 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 corresponding PWM duty cycle is calculated according to the battery remaining capacity difference, and the power difference duty cycle D2 is obtained, and the specific calculation formula is: In the formula, c is the power difference threshold; d is the battery remaining capacity difference; D2 is the power difference duty cycle, which should be between the preset minimum duty cycle threshold and the preset maximum duty cycle threshold in the embodiment, 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, and the power difference duty cycle is set to the minimum duty cycle threshold, until 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, the corresponding pulse width modulation signal is stopped to terminate the equalization discharge operation, for example, when The duty cycle is constant at 20%, and the battery remaining capacity difference d is less than the power difference threshold c, at which time the PWM signal is stopped.

[0029] Finally, the embodiment considers the pressure difference and power difference factors to determine the actual optimal duty cycle of the pulse width modulation signal. Specifically, the maximum value of the pressure difference duty cycle and the power difference duty cycle is taken as the actual optimal duty cycle, and the pulse width modulation signal with the corresponding pulse width is generated 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.

[0030] It should be noted that traditional passive resistor balancing uses a simple switch to control resistor discharge, which is equivalent to outputting a pulse signal with a 100% duty cycle. The balanced discharge efficiency of each battery is the same. However, this embodiment adopts a control method based on voltage differential to adjust the duty cycle, so that the discharge power of each battery is dynamically adjusted according to the voltage differential. Specifically, this embodiment modulates and outputs pulse signals with different duty cycles based on the battery voltage differential and power differential to control the resistor for balanced discharge. Due to the different voltage differentials between batteries, the pulse duty cycles also vary, resulting in different battery discharge powers. Compared with traditional passive balancing, this design can more accurately control the power of the balancing resistor, making the balancing time of each battery more consistent, thereby improving balancing efficiency. In addition, in traditional passive resistor balancing, the resistor continuously discharges at maximum power, releasing a large amount of heat. However, in this embodiment, by adjusting the pulse duty cycle to control the resistor discharge, the heat release of the resistor is significantly reduced compared to traditional methods. Reduced heat release 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.

[0031] In some embodiments, as Figure 4 As shown, each battery discharge control module includes a field effect tube Q1, a power resistor R1 and a current limiting resistor R5, wherein 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 field effect tube and the positive electrode DC48 of the single battery. Each battery is independently configured with a power resistor. The power resistor is used to consume the energy of the single battery during the balanced discharge process, control the battery voltage balance, and achieve controllable discharge. In this embodiment, each field effect tube corresponds to a single battery, and the field effect tube adopts an N-channel metal-oxide semiconductor field effect transistor. The source of the field-effect transistor is connected to the negative electrode DC36 of the single cell, and the gate of the field-effect transistor is connected to the pulse width modulation signal output end of the battery balancing control module through the current-limiting resistor. The field-effect transistor is used to control the current between the single cell and the power resistor according to the pulse width modulation signal. The resistance value of the current-limiting resistor is 100Ω. The current-limiting resistor is used to limit the current flowing into the gate of the field-effect transistor to prevent the MOS transistor from being damaged by overcurrent and to suppress high-frequency oscillation. In this embodiment, the process of controlling the current between the single cell 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 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. 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.

[0032] 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 process of obtaining the equalization discharge power is specifically as follows: During the equalization discharge process of the lead-acid battery pack by using the pulse width modulation signal, the power resistor heat sink temperature value in the battery discharge control module is collected in real time; The power resistor heat sink temperature value is compared with a preset temperature threshold, and when the power resistor heat sink temperature value exceeds the preset temperature threshold, 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 heat sink temperature value and the preset temperature threshold and the preset temperature threshold; 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 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.

[0033] In the maintenance process of 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 radiator, effectively controlling the temperature of the resistor and radiator, avoiding safety hazards such as fire caused by overheating, and ensuring the safety and stability 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: In the formula, 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; T is the preset temperature threshold.

[0034] Therefore, the balancing discharge power of the power resistor in the current state is calculated as follows: In the formula, is the balancing discharge power of the power resistor in the current state; U is the single battery voltage, wherein the product of the adjusted pulse width modulation signal duty cycle 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. The resistance value of the power resistor.

[0035] In some embodiments, the process of obtaining the power resistor heat sink temperature value is specifically as follows: A negative temperature coefficient thermistor is mounted on the surface of the power resistor heat sink, and the thermistor is connected to a multi-vibration circuit composed of a timer, so that the oscillation frequency of the multi-vibration 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 through the timer, and the square wave signal output by the multi-vibration 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-vibration circuit 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, and the power resistor heat sink temperature value is obtained.

[0036] 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 6 The temperature measurement module includes a thermistor NTC1, an NE555 chip (i.e. an 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 value 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 value of the resistor R9 is 4.7 , the resistor R9 is used for current limiting to protect the base of the triode Q2 and prevent 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 value of the resistor R8 is 10 , the resistance R8 is the pull-up resistance for the NE555 timer, ensuring the normal work of the chip; the reset pin 4 of the NE555 timer is enabled by default, and the thermistor and the NE555 timer in the embodiment form a multivibrator, converting the resistance value change of the thermistor into frequency change of the square wave.

[0037] In the embodiment, the capacitor C12 is used to filter the high-frequency noise introduced by the lead of the thermistor and stabilize the oscillation signal, the capacitor C12 is set to 0.047 μF in the embodiment, and the capacitance values of the capacitor C13, the capacitor C14 and the capacitor C15 are all set to 0.01 μF; the capacitor C13, the capacitor C14 and the capacitor 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 work of the NE555 timer; the base of the triode Q2 is connected to the output pin of the NE555 timer through the resistance R9, the emitter is connected to the ground, and the collector is connected to the input end (the anode of the light-emitting diode) of the optocoupler OC2; the triode Q2 is used to amplify the square wave signal output by the NE555 timer and drive the optocoupler to work, specifically, the triode Q2 acts as a switch tube, when the NE555 timer outputs a high level, the triode Q2 is turned on, and the square wave signal is transmitted to the input end of the optocoupler OC2 through the resistance R9; when the NE555 timer outputs a low level, the triode Q2 is cut off, and the square wave signal stops being transmitted; the optocoupler OC2 adopts 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 triode Q2, the cathode of the light-emitting diode is connected to the 5V power supply VCC5 through the resistance R7, the collector of the photosensitive triode of the output end of the optocoupler OC2 is connected to the battery discharge control module through the resistance R14, the collector of the photosensitive triode of the output end of the optocoupler OC2 is also connected to the ground through the resistance R10, and the emitter of the photosensitive triode is connected to the 3V power supply VCC3V3; the optocoupler OC2 realizes electrical isolation and transmits the frequency signal to the battery discharge control module; the resistance R7 is used to limit the working current of the optocoupler light-emitting diode and prevent overcurrent damage; the resistance R14 is a pull-up resistance, ensuring 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 triode Q2 to be turned on after current limiting through the resistance R9, the triode Q2 amplifies the square wave signal output by the NE555 timer, at this time, the optocoupler light-emitting diode is lighted, the output end of the optocoupler generates an isolated square wave signal, which is transmitted to the battery discharge control module after being pulled up by the resistance 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.

[0038] As Figure 7As shown, the embodiment is in the power resistor 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, its 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 two falling edges of the square wave signal, then calculates the time interval of the two falling edges, obtains the square wave period, and further calculates the square wave frequency output by the multi-vibrator, according to the square wave frequency output by the multi-vibrator, the real-time resistance value of the thermistor is obtained by using the relationship model between the square wave frequency and the resistance value of the thermistor, 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: 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.

[0039] 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, and obtains the temperature value of the power resistor radiator, so as to realize the conversion of the temperature signal into the frequency signal with strong anti-interference ability, and ensure 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: In the formula, t is the ambient temperature value; It is the logarithmic function with base 10; B is the material constant of the thermistor, and in the embodiment, the material constant of the thermistor is set to 3950K; B is the material constant of the thermistor, and in the embodiment, the material constant of the thermistor is set to 3950K; B is the material constant of the thermistor, and in the embodiment, the material constant of the thermistor is set to 3950K.

[0040] 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 resistance and instead uses PWM wave to match MOS tube to control resistance discharge equalization. According to the difference in SOC of each battery, the discharge power of the resistance 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 resistance, the embodiment significantly reduces the discharge resistance power and heat generation, greatly improves the equalization efficiency, and provides more accurate and efficient equalization management strategy for the battery pack.

[0041] In some embodiments, the equalization maintenance device for online monitoring of lead-acid battery packs provided by the embodiment further includes a power module that 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 uses a URB4805YMD10W isolation power converter that has high voltage conversion capability and good isolation performance, can convert the input 48V DC voltage to 5V DC voltage, and provides stable power supply for subsequent circuits. At the same time, its isolation characteristics can effectively reduce the interference between different circuits and ensure the electrical safety of the system. The 5VDC-to-3VDC unit uses an AMS-1117 power converter that has low noise and high precision, can further convert 5V DC voltage to 3V DC voltage, and meets the needs of some chips and circuits in the device that require lower voltage, so as to ensure that all modules in the device can work normally in a suitable voltage environment.

[0042] 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.

[0043] 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 the discharging process after 7 hours, while battery 22 ends the discharging process after 4 hours. Moreover, the final voltage is less than 10.8V (usually, the discharge end voltage of a normal performance battery 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.

[0044] 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 pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of battery;Battery discharge control module adjusts the equalization discharge power of power resistor according to the pulse width modulation signal and the temperature value of power resistor radiator obtained in advance during the charge-discharge process of lead-acid battery pack, and the equalization discharge control is carried out to lead-acid battery pack single battery 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.

[0045] 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.

[0046] In one embodiment, as shown in Figure 10 The embodiment of the present application provides a kind of equalization maintenance method of lead-acid battery pack online monitoring, the method comprises the following steps: S1. non-contact measurement is carried out to lead-acid battery pack charge-discharge current, and the state of charge of single battery is calculated by Kalman filtering and ampere-hour integration method according to the charge-discharge current of lead-acid battery pack, and the remaining capacity of battery is obtained; S2. the voltage of lead-acid battery pack single battery is measured by utilizing 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 pulse width modulation signal is modulated according to the voltage difference and the difference of the remaining capacity of battery; 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; 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.

[0047] The specific limitation of the equalization maintenance method for the online monitoring of the lead-acid battery can refer to the above limitation 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 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.

[0048] The embodiment of the present application provides an equalization maintenance method for 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 cell; 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 monitored exceeds the preset voltage difference threshold or the difference between the remaining capacities of different monomer cells exceeds the preset power difference threshold, the pulse width modulation signal is modulated according to the voltage difference and the difference between the remaining capacities; 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.

[0049] The above embodiments only express several preferred embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, which should also 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. A lead-acid battery pack online monitoring and maintenance device, characterized in that: include: The battery online monitoring module is used to perform non-contact measurement of the charge and discharge current of the lead-acid battery pack using a Hall current sensor, and calculate the state of charge of the single cell based on the charge and discharge current of the lead-acid battery pack through Kalman filtering and ampere-hour integration method to obtain the battery remaining capacity; A battery balancing control module is configured to measure the voltage of a single cell of a lead-acid battery pack using a voltage-dividing resistor method, and when it is detected that the voltage difference between the highest voltage and the lowest voltage of a single cell of the lead-acid battery pack exceeds a preset voltage difference threshold or the difference in the remaining capacity of different single cells exceeds a preset power difference threshold, modulate and output a pulse width modulation signal according to the voltage difference and the difference in the remaining capacity of the battery; The battery discharge control module is used to control the balanced discharge power of the power resistor according to the pulse width modulation signal and the pre-acquired temperature value of the power resistor heat sink during the charge and discharge process of the lead-acid battery pack, and to control the balanced discharge of the single cells of the lead-acid battery pack by using the balanced discharge power so that the balancing end time of all single cells of the lead-acid battery pack is consistent.

2. The lead-acid battery online monitoring and maintenance device according to claim 1, characterized in that: The process of acquiring the pulse width modulation signal is specifically as follows: During the charge and discharge process of the lead-acid battery pack, the battery voltage signal of each single cell in the lead-acid battery pack is collected in real time; If it is detected that the battery voltage signal is greater than a preset maximum battery voltage, the battery voltage signal is divided by a voltage-dividing resistor network based on a circuit voltage-dividing principle to obtain an initial voltage signal; Performing analog-to-digital conversion on the initial voltage signal to obtain a voltage measurement value of each single cell, and calculating a voltage difference between a maximum voltage and a minimum voltage of each single cell based on the voltage measurement value; comparing the voltage difference with a preset pressure difference threshold, and when the voltage difference exceeds the preset pressure difference threshold, calculating a pressure difference duty cycle based on a proportional relationship between the voltage difference and the preset pressure difference threshold and the preset pressure difference threshold; comparing the battery remaining capacity difference with a preset power difference threshold, and when the battery remaining capacity difference exceeds the preset power difference threshold, calculating a power difference duty cycle based on a proportional relationship between the difference between the battery remaining capacity difference and the preset power difference threshold and the preset power difference threshold; The maximum value of the voltage difference duty cycle and the charge difference duty cycle is used as the actual optimal duty cycle, and a pulse width modulation signal of a corresponding pulse width is generated according to the actual optimal duty cycle.

3. The lead-acid battery online monitoring and maintenance device according to claim 2, characterized in that: The voltage difference duty cycle and the charge difference duty cycle should both be between a preset minimum duty cycle threshold and a preset maximum duty cycle threshold.

4. The lead-acid battery online monitoring and maintenance device according to claim 3, characterized in that: If it is monitored that the voltage difference duty cycle or the battery charge difference duty cycle is less than the minimum duty cycle threshold, the minimum duty cycle threshold is used for balancing control, and the voltage difference duty cycle is constantly set to the minimum duty cycle threshold or the battery charge difference duty cycle is constantly set to the minimum duty cycle threshold until the voltage difference is less than the preset voltage difference threshold and the battery remaining capacity difference is less than the preset battery charge difference threshold, and the corresponding pulse width modulation signal is stopped from being output to terminate the balancing discharge operation.

5. The lead-acid battery online monitoring and maintenance device according to claim 1, characterized in that: The process of obtaining the balanced discharge power is specifically as follows: In the process of performing balanced discharge on the lead-acid battery pack 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; Comparing the temperature value of the power resistor heat sink with a preset temperature threshold, and generating a duty cycle adjustment trigger signal when the temperature value of the power resistor heat sink exceeds the preset temperature threshold; In response to the duty cycle adjustment trigger signal, obtaining a duty cycle adjustment coefficient according to a proportional relationship between a difference between a temperature value of the power resistor heat sink and the preset temperature threshold and the preset temperature threshold; Dynamically adjusting the duty cycle of the pulse width modulation signal according to the duty cycle adjustment coefficient to obtain an adjusted duty cycle of the pulse width modulation signal; The equivalent voltage value across the power resistor is calculated based on the adjusted duty cycle of the pulse width modulation signal and the battery voltage signal of the single battery; The current value flowing through the power resistor is calculated according to the equivalent voltage value and the resistance value of the power resistor, and the balanced discharge power of the power resistor in the current state is calculated according to the current value flowing through the power resistor and the resistance value of the power resistor.

6. The lead-acid battery online monitoring and maintenance device according to claim 5, characterized in that: The specific process of obtaining the temperature value of the power resistor radiator is as follows: A thermistor with a negative temperature coefficient is mounted on the surface of a power resistor heat sink, and the thermistor is connected to a multivibrator circuit formed by a timer, so that the oscillation frequency of the multivibrator circuit changes with the resistance value of the thermistor; The timer converts the resistance change of the thermistor into the frequency change of the square wave output by the oscillation circuit, and collects the square wave signal output by the multivibrator circuit at a preset counting frequency; By continuously capturing the time difference between two falling edges of the square wave signal, the square wave period is obtained, and the square wave frequency output by the multivibrator is calculated based on the square wave period; According to the square wave frequency, the real-time resistance value of the thermistor is inferred using a relationship model between the square wave frequency and the thermistor resistance value; The resistance-temperature characteristic relationship model of the thermistor is used to convert the real-time resistance of the thermistor into a corresponding ambient temperature value to obtain the temperature value of the power resistor heat sink.

7. The lead-acid battery online monitoring and maintenance device according to claim 2, characterized in that: The voltage-dividing resistor network consists of two voltage-dividing resistors, and the ratio of the resistance values ​​of the two voltage-dividing resistors is twice.

8. The lead-acid battery online monitoring and balancing maintenance device according to claim 1, characterized in that: Each of the battery discharge control modules 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 tube and the positive electrode of the single battery. The power resistor is used to consume the energy of the single battery during the balanced discharge process and control the battery voltage balance; The source of the field effect tube is connected to the negative electrode of the single cell, and the gate of the field effect tube is connected to the pulse width modulation signal output end of the battery balancing control module through the current limiting resistor; the field effect tube is used to control the current between the single cell 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.

9. The balancing maintenance device for online monitoring of a lead-acid battery pack according to claim 8, characterized in that: The process of controlling the current on and off 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 at a high level, the field effect transistor is controlled to be turned on, forming a discharge loop from the positive electrode of the single battery cell through the power resistor and the field effect transistor to the negative electrode of the single battery cell, so that the single battery cell connected to the field effect transistor is discharged evenly through the power resistor. During the balanced discharge process, the voltage of the single battery cell connected to the field effect transistor gradually decreases. When the voltage difference is less than the preset voltage difference threshold and the battery remaining capacity difference is less than the preset power difference threshold, the battery balancing control module is controlled to stop outputting the corresponding pulse width modulation signal and the field effect transistor is controlled to remain in the off state, and the balanced discharge process ends; When the pulse width modulation signal is at a low level, the field effect tube is controlled to be cut off, so that the discharge loop is disconnected, and the single battery connected to the field effect tube stops being balanced discharged through the power resistor.

10. A method for online monitoring and maintenance of a lead-acid battery pack, characterized in that: The method comprises the following steps: Conducting non-contact measurement of the charge and discharge current of the lead-acid battery pack, and calculating the state of charge of the single cell based on the charge and discharge current of the lead-acid battery pack by using Kalman filtering and ampere-hour integration method to obtain the remaining capacity of the battery; Measuring the voltage of the single cells of the lead-acid battery pack by using a voltage-dividing resistor method, and when it is detected that the voltage difference between the highest voltage and the lowest voltage of the single cells of the lead-acid battery pack exceeds a preset voltage difference threshold or the difference in the remaining capacity of different single cells exceeds a preset power difference threshold, modulating and outputting a pulse width modulation signal 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 pack, the balanced 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 heat sink; The balanced discharge power is used to control the balanced discharge of the single cells of the lead-acid battery group, so that the balancing end time of all the single cells of the lead-acid battery group is consistent.

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