CN101964431A - Charging and discharging method of lithium secondary battery - Google Patents
Charging and discharging method of lithium secondary battery Download PDFInfo
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Abstract
The invention relates to a multistage constant-voltage charging method and a discharging method for a lithium secondary battery. In the charging and discharging methods, a shallow charging mode and a shallow discharging mode are respectively adopted, and charging and discharging currents are decreased at the initial stage and the final stage of charging and discharging so as to lower the influence of uneven current density distribution among parallel monomer batteries or inside the batteries on battery performances, therefore, the battery performance is improved. Particularly, in the multistage constant-voltage charging method of the lithium secondary battery, the multistage constant-voltage charging is realized by judging the charging current and charging time and changing the charging voltage according to a judging result. The charging method can be used for effectively lowering the influence of the uneven current density distribution among the parallel monomer batteries or inside the batteries on the battery performances under the condition that the total charging time is not influenced greatly, thereby improving the performances of the monomer batteries or a battery pack.
Description
Technical field
The present invention relates to lithium secondary battery and use the field, relate in particular to a kind of charging and charging method of lithium secondary battery.
Background technology
Lithium secondary battery is little, in light weight because of its operating voltage height, volume, have extended cycle life, and is a kind of ideal source.
Along with the development of electric bicycle, battery-operated motor cycle, miniature electric automobile, electrocar, electronic big bus, stand-by power supply, energy-accumulating power station, also increasing to the demand of the higher battery pack of gross energy.The large-capacity battery pack electric current of monomer high capacity cell or low-voltage is big, lead is thick, energy efficiency is low owing to use, so the voltage of battery pack can not be done too lowly; But, battery consistency equal angles withstand voltage from insulation, fail safe and electronic devices and components considers that the voltage of battery pack can not be De Taigao, so the capacity of battery pack also can not be too low, takes all factors into consideration the battery pack that therefore back needs high voltage, larger capacity.And the following two kinds of combining forms of the general employing of the acquisition of the lithium secondary battery of high voltage, larger capacity.
Combining form one: the cell of several low capacities also is unified into jumbo battery; Several jumbo battery strings are unified into the jumbo battery pack of high voltage;
Combining form two: directly adopt several jumbo cells to be connected into the jumbo battery pack of high voltage.
Lithium secondary battery for combining form one, form each cell of lithium secondary battery owing to create conditions different with temperature, charge-discharge magnification, charging state, use course etc., performances such as the capacity of battery, internal resistance, charging/discharging voltage and self-discharge rate there are differences each other, along with the increase that discharges and recharges number of times (cycle-index) and service time, the consistency between the cell is variation gradually; Lithium secondary battery for combining form two, because jumbo cell is inner no matter be made of the parallel connection of a plurality of positive and negative electrode pole piece, still constitute by single positive and negative electrode pole piece, in fact finally still be equivalent to the cell parallel connection of several low capacities in the combining form one, therefore along with the increase that discharges and recharges number of times (cycle-index) and service time, the consistency between inside battery pole piece and the material is also in variation progressively.
Battery is to have polarization in charge and discharge process in addition, and polarization is divided into ohmic polarization, electrochemical polarization, concentration polarization three classes, and response speed separately is also different.The factor that influences degree of polarization is a lot, but charging and discharging currents density is big more generally speaking, and polarization is also just big more.When therefore discharging current was big more, the discharge voltage of battery was low more; When charging current was big more, the charging voltage of battery was high more.
Fig. 1 is two cells schematic diagrames in parallel.For new battery pack, the capacity of cell will be through strict screening before combination, the voltage of each cell is also substantially the same, and the internal resistance of battery, to connect charge and discharge platform (saying it is dynamic charging/discharging voltage in the strictness) under resistance, the different multiplying etc. be uppity relatively.So the convenience in order to analyze, do following hypothesis among Fig. 1: two cell initial end voltages are the same, and charging state all is 100%; Be the current discharge of constant 100A (100%) with total current after two cell parallel connections; Two each discharging currents of cell with 50A (50%), discharge capacity is identical under the identical final discharging voltage; Owing to consistency aspect reasons such as internal resistance, connection resistance, cause the discharge platform of two batteries to differ bigger, suppose the discharge platform high 0.3V of the discharge platform of battery A than battery B.Then during two cell parallel discharges discharging current percentage and discharge time progress curve generally as shown in Figure 2.
As shown in Figure 2, at the discharge initial stage, the discharging current of the battery A that discharge platform is high can be greater than the discharging current of the low battery B of discharge platform, promptly discharge the initial stage, the discharging current of battery A can be greater than the average discharge current of 50A (50%), or be called the electric current that is directly proportional with capacity, and the discharging current of battery B can be less than the average discharge current of 50A (50%); Discharging latter stage, the discharging current of battery A can promptly discharge latter stage less than the discharging current of battery B, and the discharging current of battery A can be less than average discharge current, and the discharging current of battery B can be greater than average discharge current.
Its reason is, in the cell charge and discharge process in parallel, under the normal condition according to the electrotechnics principle, the terminal voltage of every cell is the same, at the discharge initial stage since under the same electric current discharge voltage of battery A than the discharge voltage height of battery B, when having only the discharging current of battery A big relatively, the polarization of battery A could be relatively large, and the discharge voltage of battery A could reduce about 0.3V, could guarantee that like this discharge initial stage battery A is consistent with the terminal voltage of battery B.Therefore at the discharge initial stage, the discharging current of the battery A that discharge platform is high will inevitably be analyzed in theory greater than average current, and the discharging current of battery A all might be near 100% under the extreme case.Carrying out along with discharge, because the discharging current of battery A is big during beginning, its the many of Capacity Ratio battery B that emit must get more and more, also just battery B is more and more lower relatively for the charging state of battery A, the voltage of charging state correspondence is also just more and more lower, for the terminal voltage that guarantees battery A consistent with the terminal voltage of battery B, the discharging current of battery A just polarizing voltage is just more and more littler, and the discharging current of battery B is also just increasing, analyze in theory, the discharging current of discharge battery B in latter stage also might be near 100% down for extreme case.Because the heating (heating of polarization resistance) of inside battery is I2Rt (integration), and electric current is big more, polarization resistance is also just big more, calculate according to simple mathematical and just can draw the CURRENT DISTRIBUTION inequality and will inevitably cause inside battery heating increase, the average voltage of battery discharge reduces, problems such as battery output energy reduction, such as: having put electricly in the battery request 2h of 10Ah, is the highest with the energy of its output of 5A constant-current discharge 2h.
In like manner, the same to initial end voltage, charging state all is 0%, charging capacity is identical under mean charging current and same identical charge conditions such as charging cut-ff voltage, but owing to consistency aspect reasons such as internal resistance, connection resistance, can occur when causing the charging platform (dynamic electric voltage during charging) of battery to differ bigger two cell charged in parallels that the high battery charge of charging platform begins can be less than average current, but its charging current can be increasing subsequently, even the phenomenon greater than average current can occur.
Therefore no matter be combining form one or combining form two, all can be owing to charge and discharge platform, internal resistance, capacity, access times etc. between batteries in parallel connection or the pole piece in parallel inconsistent causes the inconsistent of electric current distribution, this will further cause the inconsistent of service condition between battery or the pole piece again, thereby cause finally that big, the heating of current density sometimes of battery or pole piece, discharge platform step-down, charging platform uprise, situations such as internal resistance increase, battery material structure are damaged, cycle performance variation occur.Owing to the consistency discreteness between end-of-cycle batteries in parallel connection or the pole piece strengthens, electric current distribution is also just inconsistent more, and therefore at end-of-cycle, the decay of battery performance aggravates, and easily produces separating out in flakes even the also easy safety problem that produces of lithium.
As seen the inconsistency of electric current distribution mainly is by quantity, the size of current of batteries in parallel connection, discharges and recharges under scope, the different electric currents of battery between charge-discharge characteristic, the batteries in parallel connection decision such as charge and discharge platform difference between the batteries in parallel connection.Therefore the many more battery capacities just of batteries in parallel connection quantity pole piece quantity many more or in parallel are big more and charging and discharging currents is big more, when discharging and recharging between the cell in parallel or cell internal current density variation just may be big more.This is the performance that large capacity single body battery or small-capacity cells and the performance that is unified into high capacity cell can not show a candle to the small-capacity cells that similar process conditions make, particularly in the more tangible major reason of gap in latter stage of circulation; Also be large capacity single body battery or high capacity cell good cycle under little multiplying power electric current sometimes, but the small-capacity cells that makes with respect to similar process conditions, a big bad major reason of multiplying power current cycle performance.Therefore do not advise adopting rapid large-current charging and heavy-current discharge for high capacity cell.In addition we know, the high power high capacity cell group is higher to the coherence request of battery, and is also higher to the requirement of equipment, material etc.If further analysis also can draw in charge and discharge process and battery be stopped to discharge and recharge (leaving standstill) midway, between the battery or innerly can produce the charging state balance, thereby the battery charging and discharging capacity is increased, performance series of conclusions such as improve.
Above-mentioned analysis is to being employing large capacity single body battery or low capacity cell, cylindrical battery or rectangular cell, winding process still is cell designs such as lamination technology, those equipment are the most important in the battery manufacture process, screening before the battery combination, high power high capacity cell group application notice, the problem that exists when cylindrical battery is used in combination, the points for attention of heat analysis and heat management, the physical mixed of the material of different discharge platforms is used, new used batteries mix use, the parallel connection of different capabilities battery is used, and the exploitation of battery management system etc. all has certain directive function.
Lithium secondary battery adopts in the use by battery management system overcharges and over to each cell in the lithium secondary battery; general is exactly full charging and full discharge control, just battery management system scope that every monomer battery voltage is controlled be basically the battery charge attitude be 100% and charging state be 0% o'clock voltage range.And the charging deboost of the supporting charger of lithium secondary battery is a maximum output voltage, also is battery 100% required voltage when being full of electricity basically.Because lithium secondary battery is used with electric machine controller under a lot of situations when using, the under-voltage protection value of electric machine controller also is that the magnitude of voltage when having put electricity by lithium secondary battery 100% designs basically.By above-mentioned analysis can also see consistency to series-connected cell in the battery pack influence may also the influence to batteries in parallel connection inside be not big.
Charging method when lithium secondary battery uses at present generally is to adopt simple modified constant-voltage charge, wherein the constant voltage charge process is only carried out once, and this constant charging voltage is exactly the charging deboost of the supporting charger of lithium secondary battery, also is battery 100% required voltage when being full of electricity basically.
According to Fig. 2 and above-mentioned analysis as can be known, using method for full charging commonly used at present and full discharge, in initial stage that discharges and recharges and latter stage, between the cell in parallel or the phenomenon of inside battery electric current distribution inequality can be the most obvious, this can aggravate the appearance of the situations such as heating, cycle performance of battery variation of battery or pole piece.And single step modified constant-voltage charge method commonly used also is unprofitable to the improvement of battery current density distribution inequality.
Though address the above problem the performance that improves cell is quite crucial; but as can be seen according to above-mentioned analysis; even performance is fine down in normal condition of work (such as average operating current) for each cell in the battery pack; in use because situation generations such as the protection of battery management system is not overcharged, overdischarge; if but design is selected not science; battery pack also can be easy to damage, the performance of battery pack even may can not show a candle to the poorest cell of performance.Therefore think that it is unilateral improving the viewpoint that the cell performance just will inevitably improve battery performance, we also should work hard improving on battery high rate performance and the consistency, and the effect that obtains like this may improve many that effect that cell globality the subject of knowledge and the object of knowledge can obtain will be good than a large amount of strength of cost.Correctly design in addition and employing conforms with scientific idea and practical and effective charging method and charging method, will improve the performance of battery and battery pack greatly.
The problems referred to above lithium secondary battery just need an important bottleneck using aspect the battery pack of high-energy, high current charge-discharge, long circulation life (widening consistency difference) at electric automobile, energy-accumulating power station etc.
Summary of the invention
Technical problem to be solved by this invention provides a kind of charging and charging method of new lithium secondary battery, between the cell that completely charges to improve lithium secondary battery, is prone in full discharge and the usings method such as single step modified constant-voltage charge commonly used or problems such as inside battery electric current distribution inequality, battery heating, cycle performance difference.
The technical scheme that the present invention solves the problems of the technologies described above is as follows:
A kind of multistage constant voltage charging method of lithium secondary battery may further comprise the steps:
Step a1: constant charging voltage current-limiting charge;
Step a2: judge charging current whether less than current setting value or charging interval whether greater than the time set value, if charging current less than current setting value or charging interval greater than the time set value, execution in step a3 then, otherwise execution in step a1;
Step a3: judge whether lithium secondary battery voltage reaches voltage setting value, if lithium secondary battery voltage has reached voltage setting value, then complete charge does not reach voltage setting value as if lithium secondary battery voltage, then execution in step a4;
Step a4: improve charging voltage, and execution in step a1.
Above-mentioned charging method is a kind of charging method of constant charging voltage of multistage, by the circulation of described step a1 to step a4, has realized interim change charging voltage, and has carried out the charging of constant charging voltage in each stage.This method can effectively be improved between the cell or influence that inside battery electric current distribution inequality causes battery performance under to the little situation of total charging interval influence, improves the performance of cell or battery pack.
On the basis of technique scheme, charging method of the present invention can also be done following improvement.
Further, current setting value described in the step a2 is the constant voltage charge cut-off current.
Further, time set value described in the step a2 is a constant voltage charging time.
Further, voltage setting value described in the step a3 is described lithium secondary battery pairing cell voltage when being full of electricity, and perhaps shallow charging requires the cell voltage that reaches.
Adopt the beneficial effect of above-mentioned further scheme to be, make the multistage constant voltage charging method of lithium secondary battery of the present invention be applicable to full charging and shallow charging two states, the phenomenon of current density inequality when adopting shallow charging form can effectively avoid full the charging, improve cycle performance of battery, shelf characteric and security performance, prolong the useful life of battery.
Further, before described step a1, also comprise preorder step a0: carry out low current charge.
Adopt the beneficial effect of above-mentioned further scheme to be, adopt the low current charge form at the initial stage of charging, can reduce between the cell in parallel or inside battery electric current distribution inequality to the influence of battery performance, thereby improve battery performance.
Further, the cell voltage that described shallow charging required to reach is that the battery charge attitude is at 70%~95% pairing cell voltage.
Further, by charger charging deboost value is controlled.
Adopt the beneficial effect of above-mentioned further scheme to be, charging deboost value is controlled, thereby realization realizes that to the control of battery charge attitude simply cost is low by charger.
The present invention also provides a kind of charging method of lithium secondary battery, may further comprise the steps:
Step b1: the power that reduces power consumption equipment begins discharge to reduce discharging current;
Step b2: regular picture current discharge;
Step b3: the power that reduces power consumption equipment finishes discharge to reduce discharging current.
Adopt the beneficial effect of above-mentioned charging method to be: discharge beginning and ending phase reduction discharging current discharge, can reduce between the cell in parallel or cell internal current density unevenness to the influence of battery performance, thereby improve battery performance; Adopt the power that reduces power consumption equipment to reduce discharging current, it realizes simple.
On the basis of technique scheme, charging method of the present invention can also be done following improvement.
Further, when the battery charge attitude of described lithium secondary battery 5%~40% the time, finish discharge.
Adopt the beneficial effect of above-mentioned further scheme to be, this method is a kind of shallow discharge method, the phenomenon of current density inequality in the time of can effectively avoiding full the discharge, improve cycle performance of battery, shelf characteric and prevent overdischarge, prolong the useful life of battery, and realize that battery performance combines with the effective of cost.
Further, the under-voltage protection value by increasing electric machine controller is controlled at 5%~40% with the battery charge attitude of described lithium secondary battery.
The beneficial effect that adopts above-mentioned further scheme is to realize that simply cost is low.
Description of drawings
Fig. 1 is two cells schematic diagrames in parallel;
When Fig. 2 is two cell parallel discharges discharging current percentage and discharge time progress curve chart;
Fig. 3 is a lithium secondary battery charging method flow chart of the present invention;
Fig. 4 is a lithium secondary battery charging method flow chart of the present invention.
Embodiment
Below in conjunction with accompanying drawing principle of the present invention and feature are described, institute gives an actual example and only is used to explain the present invention, is not to be used to limit scope of the present invention.
According to Fig. 2 as can be known, if discharging latter stage, battery is stopped discharge in advance, be the words of shallow discharge, the inconsistency that the discharge current density of battery A and battery B distributed when the inconsistency that the discharge current density of battery A and battery B distributes when finishing discharge will be significantly less than full discharge and finishes, between the cell in parallel or the phenomenon of inside battery discharge current density skewness can have greatly improved; Equally, at the charging initial stage, between the cell in parallel or the phenomenon of the density of charging current skewness of inside battery also can have greatly improved.If charging latter stage, battery is stopped charging in advance, be the words of shallow charging, the inconsistency that the density of charging current of battery A and battery B distributed when the inconsistency that the density of charging current of battery A and battery B distributes during complete charge can be significantly less than full charging and finishes, between the cell in parallel or the phenomenon of inside battery density of charging current skewness can have greatly improved; Equally, at the discharge initial stage, between the cell in parallel or the phenomenon of the discharge current density skewness of inside battery also can have greatly improved.
Can also draw according to Fig. 2, when the battery charge attitude is between 5%~95% when discharging and recharging between the cell in parallel or will the improving significantly of full relatively charging of the consistency of inside battery electric current distribution and full discharge, thereby help cumulative capacity in the lithium secondary battery lifetime.When discharging and recharging the optimum range of battery charge attitude specifically fixed what with the performance of battery, concrete service condition etc. very big relation is arranged all, such as, when charging and discharging currents is big more, the serviceability temperature scope is wide more, this scope also just should be more little.This wherein need limit of consideration dwindle the back to the influence of battery cost and access times to the influence of charge and discharge platform and charging state, find a preferable balance point in conjunction with actual conditions.
In addition battery being carried out shallow discharge and shallow charging control also is favourable to the shelf characteric of battery.Shallow discharge and shallow charging control can also from using method improve the actual use battery charge attitude calculate inaccurate, the problem of bringing to battery when situation such as unusual appears in battery; Reduce the possibility that battery overcharge or overdischarge appear causing unusually in battery management system, further improve the fail safe and the reliability of battery; Reduce components and parts such as battery management system and battery is produced power consumption and cross long-time not charging, the possibility that causes overdischarge to damage to battery just very likely scraps battery or performance is subjected to badly damaged because in a single day overdischarge appears in battery.
For power consumption equipments such as electric bicycle, battery-operated motor cycle required cell or battery pack, the under-voltage protection voltage with battery management system that can be suitable improves, and over-charge protective voltage reduces; The under-voltage protection voltage of electric machine controller is improved; the charging deboost of charger reduces; reach the purpose of battery being carried out shallow discharge and shallow charging control; capacity to battery pack can't cause too much influence like this; but can improve the performance of cell or battery pack preferably; and realize that simply cost is low.
According to Fig. 2 and above-mentioned analysis as can be known, in charging initial stage and latter stage charging current is reduced, the method that discharging current is reduced can reduce between the cell in parallel or inside battery current density inequality to the influence of battery performance, improve battery performance.
In addition, because the inconsistency of battery or pole piece is generally understood low battery of guiding discharge platform or pole piece, the charging platform height during charging, its constant voltage charge Capacity Ratio regular meeting is relatively large when charging with conventional charging method.When therefore just having begun to charge, the battery charge that charging platform is high can be less than average current, but its charging current can be increasing, even phenomenon greater than average current can appear, therefore in the charging process of battery, carry out a few step constant voltage charge steps more, can reduce between the cell in parallel or the inequality of inside battery charging state, thereby reduce between the cell in parallel or the inequality of inside battery electric current distribution, its reason is:
Suppose that two living batteries carry out charged in parallel, wherein battery is owing to reasons such as connecting resistance causes its loop resistance big (being similar to after many cylindrical battery parallel connections battery from the pole farthest), thereby its charging platform can be high, its charging current can be little when just beginning to charge to have put electricity back, and the phenomenon of current unevenness can be more serious.If in charging process, carry out a few step constant voltage charge steps more, during according to the battery constant voltage charge, be that the terminal voltage of battery is when constant, if the electric current during constant voltage charge is greater than the self discharge electric current of battery, the charging state of battery is raising, and just the virtual voltage of battery is raising, and the polarizing voltage in the time of can drawing the battery constant voltage charge is reducing, just charging current is reducing, therefore connect resistance to battery cause to influence meeting more and more littler.Though charging current was little when the battery that charging platform is high had just begun to charge, charging capacity is few, but at the general relative meeting of capacity that the constant voltage charge stage can fill into more when constant voltage charge (just can with charged) from the cylindrical battery of pole farthest, so constant voltage charge can make between the cell in parallel or the phenomenon of inside battery charging state inequality improves, improve between the cell in parallel or the purpose of inside battery current density inequality thereby reach, charging current diminishes during constant voltage charge in addition, help the battery heat radiation, also can reach the purpose of improving battery performance.
Based on as mentioned above, the multistage constant voltage charging method of lithium secondary battery of the present invention as shown in Figure 3, may further comprise the steps:
Step a1: constant charging voltage current-limiting charge;
Step a2: judge charging current whether less than current setting value or charging interval whether greater than the time set value, if charging current less than current setting value or charging interval greater than the time set value, execution in step a3 then, otherwise execution in step a1;
Step a3: judge whether lithium secondary battery voltage reaches voltage setting value, if lithium secondary battery voltage has reached voltage setting value, then complete charge does not reach voltage setting value as if lithium secondary battery voltage, then execution in step a4;
Step a4: improve constant voltage charge voltage, and execution in step a1.
Wherein, current setting value described in the step a2 is the constant voltage charge cut-off current; The value of time set described in the step a2 is a constant voltage charging time; Voltage setting value described in the step a3 is described lithium secondary battery pairing cell voltage when being full of electricity, and perhaps shallow charging requires the cell voltage that reaches; Before described step a1, also comprise preorder step a0: carry out low current charge; The cell voltage that described shallow charging required to reach is that the battery charge attitude is at 70%~95% pairing cell voltage; By charger charging deboost value is controlled, thereby realization is to the control of battery charge attitude.
The charging method of lithium secondary battery of the present invention as shown in Figure 4, may further comprise the steps:
Step b1: the power that reduces power consumption equipment begins discharge to reduce discharging current;
Step b2: regular picture current discharge;
Step b3: the power that reduces power consumption equipment finishes discharge to reduce discharging current.
Wherein, before described lithium secondary battery discharged fully, the battery charge attitude finished discharge at 5%~40% o'clock; Under-voltage protection value by increasing electric machine controller is controlled at 5%~40% with the battery charge attitude of described lithium secondary battery.
The multistage constant voltage charging method of lithium secondary battery of the present invention, j (j 〉=2) constant voltage charge is arranged during the stage in the charging process of battery, effect can be better when the magnitude of voltage of its constant voltage charge was the battery charge attitude voltage that the scope of discharging and recharging of battery is carried out timesharing such as j respectively.For example: when the scope that discharges and recharges of battery is full charging and full discharge, promptly the charging state scope is 0%~100%, when two constant voltage charges being arranged during the stage in the charging process, then preferably constant voltage charge voltage to be respectively charging state be 50% and 100% voltage.If the charging state scope of battery charging and discharging is 15%~90%, when three constant voltage charges being arranged during the stage in the charging process, then preferably constant voltage charge voltage to be respectively charging state be 40%, 65% and 90% voltage.For quick charge, carry out a few step constant voltage charges in the charging process and then seem particularly important.
In realizing use, battery management system has to produce according to information such as monomer battery voltage, total terminal voltage, charging and discharging currents, charging state, temperature and discharges and recharges control strategy accordingly, and be transferred to charging device or discharge equipment by communication interface, realize the function of battery management system to charging device and discharge equipment control.According to the present invention, can in the control strategy of battery management system, be added in charging current is reduced charging device, in charging process, carry out constant charging voltage charging of multistage, reduce the charging deboost value of charging device such as charger and control the control strategy that the battery charge attitude reaches shallow charging; In control strategy, be added in and make the discharging current reduction in discharge initial stage and latter stage, increase cell under-voltage protection value and control the control strategy that the battery charge attitude reaches shallow discharge, with the further performance of improving battery to discharge equipment.
Now with 345.6V, the 40Ah ferrous phosphate lithium battery group of Hybrid Vehicle 108 string, pure electric automobile is with 288V, the 100Ah lithium manganate battery groups of 78 strings and to discharge and recharge rated power be that the energy-accumulating power station of 500kW is an example with the lithium titanate battery pack of 320 768V, the 4000Ah that go here and there, and the present invention is described in further detail.
Embodiment one
According to the multistage constant voltage charging method of aforesaid lithium secondary battery, the 345.6V of Hybrid Vehicle 108 string, the concrete charge step of 40Ah ferrous phosphate lithium battery group are as follows:
The first step: the current charges of usefulness 40A 3 minutes;
Second step: with constant charging voltage is 372.6V, and current limliting is 120A, and setting constant voltage charge cut-off current is 40A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 3 minutes;
The 3rd step: greater than 3 minutes, promptly corresponding monomer battery voltage was 3.45V to electric current less than 40A or constant voltage charging time when the 372.6V constant voltage charge, after charging state is about 60%, charged to battery voltage with the electric current of 120A again and reached 378V;
The 4th step: after battery voltage reaches 378V, be 383.4V with constant charging voltage, current limliting is 40A, and setting the constant voltage charge cut-off current is that 4A carries out constant charging voltage current-limiting charge;
The 5th step: electric current is less than 4A when the 383.4V constant voltage charge, and promptly corresponding monomer battery voltage is 3.55V, after charging state is about 80%, stops charging.
Adopt said method, can effectively improve between the cell that full charging and methods such as single step modified constant-voltage charge commonly used be prone to or problem such as inside battery electric current distribution inequality, battery heating, cycle performance of battery difference, improve the fail safe and the reliability of battery, improve the performances such as cumulative capacity in the battery lifetime.
Embodiment two
According to the multistage constant voltage charging method of aforesaid lithium secondary battery, pure electric automobile is as follows with the concrete charge step of 78 288V that go here and there, 100Ah lithium manganate battery group:
The first step: with constant charging voltage is 304.2V, and current limliting is 20A, and setting the constant voltage charge cut-off current is 5A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 30 minutes;
Second step: when the 304.2V constant voltage charge electric current less than 5A or constant voltage charging time greater than 30 minutes, be that corresponding monomer battery voltage is 3.90V, after charging state is about 35%, be 312V with constant charging voltage again, current limliting is 50A, setting the constant voltage charge cut-off current is 12.5A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 30 minutes;
The 3rd step: when the 312V constant voltage charge electric current less than 12.5A or constant voltage charging time greater than 30 minutes, be that corresponding monomer battery voltage is 4.00V, after charging state is about 60%, be 319.8V with constant charging voltage again, current limliting is 20A, setting the constant voltage charge cut-off current is 5A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 30 minutes;
The 4th step: greater than 30 minutes, promptly corresponding monomer battery voltage was 4.10V to electric current less than 5A or constant voltage charging time when the 319.8V constant voltage charge, after charging state is about 85%, stopped charging.
In above-mentioned the 3rd step, be by with the charging deboost of charger by common 327.6V, be reduced to 319.8V, realize shallow charging.
Adopt said method, can effectively improve between the cell that full charging and methods such as single step modified constant-voltage charge commonly used be prone to or problem such as inside battery electric current distribution inequality, battery heating, cycle performance of battery difference, improve the fail safe and the reliability of battery, improve the performances such as cumulative capacity in the battery lifetime.
Embodiment three
According to the multistage constant voltage charging method of aforesaid lithium secondary battery, discharging and recharging rated power is the 768V of the energy-accumulating power station of 500kW with 320 strings, and the concrete charge step of the lithium titanate battery pack of 4000Ah (discharging and recharging rated current is 650A) is:
The first step: charge power (electric current the is 260A) charging with 200kW reaches 694.4V up to battery voltage;
Second step: after battery voltage reaches 694.4V, be 761.6V with constant charging voltage, current limliting is 650A (charge power is 500kW), and setting constant voltage charge cut-off current is 260A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 30 minutes;
The 3rd step: when the 761.6V constant voltage charge electric current less than 260A or constant voltage charging time greater than 30 minutes after, be 784V with constant charging voltage again, current limliting is 325A (charge power is 250kW), setting the constant voltage charge cut-off current is 130A, and constant voltage charging time is to carry out constant charging voltage current-limiting charge in 30 minutes;
The 4th step: greater than 30 minutes, promptly Dui Ying monomer battery voltage reached 2.45V to electric current less than 130A or constant voltage charging time when the 784V constant voltage charge, after charging state is about 70%, stopped to charge.
According to the charging method of aforesaid lithium secondary battery, this discharges and recharges rated power is the 768V of the energy-accumulating power station of 500kW with 320 strings, and the discharge step of the lithium titanate battery pack of 4000Ah is:
The first step: discharge power (electric current the is 260A) discharge with 200kW reaches 761.6V up to battery voltage;
Second step: when battery voltage reaches 761.6V, corresponding monomer battery voltage reaches 2.38V, charging state reaches at 60% o'clock, battery management system is gathered battery pack information, and send control information and give power consumption equipment (energy conversion system), the discharge power of energy-accumulating power station is controlled at rated power 500kW, carries out regular picture;
The 3rd step: when battery voltage reaches 694.4V, corresponding monomer battery voltage reaches 2.17V, charging state reaches at 30% o'clock, battery management system is gathered battery pack information, and sends control information and give power consumption equipment (energy conversion system), and the discharge power of energy-accumulating power station is controlled at 250kW, thereby realize that discharge reduces discharging current latter stage, when battery voltage during less than 672V or the voltage of arbitrary cell less than 2.1V, corresponding battery charge attitude is 20% o'clock, finishes discharge.
In above-mentioned the 3rd step; finish discharge and be by with energy conversion system; be that (corresponding monomer battery voltage is 1.4V from common 448V for the under-voltage protection value of electric machine controller; charging state is 0%) increase to 672V, and in battery management system, cell under-voltage protection value is increased to 2.1V by common 1.4V and realize shallow discharge.
Adopt said method, can effectively improve between the cell that full charging, full discharge and methods such as single step modified constant-voltage charge commonly used be prone to or problems such as inside battery electric current distribution inequality, battery heating, cycle performance of battery difference, improve the fail safe and the reliability of battery, dwindle the operating voltage range of energy conversion system, improve the performances such as cumulative capacity in the battery lifetime greatly.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. the multistage constant voltage charging method of a lithium secondary battery may further comprise the steps:
Step a1: constant charging voltage current-limiting charge;
Step a2: judge charging current whether less than current setting value or charging interval whether greater than the time set value, if charging current less than current setting value or charging interval greater than the time set value, execution in step a3 then, otherwise execution in step a1;
Step a3: judge whether lithium secondary battery voltage reaches voltage setting value, if lithium secondary battery voltage has reached voltage setting value, then complete charge does not reach voltage setting value as if lithium secondary battery voltage, then execution in step a4;
Step a4: improve charging voltage, and execution in step a1.
2. the multistage constant voltage charging method of lithium secondary battery according to claim 1, it is characterized in that: current setting value described in the step a2 is the constant voltage charge cut-off current.
3. the multistage constant voltage charging method of lithium secondary battery according to claim 1, it is characterized in that: the value of time set described in the step a2 is a constant voltage charging time.
4. the multistage constant voltage charging method of lithium secondary battery according to claim 1, it is characterized in that: voltage setting value described in the step a 3 is described lithium secondary battery pairing cell voltage when being full of electricity, and perhaps shallow charging requires the cell voltage that reaches.
5. the multistage constant voltage charging method of lithium secondary battery according to claim 1 is characterized in that: before described step a1, also comprise preorder step a0: carry out low current charge.
6. the multistage constant voltage charging method of lithium secondary battery according to claim 4 is characterized in that: the cell voltage that described shallow charging required to reach is that the battery charge attitude is at 70%~95% pairing cell voltage.
7. the multistage constant voltage charging method of lithium secondary battery according to claim 6 is characterized in that: by charger charging deboost value is controlled.
8. the charging method of a lithium secondary battery is characterized in that, may further comprise the steps:
Step b1: the power that reduces power consumption equipment begins discharge to reduce discharging current;
Step b2: regular picture current discharge;
Step b3: the power that reduces power consumption equipment finishes discharge to reduce discharging current.
9. the charging method of lithium secondary battery according to claim 8 is characterized in that: when the battery charge attitude of described lithium secondary battery 5%~40% the time, finish discharge.
10. the charging method of lithium secondary battery according to claim 9 is characterized in that: the under-voltage protection value by increasing electric machine controller is controlled at 5%~40% with the battery charge attitude of described lithium secondary battery.
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CN107196386A (en) * | 2017-07-26 | 2017-09-22 | 罗腾 | Accumulator charging method, device and charging pile |
CN108258346A (en) * | 2016-12-29 | 2018-07-06 | 宁德新能源科技有限公司 | Secondary battery charging method |
CN106953128B (en) * | 2017-04-27 | 2019-07-12 | 江苏聚合新能源科技有限公司 | A kind of naturally adaptive charging method of dynamic |
CN112993423A (en) * | 2021-02-19 | 2021-06-18 | 芜湖天弋能源科技有限公司 | Method for improving capacity of lithium ion battery cell module |
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CN108258346A (en) * | 2016-12-29 | 2018-07-06 | 宁德新能源科技有限公司 | Secondary battery charging method |
CN106953128B (en) * | 2017-04-27 | 2019-07-12 | 江苏聚合新能源科技有限公司 | A kind of naturally adaptive charging method of dynamic |
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CN107196386B (en) * | 2017-07-26 | 2020-04-24 | 罗腾 | Storage battery charging method and device and charging pile |
CN112993423A (en) * | 2021-02-19 | 2021-06-18 | 芜湖天弋能源科技有限公司 | Method for improving capacity of lithium ion battery cell module |
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