CN111555407B - Series-parallel battery pack integrated active equalization method based on inductive energy storage - Google Patents
Series-parallel battery pack integrated active equalization method based on inductive energy storage Download PDFInfo
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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
- H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
- B60L58/22—Balancing the charge of battery modules
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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
- H01M10/44—Methods for charging or discharging
- H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
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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
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/342—The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging
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- 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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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/92—Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
Abstract
The invention discloses an inductive energy storage based integrated active equalization method for series-parallel battery packs, wherein the series-parallel battery packs are connected in parallel by m groups of series-parallel battery packs, and each group of series-parallel battery packs comprises n monomers; the balanced topology of the series-parallel battery pack comprises (2m × n +2m +2) MOS (metal oxide semiconductor) tubes, (2m × n +2m +2) diodes and two inductors; the two inductances being respectively designated LsAnd Lp. The equalization method is characterized in that: firstly, the series-parallel battery pack balance can be realized simultaneously; when all the monomers in the series battery pack are balanced, the energy can be directly transferred from the high-energy monomer to the low-energy monomer; when the series battery packs connected in parallel are balanced, energy can be directly transferred from the high-energy series battery pack to the low-energy series battery pack. Secondly, the balanced topology energy storage unit has simple structure, small volume and simple control. And balanced topology is easy to expand, and when the number of monomers in the series battery pack or the number of the series battery packs changes, the number of corresponding MOS (metal oxide semiconductor) tubes is increased or decreased.
Description
Technical Field
The invention belongs to the technical field of power battery equalization, and relates to an integrated active equalization method for series-parallel battery packs based on inductive energy storage, which is suitable for a battery management system in a new energy automobile.
Background
In recent years, with more and more serious environmental pollution and increasingly deficient petroleum resources, new energy automobiles are also gaining popularity. The lithium battery has the advantages of high energy density and long cycle life, and is gradually the main power source of new energy automobiles. Due to the fact that the voltage and the capacity of the single battery are low, the battery is required to be connected in series and in parallel to form a battery pack in application. The single battery is influenced by factors such as production process and the like, and the phenomenon of inconsistency can occur after the battery is circularly charged and discharged for a period of time, so that the energy utilization rate and the cycle life of the battery pack are reduced, and the phenomena of overcharge and overdischarge are easily caused. The equalization technology has important significance for improving the inconsistency of the battery pack.
Currently, equalization techniques are mainly divided into two categories: passive equalization and active equalization. The passive equalization mainly adopts a resistor as a shunt of each battery, and converts redundant energy of a high-energy monomer into heat energy to be consumed. The method has the advantages of small volume and low cost, but the problems of energy loss and heat dissipation are key disadvantages. Active equalization is a hotspot of recent equalization technology research, energy is transferred from high-energy single batteries to low-energy single batteries through energy storage devices such as capacitors, inductors and converters, so that equalization of the battery pack is realized, and the equalization is also called non-energy-consumption equalization or lossless equalization. The balancing method based on the switched capacitor has the advantages of small size of a balancing circuit and easiness in control, but the balancing efficiency is low, the capacitor balancing time is long, and the problem is particularly obvious when the voltage difference between the battery monomers is not large. The equalization method based on the inductor has higher equalization efficiency, but the circuit structure is complex, the number of MOS (metal oxide semiconductor) tubes and inductors is large, the control is complex, and the reduction of the volume of the equalization system is not facilitated. The single inductance resonance circuit is switched near the resonance frequency, so that the impedance in the equalizing loop is minimum, and the equalizing method based on the single inductance resonance circuit has the advantages of high equalizing efficiency, high equalizing speed and the like, but a plurality of switching devices are required, and the control is complex. The transformer-based equalization method has the advantages of high equalization efficiency, simplicity in control and easiness in isolation, but the transformer is complex in design and has the problem of magnetic saturation, so that the equalization topology is large in size, difficult to modularize, high in cost and difficult to expand. The balancing method based on the Buck, Boost and other converters can realize bidirectional flow of energy, has high balancing efficiency and high balancing speed, but still has the defects of large volume, complex control, high cost and the like.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the existing balancing method, provides an integrated active balancing method for series-parallel battery packs based on inductive energy storage, improves the unbalance phenomenon of the series-parallel battery packs, and prolongs the service life of the series-parallel battery packs. To achieve the above objects, the present invention is implemented according to the following embodiments.
An integrated active equalization method of series-parallel battery pack based on inductive energy storage,
the series-parallel battery pack comprises m groups of series-parallel battery packs connected in parallel, and each group of series-parallel battery packs comprises n monomers;
the balanced topology of the series-parallel battery pack comprises (2m × n +2m +2) MOS (metal oxide semiconductor) tubes, (2m × n +2m +2) diodes and two inductors; the two inductances being respectively designated LsAnd Lp；
In each group of series battery packs, the left and right bridge arms of the single anode are respectively connected with the series circuit of the MOS tube and the diode, and the left and right bridge arms of the single cathode are respectively connected with the series circuit of the MOS tube and the diode; the series circuit of the MOS tube and the diode comprises an MOS tube and a diode which are connected in series;
inductor LsAn inductor L connected in series with a diode and a MOS tubepThe inductor is connected with a diode and an MOS tube in series to obtain two inductor-diode-MOS tube series circuits; the two inductor-diode-MOS tube series circuits are connected in parallel;
the tail end of a left bridge arm and the tail end of a right bridge arm of the series battery pack are connected with two ends of a series circuit of two inductors-diodes-MOS tubes which are connected in parallel;
inductance L during equalization in series batterysStoring energy, and realizing that the balance energy is directly transferred from the monomer with the highest SOC to the monomer with the lowest SOC;
inductance L when each series battery pack in series-parallel battery pack is balancedpAnd storing energy, and realizing that the balance energy is directly transferred from the series battery pack with the highest average SOC to the series battery pack with the lowest average SOC.
Preferably, the series battery packs in the series-parallel battery packs are respectively marked as P1，P2…Pm；
In each group of series-connected battery packs, each monomer is marked as B in sequencex1，Bx2，…，BxnLeft of monomerThe MOS tubes connected with the right bridge arm are marked as S in sequencex0，Sx1，…，Sx(2n+1)X is the serial number of each series battery pack connected together in parallel;
inductances being respectively denoted LsAnd LpThe MOS tube connected in series with the inductor is correspondingly marked as SsAnd Sp；
The balancing method aims at enabling the SOC of each monomer of the series battery pack to be consistent and enabling the average SOC of each series battery pack of the series and parallel battery packs to be consistent;
the above object is achieved by the steps of:
when the inconsistency of the SOC of each monomer in the series battery pack and the average SOC of each series battery pack between the series battery packs and the parallel battery packs exceeds a given threshold value, starting the balanced topology;
when each monomer in the series battery pack is balanced, the MOS tube S responsible for balancing in the series battery packsKeeping conduction; monomer BxiHas the highest SOC of (B)xjThe SOC of (1) is lowest, wherein i and j are serial numbers of the single battery packs connected in series;
the equalization process is divided into two stages: first stage, monomer BxiCorresponding MOS transistor Sx(2i-1)And Sx(2i)Conducting, monomer BxiFor inductor LsStoring energy; second stage, MOS transistor Sx(2i-1)、Sx(2i)Breaking, monomer BxjCorresponding MOS transistor Sx(2j-2)、Sx(2j+1)Conduction, inductance LsMonomer BxjCharging; finally realizing the transfer of balance energy between any monomers;
MOS tube S for balancing series battery groups connected in parallel when balancing series battery groups in series-parallel battery grouppKeeping conduction;
series battery pack P in series-parallel battery packiHas the highest average SOC of PjWherein i and j are serial numbers of the series battery packs connected together in parallel; the equalization process is divided into two stages: first stage, MOS transistor Si1、Si(2n)Conducting, series-connecting battery pack PiTo the inductance LpCharging; second stage, MOS transistor Si1、Si(2n)Disconnected, MOS tube Sj0、Sj(2n+1)Conduction, inductance LpTo the series battery PjCharging; and finally, the balance energy is transferred between any parallel battery packs.
In order to implement the above stages smoothly, parameters of core components of the circuit need to be calculated and analyzed, and appropriate circuit parameters need to be set. Firstly, parameter design is carried out on the equalization in the series battery pack. Suppose cell B in a series batteryxiHas a maximum voltage of UiMonomer BxjHas a minimum voltage of UjWherein i and j are serial numbers of the battery pack monomers connected in series; the total conducting voltage drop of all the switching devices in the loop is delta U; time is denoted t; the intra-group equalization period is denoted as T; the PWM wave duty ratios of the charging and discharging of the inductor are respectively alpha and alpha'; the corresponding inductance is denoted Ls(ii) a In order to ensure the equalizing speed and reliability, the maximum equalizing current I for equalizing the single batteries of the series battery pack needs to be determined firstlys。
In the first stage, when the MOS transistor Sx(2i-1)And Sx(2i)When conducting, the monomer BxiIs an inductance LsCharging, flowing through LsThe current of (3) rises linearly, LsAnd (4) storing energy. The time T of the first stage is alpha T, the impedance of a closed loop is ignored, and the maximum equalizing current, namely the peak current I of the inductorsComprises the following steps:
the inductance L can be obtained according to the required maximum equalizing current and the selected switching frequency fs：
Inductor current isThe expression of (a) is as follows:
when T ═ T, since T > (α + α') T, then:
further derivation yields:
at the beginning of the second phase, the MOS transistor Sx(2j-2)And Sx(2j+1)When the circuit is switched on, the inductive current is approximately linearly decreased, and the following can be obtained according to kirchhoff's law:
substituting the initial conditions above, we can obtain:
the above formula is combined with (1) to obtain:
the parameter calculation of the balance between each series battery pack in the series-parallel battery pack and the balance between each single body in the series battery pack is similar, and the parameters of the optimal energy storage inductance are different due to the fact that the voltages of the balance objects of the series battery pack and the balance objects of the single body in the series battery pack are different. Comprehensively considering the equalizing speed and reliability of the series battery packs connected in parallel, and setting the maximum equalizing current Ip. Suppose a parallel battery pack PiHas the maximum voltage of UPiGroup of batteries PjHas a minimum voltage of UPjWherein i and j are serial numbers of series battery packs connected together in parallel; the corresponding inductance is denoted Lp. Referencing parameters for cell balancing in series connected battery packsCalculating to obtain the inductance LpComprises the following steps:
in summary, the balance topology residual parameters can be obtained by the above formula according to the selection of the appropriate maximum balance current and the corresponding balance period.
Preferably, the equalization topology is controlled by a control circuit; the frequency of the control signal of the control circuit is determined according to the parameters of the inductor, the switching loss of the MOS tube, the voltage of the battery of the whole series-parallel battery pack and the voltage of the single battery.
Preferably, the duty cycle of the driving signal output by the control circuit resets the energy stored in the inductor in each signal period, that is, the current of the inductor first rises from zero and finally falls to zero.
Preferably, all the monomers in the series-parallel battery pack are secondary batteries; the secondary battery is one of a lead-acid battery, a lithium ion battery, a nickel-metal hydride battery and a super capacitor.
The invention achieves the following beneficial effects:
compared with the prior art, the method is based on inductive energy storage and establishes an integrated active equalization method for the series-parallel battery pack. The balancing method has the first characteristic that the balancing of the series-parallel battery packs can be realized simultaneously; the second characteristic is that the balanced topology energy storage unit has simple structure, small volume and simple control; the third characteristic is that the equilibrium topology is easy to expand, and when the number of monomers in the series battery pack or the number of the series battery packs changes, only the number of the corresponding MOS tubes needs to be increased or decreased.
Drawings
In order to more clearly illustrate the principle and technical solutions of the present invention in implementation, the technical solutions related to the present invention will be further described below by using the accompanying drawings, and the following drawings are only some implementation examples of the present invention, and it is obvious for those skilled in the art that other technical solutions can be obtained according to the following drawings without creative efforts.
FIG. 1 is a schematic diagram of the equalization topology of the present invention;
FIG. 2 is a first stage operation principle of the equalization process of each cell in the series battery pack;
FIG. 3 is a second stage of operation of the equalization process of each cell in the series battery;
FIG. 4 is a first stage operation principle of the equalization process between each series-connected battery pack in the series-parallel battery pack;
FIG. 5 is a second stage operation principle of the equalization process between each series-connected battery set in the series-parallel battery set;
FIG. 6 is a timing diagram of the duty cycle of the control signals of the present invention;
FIG. 7 is a series-parallel battery equalization control strategy of the present invention;
FIG. 8 is a four-string two-parallel-series-parallel battery simulation model built in MATLAB/Simulink;
FIG. 9 is a diagram of the balanced topology simulation model input condition currents of four strings of two parallel-series parallel battery packs;
FIG. 10 is a simulation curve of SOC balance for each cell in P1 in a four-string two-parallel-series-parallel battery pack;
FIG. 11 is a simulation curve of SOC balance for each cell in P2 in a four-string two-parallel-series-parallel battery pack;
FIG. 12 is a variation curve of the maximum difference of SOC of each cell in P1 and P2 of a four-string two-parallel-series-parallel battery pack;
FIG. 13 is a plot of the average SOC balance simulation for P1 and P2 for a four string two parallel-to-serial parallel battery pack;
fig. 14 is a graph of the average maximum difference in SOC variation for P1 and P2 in a four string two parallel-series parallel battery pack.
Detailed Description
The invention will be further described with reference to the drawings and specific embodiments, which are illustrative and not limiting.
Example 1
As shown in fig. 1, an integrated active equalization method for series-parallel battery pack based on inductive energy storage is as follows:
the series-parallel battery pack comprises m groups of series-parallel battery packs connected in parallel, and each group of series-parallel battery packs comprises n monomers;
the balanced topology of the series-parallel battery pack comprises (2m × n +2m +2) MOS (metal oxide semiconductor) tubes, (2m × n +2m +2) diodes and two inductors; the two inductances being respectively designated LsAnd Lp；
In each group of series battery packs, the left and right bridge arms of the single anode are respectively connected with the series circuit of the MOS tube and the diode, and the left and right bridge arms of the single cathode are respectively connected with the series circuit of the MOS tube and the diode; the series circuit of the MOS tube and the diode comprises the MOS tube and the diode which are connected in series.
Inductor LsAn inductor L connected in series with a diode and a MOS tubepThe inductor is connected with a diode and an MOS tube in series to obtain two inductor-diode-MOS tube series circuits; the two inductor-diode-MOS tube series circuits are connected in parallel;
the tail end of a left bridge arm and the tail end of a right bridge arm of the series battery pack are connected with two ends of two inductor-diode-MOS tube series circuits which are connected together in parallel.
Inductance L during equalization in series batterysStoring energy, and realizing that the balance energy is directly transferred from the monomer with the highest SOC to the monomer with the lowest SOC;
inductance L when each series battery pack in series-parallel battery pack is balancedpAnd storing energy, and realizing that the balance energy is directly transferred from the series battery pack with the highest average SOC to the series battery pack with the lowest average SOC.
The series battery packs in the series-parallel battery packs are respectively marked as P1，P2…Pm；
In each group of series-connected battery packs, each monomer is marked as B in sequencex1，Bx2，…，BxnThe MOS tubes connected with the left and right bridge arms of the single body are marked as S in sequencex0，Sx1，…，Sx(2n+1)X is the serial number of each series battery pack connected together in parallel;
inductances being respectively denoted LsAnd LpThe MOS tube connected in series with the inductor is correspondingly marked as SsAnd Sp。
The balancing method aims at enabling the SOC of each monomer of the series battery pack to be consistent and enabling the average SOC of each series battery pack of the series and parallel battery packs to be consistent;
the above object is achieved by the steps of:
when the inconsistency of the SOC of each monomer in the series battery pack and the average SOC of each series battery pack between the series battery packs and the parallel battery packs exceeds a given threshold value, starting the balanced topology;
when each monomer in the series battery pack is balanced, the MOS tube S responsible for balancing in the series battery packsKeeping conduction; monomer BxiHas the highest SOC of (B)xjIs the lowest, wherein i and j are serial numbers of the battery pack monomers connected in series.
The equalization process of each monomer in the series battery pack is divided into two stages:
as shown in FIG. 2, in the first stage, the single battery BxiCorresponding MOS transistor Sx(2i-1)And Sx(2i)Is conducted and flows through the inductor LsThe current of (2) rises linearly, the monomer BxiFor inductor LsCharging, LsEnergy is stored.
As shown in fig. 3, the MOS transistor S is at the second stagex(2i-1)、Sx(2i)Breaking, monomer BxjCorresponding MOS transistor Sx(2j-2)And Sx(2j+1)Is conducted and flows through the inductor LsCurrent of (2) linearly decreases, inductance LsMonomer BxjAnd (6) charging. The whole process realizes the direct transfer of the equalizing energy from the SOC highest monomer to the SOC lowest monomer.
MOS tube S for balancing series battery groups connected in parallel when balancing series battery groups in series-parallel battery grouppRemain on. Series battery pack P in series-parallel battery packiHas the highest average SOC of PjIs the lowest, wherein i and j are serial numbers of the series battery packs.
The equalization process between the series-connected battery packs connected in parallel is divided into two stages:
as shown in fig. 4, in the first stage, the MOS transistor Si1、Si(2n)Conducting, series-connecting battery pack PiTo the inductance LpCharging;
as shown in fig. 5, the MOS transistor S is at the second stagei1、Si(2n)Disconnected, MOS tube Sj0、Sj(2n+1)Conduction, inductance LpTo the series battery PjAnd (6) charging. The whole process realizes the direct transfer of the equalizing energy from the average SOC highest series battery pack to the average SOC lowest series battery pack.
Fig. 6 is a timing chart of the duty ratio of the control signal according to the present invention. Vx(2i-1)/Vx(2i)Denotes a MOS transistor Sx(2i-1)And Sx(2i)Drive signal of Vx(2j-2)/Vx(2j+1)Denotes a MOS transistor Sx(2j-2)And Sx(2j+1)Drive signal of Vi1/Vi(2n)Denotes a MOS transistor Si1And Si(2n)Drive signal of Vj0/Vj(2n+1)Denotes a MOS transistor Sj0And Sj(2n+1)The balance period of the driving signal is T, and the duty ratios of PWM waves corresponding to the MOS tubes are respectively alpha and alpha'.
As shown in fig. 7, it is a series-parallel battery equalization control strategy according to the present invention. The SOC is used as the consistency index of the series-parallel connection equalization, and the equalization threshold values of the series-parallel connection battery packs are respectively set for the equalization of the series-parallel connection battery packs
And series-parallel battery equalization threshold
When the maximum difference value of the SOC of each monomer in the series battery pack is larger than
When the SOC maximum difference value is smaller than the SOC maximum difference value, the balance topology starts to work
When so, the equalization topology stops working. When the average maximum difference of SOC between the series-connected battery packs connected in parallel is larger than
When the maximum difference value is less than the maximum difference value, the balanced topology starts working
When so, the equalization topology stops working.
As shown in fig. 8, the battery pack simulation model is a four-string two-parallel-series-parallel battery pack simulation model built in MATLAB/Simulink. Four strings and two groups of batteries are connected in parallel, each group of batteries in series comprises 4 monomers, and 2 groups of batteries in series are connected in parallel. The built balanced simulation model comprises a switch module, a control module, a detection module and the like. The simulation model specific parameter settings are shown in table 1.
TABLE 1 simulation parameter Table of simulation model
As shown in fig. 9, the operating condition current is input into the balanced topology simulation model of the four-string two-parallel-series-parallel battery pack. In actual work of the series-parallel battery pack, due to the influences of factors such as environment, human factors and the like, the charge-discharge state of the series-parallel battery pack is not fixed and unchanged, and in order to simulate the actual working state, namely to consider the normal working condition, the load is set according to the working condition of a UDDS (udcan dynameter Driving schedule). In one period, the average value of current output is 1.07A, the maximum value is 2.64A, the total simulation duration is 520s, and the whole working condition comprises the charge-discharge process of the series-parallel battery pack.
As shown in fig. 10, it is a simulation curve of SOC equalization of each cell in P1 in a four-string two-parallel-series-parallel battery pack. As shown in fig. 10, when the simulation starts, the SOC difference of each cell satisfies the equilibrium topology working condition, the equilibrium topology works, and the maximum SOC difference of each cell gradually decreases. After a period of time, the balancing topology stops working, and then the maximum difference value of the SOC of each monomer in the series battery pack P1 meets the precision requirement.
As shown in fig. 11, it is a simulation curve of SOC equalization of each cell in P2 in a four-string two-parallel-series-parallel battery pack. As seen from fig. 11, after a period of time passes through the simulation, the SOC difference values of the individual cells in the series battery P2 satisfy the equilibrium topology working conditions, the equilibrium topology works, the maximum SOC difference values of the individual cells gradually decrease, after a period of time passes, the equilibrium topology stops working, and thereafter, the maximum SOC difference values of the individual cells in the series battery P2 satisfy the accuracy requirement.
As shown in fig. 12, the variation curve of the maximum difference between the SOC of each cell in P1 and P2 in the four-string two-parallel-series-parallel battery pack is shown. As can be seen from fig. 12, when the series equalization of the cells in the series assembled battery P1 is finished, the equalization of the cells in the series assembled battery P2 is started, and after 79s and 107s, the maximum difference in SOC of the series connected cells in the series assembled batteries P1 and P2 respectively reaches the series assembled battery equalization threshold, and thereafter, the maximum difference in SOC of the cells in the series assembled battery P1 and P2 is kept unchanged.
As shown in fig. 13, are the P1 and P2 average SOC equalization simulation curves for a four string two parallel-to-serial parallel battery pack. As seen from fig. 13, after the equalization is completed, the average SOC difference between the series-connected battery packs P1 and P2 meets the equalization accuracy requirement.
As shown in fig. 14, the variation curves of the maximum difference of the average SOC of P1 and P2 in the four-string two-parallel-series-parallel battery pack are shown. As can be seen from fig. 14, at time 497s, the average SOC difference between the series-connected battery packs P1 and P2 meets the requirement of the balancing accuracy.
In summary, the given equalization target is met.
Claims (4)
1. An integrated active equalization method for series-parallel battery packs based on inductive energy storage is characterized in that:
the series-parallel battery pack comprises m groups of series-parallel battery packs connected in parallel, and each group of series-parallel battery packs comprises n monomers;
the balanced topology of the series-parallel battery pack comprises (2m × n +2m +2) MOS (metal oxide semiconductor) tubes, (2m × n +2m +2) diodes and two inductors; the two inductances being respectively designated LsAnd Lp；
In each group of series battery packs, the left and right bridge arms of the single anode are respectively connected with the series circuit of the MOS tube and the diode, and the left and right bridge arms of the single cathode are respectively connected with the series circuit of the MOS tube and the diode; the series circuit of the MOS tube and the diode comprises an MOS tube and a diode which are connected in series;
inductor LsAnd a diode,An MOS transistor connected in series and an inductor LpThe inductor is connected with a diode and an MOS tube in series to obtain two inductor-diode-MOS tube series circuits; the two inductor-diode-MOS tube series circuits are connected in parallel;
the tail end of a left bridge arm and the tail end of a right bridge arm of the series battery pack are connected with two ends of a series circuit of two inductors-diodes-MOS tubes which are connected in parallel;
inductance L when series battery carries out equalization in groupsStoring energy, and realizing that the balance energy is directly transferred from the monomer with the highest SOC to the monomer with the lowest SOC;
when each series battery pack in the series-parallel battery packs performs the inter-group balance, the inductor LpStoring energy, and realizing that the balance energy is directly transferred from the series battery pack with the highest average SOC to the series battery pack with the lowest average SOC;
the series battery packs in the series-parallel battery packs are respectively marked as P1，P2…Pm；
In each group of series-connected battery packs, each monomer is marked as B in sequencex1，Bx2，…，BxnThe MOS tubes connected with the left and right bridge arms of the single body are marked as S in sequencex0，Sx1，…，Sx(2n+1)X is the serial number of each series battery pack connected together in parallel;
inductances being respectively denoted LsAnd LpThe MOS tube connected in series with the inductor is correspondingly marked as SsAnd Sp；
The balancing method aims at enabling the SOC of each monomer of the series battery pack to be consistent and enabling the average SOC of each series battery pack of the series and parallel battery packs to be consistent;
the above object is achieved by the steps of:
when the inconsistency of the SOC of each monomer in the series battery pack and the average SOC of each series battery pack between the series battery packs and the parallel battery packs exceeds a given threshold value, starting the balanced topology;
when each monomer in the series battery pack is balanced, the MOS tube S responsible for balancing in the series battery packsKeeping conduction; monomer BxiHas the highest SOC of (B)xjIs the lowest, wherein i and j are series battery packsThe number of the monomers;
the equalization process is divided into two stages: first stage, monomer BxiCorresponding MOS transistor Sx(2i-1)And Sx(2i)Conducting, monomer BxiFor inductor LsStoring energy; second stage, MOS transistor Sx(2i-1)、Sx(2i)Breaking, monomer BxjCorresponding MOS transistor Sx(2j-2)、Sx(2j+1)Conduction, inductance LsMonomer BxjCharging; finally realizing the transfer of balance energy between any monomers;
MOS tube S for balancing series battery groups connected in parallel when balancing series battery groups in series-parallel battery grouppKeeping conduction;
series battery pack P in series-parallel battery packiHas the highest average SOC of PjWherein i and j are serial numbers of the series battery packs connected together in parallel; the equalization process is divided into two stages: first stage, MOS transistor Si1、Si(2n)Conducting, series-connecting battery pack PiTo the inductance LpCharging; second stage, MOS transistor Si1、Si(2n)Disconnected, MOS tube Sj0、Sj(2n+1)Conduction, inductance LpTo the series battery PjCharging; and finally, the balance energy is transferred between any parallel battery packs.
2. The integrated active equalization method for the series-parallel battery pack based on inductive energy storage according to claim 1, characterized in that: the balanced topology is controlled by a control circuit; the frequency of the control signal of the control circuit is determined according to the parameters of the inductor, the switching loss of the MOS tube, the voltage of the battery of the whole series-parallel battery pack and the voltage of the single battery.
3. The integrated active equalization method for the series-parallel battery pack based on inductive energy storage according to claim 2, characterized in that: the control circuit outputs the duty ratio of the driving signal to reset the energy stored in the inductor in each signal period, namely the current of the inductor firstly rises from zero and finally falls to zero.
4. The integrated active equalization method for series-parallel battery packs based on inductive energy storage according to any one of claims 1 to 3, characterized in that: all the monomers in the series-parallel battery pack are secondary batteries; the secondary battery is one of a lead-acid battery, a lithium ion battery, a nickel-metal hydride battery and a super capacitor.
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| CN206650492U (en) * | 2017-04-17 | 2017-11-17 | 中国矿业大学 | A kind of remote controlled type Flameproof and intrinsically safe uninterruption power source |
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| CN206650492U (en) * | 2017-04-17 | 2017-11-17 | 中国矿业大学 | A kind of remote controlled type Flameproof and intrinsically safe uninterruption power source |
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