WO2022002122A1 - 电池均流控制方法及电池均流控制系统 - Google Patents

电池均流控制方法及电池均流控制系统 Download PDF

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Publication number
WO2022002122A1
WO2022002122A1 PCT/CN2021/103511 CN2021103511W WO2022002122A1 WO 2022002122 A1 WO2022002122 A1 WO 2022002122A1 CN 2021103511 W CN2021103511 W CN 2021103511W WO 2022002122 A1 WO2022002122 A1 WO 2022002122A1
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Prior art keywords
battery
current
battery string
voltage
string
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PCT/CN2021/103511
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English (en)
French (fr)
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尹韶文
尹雪芹
景剑飞
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比亚迪股份有限公司
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Priority to EP21831784.0A priority Critical patent/EP4175108A4/en
Publication of WO2022002122A1 publication Critical patent/WO2022002122A1/zh
Priority to US18/090,390 priority patent/US20230155377A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014—Circuits for equalisation of charge between batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/106—Parallel operation of dc sources for load balancing, symmetrisation, or sharing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3835—Arrangements for monitoring battery or accumulator variables, e.g. SoC involving only voltage measurements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/102—Parallel operation of dc sources being switching converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00306—Overdischarge protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering

Definitions

  • the present disclosure relates to the technical field of battery production, and in particular, to a battery current sharing control method and a battery current sharing control system.
  • the present disclosure provides a battery current sharing control method and a battery current sharing control system to solve problems such as large capacity loss and battery deterioration caused by uneven current sharing of some battery strings in at least two parallel battery strings.
  • the present disclosure provides a battery current sharing control method, which is applied to a battery current sharing control system.
  • the battery current sharing control system is provided with a plurality of parallel battery string branches, and the battery string branches are provided with a battery string and a battery connected to the battery.
  • the current sharing DCDC converters connected in series with the battery strings including:
  • the current sharing DCDC converter is adjusted so that the output current of the battery string branch is the target current, so as to realize the current sharing control of the battery strings .
  • the battery current sharing control method before the collection of the measured current of the battery strings corresponding to each of the battery strings, the battery current sharing control method further includes:
  • the current sharing DCDC converter is adjusted so that the output voltage of the battery string branch is the target voltage, so as to realize the voltage sharing control of the battery string.
  • the determining the target voltages of all the battery string branches includes:
  • the average voltage value of the measured voltages of the battery strings corresponding to all the battery strings is determined as the target voltage of all the battery string branches;
  • the voltage of the bus bars connected to the plurality of the battery string branches is determined as the target voltage of all the battery string branches.
  • the current sharing DCDC converter is adjusted based on the target voltage and the measured voltage of the battery string, so that the output voltage of the battery string branch is the target voltage, so as to realize the voltage sharing control of the battery string, include:
  • the duty cycle of the current sharing DCDC converters is adjusted so that the output voltage of the battery string branch is the target voltage, and the battery string is realized. pressure equalization control.
  • the battery current sharing control method before the collection of the measured current of the battery strings corresponding to each of the battery strings, the battery current sharing control method further includes:
  • all the branches of the battery strings are controlled to be connected to the bus in parallel.
  • the battery current sharing control method further includes:
  • the current capacity of the battery string corresponding to any one of the battery string branches is not between the lower limit capacity of the battery string and the upper limit capacity of the battery string, disconnect the battery string branch from the busbar, and repeat the execution The collection of the measured voltage of the battery strings corresponding to each of the battery strings.
  • determining the target currents of all the battery strings based on the measured currents of the battery strings corresponding to all the battery strings including:
  • the average current of the measured currents of the battery strings corresponding to all the battery strings is taken as the target current of all the battery strings;
  • the current-sharing DCDC converter is adjusted based on the measured currents of the battery strings corresponding to all the battery strings and the target current, so that the output current of the battery string branch is the target current, thereby achieving Current sharing control of battery strings, including:
  • the measured current and the target current of all the battery strings corresponding to the battery strings are calculated to obtain the current-sharing voltage correction corresponding to the current-sharing DCDC converters connected in series with each of the battery strings.
  • the duty cycle of the current-sharing DCDC converters is adjusted so that the output current of the battery string branch is the target current, so as to realize the battery string of current sharing control.
  • the present disclosure provides a battery current sharing control system, comprising a monitoring module and a plurality of battery string branches arranged in parallel on a bus bar, the battery string branches including a battery string and a current sharing DCDC converter connected to the battery string , the monitoring module is connected to the battery string and the current sharing DCDC converter, and is used for collecting battery string status information of the battery string branch, and adjusting the current sharing DCDC converter based on the battery string status information duty cycle to achieve current sharing control.
  • the battery current sharing control system further includes a current sharing power supply; the current sharing DCDC converter is a non-isolated DCDC converter connected to the current sharing power supply; the input end of the non-isolated DCDC converter is connected to the The current sharing power supply is connected; the output end of the current sharing DCDC converter is connected with the battery string and the bus bar.
  • the current sharing DCDC converter is an isolated DCDC converter; the input end of the isolated DCDC converter is connected to the battery string; the output end of the isolated DCDC converter is connected to the battery string and the battery string The busbars are connected.
  • the duty cycle of the current sharing DCDC converter is adjusted based on the measured voltage of the battery string corresponding to each battery string and the target voltage corresponding to all battery strings, so that the battery string
  • the output voltage of the branch circuit is the target voltage, which realizes the voltage equalization control of the battery string, and can realize the purpose of parallel connection without inrush current.
  • the duty cycle of the current sharing DCDC converter is adjusted so that the output current of the battery string branch is the target current , realize the current sharing control of the battery string, realize the current sharing control, reduce the capacity loss of the battery string caused by parallel connection, improve the battery capacity utilization rate of the battery string, and reduce the energy loss caused by the internal circulation at the end of charge and discharge, It helps to ensure the service life of parallel battery strings and the safety of battery strings during charging and discharging.
  • a battery string branch is formed in series with the battery string and the current sharing DCDC converter, the monitoring module is used to collect the battery string status information of the battery string branch, and the battery string status information is processed to control the battery string status information.
  • the current sharing DCDC converter adjusts its duty cycle to adjust the output current of the battery string, so that the parallel battery string branches can achieve the purpose of current sharing, reduce the capacity loss of the battery string caused by the parallel connection, and improve the performance of each battery string.
  • the utilization rate of battery capacity can be reduced, and the energy loss caused by internal circulation at the end of charging and discharging can be reduced, which helps to ensure the service life of each battery string and the safety of each battery string during the charging and discharging process.
  • FIG. 1a-1b are schematic flowcharts of a battery current sharing control method according to an embodiment of the present disclosure
  • FIG. 2 is another schematic flowchart of a battery current sharing control method according to an embodiment of the present disclosure
  • FIG. 3 is another schematic flowchart of a battery current sharing control method according to an embodiment of the present disclosure.
  • FIG. 4 is a schematic circuit diagram of a battery current sharing control system according to an embodiment of the present disclosure.
  • FIG. 5 is another schematic circuit diagram of a battery current sharing control system in an embodiment of the present disclosure.
  • FIG. 6 is another schematic circuit diagram of a battery current sharing control system according to an embodiment of the present disclosure.
  • Spatial relational terms such as “under”, “below”, “below”, “under”, “above”, “above”, etc., may be used herein for convenience of description This describes the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, then elements or features described as “below” or “beneath” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary terms “below” and “under” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
  • An embodiment of the present disclosure provides a battery current sharing control method, the battery current sharing control method is applied to a battery current sharing control system, the battery current sharing control system is provided with a plurality of parallel battery string branches, and the battery string branches are provided with batteries string and a current sharing DCDC converter in series with the battery string.
  • the current sharing DCDC converter is a bidirectional DCDC converter, that is, a DCDC converter that can realize boost control and buck control.
  • the battery current sharing control system further includes a monitoring module connected to the battery string and the current sharing DCDC converter, the monitoring module includes a sampling circuit and a controller connected to the sampling circuit, and the sampling circuit is connected to the battery string and the current sharing DCDC converter.
  • the battery string status information includes but is not limited to the measured voltage of the battery string. , The measured current of the battery string, the current capacity of the battery string, the measured voltage of the converter, the measured current of the converter and the bus voltage, etc.
  • the controller is also connected to the current-sharing DCDC converter, which is used to comprehensively calculate and judge the status information of the battery string to form a PWM signal, which can be used to control the current-sharing DCDC converter to adjust its duty cycle and adjust each battery.
  • the output current of the string to achieve the purpose of current sharing output.
  • the battery current sharing control method includes the following steps:
  • S11 Collect the measured voltage of the battery string corresponding to each battery string.
  • the measured voltage of the battery string refers to the voltage across the battery string collected in real time.
  • the controller controls all the switch contactors 40 in the branch circuits of the battery strings to be disconnected
  • the measured voltages of the battery strings corresponding to each battery string are collected in real time through the sampling circuit, and the collected voltages are collected in real time.
  • the measured voltage of the battery string corresponding to the battery string is fed back to the controller, so that the controller can obtain the measured voltage of the battery string before all the battery strings are connected to the bus in parallel.
  • the target voltage is a desired voltage to be adjusted for the battery string branch formed by the battery string and the current sharing DCDC converter connected in series with it.
  • the maximum voltage value in the measured voltages of the battery strings corresponding to all the battery strings and the voltage values within the allowable error range thereof may be determined as the target voltages of all the battery string branches.
  • the average voltage value of the measured voltages of the battery strings corresponding to all the battery strings and the voltage values within the allowable error range thereof may be determined as the target voltages of all the battery string branches.
  • determining the target voltages of all the battery string branches includes: determining the voltages of the bus bars connected to the plurality of battery string branches as the target voltages of all the battery string branches.
  • the voltages of the bus bars connected to the plurality of battery string branches and the voltage values within the allowable error range thereof may be determined as the target voltages of all the battery string branches.
  • the controller can form a PWM signal for controlling the current-sharing DCDC converters connected in series with the battery strings according to the target voltage and the measured voltage of the battery strings of each battery string, and output the PWM signal to the current-sharing DCDC converters , adjust the duty cycle of the current sharing DCDC converter so that the output voltage of the battery string branch is the target voltage, so as to realize the conversion of the battery string and the current sharing DCDC in series before the battery string branch is connected to the bus in parallel
  • the output voltage of the battery string branch formed by the controller follows the target voltage to realize the voltage equalization control before the parallel connection of the battery string and branch, which helps to ensure that the subsequent parallel connection of the battery series can achieve the purpose of no inrush current parallel connection.
  • step S13 that is, based on the target voltage and the measured voltage of the battery string, adjust the current sharing DCDC converter to make the output voltage of the battery string branch be the target voltage, and realize the voltage sharing control of the battery string, which specifically includes the following steps :
  • the correction value of the voltage equalization voltage is the expected voltage of each current-sharing DCDC converter that needs to be adjusted before the control battery string branch is connected to the bus in parallel, so as to realize the battery formed by each current-sharing DCDC converter and its series-connected battery string.
  • the output voltage of the series branch follows the target voltage to achieve the purpose of voltage equalization control.
  • the controller uses the preset calculation formula for the correction value of the equalizing voltage to calculate the collected target voltage and the measured voltage of the battery strings at both ends of each battery string to obtain
  • the correction value of the sharing voltage corresponding to the current sharing DCDC converter connected to each battery string can be understood as the expected voltage of the current sharing DCDC converter that needs to be controlled before the branch of the battery string is connected to the bus in parallel.
  • the voltage-sharing voltage correction value adjusts the duty cycle of the current-sharing DCDC converter. Therefore, the calculation formula of the voltage-sharing voltage correction value corresponding to the target voltage acquisition method needs to be used to measure the target voltage and the measured voltage of the battery string corresponding to each battery string. The calculation is performed to ensure that the obtained correction value of the voltage-sharing voltage is more reasonable, so as to ensure that the adjustment of the duty cycle of the subsequent current-sharing DCDC converter is more convenient.
  • the correction value of the balancing voltage U obj i corresponding to the current sharing DCDC converter connected in series with the ith battery string can be obtained. .
  • the correction value of the balancing voltage U obj i corresponding to the current sharing DCDC converter connected in series with the ith battery string can be obtained. .
  • the equalizing voltage correction value U obj i ⁇ 0 Since the target voltage U dcStd is the minimum voltage value, at this time, the equalizing voltage correction value U obj i ⁇ 0, so that the current equalizing DCDC converter needs to be used to step down the output voltage of the corresponding battery string branch to the target voltage.
  • the voltage correction value of each battery string branch can be determined independently according to the difference between the measured voltage U bat i of the battery string and the target voltage U dcStd, and then the output voltage of the corresponding battery string branch is calculated by the current sharing DCDC converter. Buck or boost to target voltage. It can be understood that the step-down or step-up here depends on the positive or negative value of the equalizing voltage correction value U obj i.
  • the maximum voltage value in the measured voltages U bat i of n battery strings is determined as the target voltage as an illustration, and other embodiments are similar to the above-mentioned embodiments, and will not be further explained in this application.
  • the current- sharing power supply is controlled to start, and the constant DC output voltage is U dcHigh ;
  • the monitoring module before the battery strings with different initial capacities and different internal resistances are connected in parallel, the monitoring module firstly controls the switch contactors connected in series with the i-th battery string to close, and collects the corresponding data of the i-th battery string.
  • the collected measured battery string voltage and the determined target voltage of each battery string can be used, and then the voltage equalization voltage correction can be determined based on the target voltage and the measured voltage of the battery string. value, control the current-sharing DCDC converter to adjust its duty cycle according to the voltage-sharing voltage correction value, so as to achieve the purpose of adjusting the output current of each battery string to share the current, reduce the capacity loss caused by the parallel connection of the battery string, and avoid the internal Energy due to circulation.
  • the controller forms a PWM signal based on the correction value of the voltage-sharing voltage corresponding to each current-sharing DCDC converter, and outputs the PWM signal to the current-sharing DCDC converter to adjust the duty cycle of the current-sharing DCDC converter to Make the output voltage of the current sharing DCDC converter reach the desired correction value of the voltage sharing voltage, so that the output voltage of the battery string branch formed by the battery string and the current sharing DCDC converter in series follows the battery before the battery is connected in parallel.
  • the target voltage of the series and branch circuits realizes the voltage equalization control before the battery is connected in series and parallel, which helps to ensure that the parallel connection without inrush current can be realized when the subsequent batteries are connected in series and parallel.
  • the integral coefficient of the angle offset adjustment, s is the frequency domain, and the range of the angle offset Angle is 90° to 270°, so as to realize the adjustment of the work of each drive switch in the isolated DCDC converter based on the angle offset Angle, according to the equalizing voltage
  • the correction value U obj i adjusts the duty cycle of the ith isolated DCDC converter, so that the total voltage of the isolated DCDC converter and its series-connected battery string in all battery string branches (ie, the output voltage of the battery string branch) is
  • the target voltage U dcStd is to ensure that when all switch contactors are controlled to close so that the batteries are connected to the bus in series and parallel, parallel connection without inrush current can be achieved.
  • S14 Collect the measured current of the battery string corresponding to each battery string.
  • the measured current of the battery string is the current collected in real time from the branch of the battery string.
  • each current sharing DCDC converter still uses the target voltage for current sharing control, the current sharing output of each battery string branch cannot be guaranteed.
  • the current sharing control is also required to correct the output voltage of each current sharing DCDC converter, so as to ensure that each battery string branch can achieve current sharing output during the charging or discharging process.
  • the controller needs to adjust the current sharing DCDC converter based on the target voltage and the measured voltage of the battery string, so that the output voltage of the battery string branch is the target voltage, so as to realize the voltage sharing control of the battery string, so as to control the battery string to achieve no inrush current.
  • the measured current of the battery string corresponding to the battery string is collected in real time, so as to realize the current sharing control after the parallel connection of the battery string by using the measured current of the battery string.
  • S15 Determine the target currents of all battery strings based on the measured currents of the battery strings corresponding to all the battery strings.
  • the target current refers to the expected current that needs to be adjusted for the battery string branch formed by the battery string and the current sharing DCDC converter connected in series. Since the battery string branch includes the battery string and the current sharing DCDC converter connected in series, therefore, The target battery can be understood as the expected current of the battery string or the current-sharing DCDC converter.
  • step S15 that is, determining the target currents of all battery strings based on the measured currents of the battery strings corresponding to all the battery strings, including: based on the measured currents of the battery strings corresponding to all the battery strings, The average current is used as the target current for all strings.
  • the controller can calculate the average current of the measured current I bat i of the n battery strings, and determine the target current I obj i of the ith battery string, that is,
  • step S15 that is, determining the target currents of all battery strings based on the measured currents of the battery strings corresponding to all the battery strings, including: calculating a charge-discharge proportional coefficient based on the current capacity and charge-discharge current limit of the battery strings corresponding to all the battery strings ; Determine the target current of all battery strings based on the measured currents and charge-discharge proportional coefficients of the battery strings corresponding to all the battery strings.
  • I Discharge Rate_i is the discharge proportional coefficient of the ith battery string
  • SOC_i is the current battery capacity of the ith battery string
  • I Discharge Lim_i is the discharge current limit of the ith battery string
  • the charge is calculated scale factor I charge Rate_i, i.e. Among them, I charge Rate_i is the charging proportional coefficient of the ith battery string, SOC_i is the current battery capacity of the ith battery string, and I charge Lim_i is the charging current limit of the ith battery string.
  • I charge Rate_i is the charging proportional coefficient of the ith battery string
  • SOC_i is the current battery capacity of the ith battery string
  • I charge Lim_i is the charging current limit of the ith battery string.
  • the controller can form a PWM signal for controlling the current-sharing DCDC converter connected in series with the battery string according to the target current and the measured current of the battery string corresponding to each battery cell, and output the PWM signal to the current-sharing DCDC converter adjust the duty cycle of the current sharing DCDC converter, so that the output current of the battery string branch is the target current, so as to realize the conversion of the battery string and the current sharing DCDC connected in series after the battery string branch is connected to the bus in parallel.
  • the output current of the battery string branch formed by the controller follows the target current, that is, the current sharing control after the parallel connection of the battery string branch is realized, which helps to reduce the capacity loss caused by the parallel connection of the battery string, and avoid the energy caused by the internal circulation at the end of charge and discharge. .
  • the current sharing DCDC converter is adjusted so that the output current of the battery string branch is the target current, and the current sharing control of the battery strings is realized, including:
  • the correction value of the current-sharing voltage is the expected voltage of each current-sharing DCDC converter that needs to be adjusted after controlling the battery strings in parallel, so as to realize the output of the battery string branch formed by each current-sharing DCDC converter and its series-connected battery string. Current sharing control purpose.
  • the controller can call the pre-stored conversion logic for calculating the correction value of the current sharing voltage based on the measured current and target current of the battery strings.
  • the conversion logic processes the measured current and target current of the battery string, determines the current sharing voltage correction value corresponding to the current sharing DCDC converter connected in series with the battery string, and dynamically adjusts the output voltage of the current sharing DCDC converter based on the current sharing voltage correction value , to change the total voltage of the whole battery string branch to achieve the purpose of current sharing output of the battery string branch.
  • a corresponding PWM signal is formed based on the correction value of the current sharing voltage, and the duty cycle of the current sharing DCDC converter is adjusted by the PWM signal, so as to realize the control of the battery string and its series connection.
  • the purpose of current sharing control of the output current of the battery string branch formed by the current sharing DCDC converter For example, during the discharge process, the current sharing DCDC converter on the battery string branch with a larger measured current of the battery string reduces its output voltage, and the current sharing DCDC converter on the battery string branch with a small measured current of the battery string increases its output.
  • the current sharing DCDC converter on the battery string branch with a larger measured current of the battery string increases its output voltage, and the battery string with a smaller measured current of the battery string
  • the current sharing DCDC converter on the branch reduces its output voltage so that the output current of the battery string branch is the target current.
  • the controller needs to adjust the current sharing DCDC based on the current sharing voltage correction value and the voltage sharing voltage correction value corresponding to the current sharing DCDC converter.
  • the duty cycle of the converter makes the output current of the battery string branch the target current to realize the current sharing control of the battery string. That is, the difference between the correction value of the current sharing voltage and the correction value of the voltage sharing voltage corresponding to the current sharing DCDC converter needs to be determined as the current sharing voltage change value, and then the duty cycle of the current sharing DCDC converter is adjusted according to the current sharing voltage change value.
  • the output current of the battery string branch is set as the target current to realize the current sharing control of the battery string.
  • the current sharing power supply is mainly used to provide or absorb insufficient current or excess current in the battery string branch where each battery string is located, so as to achieve the purpose of current sharing.
  • the switch contactor C i connected in series with the ith battery string to close that is, after the battery strings are connected in parallel
  • the measured current I bat i of the battery string corresponding to the ith battery string is collected, where 1 ⁇ i ⁇ n,n is the number of battery strings, specifically the number of battery strings connected to the busbar in parallel in this example.
  • the average current of the measured current I bat i of the n battery strings is calculated, and the target current I obj i of the ith battery string is determined, that is, Alternatively, first calculate the corresponding charge-discharge proportional coefficient based on the current capacity of the battery string and the charge-discharge current limit of the i-th battery string, and then determine all the battery strings based on the measured current and charge-discharge proportional coefficient of the battery strings corresponding to all the battery strings.
  • the target current I obj i is the target current I obj i.
  • the current-sharing DCDC converter on the battery string branch with a larger measured current of the battery string reduces its output voltage
  • the current-sharing DCDC converter on the battery string branch with a small measured current of the battery string increases its output voltage.
  • the output voltage makes the output current of the battery string branch as the target current to realize the current sharing control of the battery string
  • the current sharing DCDC converter on the battery string branch with a larger measured current of the battery string increases its output voltage
  • the battery The current-sharing DCDC converter on the branch of the battery string with a smaller measured current reduces its output voltage, so that the output current of the battery string branch is the target current, and the current-sharing control of the battery string is realized.
  • each battery string branch can be dynamically adjusted to achieve current-sharing control.
  • the implementation process of the example shown in FIG. 6 is the same as the implementation process of the example shown in FIG. 5 , which is not described in detail here in order to avoid redundant description.
  • the duty cycle of the current sharing DCDC converter is adjusted based on the measured voltage of the battery string corresponding to each battery string and the target voltage corresponding to all battery strings.
  • the output voltage of the battery string branch is set as the target voltage, so as to realize the voltage equalization control of the battery string, and realize the purpose of parallel connection without inrush current.
  • the duty cycle of the current sharing DCDC converter is adjusted based on the measured current and target current of the battery strings corresponding to all battery strings, so that the output current of the battery string branch is the target current, and the current sharing control of the battery strings is realized.
  • the battery current sharing control method further includes:
  • S21 Collect the measured voltages of the branches corresponding to all battery strings in real time.
  • the measured voltage of the branch corresponding to the branch of the battery string can be understood as the sum of the measured voltage of the battery string of the battery string in the branch of the battery string and the measured voltage of the converter of the current sharing DCDC converter.
  • the controller first determines that the measured voltages of all the branches corresponding to the battery string branches are within the allowable error range of the target voltage. If the measured voltage of the branch circuit is within the allowable error range of the target voltage, when all the battery string branches are connected to the bus in parallel, the purpose of parallel connection without inrush current can be realized. At this time, if the measured voltages of the branches corresponding to all battery strings are within the allowable error range of the target voltage, it can be understood as a condition for controlling the parallel connection of all battery string branches to the bus, which can ensure that there is no impact of inrush current during the parallel connection process.
  • the battery current sharing control method further includes:
  • S31 Collect the current capacity of the battery string corresponding to all the battery string branches in real time, and determine whether the current capacity of the battery string is between the lower limit capacity of the battery string and the upper limit capacity of the battery string.
  • the current capacity of the battery string is the battery capacity of the battery string collected in real time.
  • the upper limit capacity of the battery string refers to the maximum capacity that the battery string can be charged or discharged normally.
  • the lower limit capacity of the battery string refers to the minimum capacity that the battery string can discharge or discharge normally.
  • the controller After collecting the current capacities of the battery strings corresponding to all the battery string branches, the controller first determines whether the current capacity of each battery string is between the lower limit capacity of the battery string and the upper limit capacity of the battery string. If the current capacity of the battery string is between the lower limit capacity of the battery string and the upper limit capacity of the battery string, at this time, it is determined that the branch circuit of the battery string can perform charging or discharging work normally, and no additional adjustment is required. If the current capacity of the battery string is not between the lower limit capacity of the battery string and the upper limit capacity of the battery string, it is determined that the battery string branch cannot be charged or discharged normally.
  • step S11 it is necessary to disconnect the battery string branch from the busbar, that is Control the switch contactor in the branch of the battery string to be disconnected, so that the current sharing DCDC converter is stopped, so as to avoid the current capacity of the battery string not between the lower limit capacity of the battery string and the upper limit capacity of the battery string. Affects the accuracy and reliability of the current sharing adjustment.
  • step S11 it is necessary to repeatedly perform the collection of the measured voltage of the battery string corresponding to each battery string.
  • the battery current sharing control system includes a monitoring module 10 and a plurality of battery string branches arranged in parallel on the bus bar.
  • the battery string branch includes a battery string 20 and a current sharing DCDC converter connected to the battery string 20 . 30.
  • the monitoring module 10 is connected to the battery string 20 and the current sharing DCDC converter 30, and is used to collect the battery string status information of the battery string branch, and adjust the duty cycle of the current sharing DCDC converter 30 based on the battery string status information, so as to achieve an equalization. flow control.
  • the battery string branch is a branch arranged in parallel on the busbar, and each battery string branch includes a battery string 20 and a current sharing DCDC converter 30 arranged in series.
  • the battery string 20 may be a single energy storage battery, or a plurality of energy storage battery strings 20 connected together.
  • the energy storage battery may be a battery that can be repeatedly charged and discharged, such as lithium iron phosphate and ternary lithium battery.
  • At least two battery strings 20 are arranged in parallel on the bus bar to form a battery module.
  • the battery current sharing control system can realize the current sharing adjustment of the output currents of at least two battery strings 20 in the battery module, so as to avoid some battery strings 20 being in an overcharged or overdischarged state for a long time, resulting in battery failure.
  • the inconsistency of at least two battery strings 20 in the group effectively avoids the problem of battery deterioration.
  • the current sharing DCDC converter 30 is a DCDC converter for adjusting the output current of each battery string 20. It is understandable that the current sharing DCDC converter 30 is a bidirectional DCDC converter, which can not only improve the battery string The output current of the battery string 20 can be reduced, and the output current of the battery string 20 can be reduced.
  • the current-sharing DCDC converters 30 and the battery strings 20 are connected in series to form a battery string branch. If the number of battery strings 20 in the battery module is n, then n current-sharing DCDC converters 30 are required to be connected to N battery strings 20 are connected in series to form n battery string branches, then each current-sharing DCDC converter 30 adjusts its own output voltage to ensure that the battery strings 20 in each battery string branch during the charging and discharging process share the current output the goal of.
  • each battery string branch further includes a switch contactor 40 for controlling whether the battery string branch is connected to the bus bar.
  • the switch contactor 40 is a switch connected to the battery string 20 for controlling whether the battery string 20 is connected to the bus bar.
  • each current sharing DCDC converter 30 is connected in series with a battery string 20 and a switch contactor 40 to form a battery string branch, and the switch contactor 40 is disposed on the battery string branch for controlling the battery string branch Whether it is connected to the bus.
  • the monitoring module 10 is a module in the battery current sharing control system used to realize the monitoring processing function.
  • the monitoring module 10 pre-stores a current sharing control program for implementing the monitoring processing function, and the monitoring module 10 performs processing by executing the current sharing control program to control the current sharing DCDC converter 30 connected in series with the battery string 20 to adjust the The duty cycle is adjusted to adjust the output current of each battery string 20 , so as to achieve the purpose of current sharing output.
  • the monitoring module 10 includes a sampling circuit and a controller connected to the sampling circuit.
  • the sampling circuit is connected to the battery string 20 and the current sharing DCDC converter 30, and is used for collecting the battery string status information of the battery string branch where the battery string 20 and the current sharing DCDC converter 30 are located, and feeding back the battery string status information to the controller , the battery string status information includes but is not limited to the measured voltage of the battery string, the measured current of the battery string, the current capacity of the battery string, the measured voltage of the converter, the measured current of the converter, and the bus voltage.
  • the controller is also connected to the current-sharing DCDC converter 30 for comprehensive calculation and judgment processing of the battery string status information to form a PWM signal, which can be used to control the current-sharing DCDC converter 30 to adjust its duty cycle and adjust The output current of each battery string 20 can achieve the purpose of current sharing output.
  • the controller is specifically a digital signal processor, that is, a DSP.
  • a current sharing DCDC converter 30 is connected in series on each battery string 20 to form a battery string branch, and the monitoring module 10 is connected to the battery strings 20 and the current sharing
  • the DCDC converters 30 are connected to each other, and the battery string status information of the battery string branch can be collected, and then the battery string status information can be comprehensively calculated and judged to form a PWM signal.
  • the empty ratio is used to adjust the output current of the battery strings 20 to achieve current sharing, avoid the problem caused by inconsistent output currents of at least two battery strings 20 during the charging and discharging process, improve the battery capacity utilization rate, and help ensure the battery model.
  • each battery string branch is also provided with a switch contactor 40
  • the switch contactor 40 is connected to the controller and is controlled by the controller, that is, the controller can control the switch contactor 40 on the battery string branch according to the actual situation It is closed or disconnected to connect the branch of the battery string where the battery string 20 is located to the bus, and then execute the corresponding current sharing control program, which helps to ensure the service life of each battery string 20 in the battery module and ensure that each battery The safety of the string 20 during charging and discharging.
  • a battery string branch is formed by connecting the battery string 20 and the current sharing DCDC converter 30 in series, and the monitoring module 10 is used to collect the battery string status information of the battery string branch.
  • the string status information is processed, and then the current sharing DCDC converter 30 is controlled to adjust its duty cycle, so as to adjust the output current of the battery string 20, so that the parallel battery string branches can achieve the purpose of current sharing and reduce the battery string caused by parallel connection.
  • 20 capacity loss so as to improve the battery capacity utilization rate of each battery string 20 and reduce the energy loss caused by internal circulation at the end of charging and discharging, which helps to ensure the service life of each battery string 20 and ensure the charging and discharging of each battery string 20. safety in the process.
  • the non-isolated DCDC converters 31 are arranged between the battery strings 20 and the bus bars to achieve current sharing, that is, a plurality of battery strings 20 connected in parallel are connected to one side of the non-isolated DCDC converters 31 . , the other side is connected to the bus, and the non-isolated DCDC converter 31 outputs a constant current, so that the currents of the multiple battery strings 20 are balanced.
  • the devices on both sides of the DCDC converter have a high withstand voltage level, which leads to high cost and easy damage.
  • the battery current sharing control system further includes a current sharing power supply 50; the current sharing DCDC converter 30 is a The non-isolated DCDC converter 31 connected to the current sharing power supply 50; the input terminal of the non-isolated DCDC converter 31 is connected to the current sharing power supply 50; the output terminal of the current sharing DCDC converter 30 is connected to the battery string 20 and the bus bar.
  • the first input terminal of the current sharing DCDC converter 30 is connected to the current sharing power supply 50, and the second input terminal is connected to the current sharing power supply 50; the first output terminal of the current sharing DCDC converter 30 is connected to the battery string 20, and the second output terminal connected to the bus bar; or, the first output end of the current sharing DCDC converter 30 is connected to the bus bar, and the second output end is connected to the battery string 20 .
  • the non-isolated DCDC converter 31 refers to a DCDC converter whose output GND is related to the output GND, and the non-isolated DCDC converter 31 can be two types of converters, boost and buck.
  • the current sharing power supply 50 is a power supply for realizing current sharing.
  • the current sharing power supply 50 is connected to the AC power supply through an AC contactor, for receiving the AC power input from the AC grid, and converting the AC power into DC power to provide the non-isolated DCDC converter 31 and the battery string 20, so that the battery String 20 completes charging and discharging operations.
  • the current sharing power supply 50 may use an uncontrolled rectifier source or a bidirectional direct current source (ie, ACDC).
  • the AC side of the current sharing power supply 50 is connected to the AC power grid, and the DC side is connected to the battery string 20 through the non-isolated DCDC converter 31 .
  • the first input terminal of the current sharing DCDC converter 30 is connected to the current sharing power supply 50, and the second input terminal is connected to the current sharing power supply 50; the first output terminal of the current sharing DCDC converter 30 is connected to the battery string 20, and the second input terminal is connected to the current sharing power supply 50; The two output ends are connected to the bus bar; or, the first output end of the current sharing DCDC converter 30 is connected to the bus bar, and the second output end is connected to the battery string 20 . As shown in FIG.
  • the first input terminal (ie the positive input terminal) and the second input terminal (ie the negative input terminal) of each non-isolated DCDC converter 31 are connected to the current sharing power supply 50; the first output terminal (ie the positive terminal) The output terminal) is connected to the battery string 20, the second output terminal (ie the negative output terminal) is connected to the busbar, or the first output terminal (ie the positive output terminal) is connected to the busbar, and the second output terminal (ie the negative output terminal), Connected to the battery string 20 .
  • the two input terminals of the non-isolated DCDC converter 31 are connected to the current sharing power supply 50 and are the high voltage input side; the two output terminals of the non-isolated DCDC converter 31 are respectively connected to the battery string 20 and the bus bar, which are the low voltage output side . Understandably, the high-voltage input side of all non-isolated DCDC converters 31 is connected to the current sharing power supply 50, and the low-voltage output side is connected to the battery string 20. In this way, it can be avoided that the non-isolated DCDC converter 31 is connected to the bus bar and the battery string 20 respectively.
  • a current sharing power supply 50 is used to connect at least two non-isolated DCDC converters 31 to provide energy required for the current sharing process to control the non-isolated DCDC converters 31 to achieve current sharing control; since the non-isolated DCDC converters 31
  • the input end of the DCDC converter 31 is connected to the current sharing power supply 50 to obtain the energy required for the current sharing, so that the non-isolated DCDC converter 31 can use a device with a lower withstand voltage level, which has strong reliability and is not easy to be damaged.
  • the non-isolated DCDC converter 31 includes a first resonant inductor L11 , a first driving power transistor Q11 , a second driving power transistor Q12 , a first reverse diode D11 , and a second reverse diode D11 .
  • the diode D12, the first energy storage capacitor C11 and the second energy storage capacitor 12; the first resonant inductor L11 and the first driving power tube Q11 are arranged in series between the first input end and the first output end; the first energy storage capacitor C11 One end is connected to the first resonant inductor L11 and the first driving power tube Q11, the other end is connected to the second input end and the second output end; one end of the second driving power tube Q12 is connected to the first driving power tube Q11 and the first output end , the other end is connected with the second input end and the second output end; one end of the second energy storage capacitor 12 is connected with the first driving power tube Q11 and the first output end, and the other end is connected with the second input end and the second output end;
  • the first reverse diode D11 is connected in reverse parallel with the first driving power transistor Q11; the second reverse diode D12 is connected reversely connected with the second driving power transistor Q12.
  • the first resonant inductance L11 is an inductance disposed in the non-isolated DCDC converter 31 , which can play a resonance role and help improve the efficiency of the DCDC conversion.
  • the first driving power transistor Q11 and the second driving power transistor Q12 are power transistors disposed on the non-isolated DCDC converter 31, and specifically, MOSFETs and IGBTs can be used.
  • the first driving power tube Q11 and the second driving power tube Q12 are both connected to the monitoring module 10 for complementary conduction under the control of the monitoring module 10; that is, the first driving power tube Q11 is turned on and the second driving power tube is turned on.
  • the power tube Q12 is turned off, the first driving power tube Q11 is turned off and the second driving power tube Q12 is turned on.
  • the inverse parallel connection between the first reverse diode D11 and the first driving power tube Q11 means that the first reverse diode D11 is connected in parallel with the first driving power tube Q11, and the current flowing through the first driving power tube Q11 and the current flowing through the first driving power tube Q11
  • the current of a reverse diode D11 is opposite, so that when the first driving power transistor Q11 is turned off, the first reverse diode D11 can play a freewheeling function.
  • the second reverse diode D12 and the second driving power transistor Q12 are inversely connected in parallel, which means that the second reverse diode D12 is connected in parallel with the second driving power transistor Q12, and the current flowing through the second driving power transistor Q12 is the same as the current flowing through the second driving power transistor Q12.
  • the current to the diode D12 is opposite, so that when the second driving power transistor Q12 is turned off, the second reverse diode D12 can play a freewheeling function.
  • the first energy storage capacitor C11 and the second energy storage capacitor 12 are capacitors disposed in the non-isolated DCDC converter 31 and used to store and release electrical energy during the charging and discharging process.
  • the monitoring module 10 after collecting the battery string status information, performs comprehensive calculation and judgment processing on the battery string status information to form a current sharing driving signal, and controls the first driving power tube connected to it based on the current sharing driving signal.
  • Q11 and the second driving power tube Q12 are turned on or off, and the PWM duty cycle is adjusted by PI to control the non-isolated DCDC converter 31 to adjust the output current of the corresponding battery string 20 to achieve the purpose of current sharing and avoid the charging and discharging process
  • the problem caused by the inconsistent current of each battery string 20 in the battery module can improve the utilization rate of battery capacity, help to ensure the service life of each battery string 20 in the battery module, and ensure the safety of each battery string 20 during charging and discharging.
  • the current sharing power supply 50 is connected to the non-isolated DCDC converter 31 to provide the energy required for the current sharing process to control the non-isolated DCDC converter 31 to achieve current sharing; since the non-isolated DCDC converter 31 does not need to be connected to the bus bar , in order to obtain the energy required for current sharing, so that the non-isolated DCDC converter 31 can use devices with lower withstand voltage levels, that is, devices such as inductors, capacitors, and power switches, which help reduce device costs and have strong reliability. And not easy to damage the advantage.
  • the current sharing DCDC converter 30 is an isolated DCDC converter 32 ; the input end of the isolated DCDC converter 32 is connected to the battery string 20 ; the output end of the isolated DCDC converter 32 is connected to the battery string 20 is connected to the bus bar.
  • the isolated DCDC converter 32 refers to a DCDC converter in which the output GND is independent of the input GND.
  • both the first input terminal and the second input terminal of the isolated DCDC converter 32 are connected to the battery string 20, and the first output terminal and the second output terminal of the isolated DCDC converter 32 are respectively connected to the battery string 20 and the bus bar,
  • the isolated DCDC converter 32 is controlled by the monitoring module 10 to adjust the output cells of the battery string 20, so as to control at least two The purpose of current sharing of the battery strings 20 .
  • the isolated DCDC converter 32 connected to each battery string 20 is connected to the monitoring module 10 , and under the control of the current sharing driving signal of the monitoring module 10 , the output current of each battery string 20 can be adjusted to realize parallel arrangement
  • the purpose of current sharing of at least two battery strings 20 is to reduce the capacity loss caused by parallel connection and the energy loss caused by internal circulation at the end of charging and discharging. Since the two input terminals of each isolated DCDC converter 32 are connected to the battery string 20 , the energy required for current sharing is provided through the battery string 20 , so that the voltage of the input terminal is relatively small, so that the isolated DCDC converter 32 can use a withstand voltage inside. Lower grade devices without the need for additional current sharing power supplies 50 can significantly reduce cost.
  • the battery string 20 is used as the current sharing power supply 50 required by the isolated DCDC converter 32 , when any one of the input end and the output end of the isolated DCDC converter 32 has an extreme short circuit condition, the other end will not be operated. Avoid fault spread, high reliability.
  • the first input end of the isolated DCDC converter 32 is connected to the battery string 20 , and the second input end is connected to the battery string 20 ; the first output end of the isolated DCDC converter 32 is connected to the battery string 20 , and the second input end is connected to the battery string 20 .
  • the output end is connected to the bus bar; or, the first output end of the isolated DCDC converter 32 is connected to the bus bar, and the second output end is connected to the battery string 20 .
  • the isolated DCDC converter 32 includes a high-frequency transformer T21, a second resonant inductor L21, a first bridge rectifier circuit, a second bridge rectifier circuit and a filter capacitor C21; the first bridge rectifier circuit is set at a high The primary side of the high-frequency transformer T21 is connected to the first input terminal and the second input terminal; the second bridge rectifier circuit is arranged on the secondary side of the high-frequency transformer T21 and is connected to the first output terminal and the second output terminal; The two resonant inductors L21 are arranged between the primary side of the high-frequency transformer T21 and the first bridge rectifier circuit; the filter capacitor C21 is arranged between the first output end and the second output end, and is connected in parallel with the second bridge rectifier circuit.
  • the first bridge rectifier circuit and the second bridge rectifier circuit are bridge rectifier circuits respectively arranged on the primary side and the secondary side of the high-frequency transformer T21. They are bridge structures formed by connecting four diodes, which can convert alternating current into Unidirectional pulsating direct current for rectification purposes.
  • the second resonant inductance L21 is an inductance disposed in the isolated DCDC converter 32 , which can play a resonant role and help improve the efficiency of the DCDC conversion.
  • the filter capacitor C21 is a capacitor arranged in the isolated DCDC converter 32 and can play a filtering role, and is mainly used to filter out the AC component in the unidirectional pulsating DC power.
  • the first bridge rectifier circuit and the second bridge rectifier circuit are both connected to the monitoring module 10 for processing according to the current sharing drive signal output by the monitoring module 10 to control the first bridge rectifier circuit and the first bridge rectifier circuit.
  • the closing or opening of each diode in the bridge rectifier circuit so as to adjust the duty cycle of the first bridge rectifier circuit and the second bridge rectifier circuit, so as to achieve the effect of boosting and reducing the voltage, so as to adjust each battery string 20 for the purpose of output current sharing.
  • the first bridge rectifier circuit is connected to the high-frequency transformer T21 through the first resonant inductor L11 , and the other end is connected to the battery string 20 for rectifying the current input by the battery string 20 .
  • the second bridge rectifier circuit is connected to the battery string 20 and the bus bar, and can input the rectified current to the battery string 20 to adjust the output current of the battery string 20 .
  • the first bridge rectifier circuit includes a first drive switch Q21 and a second drive switch Q22 connected to the first input terminal, and a third drive switch connected to the second input terminal.
  • the driving switch tube Q21 and the third driving switch tube Q23 are complementarily turned on; the second driving switch tube Q22 is connected with the fourth driving switch tube Q24, and the monitoring module 10 is connected with the second driving switch tube Q22 and the fourth driving switch tube Q24, using It is used to control the second driving switch tube Q22 and the fourth driving switch tube Q24 to conduct complementary conduction; one end of the primary side of the high-frequency transformer T21 is connected to the first driving switch tube Q21 and the third driving switch tube Q23 through the second resonant inductor L21, and the other One end is connected to the second drive switch tube Q22 and the fourth drive switch tube Q24; the second bridge rectifier circuit includes a fifth drive switch tube Q25 and a sixth drive switch tube Q26 connected to the first output end, and the second output end The connected seventh drive switch tube Q27 and the eighth drive switch tube Q28; the fifth drive switch tube Q25 and the seventh drive switch tube Q27 are connected, and the monitoring module 10 is connected with the fifth drive switch tube Q25 and the seventh drive switch tube Q27,
  • a reverse freewheeling diode and a filter capacitor C21 are connected in parallel with the sixth driving switch tube Q26, the seventh driving switch tube Q27 and the eighth driving switch tube Q28.
  • Q21, Q22, Q23 and Q24 form a first bridge rectifier circuit, which is arranged on the primary side of the high-frequency transformer T21 to isolate the high-voltage input side of the DCDC converter 32; the monitoring module 10 is connected to Q21, Q22, Q23 And Q24, Q21 and Q23 can be controlled to be complementary turned on, and Q22 and Q24 can be controlled to be complementary turned on, so that the duty ratio of each driving switch on the high-voltage input side of the isolated DCDC converter 32 is 50%.
  • Q25 , Q26 , Q27 and Q28 form a second bridge rectifier circuit, and the secondary side of the high-frequency transformer T21 is arranged on the low-voltage output side of the isolated DCDC converter 32 .
  • the monitoring module 10 is connected to Q25, Q26, Q27 and Q28, and is used to control the complementary conduction of Q25 and Q27, and control the complementary conduction of Q26 and Q28, so as to isolate the duty of each driving switch on the low-voltage output side of the DCDC converter 32
  • the ratio is 50%. It can be understood that the modulation signals of the driving switch on the high-voltage input side and the driving switch on the low-voltage output side of the isolated DCDC converter 32 are the same.
  • the angle difference between the switching tubes realizes the function of boosting or decreasing the voltage, so as to adjust the output current of the battery string 20 and achieve the purpose of current sharing.

Abstract

本公开涉及一种电池均流控制方法及电池均流控制系统。该方法包括：采集每个所述电池串对应的电池串实测电流；基于所有所述电池串对应的电池串实测电流，确定所有所述电池串的目标电流；基于所有所述电池串对应的电池串实测电流和所述目标电流，调节所述均流DCDC转换器，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制。该方法可实现减少因并联而导致电池串容量损失，提高电池串的电池容量利用率。

Description

电池均流控制方法及电池均流控制系统
相关申请的交叉引用
本公开要求于2020年06月30日提交的申请号为202010615141.X，名称为“电池均流控制方法及电池均流控制系统”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及电池生产技术领域，尤其涉及一种电池均流控制方法及电池均流控制系统。
背景技术
当前电池串并联接入母线时，由于电池串生产制造的不一致性和使用环境的原因，其容量、内阻、电压及自放电率均会存在一定的差异，在电池串充放电过程中，会导致部分电池串出现过充或过充现象，即并联的电池串不均流。随着电池串充放电循环次数的增加以及存储时间和温度等因素的影响，使得部分电池串长时间处于过充或过放状态，一方面会加剧电池串的不一致性，另一方面会逐步出现电池劣化问题，最终导致电池串均失去存储电能的能力。
公开内容
本公开提供一种电池均流控制方法及电池均流控制系统，以解决并联的至少两个电池串中部分电池串不均流所导致的容量损失大和电池劣化等问题。
本公开提供一种电池均流控制方法，应用于电池均流控制系统，所述电池均流控制系统设有多个并联的电池串支路，所述电池串支路上设有电池串和与所述电池串串联的均流DCDC转换器，包括：
采集每个所述电池串对应的电池串实测电流；
基于所有所述电池串对应的电池串实测电流，确定所有所述电池串的目标电流；
基于所有所述电池串对应的电池串实测电流和所述目标电流，调节所述均流DCDC转换器，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制。
可选地，在所述采集每个所述电池串对应的电池串实测电流之前，所述电池均流控制方法还包括：
采集每个所述电池串对应的电池串实测电压；
确定所有所述电池串支路的目标电压；
基于所述目标电压和所述电池串实测电压，调节均流DCDC转换器，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制。
可选地，所述确定所有所述电池串支路的目标电压，包括：
基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压中的最大电压值确定为所有所述电池串支路的目标电压；
或者，基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压中的最小电压值确定为所有所述电池串支路的目标电压；
或者，基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压的平均电压值确定为所有所述电池串支路的目标电压；
或者，将与多个所述电池串支路连接的母线的电压确定为所有所述电池串支路的目标电压。
可选地，所述基于所述目标电压和所述电池串实测电压，调节均流DCDC转换器，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制，包括：
采用与所述目标电压相对应的均压电压修正值计算公式，对所述目标电压以及每一个所述电池串对应的电池串实测电压进行计算，获取与每一所述电池串串联的均流DCDC转换器对应的均压电压修正值；其中，所述均压电压修正值计算公式为U obji＝U dcStd-U bati，U obji为均压电压修正值，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压；
基于每一所述均流DCDC转换器对应的均压电压修正值，调节所述均流DCDC转换器的占空比，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制。
可选地，在所述采集每个所述电池串对应的电池串实测电流之前，所述电池均流控制方法还包括：
实时采集所有所述电池串对应的支路实测电压；
若所有所述电池串对应的支路实测电压在所述目标电压的允许误差范围内，则控制所有所述电池串支路并联至母线上。
可选地，在所述控制所有所述电池串支路并联至母线上之后，所述电池均流控制方法还包括：
实时采集所有所述电池串支路对应的电池串当前容量，判断所述电池串当前容量是否在电池串下限容量和电池串上限容量之间；
若任一所述电池串支路对应的所述电池串当前容量不在所述电池串下限容量与所述电池串上限容量之间，则断开所述电池串支路与母线的连接，重复执行所述采集每个所述电池串对应的电池串实测电压。
可选地，所述基于所有所述电池串对应的电池串实测电流，确定所有所述电池串的目标电流，包括：
基于所有所述电池串对应的电池串实测电流，将所有所述电池串对应的电池串实测电流的平均电流作为所有所述电池串的目标电流；
或者，基于所有所述电池串对应的电池串当前容量和充放电电流限值计算充放电比例系数；基于所有所述电池串对应的电池串实测电流和所述充放电比例系数，确定所有所述电池串的目标电流。
可选地，所述基于所有所述电池串对应的电池串实测电流和所述目标电流，调节所述均流DCDC转换器，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制，包括：
采用均流电压修正值计算公式，对所有所述电池串对应的电池串实测电流和所述目标电流进行计算，获取与每一所述电池串串联的均流DCDC转换器对应的均流电压修正值；所述均流电压修正值计算公式为DaltaU obji＝(I bati-I obji)*(K p+K i/s)，DaltaU obji为第i个电池串的均流电压修正值，I bati为第i个电池串的电池串实测电流，I obji为第i个电池串的目标电流，K p为预先设置的比例系数，K i为预先设置的积分系数，s为频域；
基于每一所述均流DCDC转换器对应的均流电压修正值，调节所述均流DCDC转换器的占空比，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制。
本公开提供一种电池均流控制系统，包括监控模块和并联设置在母线上的多个电池串支路，所述电池串支路包括电池串和与所述电池串相连的均流DCDC转换器，所述监控模块与所述电池串和所述均流DCDC转换器相连，用于采集所述电池串支路的电池串状态信息，基于所述电池串状态信息调节所述均流DCDC转换器的占空比，实现均流控制。
可选地，所述电池均流控制系统还包括均流电源；所述均流DCDC转换器为与所述均流电源相连的非隔离DCDC转换器；所述非隔离DCDC转换器的输入端与所述均流电源相连；所述均流DCDC转换器的输出端与所述电池串和所述母线相连。
可选地，所述均流DCDC转换器为隔离DCDC转换器；所述隔离DCDC转换器的输入端与所述电池串相连；所述隔离DCDC转换器的输出端与所述电池串和所述母线相连。
上述电池均流控制方法中，在电池串并联之前，基于每一电池串对应的电池串实测电压和所有电池串对应的目标电压，调节均流DCDC转换器的占空比，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制，可实现无冲击电流并联目的。在电池串并联之后，基于所有所述电池串对应的电池串实测电流和所述目标电流，调节均流DCDC转换器的占空比，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制，实现均流控制，减少因并联而导致的电池串的容量损失，以提高电池串的电池容量利用率，并可减少充放电结束时内部环流导致的能量损耗，有助于保障并联电池串的使用寿命，保障电池串充放电过程中的安全性。
上述电池均流控制系统中，在电池串与均流DCDC转换器串联形成一电池串支路，利用监控模块采集电池串支路的电池串状态信息，通过对电池串状态信息进行处理，进而控制均流DCDC转换器调节其占空比，实现进行调节电池串的输出电流，使并联的电池串支路实现均流目的，减少因并联而导致的电池串的容量损失，以提高各个电池串的电池容量利用率，并可减少充放电结束时内部环流导致的能量损耗，有助于保障各个电池串的使用寿命，保障各个电池串充放电过程中的安全性。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对本公开实施例的描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1a-图1b是本公开一实施例中电池均流控制方法的一流程示意图；
图2是本公开一实施例中电池均流控制方法的另一流程示意图；
图3是本公开一实施例中电池均流控制方法的另一流程示意图；
图4是本公开一实施例中电池均流控制系统的一电路示意图；
图5是本公开一实施例中电池均流控制系统的另一电路示意图；
图6是本公开一实施例中电池均流控制系统的另一电路示意图。
具体实施方式
下面将结合本公开实施例中的附图，对本公开实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本公开一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他 实施例，都属于本公开保护的范围。
应当理解的是，本公开能够以不同形式实施，而不应当解释为局限于这里提出的实施例。相反地，提供这些实施例将使公开彻底和完全，并且将本公开的范围完全地传递给本领域技术人员。在附图中，为了清楚，层和区的尺寸以及相对尺寸可能被夸大自始至终相同附图标记表示相同的元件。
应当明白，当元件或层被称为“在…上”、“与…相邻”、“连接到”或“耦合到”其它元件或层时，其可以直接地在其它元件或层上、与之相邻、连接或耦合到其它元件或层，或者可以存在居间的元件或层。相反，当元件被称为“直接在…上”、“与…直接相邻”、“直接连接到”或“直接耦合到”其它元件或层时，则不存在居间的元件或层。应当明白，尽管可使用术语第一、第二、第三等描述各种元件、部件、区、层和/或部分，这些元件、部件、区、层和/或部分不应当被这些术语限制。这些术语仅仅用来区分一个元件、部件、区、层或部分与另一个元件、部件、区、层或部分。因此，在不脱离本公开教导之下，下面讨论的第一元件、部件、区、层或部分可表示为第二元件、部件、区、层或部分。
空间关系术语例如“在…下”、“在…下面”、“下面的”、“在…之下”、“在…之上”、“上面的”等，在这里可为了方便描述而被使用从而描述图中所示的一个元件或特征与其它元件或特征的关系。应当明白，除了图中所示的取向以外，空间关系术语意图还包括使用和操作中的器件的不同取向。例如，如果附图中的器件翻转，然后，描述为“在其它元件下面”或“在其之下”或“在其下”元件或特征将取向为在其它元件或特征“上”。因此，示例性术语“在…下面”和“在…下”可包括上和下两个取向。器件可以另外地取向(旋转90度或其它取向)并且在此使用的空间描述语相应地被解释。
在此使用的术语的目的仅在于描述具体实施例并且不作为本公开的限制。在此使用时，单数形式的“一”、“一个”和“所述/该”也意图包括复数形式，除非上下文清楚指出另外的方式。还应明白术语“组成”和/或“包括”，当在该说明书中使用时，确定所述特征、整数、步骤、操作、元件和/或部件的存在，但不排除一个或更多其它的特征、整数、步骤、操作、元件、部件和/或组的存在或添加。在此使用时，术语“和/或”包括相关所列项目的任何及所有组合。
为了彻底理解本公开，将在下列的描述中提出详细的结构及步骤，以便阐释本公开提出的技术方案。本公开的较佳实施例详细描述如下，然而除了这些详细描述外，本公开还可以具有其他实施方式。
本公开实施例提供一种电池均流控制方法，该电池均流控制方法应用于电池均流控制系统，电池均流控制系统设有多个并联的电池串支路，电池串支路上设有电池串和与电池串串联的均流DCDC转换器。该均流DCDC转换器是双向DCDC转换器，即可以实现升压控制和降压控制的DCDC转换器。本示例中，电池均流控制系统还包括与电池串和均流DCDC转换器相连的监控模块，该监控模块包括采样电路和与采样电路相连的控制器，采样电路与电池串和均流DCDC转换器相连，用于采集电池串和均流DCDC转换器所在的电池串支路的电池串状态信息，并将电池串状态信息反馈给控制器，该电池串状态信息包括但不限于电池串实测电压、电池串实测电流、电池串当前容量、转换器实测电压、转换器实测电流和母线电压等。控制器还与均流DCDC转换器相连，用于在对电池串状态信息进行综合计算和判断处理，形成PWM信号，可通过该PWM信号控制均流DCDC转换器调整其占空比，调节各个电池串的输出电流，以达到均流输出目的。
在一实施例中，如图1a-图1b所示，电池均流控制方法包括如下步骤：
S11：采集每个电池串对应的电池串实测电压。
其中，电池串实测电压是指实时采集到的电池串两端的电压。
本示例中，在电池串并联之前，即控制器控制所有电池串支路中的开关接触器40全部断开时，通过采样电路实时采集各个电池串对应的电池串实测电压，并将采集到的电池串对应的电池串实测电压反馈给控制器，以使控制器获取在所有电池串并联接入母线之前的电池串实测电压。
S12：确定所有电池串支路的目标电压。
其中，目标电压是电池串及与其串联的均流DCDC转换器所形成的电池串支路所需调节的期望电压。
作为一示例，确定所有电池串支路的目标电压，包括：基于所有电池串对应的电池串实测电压，将所有电池串对应的电池串实测电压中的最大电压值确定为所有电池串支路的目标电压。例如，控制器在获取所有电池串的电池串实测电压之后，从所有电池串的电池串实测电压中选择最大电压值确定为目标电压，即U dcStd＝max[U bati]，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压，n为电池串的数量。本示例中，可以将将所有电池串对应的电池串实测电压中的最大电压值以及其允许误差范围内的电压值确定为所有电池串支路的目标电压。
作为一示例，确定所有电池串支路的目标电压，包括：基于所有电池串对应的电池串实测电压，将所有电池串对应的电池串实测电压中的最小电压值确定为所有电池串支 路的目标电压。例如，控制器在获取所有电池串的电池串实测电压之后，从所有电池串的电池串实测电压中选择最小电压值确定为目标电压，即U dcStd＝min[U bati]，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压，n为电池串的数量。本示例中，可以将所有电池串对应的电池串实测电压中的最小电压值以及其允许误差范围内的电压值确定为所有电池串支路的目标电压。
作为一示例，确定所有电池串支路的目标电压，包括：基于所有电池串对应的电池串实测电压，将所有电池串对应的电池串实测电压的平均电压值确定为所有电池串支路的目标电压。例如，控制器在获取所有电池串的电池串实测电压之后，从所有电池串的电池串实测电压中选择平均电压值确定为目标电压，即U dcStd＝avg[U bati]，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压，n为电池串的数量。本示例中，可以将所有电池串对应的电池串实测电压的平均电压值以及其允许误差范围内的电压值确定为所有电池串支路的目标电压。
作为一示例，确定所有电池串支路的目标电压，包括：将与多个电池串支路连接的母线的电压确定为所有电池串支路的目标电压。本示例中，可以将与多个电池串支路连接的母线的电压以及其允许误差范围内的电压值确定为所有电池串支路的目标电压。
S13：基于目标电压和电池串实测电压，调节均流DCDC转换器，使电池串支路的输出电压为目标电压，实现电池串的均压控制。
本示例中，控制器可以根据目标电压和每一电池串的电池串实测电压，形成用于控制与电池串串联的均流DCDC转换器的PWM信号，并将PWM信号输出给均流DCDC转换器，调节均流DCDC转换器的占空比，以使电池串支路的输出电压为的目标电压，以实现在电池串支路并联接入母线之前，使得电池串和与其串联的均流DCDC转换器所形成的电池串支路的输出电压跟随目标电压，实现电池串支路并联之前的均压控制，有助于保障后续电池串并联时可实现无冲击电流并联的目的。
在一实施例中，步骤S13，即基于目标电压和电池串实测电压，调节均流DCDC转换器，使电池串支路的输出电压为目标电压，实现电池串的均压控制，具体包括如下步骤：
S131：采用与目标电压相对应的均压电压修正值计算公式，对目标电压以及每一个电池串对应的电池串实测电压进行计算，获取与每一电池串串联的均流DCDC转换器对应的均压电压修正值；所述均压电压修正值计算公式为U obji＝U dcStd-U bati，U obji为均压电压修正值，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压。
其中，均压电压修正值是在控制电池串支路并联接入母线之前需调节的各个均流DCDC转换器的期望电压，以实现各个均流DCDC转换器及其串联的电池串所形成的电池串支路的输出电压跟随目标电压，以实现均压控制目的。
本示例中，在电池串支路并联接入母线之前，控制器采用预先设置的均压电压修正值计算公式，对采集到的目标电压和各个电池串两端的电池串实测电压进行计算，以获取与每个电池串相连的均流DCDC转换器对应的均压电压修正值，该均压电压修正值可以理解为在电池串支路并联接入母线之前需控制均流DCDC转换器的期望电压。
可以理解地，由于步骤S12中确定所有电池串支路的目标电压的方式有多种，每一种方式所确定的目标电压大小不相同，由于后续需基于目标电压和电池串实测电压所确定的均压电压修正值调整均流DCDC转换器的占空比，因此，需采用与目标电压获取方式相对应的均压电压修正值计算公式，对目标电压以及每一个电池串对应的电池串实测电压进行计算，以保证获取的均压电压修正值更合理，从而保障后续均流DCDC转换器的占空比的调整更方便。
作为一示例，在上述步骤S12中将n个电池串实测电压U bati中的最大电压值确定为目标电压U dcStd(即U dcStd＝max[U bati])时，与目标电压相对应的均压电压修正值计算公式为U obji＝U dcStd-U bati，利用上述公式进行计算，可获取与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji。由于目标电压U dcStd为最大电压值，此时，均压电压修正值U obji≥0，使得后续需利用均流DCDC转换器将相应电池串支路的输出电压升压至目标电压。
作为一示例，在上述步骤S12中将n个电池串实测电压U bati中的最小电压值确定为目标电压U dcStd(即U dcStd＝min[U bati])时，与目标电压相对应的均压电压修正值计算公式为U obji＝U dcStd-U bati，利用上述公式进行计算，可获取与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji。由于目标电压U dcStd为最小电压值，此时，均压电压修正值U obji≤0，使得后续需利用均流DCDC转换器将相应电池串支路的输出电压降压至目标电压。
作为一示例，在上述步骤S12中将n个电池串实测电压U bati中的平均电压值确定为目标电压U dcStd(即U dcStd＝avg[U bati])时，与目标电压相对应的均压电压修正值计算公 式为U obji＝U bati-U dcStd，利用上述公式进行计算，可获取与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji。即每个电池串支路的均压电压修正值可以根据电池串实测电压U bati与目标电压U dcStd的差值进行单独确定，再利用均流DCDC转换器将相应电池串支路的输出电压降压或者升压至目标电压。可以理解地，此处的降压或升压取决于均压电压修正值U obji的正负。
作为一示例，在上述步骤S12中将与多个电池串支路连接的母线的电压确定为所有电池串支路的目标电压，与目标电压相对应的均压电压修正值计算公式为U obji＝U bati-U dcStd，利用上述公式进行计算，可获取与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji。即每个电池串支路的均压电压修正值可以根据电池串实测电压U bati与目标电压U dcStd的差值进行单独确定，再利用均流DCDC转换器将相应电池串支路的输出电压降压或者升压至目标电压。可以理解地，此处的降压或升压取决于均压电压修正值U obji的正负。
下述实施例中均以将n个电池串实测电压U bati中的最大电压值确定为目标电压作为说明，其余实施例中均与上述实施例相似，在本申请中不做进一步的阐释。
例如，在图5所示的示例中，先控制均流电源启动，恒定直流输出电压为U dcHigh；采集第i个电池串对应的电池串实测电压U bati，其中，1≤i≤n,n为电池串的数量；接着，可以将n个电池串实测电压U bati中的最大电压值确定为目标电压U dcStd，即U dcStd＝max[U bati]；然后，根据目标电压U dcStd和电池串实测电压U bati，确定与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji，即U obji＝U dcStd-U bati；最后，控制各个非隔离DCDC转换器的低压输出侧恒压启动，即根据均压电压修正值U obji调整第i个非隔离DCDC转换器的占空比，以使所有电池串支路中非隔离DCDC转换器及其串联的电池串的总电压(即电池串支路的输出电路)为目标电压U dcStd，进而控制各个开关接触器闭合，以实现无冲击电流并联。
例如，在图6所示的示例中，在不同初始容量不同内阻的电池串并联之前，监控模块先依次控制与第i个电池串串联的开关接触器闭合，采集第i个电池串对应的电池串实测电压U bati，其中，1≤i≤n,n为电池串的数量；接着，可以将n个电池串实测电压U bati 中的最大电压值确定为目标电压U dcStd，即U dcStd＝max[U bati]；然后，根据目标电压U dcStd和电池串实测电压U bati，确定与第i个电池串串联的均流DCDC转换器对应的均压电压修正值U obji，即U obji＝U dcStd-U bati；最后，控制各个隔离DCDC转换器的低压输出侧以恒压启动，即根据均压电压修正值U obji调整第i个隔离DCDC转换器的占空比，以使所有电池串支路中隔离DCDC转换器及其串联的电池串的总电压(即电池串支路的输出电压为目标电压U dcStd，进而控制各个开关接触器闭合，以实现无冲击电流并联。
本实施例中，可实现在电池串并联接入母线之前，利用采集到的每个电池串的电池串实测电压和所确定的目标电压，再基于目标电压和电池串实测电压确定均压电压修正值，根据均压电压修正值控制均流DCDC转换器调节其占空比，以实现各个调节电池串的输出电流均流的目的，减少电池串因并联导致的容量损失，避免充放电结束时内部环流导致的能量。
S132：基于每一均流DCDC转换器对应的均压电压修正值，调节均流DCDC转换器的占空比，使电池串支路的输出电压为目标电压，实现电池串的均压控制。
本示例中，控制器基于每一均流DCDC转换器对应的均压电压修正值形成PWM信号，并将该PWM信号输出给均流DCDC转换器，调节均流DCDC转换器的占空比，以使均流DCDC转换器的输出电压达到期望的均压电压修正值，以实现在电池串并联之前，使得电池串和与其串联的均流DCDC转换器所形成的电池串支路的输出电压跟随电池串支路的目标电压，实现电池串并联之前的均压控制，有助于保障后续电池串并联时可实现无冲击电流并联的目的。
如图6所示，隔离DCDC转换器的高压输入侧的第一桥式整流电路中Q1与Q3互补导通，Q2与Q4互补导通，均为50％占空比；低压输出侧的第二桥式整流电路中的Q5与Q7互补导通，Q6与Q8互补导通，均为50％占空比；可通过改变高压输入侧和低压输出侧调制信号的角度差值来实现升压或降压功能，以实现输出电流或者吸收电流功能。例如，若希望将隔离DCDC转换器的低压输出侧输出电压初始时刻为0V，逐步增加到均压电压修正值U obji，可设置初始相位差Angle_std为180°，然后，闭环PI调节确定其角度偏移Angle＝(U obji-U bati)*(K p_angle+K i_angle/s)+Angle_std，K p_angle为预先设置的用于进行角度偏移调整的比例系数，K i为预先设置的用于进行角度偏移调整的积分系数，s为频域，该角度偏移Angle的范围为90°到270°，以实现基于角度偏移Angle调整隔 离DCDC转换器中各个驱动开关管工作，根据均压电压修正值U obji调整第i个隔离DCDC转换器的占空比，以使所有电池串支路中隔离DCDC转换器及其串联的电池串的总电压(即电池串支路的输出电压)为目标电压U dcStd，以保证在控制所有开关接触器闭合，以使电池串并联接入母线时，可实现无冲击电流并联。
S14：采集每个电池串对应的电池串实测电流。
其中，电池串实测电流是实时采集到电池串支路的电流。
由于在电池串支路并联接入到母线时，若各个均流DCDC转换器仍采用目标电压进行均流控制，无法保障各个电池串支路均流输出，其原因在于，各个电池串支路的总电压完全相同，但不同电池串支路的内阻存在差异，根据I＝U/R，会导致充电或放电过程中，各个电池串支路的输出电流与其内阻成反比，因此，在所有电池串支路并联接入母线时，也需加入均流控制，以修正各个均流DCDC转换器的输出电压，从而保证充电或放电过程中，各个电池串支路通过实现均流输出。因此，控制器需在基于目标电压和电池串实测电压，调节均流DCDC转换器，使电池串支路的输出电压为目标电压，实现电池串的均压控制，以控制电池串实现无冲击电流并联之后，实时采集的电池串对应的电池串实测电流，以便利用该电池串实测电流实现电池串并联之后的均流控制。
S15：基于所有电池串对应的电池串实测电流，确定所有电池串的目标电流。
其中，目标电流是指电池串及与其串联的均流DCDC转换器所形成的电池串支路所需调节的期望电流，由于电池串支路包括串联的电池串和均流DCDC转换器，因此，该目标电池可以理解为电池串或者均流DCDC转换器的期望电流。
作为一示例，步骤S15，即基于所有电池串对应的电池串实测电流，确定所有电池串的目标电流，包括：基于所有电池串对应的电池串实测电流，将所有电池串对应的电池串实测电流的平均电流作为所有电池串的目标电流。例如，控制器可计算n个电池串实测电流I bati的平均电流，确定第i个电池串的目标电流I obji，即
Figure PCTCN2021103511-appb-000001
作为一示例，步骤S15，即基于所有电池串对应的电池串实测电流，确定所有电池串的目标电流，包括：基于所有电池串对应的电池串当前容量和充放电电流限值计算充放电比例系数；基于所有电池串对应的电池串实测电流和充放电比例系数，确定所有电池串的目标电流。
作为一示例，在电池串放电过程中，需根据第i个电池串对应的电池当前容量SOC_i和放电电流限值I DischargeLim_i，计算放电比例系数I DischargeRate_i，即
Figure PCTCN2021103511-appb-000002
其中，I DischargeRate_i为第i个电池串的放电比例系数，SOC_i为第i个电池串的电池当前容量，I DischargeLim_i为第i个电池串的放电电流限值；接着，基于n个电池串实测电流I bati和放电比例系数I DischargeRate_i，确定第i个电池串的目标电流I obji，即
Figure PCTCN2021103511-appb-000003
作为一示例，在电池串充电过程中，需根据第i个电池串对应的电池当前容量SOC_i和充电电流限值I chargeLim_i，计算充电比例系数I chargeRate_i，即
Figure PCTCN2021103511-appb-000004
其中，I chargeRate_i为第i个电池串的充电比例系数，SOC_i为第i个电池串的电池当前容量，I chargeLim_i为第i个电池串的充电电流限值。接着，基于n个电池串实测电流I bati和充电比例系数I chargeRate_i，确定第i个电池串的目标电流I obji，即
Figure PCTCN2021103511-appb-000005
S16：基于所有电池串对应的电池串实测电流和目标电流，调节均流DCDC转换器，使电池串支路的输出电流为目标电流，实现电池串的均流控制。
本示例中，控制器可以根据目标电流和每一电池器对应的电池串实测电流，形成用于控制与电池串串联的均流DCDC转换器的PWM信号，并将PWM信号输出给均流DCDC转换器，调节均流DCDC转换器的占空比，以使电池串支路的输出电流为目标电流，以实现在电池串支路并联接入母线之后，使得电池串和与其串联的均流DCDC转换器所形成的电池串支路的输出电流跟随目标电流，即实现电池串支路并联之后的均流控制，有助减少电池串因并联导致的容量损失，避免充放电结束时内部环流导致的能量。
在一实施例中，基于所有电池串对应的电池串实测电流和目标电流，调节均流DCDC转换器，以使电池串支路的输出电流为目标电流，实现电池串的均流控制，包括：
S161：采用均流电压修正值计算公式，对所有电池串对应的电池串实测电流和目标电流进行计算，获取与每一电池串串联的均流DCDC转换器对应的均流电压修正值；均流电压修正值计算公式为DaltaU obji＝(I bati-I obji)*(K p+K i/s)，DaltaU obji为第i个电池串的均流电压修正值，I bati为第i个电池串的电池串实测电流，I obji为第i个电池串的目标电流，K p为预先设置的比例系数，K i为预先设置的积分系数，s为频域。
其中，均流电压修正值是在控制电池串并联之后需要调节的各个均流DCDC转换器 的期望电压，以实现各个均流DCDC转换器及其串联的电池串所形成的电池串支路的输出电流均流控制目的。
本示例中，控制器在获取基于所有电池串对应的电池串实测电流和目标电流后，可调用预先存储用于实现基于电池串实测电流和目标电流计算均流电压修正值对应的换算逻辑，利用换算逻辑对上述电池串实测电流和目标电流进行处理，确定与电池串串联的均流DCDC转换器对应的均流电压修正值，基于该均流电压修正值动态调节均流DCDC转换器的输出电压，改变整体电池串支路的总电压，以实现电池串支路均流输出的目的。
S162：基于每一均流DCDC转换器对应的均流电压修正值，调节均流DCDC转换器的占空比，使电池串支路的输出电流为目标电流，实现电池串的均流控制。
本示例中，控制器在获取均流电压修正值之后，基于均流电压修正值形成对应的PWM信号，通过该PWM信号调整均流DCDC转换器的占空比，以实现控制电池串及其串联的均流DCDC转换器所形成的电池串支路的输出电流均流控制的目的。例如，在放电过程中，电池串实测电流较大的电池串支路上的均流DCDC转换器降低其输出电压，电池串实测电流较小的电池串支路上的均流DCDC转换器升高其输出电压，使电池串支路的输出电流为目标电流；充电过程中，电池串实测电流较大的电池串支路上的均流DCDC转换器升高其输出电压，电池串实测电流较小的电池串支路上的均流DCDC转换器降低其输出电压，使电池串支路的输出电流为目标电流。
作为一示例，控制器在获取基于每一均流DCDC转换器对应的均流电压修正值之后，需基于均流DCDC转换器对应的均流电压修正值和均压电压修正值，调节均流DCDC转换器的占空比，使电池串支路的输出电流为目标电流，实现电池串的均流控制。即需基于均流DCDC转换器对应的均流电压修正值和均压电压修正值的差值确定为均流电压变化值，再根据均流电压变化值调节均流DCDC转换器的占空比，使电池串支路的输出电流为目标电流，实现电池串的均流控制。
例如，在图5所示的示例中，均流电源主要用于提供或者吸收各个电池串所在电池串支路中不足的电流或者多余的电流，以实现均流目的。设在控制与第i个电池串串联的开关接触器C i闭合之后，即电池串并联之后，采集第i个电池串对应的电池串实测电流I bati，其中，1≤i≤n,n为电池串的数量，本示例中具体为并联接入母线的电池串的数量。然后，计算n个电池串实测电流I bati的平均电流，确定第i个电池串的目标电流I obji，即
Figure PCTCN2021103511-appb-000006
或者，先通过第i个电池串的电池串当前容量和充放电电流限 值计算其对应的充放电比例系数，再基于所有电池串对应的电池串实测电流和充放电比例系数，确定所有电池串的目标电流I obji。接着，根据电池串实测电流I bati和目标电流I obji，根据DaltaU obji＝(I bati-I obji)*(K p+K i/s)确定第i个均流DCDC转换器的均流电压修正值DaltaU obji。之后，根据均流电压修正值DaltaU obji和均压电压修正值U obji，确定均流电压变化值U obji'，其中，U obji'＝U obji-DaltaU obji；最后，根据均流电压变化值U obji'确定其对应的调整驱动信号，基于调整驱动信号控制均流DCDC转换器调节占空比，以实现均流控制。即可实现在放电过程中，电池串实测电流较大的电池串支路上的均流DCDC转换器降低其输出电压，电池串实测电流较小的电池串支路上的均流DCDC转换器升高其输出电压使电池串支路的输出电流为目标电流，实现电池串的均流控制；充电过程中，电池串实测电流较大的电池串支路上的均流DCDC转换器升高其输出电压，电池串实测电流较小的电池串支路上的均流DCDC转换器降低其输出电压，使电池串支路的输出电流为目标电流，实现电池串的均流控制。本示例中，放电过程中各个电池串支路中不足的电流由均流电源提供；充电过程中任意电池串支路中多余的电流注入均流电源中，需要各个电池串支路的内阻不同且动态变化，但通过调节各个均流DCDC转换器的占空比，可动态调节各个电池串支路实现均流控制。图6所示的示例的实现过程与图5所示的示例的实现过程相同，为避免赘述，此处不一一详述。
本实施例所提供的电池均流控制方法中，在电池串并联之前，基于每一电池串对应的电池串实测电压和所有电池串对应的目标电压，调节均流DCDC转换器的占空比，使电池串支路的输出电压为目标电压，实现电池串的均压控制，可实现无冲击电流并联目的。在电池串并联之后，基于所有电池串对应的电池串实测电流和目标电流，调节均流DCDC转换器的占空比，使电池串支路的输出电流为目标电流，实现电池串的均流控制，实现均流控制，减少因并联而导致的电池串的容量损失，以提高电池串的电池容量利用率，并可减少充放电结束时内部环流导致的能量损耗，有助于保障并联电池串的使用寿命，保障电池串充放电过程中的安全性。
在一实施例中，如图2所示，即在步骤S14之前，在采集每个电池串对应的电池串实测电流之前，电池均流控制方法还包括：
S21:实时采集所有电池串对应的支路实测电压。
其中，电池串支路对应的支路实测电压可以理解为电池串支路中的电池串的电池串实测电压与均流DCDC转换器的转换器实测电压之和。
S22：若所有电池串对应的支路实测电压在目标电压的允许误差范围内，则控制所有电池串支路并联至母线上。
本示例中，控制器在获取电池串支路对应的支路实测电压之后，先判断所有电池串支路对应的支路实测电压在目标电压的允许误差范围内，若所有电池串支路对应的支路实测电压均在目标电压的允许误差范围内，则将所有电池串支路并联接入母线时，可实现无冲击电流并联的目的。此时，所有电池串对应的支路实测电压在目标电压的允许误差范围内可以理解为控制所有电池串支路并联接入母线的条件，可保证并联过程中无冲击电流的影响。
在一实施例中，如图3所示，在步骤S22之后，即在控制所有电池串支路并联至母线上之后，电池均流控制方法还包括：
S31：实时采集所有电池串支路对应的电池串当前容量，判断电池串当前容量是否在电池串下限容量和电池串上限容量之间。
其中，电池串当前容量是实时采集到的电池串的电池容量。电池串上限容量是指电池串可以正常充电或放电的最大容量。电池串下限容量是指电池串可以正常放电或放电的最小容量。
S32：若任一电池串支路对应的电池串当前容量不在电池串下限容量与电池串上限容量之间，则断开电池串支路与母线的连接，重复执行采集每个电池串对应的电池串实测电压。
本示例中，控制器在采集所有电池串支路对应的电池串当前容量之后，先判断每一电池串当前容量是否在电池串下限容量和电池串上限容量之间。若电池串当前容量在电池串下限容量和电池串上限容量之间，此时，认定该电池串支路可以正常进行充电或者放电工作，无需另外调整。若电池串当前容量不在电池串下限容量和电池串上限容量之间，此时，认定该电池串支路不能正常进行充电或者放电工作，因此，需断开电池串支路与母线的连接，即控制电池串支路中的开关接触器断开，使其均流DCDC转换器停机，以避免电池串当前容量不在电池串下限容量和电池串上限容量之间的电池串支路接入母线上，影响均流调整的准确性和可靠性。本示例中，在断开电池串支路与母线的连接之后，需重复执行采集每个电池串对应的电池串实测电压，即重复执行步骤S11。
本公开实施例提供一种电池均流控制系统。如图4所示，该电池均流控制系统包括监控模块10和并联设置在母线上的多个电池串支路，电池串支路包括电池串20和与电池串20相连的均流DCDC转换器30，监控模块10与电池串20和均流DCDC转换器30相连，用于采集电池串支路的电池串状态信息，基于电池串状态信息调节均流DCDC转 换器30的占空比，实现均流控制。
其中，电池串支路是并联设置在母线上的支路，每一电池串支路包括串联设置的电池串20和均流DCDC转换器30。
其中，电池串20可以为单个储能电池，也可以为多个储能电池串20联形成，该储能电池可以为磷酸铁锂、三元锂电池等可反复充放电池的电池。至少两个电池串20并联设置在母线上，形成电池模组。本示例中，电池均流控制系可实现对电池模组中的至少两个电池串20的输出电流进行均流调整，以避免部分电池串20长期处于过充状态或者过放状态，导致电池模组中至少两个电池串20的不一致性，有效避免电池劣化的问题。
其中，均流DCDC转换器30是用于实现调节各个电池串20的输出电流均流的DCDC转换器，可以理解地，该均流DCDC转换器30为双向DCDC转换器，既可以实现提高电池串20的输出电流，又可以降低电池串20的输出电流。
本示例中，均流DCDC转换器30和电池串20串联形成一电池串支路，若电池模组中的电池串20的数量为n个，则需采用n个均流DCDC转换器30分别与n个电池串20串联，以形成n个电池串支路，则各个均流DCDC转换器30通过调节其自身的输出电压，保证充放电过程中各个电池串支路中的电池串20均流输出的目的。
进一步地，每一电池串支路还包括用于控制电池串支路是否接入母线的开关接触器40。其中，开关接触器40是与电池串20相连的用于控制该电池串20是否接入母线的开关。本示例中，每一均流DCDC转换器30与一电池串20和一开关接触器40串联形成一电池串支路，开关接触器40设置在电池串支路上，用于控制该电池串支路是否接入母线。
其中，监控模块10是电池均流控制系统中用于实现监控处理功能的模块。作为一示例，监控模块10中预先存储用于实现监控处理功能的均流控制程序，该监控模块10通过执行该均流控制程序进行处理，控制与电池串20串联的均流DCDC转换器30调节占空比，以实现调节各个电池串20的输出电流，从而达到均流输出目的。
作为一示例，监控模块10包括采样电路和与采样电路相连的控制器。采样电路与电池串20和均流DCDC转换器30相连，用于采集电池串20和均流DCDC转换器30所在的电池串支路的电池串状态信息，并将电池串状态信息反馈给控制器，该电池串状态信息包括但不限于电池串实测电压、电池串实测电流、电池串当前容量、转换器实测电压、转换器实测电流和母线电压等。控制器还与均流DCDC转换器30相连，用于在对电池串状态信息进行综合计算和判断处理，形成PWM信号，可通过该PWM信号控制均流DCDC 转换器30调整其占空比，调节各个电池串20的输出电流，从而达到均流输出目的。本示例中，控制器具体为数字信号处理器，即DSP。
以图4中三个电池串20并联形成的电池模组为例，在制造工艺和使用工况等因素不同的情况下，会导致在一段时间后，三个电池串20的内阻和容量出现偏差，此时，若直接并联三个电池串20进行充放电；由于电阻不同，会导致充放电过程中输出电流出现明显差异，无法同时充满或者放空，会导致较大的容量损失；而且，在充放电后期，由于内阻快速增大，但各电池串20增大的速率不同，会导致部分电池串20充放电电流急剧增大甚至超出电池允许范围，导致电池串20的使用寿命缩短，甚至出现起火等安全事故。为了克服直接将至少两个电池串20并联到母线所存在的上述问题，在每个电池串20上串联一个均流DCDC转换器30形成电池串支路，监控模块10与电池串20和均流DCDC转换器30相连，可以通过采集电池串支路的电池串状态信息，再对电池串状态信息进行综合计算和判断处理，形成PWM信号，根据该PWM信号控制均流DCDC转换器30调整其占空比，以达到调节电池串20的输出电流实现均流目的，避免至少两个电池串20在充放电过程中输出电流不一致所导致的问题，可提高电池容量利用率，有助于保障电池模组中各个电池串20的使用寿命，保障各个电池串20充放电过程中的安全性。由于每一电池串支路上还设有一个开关接触器40，该开关接触器40与控制器相连并接受控制器的控制，即控制器可以根据实际情况，控制电池串支路上的开关接触器40闭合或者断开，以将电池串20所在的电池串支路接入到母线上，进而执行相应的均流控制程序，有助于保障电池模组中各个电池串20的使用寿命，保障各个电池串20充放电过程中的安全性。
本实施例所提供的电池均流控制系统中，在电池串20与均流DCDC转换器30串联形成一电池串支路，利用监控模块10采集电池串支路的电池串状态信息，通过对电池串状态信息进行处理，进而控制均流DCDC转换器30调节其占空比，实现进行调节电池串20的输出电流，使并联的电池串支路实现均流目的，减少因并联而导致的电池串20的容量损失，以提高各个电池串20的电池容量利用率，并可减少充放电结束时内部环流导致的能量损耗，有助于保障各个电池串20的使用寿命，保障各个电池串20充放电过程中的安全性。
在一实施例中，现有技术中通过在电池串20与母线之间设置非隔离DCDC转换器31实现电流均流，即在非隔离DCDC转换器31的一侧连接并联的多个电池串20，另一侧连接母线，通过非隔离DCDC转换器31输出恒定电流，使得多个电池串20电流均衡，但这种方式存在如下不足：非隔离DCDC转换器31两侧均为数百伏高压，导致DCDC转 换器两侧的器件耐压等级高，使得成本较高且容易损坏。
为了克服现有技术中非隔离DCDC转换器31直接与母线和电池串20相连所存在的不足，如图5所示，电池均流控制系统还包括均流电源50；均流DCDC转换器30为与均流电源50相连的非隔离DCDC转换器31；非隔离DCDC转换器31的输入端与均流电源50相连；均流DCDC转换器30的输出端与电池串20和母线相连。
均流DCDC转换器30的第一输入端与均流电源50相连，第二输入端与均流电源50相连；均流DCDC转换器30的第一输出端与电池串20相连，第二输出端和母线相连；或者，均流DCDC转换器30的第一输出端与母线相连，第二输出端与电池串20相连。
其中，非隔离DCDC转换器31是指输出的GND与输出的GND有关系的DCDC转换器，非隔离DCDC转换器31可以为boost和buck这两种类型的转换器。
其中，均流电源50是用于实现均流的电源。本示例中，均流电源50与交流电源通过交流接触器相连，用于接收交流电网输入的交流电，并将交流电转换成直流电，以提供给非隔离DCDC转换器31和电池串20，以使电池串20完成充放电操作。作为一示例，均流电源50可采用不控整流源或者双向直流源(即ACDC)。本示例中，均流电源50的交流侧与交流电网相连，直流侧与电池串20通过非隔离DCDC转换器31相连。
具体地，均流DCDC转换器30的第一输入端与均流电源50相连，第二输入端与均流电源50相连；均流DCDC转换器30的第一输出端与电池串20相连，第二输出端和母线相连；或者，均流DCDC转换器30的第一输出端与母线相连，第二输出端与电池串20相连。如图5所示，每一非隔离DCDC转换器31的第一输入端(即正极输入端)和第二输入端(即负极输入端)与均流电源50相连；第一输出端(即正极输出端)与电池串20相连，第二输出端(即负极输出端)与母线相连，或者，第一输出端(即正极输出端)与母线相连，第二输出端(即负极输出端)，与电池串20相连。此时，非隔离DCDC转换器31的两个输入端与均流电源50相连，为高压输入侧；非隔离DCDC转换器31的两个输出端分别与电池串20和母线相连，为低压输出侧。可以理解地，所有非隔离DCDC转换器31的高压输入侧与均流电源50相连，低压输出侧与电池串20相连，这种方式可以避免非隔离DCDC转换器31分别与母线和电池串20相连的所存在的不足，可以有效降低非隔离DCDC转换器31的输入端和输出端的电压，无需采用耐压等级较高的器件，有助于降低电路成本并保障电路的使用寿命。本示例中，采用均流电源50与至少两个非隔离DCDC转换器31相连，提供均流过程所需的能量，以控制非隔离DCDC转换器31实现均流控制；由于非隔离DCDC转换器31的输入端与均流电源50相连，获取均流所需的能量，使得非隔离DCDC转换器31内部可采用耐压等级较低的器件，可靠 性强且不易损坏。
在一实施例中，如图5所示，非隔离DCDC转换器31包括第一谐振电感L11、第一驱动功率管Q11、第二驱动功率管Q12、第一反向二极管D11、第二反向二极管D12、第一储能电容C11和第二储能电容12；第一谐振电感L11和第一驱动功率管Q11串联设置在第一输入端和第一输出端之间；第一储能电容C11一端与第一谐振电感L11和第一驱动功率管Q11相连，另一端与第二输入端和第二输出端相连；第二驱动功率管Q12一端与第一驱动功率管Q11和第一输出端相连，另一端与第二输入端和第二输出端相连；第二储能电容12一端与第一驱动功率管Q11和第一输出端相连，另一端与第二输入端和第二输出端相连；第一反向二极管D11与第一驱动功率管Q11反向并联；第二反向二极管D12与第二驱动功率管Q12反向并联。
其中，第一谐振电感L11是设置在非隔离DCDC转换器31中的电感，可起到谐振作用，有助于提高DCDC转换的效率。
其中，第一驱动功率管Q11和第二驱动功率管Q12是设置在非隔离DCDC转换器31上的功率管，具体可以采用MOSFET和IGBT。本示例中，第一驱动功率管Q11和第二驱动功率管Q12均与监控模块10相连，用于在监控模块10的控制下互补导通；即第一驱动功率管Q11导通则第二驱动功率管Q12断开，第一驱动功率管Q11断开则第二驱动功率管Q12导通。
其中，第一反向二极管D11与第一驱动功率管Q11反向并联是指第一反向二极管D11与第一驱动功率管Q11并联，且流经第一驱动功率管Q11的电流和流经第一反向二极管D11的电流相反，使得第一驱动功率管Q11关闭时，第一反向二极管D11可起到续流作用。第二反向二极管D12与第二驱动功率管Q12反向并联是指第二反向二极管D12与第二驱动功率管Q12并联，且流经第二驱动功率管Q12的电流和流经第二反向二极管D12的电流相反，使得第二驱动功率管Q12关闭时，第二反向二极管D12可起到续流作用。
其中，第一储能电容C11和第二储能电容12是设置在非隔离DCDC转换器31中，用于在充放电过程中实现电能的存储和释放的电容。
本示例中，监控模块10在采集到电池串状态信息之后，对电池串状态信息进行综合计算和判断处理，以形成均流驱动信号，基于该均流驱动信号控制与其相连的第一驱动功率管Q11和第二驱动功率管Q12导通或断开，通过PI调节PWM占空比，以控制非隔离DCDC转换器31调节相应的电池串20的输出电流，以达到均流目的，避免充放电过程中各个电池串20由于电流不一致而导致的问题，从而提高电池容量利用率，有助于保障电池模组中各个电池串20的使用寿命，保障各个电池串20充放电过程中的安全 性。本示例中，采用均流电源50与非隔离DCDC转换器31相连，提供均流过程所需的能量，以控制非隔离DCDC转换器31实现均流；由于非隔离DCDC转换器31无需与母线相连，以获取均流所需的能量，使得非隔离DCDC转换器31内部可采用耐压等级较低的器件，即电感、电容和功率开关管等器件，有助于降低器件成本，具有可靠性强且不易损坏的优点。
在一实施例中，如图6所示，均流DCDC转换器30为隔离DCDC转换器32；隔离DCDC转换器32的输入端与电池串20相连；隔离DCDC转换器32的输出端与电池串20和母线相连。
其中，隔离DCDC转换器32是指输出的GND与输入的GND无关系的DCDC转换器。本示例中，隔离DCDC转换器32的第一输入端和第二输入端均与电池串20相连，隔离DCDC转换器32的第一输出端和第二输出端分别与电池串20和母线相连，以将电池串20作为隔离DCDC转换器32的均流电源50，无需额外增加均流电源50，通过监控模块10控制隔离DCDC转换器32，调节电池串20的输出电池，以实现控制至少两个电池串20均流的目的。
本示例中，与每一电池串20相连的隔离DCDC转换器32与监控模块10相连，可在监控模块10的均流驱动信号的控制下，调节各个电池串20的输出电流，以实现并联设置的至少两个电池串20均流的目的，减少并联导致的容量损失和充放电结束时内部环流所导致的能量损耗。由于每一隔离DCDC转换器32的两个输入端与电池串20相连，通过电池串20提供均流所需的能量，使其输入端的电压较小，使得隔离DCDC转换器32内部可采用耐压等级较低的器件，且无需额外增加均流电源50，可显著降低成本。由于采用电池串20作为隔离DCDC转换器32所需的均流电源50，使得隔离DCDC转换器32的输入端和输出端中的任一个出现短路极端工况时，均不会导致另一端操作，避免故障扩散，可靠性较高。
在一实施例中，隔离DCDC转换器32的第一输入端与电池串20相连，第二输入端与电池串20相连；隔离DCDC转换器32的第一输出端与电池串20相连，第二输出端与母线相连；或者，隔离DCDC转换器32的第一输出端与母线相连，第二输出端与电池串20相连。如图6所示，隔离DCDC转换器32包括高频变压器T21、第二谐振电感L21、第一桥式整流电路、第二桥式整流电路和滤波电容C21；第一桥式整流电路设置在高频变压器T21的原边，并与第一输入端和第二输入端相连；第二桥式整流电路设置在高频变压器T21的副边，并与第一输出端和第二输出端相连；第二谐振电感L21设置在高频变压器T21的原边与第一桥式整流电路之间；滤波电容C21设置在第一输出端与第二输 出端之间，与第二桥式整流电路并联。
第一桥式整流电路和第二桥式整流电路是分别设置在高频变压器T21的原边和副边的桥式整流电路，是由四个二极管相连形成的桥式结构，可将交流电转换成单向脉动直流电，用于实现整流目的。第二谐振电感L21是设置在隔离DCDC转换器32中的电感，可起到谐振作用，有助于提高DCDC转换的效率。滤波电容C21是设置在隔离DCDC转换器32中，可起滤波作用的电容，主要用于滤除滤除单向脉动直流电中的交流成分。
本示例中，第一桥式整流电路和第二桥式整流电路均与监控模块10相连，用于根据监控模块10输出的均流驱动信号进行处理，以控制第一桥式整流电路和第一桥式整流电路中各个二极管的闭合或者断开，从而达到调节第一桥式整流电路和第二桥式整流电路的占空比，以达到升压和降压效果，以达到调节各个电池串20的输出电流均流的目的。该第一桥式整流电路通过第一谐振电感L11连接高频变压器T21，另一端与电池串20相连，用于实现对电池串20输入的电流进行整流的作用。第二桥式整流电路与电池串20和母线相连，可将整流后的电流输入到电池串20上，以调节电池串20的输出电流。
在一实施例中，如图6所示，第一桥式整流电路包括与第一输入端相连的第一驱动开关管Q21和第二驱动开关管Q22、与第二输入端相连的第三驱动开关管Q23和第四驱动开关管Q24；第一驱动开关管Q21与第三驱动开关管Q23相连，监控模块10与第一驱动开关管Q21和第三驱动开关管Q23相连，用于控制第一驱动开关管Q21和第三驱动开关管Q23互补导通；第二驱动开关管Q22与第四驱动开关管Q24相连，监控模块10与第二驱动开关管Q22和第四驱动开关管Q24相连，用于控制第二驱动开关管Q22和第四驱动开关管Q24互补导通；高频变压器T21的原边一端通过第二谐振电感L21与第一驱动开关管Q21和第三驱动开关管Q23相连，另一端与第二驱动开关管Q22和第四驱动开关管Q24相连；第二桥式整流电路包括与第一输出端相连的第五驱动开关管Q25和第六驱动开关管Q26、与第二输出端相连的第七驱动开关管Q27和第八驱动开关管Q28；第五驱动开关管Q25和第七驱动开关管Q27相连，监控模块10与第五驱动开关管Q25和第七驱动开关管Q27相连，用于控制第五驱动开关管Q25和第七驱动开关管Q27互补导通；第六驱动开关管Q26和第八驱动开关管Q28相连，监控模块10与第六驱动开关管Q26和第八驱动开关管Q28相连，用于控制第六驱动开关管Q26和第八驱动开关管Q28互补导通；高频变压器T21的副边一端与第五驱动开关管Q25和第七驱动开关管Q27相连，另一端与第六驱动开关管Q26和第八驱动开关管Q28相连；第一驱动开关管Q21、第二驱动开关管Q22、第三驱动开关管Q23、第四驱动开关管Q24、第五驱动开关管Q25、 第六驱动开关管Q26、第七驱动开关管Q27和第八驱动开关管Q28各并联一个反向续流二极管和滤波电容C21。
本示例中，Q21、Q22、Q23和Q24形成第一桥式整流电路，设置在高频变压器T21的原边上，为隔离DCDC转换器32的高压输入侧；监控模块10与Q21、Q22、Q23和Q24，可控制Q21和Q23互补导通，并控制Q22和Q24互补导通，使得隔离DCDC转换器32的高压输入侧各个驱动开关管的占空比均为50％。Q25、Q26、Q27和Q28形成第二桥式整流电路，设置高频变压器T21的副边上，为隔离DCDC转换器32的低压输出侧。监控模块10与Q25、Q26、Q27和Q28相连，用于控制Q25和Q27互补导通，并控制Q26和Q28互补导通，使得隔离DCDC转换器32的低压输出侧的各个驱动开关管的占空比均为50％。可以理解地，隔离DCDC转换器32的高压输入侧上的驱动开关管和低压输出侧上的驱动开关管的调制信号相同，可通过调节高压输入侧上的驱动开关管和低压输出侧上的驱动开关管之间的角度差值，实现升压或降压功能，以实现调节电池串20的输出电流，达到均流目的。
以上所述实施例仅用以说明本公开的技术方案，而非对其限制；尽管参照前述实施例对本公开进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本公开各实施例技术方案的精神和范围，均应包含在本公开的保护范围之内。

Claims (11)

  1. 一种电池均流控制方法，应用于电池均流控制系统，所述电池均流控制系统设有多个并联的电池串支路，所述电池串支路上设有电池串和与所述电池串串联的均流DCDC转换器，其特征在于，包括：
    采集每个所述电池串对应的电池串实测电流；
    基于所有所述电池串对应的电池串实测电流，确定所有所述电池串的目标电流；
    基于所有所述电池串对应的电池串实测电流和所述目标电流，调节所述均流DCDC转换器，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制。
  2. 如权利要求1所述的电池均流控制方法，其特征在于，在所述采集每个所述电池串对应的电池串实测电流之前，所述电池均流控制方法还包括：
    采集每个所述电池串对应的电池串实测电压；
    确定所有所述电池串支路的目标电压；
    基于所述目标电压和所述电池串实测电压，调节均流DCDC转换器，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制。
  3. 如权利要求2所述的电池均流控制方法，其特征在于，所述确定所有所述电池串支路的目标电压，包括：
    基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压中的最大电压值确定为所有所述电池串支路的目标电压；
    或者，基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压中的最小电压值确定为所有所述电池串支路的目标电压；
    或者，基于所有所述电池串对应的电池串实测电压，将所有所述电池串对应的电池串实测电压的平均电压值确定为所有所述电池串支路的目标电压；
    或者，将与多个所述电池串支路连接的母线的电压确定为所有所述电池串支路的目标电压。
  4. 如权利要求2所述的电池均流控制方法，其特征在于，所述基于所述目标电压和所述电池串实测电压，调节均流DCDC转换器，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制，包括：
    采用与所述目标电压相对应的均压电压修正值计算公式，对所述目标电压以及每一个所述电池串对应的电池串实测电压进行计算，获取与每一所述电池串串联的均流DCDC转换器对应的均压电压修正值；其中，所述均压电压修正值计算公式为 U obji＝U dcStd-U bati，U obji为均压电压修正值，U dcStd为目标电压，U bati为第i个电池串的电池串实测电压；
    基于每一所述均流DCDC转换器对应的均压电压修正值，调节所述均流DCDC转换器的占空比，使所述电池串支路的输出电压为所述目标电压，实现电池串的均压控制。
  5. 如权利要求2所述的电池均流控制方法，其特征在于，在所述采集每个所述电池串对应的电池串实测电流之前，所述电池均流控制方法还包括：
    实时采集所有所述电池串对应的支路实测电压；
    若所有所述电池串对应的支路实测电压在所述目标电压的允许误差范围内，则控制所有所述电池串支路并联至母线上。
  6. 如权利要求5所述的电池均流控制方法，其特征在于，在所述控制所有所述电池串支路并联至母线上之后，所述电池均流控制方法还包括：
    实时采集所有所述电池串支路对应的电池串当前容量，判断所述电池串当前容量是否在电池串下限容量和电池串上限容量之间；
    若任一所述电池串支路对应的所述电池串当前容量不在所述电池串下限容量与所述电池串上限容量之间，则断开所述电池串支路与母线的连接，重复执行所述采集每个所述电池串对应的电池串实测电压。
  7. 如权利要求1所述的电池均流控制方法，其特征在于，所述基于所有所述电池串对应的电池串实测电流，确定所有所述电池串的目标电流，包括：
    基于所有所述电池串对应的电池串实测电流，将所有所述电池串对应的电池串实测电流的平均电流作为所有所述电池串的目标电流；
    或者，基于所有所述电池串对应的电池串当前容量和充放电电流限值计算充放电比例系数；基于所有所述电池串对应的电池串实测电流和所述充放电比例系数，确定所有所述电池串的目标电流。
  8. 如权利要求1所述的电池均流控制方法，其特征在于，所述基于所有所述电池串对应的电池串实测电流和所述目标电流，调节所述均流DCDC转换器，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制，包括：
    采用均流电压修正值计算公式，对所有所述电池串对应的电池串实测电流和所述目标电流进行计算，获取与每一所述电池串串联的均流DCDC转换器对应的均流电压修正值；所述均流电压修正值计算公式为DaltaU obji＝(I bati-I obji)*(K p+K i/s)，DaltaU obji为第i个电池串的均流电压修正值，I bati为第i个电池串的电池串实测电流，I obji为第i个 电池串的目标电流，K p为预先设置的比例系数，K i为预先设置的积分系数，s为频域；
    基于每一所述均流DCDC转换器对应的均流电压修正值，调节所述均流DCDC转换器的占空比，使所述电池串支路的输出电流为所述目标电流，实现电池串的均流控制。
  9. 一种电池均流控制系统，其特征在于，包括监控模块和并联设置在母线上的多个电池串支路，所述电池串支路包括电池串和与所述电池串相连的均流DCDC转换器，所述监控模块与所述电池串和所述均流DCDC转换器相连，用于采集所述电池串支路的电池串状态信息，基于所述电池串状态信息调节所述均流DCDC转换器的占空比，实现均流控制。
  10. 如权利要求9所述的电池均流控制系统，其特征在于，所述电池均流控制系统还包括均流电源；所述均流DCDC转换器为与所述均流电源相连的非隔离DCDC转换器；所述非隔离DCDC转换器的输入端与所述均流电源相连；所述均流DCDC转换器的输出端与所述电池串和所述母线相连。
  11. 如权利要求9所述的电池均流控制系统，其特征在于，所述均流DCDC转换器为隔离DCDC转换器；所述隔离DCDC转换器的输入端与所述电池串相连；所述隔离DCDC转换器的输出端与所述电池串和所述母线相连。
PCT/CN2021/103511 2020-06-30 2021-06-30 电池均流控制方法及电池均流控制系统 WO2022002122A1 (zh)

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