CN110120558B - Active equalization control method and control system of lithium ion battery - Google Patents

Active equalization control method and control system of lithium ion battery Download PDF

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CN110120558B
CN110120558B CN201910173086.0A CN201910173086A CN110120558B CN 110120558 B CN110120558 B CN 110120558B CN 201910173086 A CN201910173086 A CN 201910173086A CN 110120558 B CN110120558 B CN 110120558B
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lithium ion
battery
value
ion battery
voltage
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CN110120558A (en
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徐渊
张超
马佳艺
李峰
张霞
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Shanghai Electric Group Corp
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Shanghai Electric Group Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/446—Initial charging measures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/482—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for several batteries or cells 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
    • H02J7/0013—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
    • H02J7/0018—Circuits for equalisation of charge between batteries using separate charge circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

The invention relates to the technical field of battery management systems, in particular to an active equalization control method and a control system of a lithium ion battery, wherein the lithium ion battery is provided with a plurality of battery monomers connected in series, and the method comprises the following steps: step S1, estimating an initial value of the residual capacity of the lithium ion battery, and acquiring an estimated value of the residual capacity of the lithium ion battery and a voltage detection value of the lithium ion battery in real time; step S2, respectively calculating the average value of the residual electric quantity of the lithium ion battery and the average value of the voltage of the lithium ion battery according to the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery; step S3, judging the battery monomer needing to be balanced according to the average value of the residual electric quantity and the average value of the voltage; and step S4, balancing the battery cells needing balancing. Has the advantages that: the precision and the reliability of the balance system can be improved, the service efficiency of the battery is increased, the service life of the battery is prolonged, the control method is simple, the requirement on a controller is reduced, and the reliability of the system is improved.

Description

Active equalization control method and control system of lithium ion battery
Technical Field
The invention relates to the technical field of battery management systems, in particular to an active equalization control method and system for a lithium ion battery.
Background
In the prior art, the voltage ratio of a single battery in a lithium ion battery is relatively small, and a plurality of single batteries are generally connected in series to form a battery pack to be used so as to achieve a required high voltage, but in the using process, due to different environmental factors such as the properties and the temperature of the single batteries, the capacity of each single battery is different. The capacity of the battery pack has a barrel effect, is limited to the battery cell with the highest capacity during charging, and is limited to the battery cell with the lowest capacity during discharging, and imbalance among the battery cells reduces the service life of the battery cells, so that the balance among the battery cells is necessary.
At present, battery equalization is mainly divided into passive equalization and active equalization, wherein the passive equalization is to convert redundant charges of a battery into heat through a resistor and dissipate the heat, which causes energy waste; active equalization is to transfer the energy of the battery with more charge to the battery with less charge, so as to achieve the purpose of equalization.
For example, patent CN105140981A provides an active equalization control method for a lithium battery, which detects the voltage and current of a battery, and then controls the duty ratio of a switching device by estimating the SOC (State of charge) value and comparing the SOC value with the average value, so as to actively equalize the single battery; patent CN107046313A proposes a battery active equalization method, which includes collecting the voltage of each single battery of a battery pack and calculating the average voltage of all the single batteries of the battery pack, comparing whether the voltage of the single batteries is equal to the average voltage, calculating the average current of all the single batteries of the battery pack, calculating the current difference between the current of all the single batteries of the battery pack and the average current, calculating the capacity of the single batteries to be equalized according to the integral of the current difference over the time of closing a current equalizer, and performing capacity equalization on the single batteries of the battery pack; patent CN107623343A discloses an active equalization method and device for lithium ion battery, which determine whether voltages of each battery cell are equalized according to collected voltages of each battery cell, and if the voltages of each battery cell of the battery are unbalanced, charge the battery cell to be equalized by using an external equalization power supply until the voltages are equalized.
In the above patents, patent CN105140981A performs active equalization according to the estimated SOC, and the UKF estimation method used herein has accuracy depending on the accuracy of the battery electrical model and a relatively large computation amount, and needs to select a simple and reasonable battery model and a processor with a relatively high computation speed, and the accuracy of SOC estimation directly affects the accuracy of active equalization; the patent CN107046313A balances the single battery by comparing the difference of the single voltages and then calculating the capacity required for battery balancing, and only balances the battery according to the difference of the single voltages, where the battery voltage is affected by internal resistance, environment, and other factors, and the difference of the voltages cannot accurately reflect the imbalance of the battery capacity; patent CN107623343A judges whether balanced and utilizes external power supply to charge the monomer through the difference of comparison monomer voltage, has reduced software control's complexity, but needs to increase extra battery package, has not only increased the cost, has also increased the volume of equipment.
Therefore, a technical study for solving the problem of single active equalization technology of the lithium ion battery in the prior art is needed.
Disclosure of Invention
In view of the above problems in the prior art, an active equalization control method and system for a lithium ion battery are provided.
The specific technical scheme is as follows:
an active equalization control method for a lithium ion battery, wherein the lithium ion battery is provided with a plurality of battery cells connected in series, and the method comprises the following steps:
step S1, estimating an initial value of the residual capacity of the lithium ion battery, and acquiring an estimated value of the residual capacity of the lithium ion battery and a voltage detection value of the lithium ion battery in real time;
step S2, respectively calculating the average value of the residual electric quantity of the lithium ion battery and the average value of the voltage of the lithium ion battery according to the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery;
step S3, judging the battery monomer needing to be balanced according to the average value of the residual electric quantity and the average value of the voltage;
and step S4, balancing the battery cells needing balancing.
Preferably, in step S1, the step of estimating the initial value of the remaining capacity of the lithium ion battery includes:
step S10, detecting the standing time of the lithium ion battery, and judging whether the standing time is more than a preset time;
if yes, go to step S11;
if not, go to step S12;
step S11, calculating the remaining power of the lithium ion battery as an initial remaining power value by using an open circuit voltage method;
and step S12, calculating the residual capacity of the lithium ion battery as an initial value of the residual capacity by adopting an ampere-hour integral method.
Preferably, in step S1, the ampere-hour integration method is adopted to obtain the estimated remaining capacity of the lithium ion battery and the voltage detection value of the lithium ion battery in real time.
Preferably, the step S3 includes:
step S30, judging whether the voltage average value of the lithium ion battery is in a preset platform area;
if yes, go to step S31;
if not, go to step S33;
step S31, judging whether the average value of the residual electric quantity of the lithium ion battery is larger than a first preset proportion value or not and whether the average value of the voltage of the lithium ion battery is larger than a first preset voltage value or not;
if yes, go to step S4;
if not, go to step S32;
the step S32 is to determine whether the average voltage value of the lithium ion battery is greater than a second preset voltage value and whether the average remaining power value of the lithium ion battery is greater than a second preset proportion value;
if yes, go to step S4;
if not, go to step S2;
the step S33 of determining whether the average value of the remaining power of the lithium ion battery is greater than the first preset ratio and the average value of the voltage of the lithium ion battery is greater than a third preset voltage;
if yes, go to step S4;
if not, go to step S34;
the step S34 of determining whether the average voltage value of the lithium ion battery is greater than a fourth preset voltage value and the average remaining power value of the lithium ion battery is greater than the second preset proportion value;
if yes, go to step S4;
if not, the process goes to step S2.
Preferably, the step S4 includes:
step S40, balancing the battery cells needing balancing;
step S41, judging whether the difference value between the residual capacity average value and the voltage average value is smaller than a preset difference value;
if yes, ending the equalization;
if not, the process goes to step S40.
Preferably, the step S40 includes:
when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is larger than zero, discharging the single battery;
and when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is less than zero, charging the single battery.
Preferably, the preset time is set to at least 2 h.
Preferably, the first preset proportion value is set to be at least 2%;
the second preset proportion value is set to at least 1%.
Preferably, the first preset voltage value is set to be at least 10 mV;
the second preset voltage value is at least set to be 30 mV;
the third preset voltage value is at least set to be 60 mV;
the fourth preset voltage value is set to be at least 100 mV.
The invention also includes an active equalization control system for lithium ion batteries, comprising:
the battery pack comprises a plurality of battery monomers which are connected in series;
the battery information acquisition module is connected with the battery pack so as to acquire the battery information of each single battery in the battery pack;
the circuit selection module comprises a single selection switch and a positive and negative selection switch;
the single body selection switch is connected between every two single batteries and is used for communicating the single batteries needing to be subjected to balance control;
the positive and negative electrode selection switch is connected with the single body selection switch and is used for communicating the positive and negative electrodes of the single battery body;
the equalizing circuit comprises a forward converter and at least four forward conversion switching devices;
the secondary side of the forward converter is connected with the positive and negative electrode selection switch, and the primary side of the forward converter is connected with the positive and negative electrodes of the battery pack;
the equalizing circuit is used for adjusting the energy flow between each battery monomer and the battery pack by controlling the duty ratios of at least four forward conversion switching devices;
the balance control module is respectively connected with the battery information acquisition module, the battery selection module and the balance circuit;
the balance control module is used for gating the single body selection switch and the positive and negative selection switches corresponding to the single battery according to the battery information acquired by the battery acquisition system, and balancing the single battery needing to be balanced by estimating the residual electric quantity estimated value of the single battery and taking the residual electric quantity average value of the single battery and the voltage average value of the single battery as judgment basis.
The technical scheme of the invention has the beneficial effects that: the problem that the active equalization technology of the lithium ion battery is single in the prior art is solved, the single battery needing equalization is equalized by taking the average value of the residual electric quantity and the average value of the voltage of the single battery as the judgment basis of the active equalization, the equalization precision and the equalization reliability can be improved, the service efficiency of the battery is increased, the service life of the battery is prolonged, the control method is simple, the requirement on a controller is lowered, and the reliability of a system is improved.
Drawings
Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings. The drawings are, however, to be regarded as illustrative and explanatory only and are not restrictive of the scope of the invention.
Fig. 1 is a flowchart illustrating steps of an active equalization control method for a lithium ion battery according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating steps of an embodiment of an active equalization control method for a lithium ion battery according to the present invention;
fig. 3 is a schematic block diagram of an active equalization control system of a lithium ion battery according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
At present, battery equalization is mainly divided into passive equalization and active equalization, wherein the passive equalization is to convert redundant charges of a battery into heat through a resistor and dissipate the heat, which causes energy waste; active equalization is to transfer the energy of the battery with more charge to the battery with less charge, so as to achieve the purpose of equalization.
The invention includes an active equalization control method of lithium ion battery, the lithium ion battery has plural battery monomers connected in series, including:
step S1, estimating an initial value of the residual capacity of the lithium ion battery, and acquiring an estimated value of the residual capacity of the lithium ion battery and a voltage detection value of the lithium ion battery in real time;
step S2, respectively calculating the average value of the residual electric quantity of the lithium ion battery and the average value of the voltage of the lithium ion battery according to the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery;
step S3, judging the battery monomer needing to be balanced according to the average value of the residual electric quantity and the average value of the voltage;
and step S4, balancing the battery cells needing balancing.
Through the technical scheme of the active equalization control method of the lithium ion battery, as shown in fig. 1, the problem that the active equalization technology of the lithium ion battery is single in the prior art is effectively solved, the average value of the remaining power and the average value of the voltage of the single battery are used as the judgment basis of the active equalization, the single battery needing to be equalized is equalized, the equalization precision and the equalization reliability can be improved, the service efficiency of the battery is increased, the service life of the battery is prolonged, the control method is simple, the requirement on a controller is reduced, and the system reliability is improved.
In a preferred embodiment, in step S1, the step of estimating the initial value of the remaining capacity of the lithium ion battery is:
step S10, detecting the standing time of the lithium ion battery, and judging whether the standing time is more than a preset time;
if yes, go to step S11;
if not, go to step S12;
step S11, calculating the residual capacity of the lithium ion battery as the initial value of the residual capacity by adopting an open circuit voltage method;
and step S12, calculating the residual capacity of the lithium ion battery as an initial value of the residual capacity by adopting an ampere-hour integral method.
Specifically, as shown in fig. 1 and 2, there are many methods for estimating the remaining power of the lithium ion battery, and since the technical scheme uses an ampere-hour integration method, it is necessary to estimate an initial value of the remaining power of the lithium ion battery, first detect the standing time of the lithium ion battery, and determine whether the standing time is greater than 2 hours, which has the advantages of making the acquired initial value of the remaining power of the lithium ion battery more accurate as the initial value of the remaining power, that is, reducing an error of estimating the initial value of the remaining power and estimating the initial value of the remaining power by using a method combining an open-circuit voltage method and the ampere-hour integration method, and thus has the advantages of using different methods to estimate the initial value of the remaining power, having a reference value, and improving the estimation accuracy. It should be noted that the open-circuit voltage method and the ampere-hour integration method are widely applied in the technical field, and the process of calculating the remaining power of the lithium ion battery is not described herein again.
In a preferred embodiment, in step S1, an ampere-hour integration method is used to obtain the estimated remaining capacity of the lithium ion battery and the detected voltage of the lithium ion battery in real time.
Specifically, with reference to fig. 1 and 2, the estimated remaining power value of the lithium ion battery is estimated by using the estimated initial remaining power value and using an ampere-hour integration method, wherein errors of the estimated remaining power value calculated by the ampere-hour integration method accumulate with time, and the battery voltage is affected by internal resistance, environment and other factors, so that the scheme uses a method of combining the estimated remaining power value and the battery voltage to balance the battery, that is, to calculate the average remaining power value and the average voltage value respectively, thereby effectively solving the problem of single active equalization technique of the lithium ion battery in the prior art, balancing the single battery to be equalized by using the average remaining power value and the average voltage value of the single battery as the basis for judging the active equalization, improving the accuracy and reliability of equalization, increasing the use efficiency of the battery, and prolonging the service life of the battery, the method is simple in calculation method, small in calculation amount, high in calculation accuracy and precision and convenient for popularization of users.
In a preferred embodiment, step S3 includes:
step S30, judging whether the voltage average value of the lithium ion battery is in a preset platform area;
if yes, go to step S31;
if not, go to step S33;
step S31, judging whether the average value of the residual electric quantity of the lithium ion battery is larger than a first preset proportion value or not and whether the average value of the voltage of the lithium ion battery is larger than a first preset voltage value or not;
if yes, go to step S4;
if not, go to step S32;
step S32, judging whether the average voltage value of the lithium ion battery is larger than a second preset voltage value and the average remaining power value of the lithium ion battery is larger than a second preset proportion value;
if yes, go to step S4;
if not, go to step S2;
step S33, judging whether the average value of the residual electric quantity of the lithium ion battery is larger than a first preset proportion value or not and whether the average value of the voltage of the lithium ion battery is larger than a third preset voltage value or not;
if yes, go to step S4;
if not, go to step S34;
step S34, judging whether the average voltage value of the lithium ion battery is larger than a fourth preset voltage value and whether the average remaining power value of the lithium ion battery is larger than a second preset proportion value;
if yes, go to step S4;
if not, the process goes to step S2.
In the technical scheme, the first preset proportion value is at least set to be 2%;
the second preset proportion value is set to be at least 1%;
the first preset voltage value is set to be at least 10 mV;
the second preset voltage value is set to be at least 30 mV;
the third preset voltage value is at least set to 60 mV;
the fourth predetermined voltage value is set to at least 100 mV.
Specifically, referring to fig. 1 and 2, the battery cell requiring equalization is determined according to the average value of the remaining power and the average value of the voltage, and since the charging curve of the lithium ion lithium battery has a voltage plateau region, the voltage threshold of the battery cell is divided into three segments, wherein the SOC average value and the average value of the battery cell are respectively calculated, the difference between each segment of the battery cell and the average value is calculated, and then whether the average value of the voltage is in the plateau region is determined; when the average voltage value is in the plateau region, balancing the single batteries when the absolute delta SOC is more than 2% and the absolute delta U is more than 10mV or the absolute delta U is more than 30mV and the absolute delta SOC is more than 1% electricity; and when the voltage average value is not in the plateau region, balancing the single batteries when the absolute value delta SOC is more than 2% and the absolute value delta U is more than 60mV or the absolute value delta U is more than 100mV and the absolute value delta SOC is more than 1%.
It should be noted that, the first preset ratio, the second preset ratio, the first preset voltage, the second preset voltage, the third preset voltage, and the fourth preset voltage are all obtained through data experiments as references, and are not described herein again.
Further, the active equalization scheme proposed by the scheme is different from the existing scheme in that: (1) the balance control is carried out on the single battery by comprehensively considering the estimated value SOC of the residual electric quantity and the voltage difference value of the single battery, so that the balance precision and the balance reliability can be improved, the service efficiency of the battery is increased, and the service life of the battery is prolonged; (2) when the voltage difference value of the single battery is judged, the charging curve graph of the lithium ion lithium battery is considered to have a platform area, the threshold value of the voltage of the single battery is divided into three sections, and the calculation precision is improved; (3) the method of combining the open-circuit voltage method and the ampere-hour integration method is adopted to calculate the estimated value SOC of the residual electric quantity, so that the calculation error of the SOC of the residual electric quantity is reduced; (4) the control method is simple, the requirement on the controller is reduced, and the reliability of the system is improved.
In a preferred embodiment, step S4 includes:
step S40, balancing the battery cells needing balancing;
step S41, judging whether the difference value between the average value of the residual electric quantity and the average value of the voltage is smaller than a preset difference value;
if yes, ending the equalization;
if not, the process goes to step S40.
In the above technical solution, step S40 includes:
when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is greater than zero, discharging the battery monomer;
and when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is less than zero, charging the single battery.
Specifically, as shown in fig. 1 and 2, the charge and discharge directions are determined by the positive and negative values of Δ SOC, if the charge and discharge directions are greater than 0, the single battery is discharged, if the charge and discharge directions are less than 0, the single battery is charged, and when the SOC difference value and the battery single voltage difference value are within a reasonable range, the equalization is stopped. Further, balance control is carried out on the single batteries by comprehensively considering the residual capacity SOC and the voltage difference value of the single batteries, balance precision and balance reliability can be improved, the service efficiency of the batteries is increased, and the service life of the batteries is prolonged.
The present invention further includes an active equalization control system for lithium ion batteries, as shown in fig. 3, including:
a battery pack 1, wherein the battery pack 1 comprises a plurality of battery monomers which are connected in series;
the battery information acquisition module 2 is connected with the battery pack 2 to acquire the battery information of each battery monomer in the battery pack 1;
the circuit selection module 3, the circuit selection module 3 includes a monomer selection switch 30 and a positive and negative selection switch 31;
the single body selection switch 30 is connected between every two single batteries and is used for communicating the single batteries needing to be subjected to balance control;
the positive and negative electrode selection switch 31 is connected with the single body selection switch 30, and the positive and negative electrode selection switch 31 is used for communicating the positive and negative electrodes of the single battery body;
the equalizing circuit 4, the equalizing circuit 4 includes a forward converter 40 and at least four forward conversion switching devices 41;
the secondary side of the forward converter 40 is connected with the positive and negative electrode selection switch 31, and the primary side of the forward converter 40 is connected with the positive and negative electrodes of the battery pack 1;
the equalizing circuit 4 adjusts the energy flow between each battery cell and the battery pack 1 by controlling the duty ratios of at least four forward conversion switching devices 41;
the balance control module 5 is connected with the battery information acquisition module 2, the battery selection module 3 and the balance circuit 4 respectively;
the balance control module 5 is configured to gate the cell selection switch 30 and the positive and negative selection switches 31 corresponding to the single cells according to the battery information acquired by the battery acquisition system 5, and balance the single cells requiring balancing by estimating the remaining power of the single cells and using the average value of the remaining power of the single cells and the average value of the voltage of the single cells as a judgment basis.
Specifically, as shown in fig. 3, the equalizing system provided by the present invention includes a battery pack 1, a battery information acquisition module 2, a battery selection module 3, an equalizing circuit 4, and an equalizing control module 5, wherein the battery pack 1 is connected to a secondary side of a forward converter 40 in the equalizing circuit 4 through a cell selection switch 30 and a positive/negative selection switch 31, the cell selection switch 30 is used to select and communicate a battery cell to be equalized, two adjacent switches are gated each time, the positive/negative selection switch 31 is used to ensure that the positive/negative electrode of the battery cell is correspondingly connected to the positive/negative electrode of the forward converter 40, and the primary side of the forward converter 40 is connected to the positive/negative electrode of the battery pack 1.
Further, the duty ratio of the four forward converter switches 41 is controlled to realize that each single battery and the whole battery pack 1 perform bidirectional energy flow, the battery information acquisition module 2 is used for acquiring information of battery voltage, current, battery temperature, board temperature and the like of the single batteries, and transmitting the information to the balance control module 5 through SPI communication, when the battery information acquisition module 2 detects that the single batteries are unbalanced, the balance control module 5 firstly estimates the residual electric quantity estimated value SOC of the battery pack 1 according to the information acquired by the battery information acquisition module 2, and judges the single battery needing to be balanced by taking the residual electric quantity estimated value SOC and the voltage of the single battery as the basis, gates a single selection switch and a positive and negative selection switch corresponding to the single battery, and then calculates the duty ratios of the four forward converter switches 41 according to the preset balance current value and the charging and discharging directions to perform single battery electricity charging And balancing the batteries until the difference value between the SOC and the battery voltage is smaller than a set value.
Furthermore, the active equalization control method of the lithium ion battery is applied to an active equalization control system of the lithium ion battery, the problem that the active equalization technology of the lithium ion battery is single in the prior art is effectively solved, the single battery needing equalization is equalized by taking the average value of the residual electric quantity and the average value of the voltage of the single battery as the judgment basis of the active equalization, the equalization precision and the equalization reliability can be improved, the use efficiency of the battery is increased, the service life of the battery is prolonged, the control method is simple, the requirement on a controller is reduced, and the reliability of the system is improved.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims (9)

1. An active equalization control method for a lithium ion battery having a plurality of cells connected in series, comprising:
step S1, estimating an initial value of the residual capacity of the lithium ion battery, and acquiring an estimated value of the residual capacity of the lithium ion battery and a voltage detection value of the lithium ion battery in real time;
step S2, respectively calculating the average value of the residual electric quantity of the lithium ion battery and the average value of the voltage of the lithium ion battery according to the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery;
step S3, judging the battery monomer needing to be balanced according to the average value of the residual electric quantity and the average value of the voltage;
step S4, balancing the battery cells needing balancing;
the step S3 includes:
step S30, judging whether the voltage average value of the lithium ion battery is in a preset platform area;
if yes, go to step S31;
if not, go to step S33;
step S31, judging whether the average value of the residual electric quantity of the lithium ion battery is larger than a first preset proportion value or not and whether the average value of the voltage of the lithium ion battery is larger than a first preset voltage value or not;
if yes, go to step S4;
if not, go to step S32;
the step S32 is to determine whether the average voltage value of the lithium ion battery is greater than a second preset voltage value and whether the average remaining power value of the lithium ion battery is greater than a second preset proportion value;
if yes, go to step S4;
if not, go to step S2;
the step S33 of determining whether the average value of the remaining power of the lithium ion battery is greater than the first preset ratio and the average value of the voltage of the lithium ion battery is greater than a third preset voltage;
if yes, go to step S4;
if not, go to step S34;
the step S34 of determining whether the average voltage value of the lithium ion battery is greater than a fourth preset voltage value and the average remaining power value of the lithium ion battery is greater than the second preset proportion value;
if yes, go to step S4;
if not, the process goes to step S2.
2. The active equalization control method for lithium ion battery according to claim 1, wherein in the step S1, the step of estimating the initial value of the remaining capacity of the lithium ion battery comprises:
step S10, detecting the standing time of the lithium ion battery, and judging whether the standing time is more than a preset time;
if yes, go to step S11;
if not, go to step S12;
step S11, calculating the remaining power of the lithium ion battery as an initial remaining power value by using an open circuit voltage method;
and step S12, calculating the residual capacity of the lithium ion battery as an initial value of the residual capacity by adopting an ampere-hour integral method.
3. The active equalization control method for lithium ion batteries according to claim 2, wherein in step S1, the ampere-hour integration method is adopted to obtain the estimated remaining capacity of the lithium ion battery and the detected voltage of the lithium ion battery in real time.
4. The active equalization control method for lithium ion batteries according to claim 1, wherein the step S4 comprises:
step S40, balancing the battery cells needing balancing;
step S41, judging whether the difference value between the residual capacity average value and the voltage average value is smaller than a preset difference value;
if yes, ending the equalization;
if not, the process goes to step S40.
5. The active equalization control method for lithium ion batteries according to claim 4, wherein the step S40 comprises:
when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is larger than zero, discharging the single battery;
and when the difference value between the estimated value of the residual capacity of the lithium ion battery and the average value of the residual capacity is less than zero, charging the single battery.
6. The active equalization control method of a lithium ion battery according to claim 2, wherein the preset time is set to at least 2 h.
7. The active equalization control method for lithium ion batteries according to claim 1, wherein the first preset proportion value is set to at least 2%;
the second preset proportion value is set to at least 1%.
8. The active equalization control method for lithium ion batteries according to claim 1, wherein the first preset voltage value is set to at least 10 mV;
the second preset voltage value is at least set to be 30 mV;
the third preset voltage value is at least set to be 60 mV;
the fourth preset voltage value is set to be at least 100 mV.
9. An active equalization control system of a lithium ion battery, characterized in that the active equalization control method of the lithium ion battery according to any one of claims 1 to 8 is adopted, and comprises the following steps:
the battery pack comprises a plurality of battery monomers which are connected in series;
the battery information acquisition module is connected with the battery pack so as to acquire the battery information of each single battery in the battery pack;
the circuit selection module comprises a single selection switch and a positive and negative selection switch;
the single body selection switch is connected between every two single batteries and is used for communicating the single batteries needing to be subjected to balance control;
the positive and negative electrode selection switch is connected with the single body selection switch and is used for communicating the positive and negative electrodes of the single battery body;
the equalizing circuit comprises a forward converter and at least four forward conversion switching devices;
the secondary side of the forward converter is connected with the positive and negative electrode selection switch, and the primary side of the forward converter is connected with the positive and negative electrodes of the battery pack;
the equalizing circuit is used for adjusting the energy flow between each battery monomer and the battery pack by controlling the duty ratios of at least four forward conversion switching devices;
the balance control module is respectively connected with the battery information acquisition module, the circuit selection module and the balance circuit;
the balance control module is used for gating the single body selection switch and the positive and negative selection switches corresponding to the single battery according to the battery information acquired by the battery acquisition system, and balancing the single battery needing to be balanced by estimating the residual electric quantity estimated value of the single battery and taking the residual electric quantity average value of the single battery and the voltage average value of the single battery as judgment basis.
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