CN204424402U - The passive equalizing system of ferric phosphate lithium cell group - Google Patents

The passive equalizing system of ferric phosphate lithium cell group Download PDF

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Publication number
CN204424402U
CN204424402U CN201420842195.XU CN201420842195U CN204424402U CN 204424402 U CN204424402 U CN 204424402U CN 201420842195 U CN201420842195 U CN 201420842195U CN 204424402 U CN204424402 U CN 204424402U
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battery core
lithium cell
ferric phosphate
phosphate lithium
dump energy
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梅敬瑶
胡建国
黄世霖
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Ningde Shidai Runzhi Software Technology Co.,Ltd.
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Ningde Contemporary Amperex Technology Co Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

The utility model discloses a kind of passive equalizing system of ferric phosphate lithium cell group, comprising: memory module, acquisition module, judge module, acquisition module and balance module.Memory module is for storing the voltage and dump energy corresponding relation that accurately can inquire about dump energy; Acquisition module is for gathering the open circuit voltage of each battery core under inactive state; Judge module can accurately be inquired about in the voltage range of dump energy for judging whether open circuit voltage is in; Acquisition module be used for open circuit voltage be in accurately can inquire about dump energy voltage range in time, according to open circuit voltage and voltage and the dump energy corresponding relation that accurately can inquire about dump energy, obtain the dump energy of the corresponding battery core of open circuit voltage and determine the balanced capacity of each battery core; Acquisition module is also for the balanced discharge time of the balanced discharge electric current and each battery core that calculate each battery core; Balance module is used for carrying out passive equilibrium treatment based on the balanced discharge time of each battery core to battery pack.

Description

The passive equalizing system of ferric phosphate lithium cell group
Technical field
The utility model relates to field of lithium ion battery, particularly a kind of passive equalizing system of ferric phosphate lithium cell group.
Background technology
LiFePO4 (Lithium Ion phosphate, LFP) battery is a environmental protection battery.Compared with general lithium battery, ferric phosphate lithium cell has that fail safe is high, battery cycle life is long, can fast charging and discharging, advantages such as weight is little, high temperature resistant under equal energy density, thus has good application prospect.Such as, ferric phosphate lithium cell group can be applied to EV (electric vehicle, electric automobile), ESS (Energy Storage System, energy-storage system) etc.Common application has electric bicycle, electric bus etc.
Ferric phosphate lithium cell group is in series by the battery core of multiple single-unit.Due to the restriction of technological level, certain deviation is there is between battery core, battery core is in use along with charge and discharge cycles number of times increases and the impact such as memory time, temperature simultaneously, battery core capacity attenuation also can be inconsistent, thus cause state-of-charge (the State of Charge of battery core in same battery pack, SoC) occur inconsistent, cause the unbalanced of battery core in same battery pack.SoC, also referred to as " dump energy ", represents that battery uses the ratio of the capacity of a period of time or the residual capacity after lying idle for a long time and its fully charged state, represents with percentage.Its span of SoC is 0 ~ 1, represents that battery discharge is complete, represent that battery is full of completely as SoC=1 as SoC=0.
This unbalanced performance that can reduce ferric phosphate lithium cell group of ferric phosphate lithium cell group, reduces the life-span of ferric phosphate lithium cell group.Therefore, need to carry out equilibrium to ferric phosphate lithium cell group, to make the dump energy SoC difference of each battery core in ferric phosphate lithium cell group in certain error range.
Utility model content
Technical problem to be solved in the utility model is the passive equalizing system providing a kind of ferric phosphate lithium cell group, improves the performance of ferric phosphate lithium cell group, extends the life-span of ferric phosphate lithium cell group.
The utility model realizes like this, a kind of passive equalizing system of ferric phosphate lithium cell group is provided, comprising: accurately can inquire about the voltage of dump energy and the memory module of dump energy corresponding relation for storing, and for the acquisition module of the open circuit voltage of each battery core in described ferric phosphate lithium cell group under gathering inactive state;
Also comprising the judge module be connected with described acquisition module, described judge module, for judging whether described ferric phosphate lithium cell group remains static, and judging described open circuit voltage can accurately be inquired about in the voltage range of dump energy described in whether being in;
Also comprise the acquisition module be connected with described judge module, described memory module and described acquisition module respectively; Described acquisition module, for the judged result according to described judge module, when described open circuit voltage is in the described voltage range accurately can inquiring about dump energy, voltage and the dump energy corresponding relation of dump energy accurately can be inquired about described in storing according to described open circuit voltage and described memory module, obtain the dump energy of the corresponding described battery core of described open circuit voltage, and determine the balanced capacity of battery core described in each according to the dump energy of battery core described in each; And according to passive balancing principle, calculate the balanced discharge electric current of battery core described in each, and according to the balanced capacity of battery core described in each and balanced discharge electric current, calculate the balanced discharge time of battery core described in each;
And the balance module to be connected with described acquisition module, described balance module be used for obtaining based on described acquisition module each described in balanced discharge time of battery core passive equilibrium treatment is carried out to described ferric phosphate lithium cell group.
Further, described system also comprises the energy consuming circuitry be connected with each described battery core; The switching device being communicated with or disconnecting under described energy consuming circuitry comprises equalization discharge resistance and controls at described balance module.
Further, described switching device comprises fet; One end of described equalization discharge resistance is electrically connected with the positive pole of corresponding battery core; The other end of described equalization discharge resistance is electrically connected the drain electrode of described fet; The source electrode of described fet is electrically connected to the negative pole of described corresponding battery core; The grid of described fet is electrically connected to described balance module.
In the passive equalizing system of the ferric phosphate lithium cell group in the utility model one embodiment, use accurate dump energy difference as the foundation of equilibrium, and LFP battery pack be in voltage high-end time carry out passive equilibrium, make balanced to judge and execution not necessarily judges to perform opportunity at the same time.Further, the passive equalizing system of the ferric phosphate lithium cell group of the utility model embodiment, has been separated the screening of basis for estimation and the execution of balancing actions, has which enhanced the reliability of basis for estimation, also can perform equilibrium under when machine in office.The passive equalizing system of the ferric phosphate lithium cell group of the utility model embodiment, can improve the performance of LFP battery pack, extends the life-span of LFP battery pack.
Accompanying drawing explanation
Fig. 1 is the flow chart of the passive equalization methods of ferric phosphate lithium cell group in the utility model one embodiment.
Fig. 2 is a kind of performance diagram of LiFePO4 battery core.
Fig. 3 for be ± 5mV in voltage sample precision, the curve chart for determining accurately to inquire about the voltage range of dump energy that obtained by the analysis of battery core characteristic curve when being 3% of dump energy error threshold.
Fig. 4 is the flow chart of the passive equalization methods of ferric phosphate lithium cell group in another embodiment of the utility model.
Fig. 5 is the flow chart of the passive equalization methods of ferric phosphate lithium cell group in another embodiment of the utility model.
Fig. 6 is the structural representation of the passive equalizing system of ferric phosphate lithium cell group in the utility model one embodiment.
Fig. 7 is the structural representation of the passive equalizing system of ferric phosphate lithium cell group in another embodiment of the utility model.
Embodiment
Central scope of the present utility model is: use accurate dump energy SoC difference as the foundation of equilibrium, and LFP battery pack be in voltage high-end time carry out passive balancing actions, the screening of separating equilibrium basis for estimation and the execution of balancing actions, make balanced judgement and execution not necessarily judge at the same time to perform opportunity.
In order to make technical problem to be solved in the utility model, technical scheme and beneficial effect clearly understand, below in conjunction with drawings and Examples, the utility model is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
Fig. 1 is the flow chart of the passive equalization methods of ferric phosphate lithium cell group in the utility model one embodiment.As shown in Figure 1, in the present embodiment, the passive equalization methods of ferric phosphate lithium cell group can comprise the steps:
Step S101, determines the voltage range accurately can inquiring about dump energy SoC of each battery core in ferric phosphate lithium cell group and determines accurately to inquire about voltage and the dump energy corresponding relation of dump energy.
In one embodiment, the voltage range accurately can inquiring about dump energy SoC can be determined by battery core characteristic curve, voltage sample precision and dump energy SoC error threshold three.The mode accurately can inquiring about the voltage range of dump energy SoC is determined below for Fig. 2 and Fig. 3 brief description.
Fig. 2 is a kind of performance diagram of LiFePO4 battery core.Fig. 3 for be ± 5mV in voltage sample precision, the curve chart for determining accurately to inquire about the voltage range of dump energy SoC that obtained by the battery core characteristic curve analysis in Fig. 2 when being 3% of dump energy error threshold.In figure 3, " line " represents the error threshold expected.Referring to figs. 2 and 3, known, at 2710mV (millivolt) voltage range to 3283mV and the voltage range of 3299mV to 3317mV, can accurately inquire about the value of dump energy SoC by open circuit voltage and dump energy corresponding relation according to open circuit voltage.Therefore, the union of the voltage range of 2710mV to 3283mV and the voltage range of 3299mV to 3317mV is the voltage range accurately can inquiring about dump energy SoC.The above-mentioned voltage range accurately can inquiring about dump energy can be determined jointly by battery core characteristic curve, voltage sample precision and dump energy error threshold three, and the open circuit voltage that accurately can inquire about dump energy and dump energy relation table record can be adopted accurately can to inquire about corresponding relation between the voltage of dump energy and dump energy.
It should be noted that, the characteristic curve of ferric phosphate lithium cell is similar, and different ferric phosphate lithium cell battery core formulas, will change battery core characteristic curve, also can cause the change of parameter, therefore, above-mentioned parameter is mainly used in exemplary illustration.
In addition, when the material, technique etc. of each battery core are identical, the characteristic curve of each battery core is also identical, thus, each battery core has the identical voltage range accurately can inquiring about dump energy, and namely in ferric phosphate lithium cell group, all battery cores can have the identical open circuit voltage accurately can inquiring about dump energy and dump energy relation table.In one embodiment, voltage and the dump energy corresponding relation that accurately can inquire about dump energy also can adopt the no platform region 230 in Fig. 2 to represent.
Step S103, gathers the open circuit voltage of each battery core in ferric phosphate lithium cell group under inactive state;
In one embodiment, step S103 specifically comprises: judge whether ferric phosphate lithium cell group remains static; If ferric phosphate lithium cell group remains static, then gather the open circuit voltage of each battery core in ferric phosphate lithium cell group.
In one embodiment, judge whether ferric phosphate lithium cell group remains static can comprise: judge whether the electric current of ferric phosphate lithium cell group is less than 0.03C (coulomb) or is less than 3A (ampere) and continues more than 30min (minute); If so, then confirm that ferric phosphate lithium cell group remains static.
Step S105, judges whether the open circuit voltage gathered is in and can accurately inquires about in the voltage range of dump energy; If the open circuit voltage gathered is in and can accurately inquires about in the voltage range of dump energy, then perform step S107, otherwise terminate;
Step S107, according to the open circuit voltage gathered and voltage and the dump energy corresponding relation that accurately can inquire about dump energy, obtains the dump energy of the corresponding battery core of the open circuit voltage gathered, and determines the balanced capacity of each battery core according to the dump energy of each battery core; The balanced capacity of each battery core equals the difference of minimum value in the capacity of all battery cores in the capacity of each battery core and ferric phosphate lithium cell group; The capacity of battery core equals the product of the rated capacity of battery core and the residual electric quantity of battery core;
In one embodiment, determine that the balanced capacity of each battery core can comprise the steps: according to the dump energy of each battery core in step S107
Obtain the dump energy difference of each battery core in battery pack, wherein, dump energy difference equals the dump energy of battery core and the difference of dump energy minimum value, and dump energy minimum value refers to the minimum value in the dump energy of all battery cores in ferric phosphate lithium cell group; Determine the balanced capacity of corresponding battery core according to dump energy difference, the balanced capacity of battery core equals the product of the rated capacity of battery core and the dump energy difference of this battery core.
If set the dump energy of an xth battery core in ferric phosphate lithium cell group as SoC (x), in the dump energy of all battery cores of ferric phosphate lithium cell group, minimum value is SoCmin, then SoC (x) and the difference DELTA SoC (x) of SoCmin are the dump energy difference of an xth battery core in ferric phosphate lithium cell group, Δ SoC (x)=SoC (x)-SoCmin.
If the capacity of an xth battery core is Cap (x) in ferric phosphate lithium cell group, an xth battery core needs balanced capacity to be Δ Cap (x), rated capacity * Δ SoC (x) of Δ Cap (x)=xth battery core, the symbol " * " in this formula is multiplication sign.
Step S109, according to passive balancing principle, calculates the balanced discharge electric current of each battery core, and according to the balanced capacity of each battery core and balanced discharge electric current, calculates the balanced discharge time of each battery core;
In one embodiment, balanced discharge electric current can according to the external voltage of each battery core and balanced discharge resistance calculations, as balanced discharge electric current=external voltage/balanced discharge resistance.The large I of balanced discharge resistance is according to decisions such as the heat-sinking capability of ferric phosphate lithium cell group and resistor powers: if the heat-sinking capability of battery pack is better or power is larger, larger current can be accepted, select less balanced discharge resistance, otherwise select larger balanced discharge resistance.In one embodiment, balanced discharge electric current=3.3/ balanced discharge resistance can be estimated.
In other embodiments, balanced discharge resistance can be set to variable resistor, its can under the control of micro control system (MCU) size of adjusting resistance value, thus the thermal discharge of balanced discharge resistance can be regulated to cause the temperature of ferric phosphate lithium cell group to raise further to prevent due to passive balanced discharge according to the temperature of ferric phosphate lithium cell group.In addition, single can be regulated according to the actual requirements to start balanced maximum length in time and adjacent twice balanced time out, as accelerated the velocity of discharge or reducing the velocity of discharge.In other words, step S109 can comprise further: the temperature detecting ferric phosphate lithium cell group; If when the temperature of ferric phosphate lithium cell group is higher than desired temperature, the single adjusting each battery core starts balanced maximum length in time and adjacent twice balanced time out, thus reaches the object of protection battery core further.Desired temperature can set according to the safety requirements of battery pack.
Step S111, carries out passive equilibrium treatment based on the balanced discharge time of each battery core in ferric phosphate lithium cell group to ferric phosphate lithium cell group.
Wherein, carry out passive equilibrium treatment to ferric phosphate lithium cell group can comprise the steps:
The average voltage of ferric phosphate lithium cell group and the voltage threshold preset are compared; If the average voltage of ferric phosphate lithium cell group is greater than voltage threshold, then carry out equalization discharge to Q the battery core that the balanced discharge time in ferric phosphate lithium cell group is greater than 0, Q is natural number.If the average voltage of ferric phosphate lithium cell group is less than voltage threshold, then passive equilibrium treatment is not carried out to ferric phosphate lithium cell group.
Wherein, voltage threshold is used for being divided into the high-end and voltage low side of voltage by artificial for the voltage of overall ferric phosphate lithium cell group.Generally using the voltage of the average voltage of battery core in ferric phosphate lithium cell group at the flex point place in platform area and no platform district as voltage threshold, be designated as Vg.In ferric phosphate lithium cell group, the average voltage of battery core is greater than Vg then to think that ferric phosphate lithium cell group is in voltage high-end, otherwise is in voltage low side.In one embodiment, voltage threshold Vg can adopt step below to determine:
Battery core characteristic curve in Fig. 2 is divided into platform area 210 and no platform district 230, and obtains the knee voltage at the flex point D place between no platform district 230 and platform area 210, be designated as V d; According to knee voltage V dand compensation rate offset calculating voltage threshold value Vg, voltage threshold Vg=knee voltage V d+ compensation rate offset;
Wherein, compensation rate offset can according to calculating such as sampling error, conversion dump energy SoC error, the volume error of balanced a bit of time.If compensation rate offset is comparatively large, the chance of the passive equilibrium of ferric phosphate lithium cell group will reduce, but can improve the fail safe of ferric phosphate lithium cell group.In one embodiment, the desirable 50mV of compensation rate offset.
When the balanced discharge time of each battery core is all 0, passive equilibrium terminates.
The passive equalization methods of the ferric phosphate lithium cell group of the utility model embodiment, use accurate dump energy SoC difference as the foundation of equilibrium, and ferric phosphate lithium cell group be in voltage high-end time carry out passive equilibrium, make balanced to judge and execution not necessarily judges to perform opportunity at the same time.Further, the passive equalization methods of the ferric phosphate lithium cell group of the utility model embodiment, has been separated the screening of basis for estimation and the execution of balancing actions, has which enhanced the reliability of basis for estimation, also can perform equilibrium under when machine in office.The passive equalization methods of the ferric phosphate lithium cell group of the utility model embodiment, can improve the performance of ferric phosphate lithium cell group, extends the life-span of ferric phosphate lithium cell group.
Fig. 4 is the another kind of flow chart of the passive equalization methods of ferric phosphate lithium cell group in the utility model embodiment.As shown in Figure 4, in the present embodiment, the passive equalization methods of ferric phosphate lithium cell group can comprise the steps:
Step 401 ~ 411 are identical with above-mentioned steps 101 ~ 111, repeat no more herein.
Step S413, every the scheduled time as 30 minutes or 1 hour, judges whether the balanced discharge time of each battery core is all 0; If the balanced discharge time of all battery cores is all 0 in ferric phosphate lithium cell group, then perform step S419, otherwise, if the balanced discharge time also having battery core in ferric phosphate lithium cell group is not 0, then perform step S417;
Step S417, according to the actual discharge time of each battery core, upgrades the balanced discharge time of each battery core, then performs step S411;
Step S419, terminates balanced.
In the passive equalization methods of the ferric phosphate lithium cell group of the utility model embodiment, the balanced discharge time of each battery core is upgraded by the actual discharge time of each battery core, overdischarge can be avoided to cause the performance of ferric phosphate lithium cell group reduce or damage, thus improve the performance of ferric phosphate lithium cell group further, extend the life-span of ferric phosphate lithium cell group.
Fig. 5 is the another kind of flow chart of the passive equalization methods of ferric phosphate lithium cell group in the utility model embodiment.As shown in Figure 5, in the present embodiment, the passive equalization methods of ferric phosphate lithium cell group can comprise the steps:
Step 501 ~ 511 are identical with above-mentioned steps 101 ~ 111, repeat no more herein.
Step S513, every the scheduled time as 30 minutes or 1 hour, judges whether the balanced discharge time of each battery core is all 0; If the balanced discharge time of all battery cores is all 0 in ferric phosphate lithium cell group, then perform step S519, otherwise, if the balanced discharge time also having battery core in ferric phosphate lithium cell group is not 0, then perform step S515;
Step S515, judges whether ferric phosphate lithium cell group remains static and whether the open circuit voltage of Real-time Collection is in and can accurately inquires about in the voltage range of dump energy; If NO, then step S517 is performed; If yes, then step S507 is performed;
Step S517, according to the actual discharge time of each battery core, upgrades the balanced discharge time of each battery core, then performs step S511;
Step S519, terminates balanced.
In the passive equalization methods of the ferric phosphate lithium cell group of the utility model embodiment, every the scheduled time as 30 minutes or judgement in 1 hour, redefine the balanced discharge time of each battery core according to the voltage and dump energy corresponding relation that accurately can inquire about dump energy or upgrade the balanced discharge time of each battery core according to the actual discharge time of each battery core, overdischarge can be avoided to cause the performance of ferric phosphate lithium cell group reduce or damage, thus improve the performance of ferric phosphate lithium cell group further, extend the life-span of ferric phosphate lithium cell group.
Be further described below by the passive equalization methods of the example of in embody rule scene to ferric phosphate lithium cell group of the present utility model.
In this concrete example, comprise the steps:
Step a, by battery management system (battery management system, BMS) battery core voltage in Real-time Collection ferric phosphate lithium cell group, under inactive state, can accurately inquire about in the voltage range of dump energy if the voltage of all battery cores all drops on, the dump energy SoC of each battery core is then obtained according to the voltage and dump energy corresponding relation that accurately can inquire about dump energy, the SoC of an xth battery core is designated as SoC (x) (x represents the subscript of battery core, lower same);
Step b, minimum value is picked out from the dump energy SoC of all battery cores of ferric phosphate lithium cell group, be designated as SoCmin, the dump energy difference obtaining each battery core and least residue electricity SoCmin according to SoC (x) and SoCmin is recorded as Δ SoC, the dump energy difference of an xth battery core, be recorded as Δ SoC (x), Δ SoC (x)=SoC (x)-SoCmin;
Step c, rated capacity * Δ SoC (x) according to balanced capacity Δ Cap (x)=xth battery core of an xth battery core converts, obtain balanced capacity Δ Cap (x) of the needs equilibrium of each battery core, and record, wherein, the rated capacity of each battery core is known;
Steps d, according to passive balancing principle, calculates the balanced discharge electric current of each battery core, and according to the balanced capacity of each battery core and balanced discharge electric current, calculates the balanced discharge time of each battery core;
Step e, with voltage threshold Vg for boundary, high-end and the voltage low side of voltage is divided into by artificial for the voltage of overall ferric phosphate lithium cell group, if the average voltage of battery core is greater than voltage threshold Vg in ferric phosphate lithium cell group, think that ferric phosphate lithium cell group is in voltage high-end, otherwise, if the average voltage of battery core is less than voltage threshold Vg in ferric phosphate lithium cell group, think that ferric phosphate lithium cell group is in voltage low side;
Step f, if to be in voltage high-end for ferric phosphate lithium cell group, then carry out equalization discharge to Q the battery core that the balanced discharge time in ferric phosphate lithium cell group is greater than 0, Q is natural number.If ferric phosphate lithium cell group is in voltage low side, then passive equilibrium treatment is not carried out to ferric phosphate lithium cell group.
Step g, in equalization discharge process, adds up the discharge time of each battery core;
Step h, at set intervals (such as 30min or 1 hour), judge whether the balanced discharge time of each battery core is all 0; If the balanced discharge time of all battery cores is all 0 in ferric phosphate lithium cell group, then terminate equilibrium, otherwise, judge whether ferric phosphate lithium cell group remains static and whether the open circuit voltage of Real-time Collection is in and can accurately inquires about in the voltage range of dump energy; If NO, according to the actual discharge time of each battery core, upgrade the balanced discharge time of each battery core, then perform step f; If yes, then step a is performed.
Fig. 6 is a kind of structured flowchart of the passive equalizing system of ferric phosphate lithium cell group in the utility model embodiment.As shown in Figure 6, in the present embodiment, the energy consuming circuitry 180 that the passive equalizing system of ferric phosphate lithium cell group can comprise memory module 100, acquisition module 110, judge module 120, acquisition module 140, balance module 160 and be connected with each battery core.
Wherein, memory module 100 is for storing the voltage and dump energy corresponding relation that accurately can inquire about dump energy.
Acquisition module 110 is for gathering the open circuit voltage of each battery core in ferric phosphate lithium cell group under inactive state.
Judge module 120 for judging whether ferric phosphate lithium cell group remains static, and judges whether the open circuit voltage gathered is in and can accurately inquires about in the voltage range of dump energy.In one embodiment, judge module 120 judges whether the electric current of ferric phosphate lithium cell group is less than 0.03C (coulomb) or is less than 3A (ampere) and continues more than 30min (minute); If the electric current of ferric phosphate lithium cell group is less than 0.03C (coulomb) or is less than 3A (ampere) and continues more than 30min (minute), then judge module 120 confirms that ferric phosphate lithium cell group remains static.
Acquisition module 140 for gather open circuit voltage be in accurately can inquire about dump energy voltage range in time, according to the open circuit voltage gathered and voltage and the dump energy corresponding relation that accurately can inquire about dump energy, obtain the dump energy of the corresponding battery core of the open circuit voltage gathered, and determine the balanced capacity of each battery core according to the dump energy of each battery core; The balanced capacity of each battery core equals the difference of minimum value in the capacity of all battery cores in the capacity of each battery core and ferric phosphate lithium cell group; The capacity of battery core equals the product of the rated capacity of battery core and the residual electric quantity of battery core.
Acquisition module 140 also for according to passive balancing principle, calculates the balanced discharge electric current of each battery core, and according to the balanced capacity of each battery core and balanced discharge electric current, calculates the balanced discharge time of each battery core.
Balance module 160 is for carrying out passive equilibrium treatment based on the balanced discharge time of each battery core in ferric phosphate lithium cell group to ferric phosphate lithium cell group.In one embodiment, balance module 160 is for comparing the average voltage of ferric phosphate lithium cell group and the voltage threshold preset; If the average voltage of ferric phosphate lithium cell group is greater than default voltage threshold, then equalization discharge is carried out to the battery core that the balanced discharge time in ferric phosphate lithium cell group is greater than 0; If the average voltage of ferric phosphate lithium cell group is less than voltage threshold, then passive equilibrium treatment is not carried out to ferric phosphate lithium cell group.
Energy consuming circuitry 180 for consuming the electricity in battery core by heating in passive balancing procedure.In one embodiment, energy consuming circuitry 180 comprises equalization discharge resistance 182 with the switching device 184 that can be communicated with under balance module 160 controls or disconnect as relay, fet etc.For the battery core Ct in Fig. 6 and switching device 184 for fet, the positive pole of battery core Ct is electrically connected one end of equalization discharge resistance 182; The other end of equalization discharge resistance 182 is electrically connected the drain electrode of fet 184; The source electrode of fet 184 is electrically connected to the negative pole of battery core Ct; The grid of fet 184 is electrically connected to balance module 160.In passive balancing procedure, balance module 160 controls fet 184 conducting, energy consuming circuitry 180 is closed, thus makes equalization discharge resistance 182 generate heat the electric energy discharged on battery core Ct.
In addition, in one embodiment, judge module 120 to be further used for every the scheduled time, as 30 minutes or 1 hour, judging whether the balanced discharge time of each battery core is all 0; And when in ferric phosphate lithium cell group, the balanced discharge time of battery core is not 0 in addition, notice acquisition module 140 upgrades the balanced discharge time of each battery core according to the actual discharge time of each battery core.
In one embodiment, judge module 120 to be further used for every the scheduled time, as 30 minutes or 1 hour, judging whether the balanced discharge time of each battery core is all 0; And when the balanced discharge time of battery core is not 0 in addition in ferric phosphate lithium cell group, judge whether ferric phosphate lithium cell group remains static and whether the open circuit voltage of Real-time Collection is in and can accurately inquires about in the voltage range of dump energy; If NO, notify that acquisition module 140 upgrades the balanced discharge time of each battery core according to the actual discharge time of each battery core; If yes, then notify that acquisition module 140 is according to the open circuit voltage of Real-time Collection and voltage and the dump energy corresponding relation that accurately can inquire about dump energy, obtain the dump energy of the corresponding battery core of open circuit voltage of Real-time Collection, and determine the balanced capacity of each battery core according to the dump energy of each battery core.
The passive equalizing system of the ferric phosphate lithium cell group of the utility model embodiment, use accurate dump energy SoC difference as the foundation of equilibrium, and ferric phosphate lithium cell group be in voltage high-end time carry out passive balancing actions, make balanced to judge and execution not necessarily judges to perform opportunity at the same time.Further, the passive equalizing system of the ferric phosphate lithium cell group of the utility model embodiment, has been separated the screening of basis for estimation and the execution of balancing actions, has which enhanced the reliability of basis for estimation, also can perform equilibrium under when machine in office.The passive equalizing system of the ferric phosphate lithium cell group of the utility model embodiment, can improve the performance of ferric phosphate lithium cell group, extends the life-span of ferric phosphate lithium cell group.In addition, every the scheduled time as 30 minutes or judgement in 1 hour, redefine the balanced discharge time of each battery core according to the voltage and dump energy corresponding relation that accurately can inquire about dump energy or upgrade the balanced discharge time of each battery core according to the actual discharge time of each battery core, overdischarge can be avoided to cause the performance of ferric phosphate lithium cell group reduce or damage, thus improve the performance of ferric phosphate lithium cell group further, extend the life-span of ferric phosphate lithium cell group.
Fig. 7 is the another kind of structured flowchart of the passive equalizing system of ferric phosphate lithium cell group in the utility model embodiment.As shown in Figure 7, compared with the embodiment shown in Fig. 6, in the present embodiment, in the passive equalizing system of ferric phosphate lithium cell group, the equalization discharge resistance 182a of energy consuming circuitry 180a is variable resistor.Wherein, the resistance value of equalization discharge resistance 182a can change under the control of balance module 160.Now, acquisition module 110 is also for the temperature of acquisition testing ferric phosphate lithium cell group; Balance module 160, for when the temperature of ferric phosphate lithium cell group is higher than desired temperature, controls balanced discharge resistance 182a and reduces resistance value.Because the resistance value of equalization discharge resistance 182a can change under the control of balance module 160, therefore, the thermal discharge of balanced discharge resistance 182a can be regulated to cause the temperature of ferric phosphate lithium cell group to raise further to prevent due to passive balanced discharge according to the temperature of ferric phosphate lithium cell group, and the balanced discharge time can be regulated according to the actual requirements, as accelerated the velocity of discharge or reducing the velocity of discharge.
In addition, in other embodiments, acquisition module 110 is also for the temperature of acquisition testing ferric phosphate lithium cell group; Acquisition module 140 is also for when acquisition module 110 detects the temperature of ferric phosphate lithium cell group higher than desired temperature, and the single adjusting each battery core starts balanced maximum length in time and adjacent twice balanced time out.
The foregoing is only preferred embodiment of the present utility model; not in order to limit the utility model; all do within spirit of the present utility model and principle any amendment, equivalent to replace and improvement etc., all should be included within protection range of the present utility model.

Claims (3)

1. the passive equalizing system of a ferric phosphate lithium cell group, it is characterized in that, comprise: accurately can inquire about the voltage of dump energy and the memory module of dump energy corresponding relation for storing, and for the acquisition module of the open circuit voltage of each battery core in described ferric phosphate lithium cell group under gathering inactive state;
Also comprising the judge module be connected with described acquisition module, described judge module, for judging whether described ferric phosphate lithium cell group remains static, and judging described open circuit voltage can accurately be inquired about in the voltage range of dump energy described in whether being in;
Also comprise the acquisition module be connected with described judge module, described memory module and described acquisition module respectively; Described acquisition module, for the judged result according to described judge module, when described open circuit voltage is in the described voltage range accurately can inquiring about dump energy, voltage and the dump energy corresponding relation of dump energy accurately can be inquired about described in storing according to described open circuit voltage and described memory module, obtain the dump energy of the corresponding described battery core of described open circuit voltage, and determine the balanced capacity of battery core described in each according to the dump energy of battery core described in each; And according to passive balancing principle, calculate the balanced discharge electric current of battery core described in each, and according to the balanced capacity of battery core described in each and balanced discharge electric current, calculate the balanced discharge time of battery core described in each;
And the balance module to be connected with described acquisition module, described balance module be used for obtaining based on described acquisition module each described in balanced discharge time of battery core passive equilibrium treatment is carried out to described ferric phosphate lithium cell group.
2. the passive equalizing system of ferric phosphate lithium cell group according to claim 1, is characterized in that, also comprises the energy consuming circuitry be connected with each described battery core;
The switching device being communicated with or disconnecting under described energy consuming circuitry comprises equalization discharge resistance and controls at described balance module.
3. the passive equalizing system of ferric phosphate lithium cell group according to claim 2, is characterized in that, described switching device comprises fet; One end of described equalization discharge resistance is electrically connected with the positive pole of corresponding battery core; The other end of described equalization discharge resistance is electrically connected the drain electrode of described fet; The source electrode of described fet is electrically connected to the negative pole of described corresponding battery core; The grid of described fet is electrically connected to described balance module.
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CN107097668A (en) * 2017-05-03 2017-08-29 东莞钜威动力技术有限公司 The passive equalizing circuit and its equalization methods and abatement detecting method of electric automobile
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