CN115347652B - Low-temperature charging optimization method and system for lithium battery and storage medium - Google Patents
Low-temperature charging optimization method and system for lithium battery and storage medium Download PDFInfo
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- CN115347652B CN115347652B CN202211269956.2A CN202211269956A CN115347652B CN 115347652 B CN115347652 B CN 115347652B CN 202211269956 A CN202211269956 A CN 202211269956A CN 115347652 B CN115347652 B CN 115347652B
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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
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/007188—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters
- H02J7/007192—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature
- H02J7/007194—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature of the battery
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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
- H01M10/443—Methods for charging or discharging in response to temperature
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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
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
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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
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
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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
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Abstract
The invention provides a method, a system and a storage medium for optimizing low-temperature charging of a lithium battery, wherein the method comprises the following steps: acquiring the current temperature of the lithium battery system, and judging whether the current temperature is greater than or equal to a preset temperature threshold value; if so, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, and determining the current charging level and the current charging interval of the lithium battery system, and the current charging level and the current charging power in the current charging interval; calculating the charging time required when the state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level according to the charging power; determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval; and heating and charging the lithium battery system according to the optimal heating rate and the current charging power. The technical problem of long charging time of the lithium battery in a low-temperature state in the prior art is solved.
Description
Technical Field
The invention relates to the technical field of charging, in particular to a method and a system for optimizing low-temperature charging of a lithium battery and a storage medium.
Background
Lithium ion batteries are easy to generate lithium precipitation when being charged in a low-temperature environment (generally below 0 ℃), further deterioration of the lithium ion batteries can form lithium dendrites, short circuit failure in the battery core is caused, and potential safety hazards are generated. In order to avoid the problem of lithium deposition, a charging current is generally reduced (generally-10 ℃ or lower at an extremely low temperature, charging is not allowed) in accordance with a charging window (charging MAP), and a small charging current means a long charging time, and affects the use experience. Therefore, for a specified battery cell, under a low-temperature environment, the battery cell is insulated, and the battery cell is isolated from the outside to keep a non-low-temperature environment state, which is a current mainstream solution, but the solution needs a heat insulation material with reasonable design according to the use temperature, so that the material cost is greatly increased. Another desirable solution is to heat the cells first to a certain temperature to recharge. However, if the technical scheme of "heating before recharging" is not used properly, the switching between the two stages of "heating" and "charging" is not reasonable, which easily causes the problems of battery overheating, large temperature difference between different positions of the battery, long charging time, large energy consumption in the whole process, etc. which affect the safety, consistency and energy loss of the battery, therefore, how to find the optimal charging access point is very important, both the charging safety and the overall charging time are ensured to be the shortest.
Disclosure of Invention
Based on this, the present invention provides a method, a system and a storage medium for optimizing low-temperature charging of a lithium battery, which are used to solve the technical problem that a lithium battery in the prior art has a long charging time in a low-temperature state.
The invention provides a low-temperature charging optimization method for a lithium battery, which comprises the following steps:
acquiring the current temperature of a lithium battery system, and judging whether the current temperature is greater than or equal to a preset temperature threshold value;
if yes, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, and determining the current charging level and the current charging interval of the lithium battery system, and the current charging power of the current charging level and the current charging interval;
calculating the charging time required when the state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level according to the charging power;
determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
and heating and charging the lithium battery system according to the optimal heating rate and the current charging power.
Preferably, after the step of charging the lithium battery system while heating according to the optimal heating rate and the current charging power, the method further comprises:
judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system or not and whether the current temperature reaches the rated temperature of the lithium battery system or not;
if the current charge state and the temperature do not reach the charge threshold and the rated temperature of the lithium battery system, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, re-determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval, and charging the lithium battery system while heating at the current charging power and the optimal heating rate;
and if the current charge state does not reach the charge threshold value of the lithium battery system, but the current temperature reaches the rated temperature of the lithium battery system, stopping heating the lithium battery system, and purely charging the lithium battery system by using the current charging power.
Preferably, the step of charging the lithium battery system while heating according to the optimal heating rate and the current charging power further includes:
judging whether the optimal heating rate is smaller than or equal to a heating rate threshold value;
if so, performing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power;
and if not, charging the lithium battery system while heating according to the heating rate threshold value and the current charging power.
Preferably, if not, the step of charging the lithium battery system while heating according to the heating rate threshold and the current charging power further includes:
according to the current maximum heating rate and the current charging power, calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charging level;
calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
comparing whether the temperature of the current charging power during the charging is less than or equal to the lower limit value of the temperature of the next adjacent charging interval or not;
when the temperature of the lithium battery system after the current charging power is completely charged is equal to the lower limit value of the temperature of the next adjacent charging interval, reducing the current charging power of the lithium battery system to heat the lithium battery system while charging so that the current temperature of the lithium battery system can reach the lower limit value of the temperature of the next adjacent charging interval before the current state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level;
and when the temperature of the lithium battery system after the charging is finished under the current charging power is lower than the lower limit value of the temperature of the next adjacent charging interval, executing the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power.
Preferably, the step of obtaining the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold further includes:
and if not, heating the lithium battery system until the current temperature reaches the preset temperature threshold.
Preferably, the step of obtaining the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold further includes:
and if not, heating the lithium battery system until the current temperature reaches the preset temperature threshold.
Preferably, the optimal heating rate includes a heating rate of the heating liquid, a heat generation rate of the battery cell, and a heat dissipation rate of the battery system.
In another aspect of the present invention, a low-temperature charging optimization system for a lithium battery is further provided, where the system includes:
the identification module is used for acquiring the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold value;
the acquisition module is used for inquiring charging MAP (MAP) based on the current temperature and the current charge state of the lithium battery system when the current temperature is greater than or equal to a preset temperature threshold value, and determining the current charging level and the current charging interval of the lithium battery system and the current charging power under the current charging level and the current charging interval;
the calculation module is used for calculating the charging time required by the lithium battery system when the charge state reaches the charge state upper limit value of the current charging level according to the charging power;
the selection module is used for determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
and the execution module is used for heating and charging the lithium battery system simultaneously according to the optimal heating rate and the current charging power.
Preferably, the system further comprises a first judging module, and the first judging module comprises:
the first judging unit is used for judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system and whether the current temperature reaches the rated temperature of the lithium battery system;
the first execution unit is used for inquiring a charging MAP (MAP) based on the current temperature and the current charge state of the lithium battery system if the current charge state and the temperature do not reach the charge threshold and the rated temperature of the lithium battery system, re-determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval, and charging the lithium battery system while heating at the current charging power and the optimal heating rate;
and the second execution unit is used for stopping heating the lithium battery system and purely charging the lithium battery system with the current charging power if the current charge state does not reach the charge threshold value of the lithium battery system but the current temperature reaches the rated temperature of the lithium battery system.
Preferably, the system further includes a second determining module, and the second determining module includes:
a second judgment unit configured to judge whether the optimal heating rate is less than or equal to a heating rate threshold;
the third execution unit is used for executing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power when the optimal heating rate is less than or equal to a heating rate threshold value;
and the fourth execution unit is used for charging the lithium battery system while heating according to the heating rate threshold and the current charging power when the optimal heating rate is greater than the heating rate threshold.
Preferably, the second determination module further includes:
the first calculation unit is used for calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charge level according to the current maximum heating rate and the current charging power;
the second calculating unit is used for calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
the comparison unit is used for comparing whether the temperature when the current charging power is completely charged is less than or equal to the lower temperature limit value of the next adjacent charging interval or not;
a fifth execution unit, configured to, when the temperature when the current charging power is completely charged is equal to the lower limit of the temperature of the next adjacent charging interval, reduce the current charging power to the lithium battery system to heat the lithium battery system while charging, so that the current temperature of the lithium battery system may reach the lower limit of the temperature of the next adjacent charging interval before the current state of charge reaches the upper limit of the state of charge of the current charging level;
and the sixth execution unit is used for executing the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power when the temperature of the current charging power after the charging is finished is smaller than the temperature lower limit value of the next adjacent charging interval.
Preferably, the identification module comprises:
and the heating module is used for heating the lithium battery system if the current temperature reaches the preset temperature threshold value.
In another aspect, the present invention further provides a storage medium, on which a computer program is stored, where the program is executed by a processor to implement the method for optimizing low-temperature charging of a lithium battery.
Compared with the prior art, the invention has the beneficial effects that:
the charging method comprises the steps of inquiring charging MAP by acquiring current temperature and state of charge to determine the current charging power of the current charging level and the current charging interval, calculating the shortest charging time required before the state of charge reaches the lower limit value of the state of charge of the next charging level according to the charging power, and setting an optimal heating rate according to the shortest charging time and the difference value between the current temperature and the lower limit value of the temperature of the next optimal charging interval, so that the temperature can reach the lower limit value of the temperature of the next optimal charging interval preferentially before the current state of charge of the lithium battery system jumps, the charging path of the lithium battery system is mainly based on the maximum charging power as far as possible, the time required for charging is greatly reduced on the premise of ensuring safety, and the technical problem that the charging time of the lithium battery in the prior art is long in the low-temperature state is solved.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a method for optimizing low-temperature charging of a lithium battery according to a first embodiment of the present invention;
FIG. 2 is a charging MAP according to a second embodiment of the present invention;
fig. 3 is a block diagram of a low-temperature charging optimization system for a lithium battery according to a fourth embodiment of the present invention;
the following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for purposes of illustration only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Example one
Referring to fig. 1, a method for optimizing low-temperature charging of a lithium battery in a first embodiment of the present invention includes the following steps:
step S101, acquiring the current temperature of a lithium battery system, and judging whether the current temperature is greater than or equal to a preset temperature threshold value;
specifically, the method comprises the steps of firstly obtaining the real-time temperature of the lithium battery system, comparing the real-time temperature with a preset temperature threshold, and if the real-time temperature is higher than the preset temperature threshold, indicating that the lithium battery can be charged in the current environment without heating; if the real-time temperature is lower than the preset temperature threshold value, the lithium battery system needs to be heated by the battery core heating device, so that the working temperature of the heated lithium battery system is not lower than the critical temperature value of lithium analysis, namely, the problem of low-temperature lithium analysis can be avoided.
Step S102, if yes, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, and determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval;
specifically, under the condition that the current temperature and the current state of charge of the lithium battery system are known, the maximum charging power allowed in the current charging interval can be obtained by inquiring the charging MAP, and the calculation is specifically performed according to the following calculation formula:
P=f(T k ,SoC k-1 );
wherein, P represents charging power, T k Representing the current temperature, the SoC k-1 Representing the current state of charge;
it should be explained that the charging power corresponds to a temperature range and a state-of-charge range, that is, a charging interval and a charging level, and in practical applications, if the measured temperature and the measured state-of-charge fall into the charging interval and the charging level corresponding to the charging power at the same time, it indicates that the charging power corresponding to the temperature range and the charging level can be used as the maximum charging power for charging. For safe charging, charging must be performed strictly in accordance with the charging MAP.
Step S103, calculating the charging time required when the state of charge of the lithium battery system reaches the state of charge upper limit value of the current charging level according to the charging power.
Specifically, the lithium battery is charged with the maximum charging power corresponding to the current charging interval, and the shortest charging time when the current state of charge reaches the state of charge upper limit value of the current charging level is predicted.
Step S104, determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
specifically, in the charging MAP, it is assumed that the charging power corresponding to the charging MAP is larger as the temperature increases before the current state of charge reaches the state of charge lower limit value of the next charging level, and therefore, the overall charging efficiency can be improved by preferentially heating the lithium battery system before the state of charge reaches the state of charge lower limit value of the next charging level.
Therefore, the objective of this step is to set an optimal heating rate, so that the temperature of the lithium battery system can preferentially reach the lower limit of the temperature of the next optimal charging interval before the current state of charge of the lithium battery system reaches the lower limit of the state of charge of the next charging level within the charging time, so that the lithium battery system is preferentially charged with the charging power corresponding to the charging interval, and the charging path of the lithium battery system is mainly based on the maximum charging power.
It should be explained that, for different lithium battery systems, due to different physical and chemical properties of the battery cells, the corresponding optimal charging intervals are different, so the optimal charging interval in this embodiment needs to be adaptively set according to the characteristics of the lithium battery system.
In this embodiment, the calculation formula of the charging time is as follows:
t 2-k =(T k -T k-1 )/(υ L-h +υ P-h -υ P-c );
wherein, t 2-k Indicating the charging time, T k Lower limit value of temperature, T, representing the next charging interval k-1 Indicating the temperature, upsilon, of the current charging interval L-h Indicating the heating rate, upsilon, of the heating liquid P-h Denotes the rate of heat generation, upsilon, of the cell P-c Indicating the rate of heat removal from the battery system.
It can be understood that the heating rate can be determined on the premise that the difference between the charging time and the current temperature and the lower temperature limit value of the next optimal charging interval is known.
And S105, heating and charging the lithium battery system according to the optimal heating rate and the current charging power.
In summary, in the method for optimizing low-temperature charging of a lithium battery in the above embodiments of the present invention, the charging MAP is queried by obtaining the current temperature and the state of charge, so as to determine the current charging power at the current charging level and the current charging power in the current charging interval, calculate the shortest charging time required before the state of charge reaches the lower limit value of the state of charge at the next charging level according to the charging power, and set an optimal heating rate according to the shortest charging time and the difference between the current temperature and the lower limit value of the temperature in the next optimal charging interval, so that the temperature of the lithium battery system can preferentially reach the lower limit value of the temperature in the next optimal charging interval before the current state of charge jumps, so that the charging path of the lithium battery system is dominated by the maximum charging power as much as possible, on the premise of ensuring safety, the time required for charging is greatly reduced, and the technical problem in the prior art that the charging time of the lithium battery is long in the low-temperature state is solved.
Example two
The method for optimizing the low-temperature charging of the lithium battery in the second embodiment of the invention comprises the following steps:
s11, acquiring the current temperature of the lithium battery system, and judging whether the current temperature is greater than or equal to a preset temperature threshold value;
s12, if yes, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, and determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval;
s13, calculating the charging time required when the charge state of the lithium battery system reaches the charge state upper limit value of the current charging level according to the charging power;
s14, determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
and S15, heating and charging the lithium battery system simultaneously according to the optimal heating rate and the current charging power.
It should be noted that, in the present embodiment, reference may be made to the first embodiment for parts not described in step S11, step S12, step S13, step S14, and step S15.
Preferably, after the step of charging the lithium battery system while heating according to the optimal heating rate and the current charging power, the method further comprises:
judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system or not and whether the current temperature reaches the rated temperature of the lithium battery system or not;
if the current charge state and the current temperature do not reach the charge threshold value and the rated temperature of the lithium battery system, returning to the step S12;
and if the current charge state does not reach the charge threshold value of the lithium battery system, but the current temperature reaches the rated temperature of the lithium battery system, stopping heating the lithium battery system, and carrying out pure charging on the lithium battery system by using the current charging power, wherein the charge threshold value represents an SoC value when the charging is finished, and the charge threshold value represents a temperature value when the heating is finished.
It can be understood that, this step is used to detect whether the current SoC of the lithium battery system is equal to 80%, that is, determine whether the current lithium battery system is full, when the SoC is equal to 80%, indicate full charge, stop charging and heating the lithium battery, otherwise, if not, return to step S12, query the charging MAP based on the changed temperature and state of charge again to determine the charging power, and the heating rate adopted under the charging power, and continue to heat the lithium battery while charging according to the newly determined heating rate and charging power; wherein, if it has reached rated temperature to detect the current temperature of lithium battery system, then can not heat lithium battery system again, avoid lithium battery system overheating and take place danger.
Preferably, the step of charging the lithium battery system while heating according to the optimal heating rate and the current charging power further includes:
judging whether the optimal heating rate is smaller than or equal to a heating rate threshold value;
if so, performing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power;
and if not, heating and charging the lithium battery system while heating according to the heating rate threshold and the current charging power.
Preferably, if not, the step of charging the lithium battery system while heating according to the heating rate threshold and the current charging power further includes:
according to the current maximum heating rate and the current charging power, calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charging level;
calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
comparing whether the temperature of the current charging power during the charging is less than or equal to the lower limit value of the temperature of the next adjacent charging interval or not;
when the temperature of the lithium battery system after the current charging power is completely charged is equal to the lower limit value of the temperature of the next adjacent charging interval, reducing the current charging power of the lithium battery system to heat the lithium battery system while charging so that the current temperature of the lithium battery system can reach the lower limit value of the temperature of the next adjacent charging interval before the current state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level;
and when the temperature of the lithium battery system is lower than the lower limit value of the temperature of the next adjacent charging interval when the current charging power is completely charged, executing the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power.
In practical application, assuming that the current state of charge does not exceed the upper limit of the state of charge of the current charging level, the charging power of the lithium battery system increases with the continuous increase of the temperature, and when the heating rate is adjusted to the heating threshold, the situation that the charging rate is greater than or equal to the heating rate may occur, so that the current state of charge of the lithium battery system just reaches the upper limit of the state of charge of the current charging level when the current temperature of the lithium battery system reaches the lower limit of the temperature of the next adjacent charging interval in the charging process.
Therefore, in this step, when the current state of charge reaches the upper limit value of the state of charge of the charging level, the state of charge increment and the temperature rise of the current lithium battery system can be calculated by adopting an ampere-hour integration method, the temperature and the state of charge at the end of the current charging power can be predicted according to the state of charge increment and the temperature rise, and if the current temperature reaches the lower limit value of the temperature of the next adjacent charging interval, the current state of charge just reaches the upper limit value of the state of charge of the current charging level, the current charging power can be slightly reduced to carry out heating while charging, so that the current temperature of the lithium battery system can reach the lower limit value of the temperature of the next adjacent charging interval before the current state of charge reaches the upper limit value of the state of charge of the current charging level, the lithium battery system preferentially selects the charging power corresponding to the charging interval, and the whole charging path is shortened.
Specifically, referring to fig. 2, a charging MAP of the lithium battery system is shown, in the drawing, a table corresponding to a horizontal direction indicates a variation relationship between the charging power and the temperature and is named as a charging interval, a table corresponding to a vertical direction indicates a variation relationship between the charging power and the SoC and is named as a charging level, and the purpose of the step is to enable the whole charging path to move horizontally as much as possible and select high power for charging.
Preferably, the step of obtaining the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold further includes:
and if not, heating the lithium battery system until the current temperature reaches the preset temperature threshold.
It can be understood that if the real-time temperature is lower than the preset temperature threshold, the lithium battery system needs to be heated by the cell heating device, so that the working temperature of the heated lithium battery system is not lower than the critical temperature value for lithium precipitation, that is, the problem of low-temperature lithium precipitation no longer occurs.
In summary, in the method for optimizing low-temperature charging of a lithium battery in the above embodiment of the present invention, charging MAP is queried by obtaining a current temperature and a current state of charge to determine a current charging power at a current charging level and a current charging interval, a shortest charging time required before a state of charge reaches a lower limit of a state of charge of a next charging level is calculated according to the charging power, and an optimal heating rate is set according to the shortest charging time and a difference between the current temperature and a lower limit of a temperature of a next optimal charging interval, so that a temperature of a lithium battery system can preferentially reach the lower limit of the temperature of the next optimal charging interval before the current state of charge jumps, a charging path of the lithium battery system is mainly based on the maximum charging power as much as possible, and on the premise of ensuring safety, time required for charging is greatly reduced, and a technical problem that a lithium battery in the prior art has a long charging time at a low temperature is solved.
EXAMPLE III
The method for optimizing low-temperature charging of the lithium battery in the third embodiment of the invention specifically comprises the following three charging paths:
a first charging path:
Step 2, heating the battery;
step 3, when the battery temperature T is lower than T 1 While, heating was continued until T = T 1 ;
Step 4, obtaining/inputting charging MAP of the battery according to a function P = f (T) k ,SoC k-1 ) Determining the charging power of the current step, and calculating the minimum time t required by the temperature jump to the lower limit value of the temperature of the next charging interval in the current SoC according to the charging power 2-k According to t 2-k Calculating the SoC (delta kSoC) increased in the charging process according to an ampere-hour integral method, and calculating the temperature rise (delta T) in the process at the same time 2-k );
Step 5, obtaining/inputting charging MAP of the battery, and the current temperature T 2-K =T k +ΔT 2-k At the temperature, judging the maximum value of SoC in the adjacent charging levels in the previous step, and judging the current SoC = SoC k Whether the + Δ SoC value exceeds a maximum value;
and 6, if the SoC does not exceed the maximum value, ending the charging until the battery is charged to SoC = 80%.
A second charging path:
step 8, obtaining/inputting charging MAP of the battery, wherein the current SoC (SoC = SoC) k + Δ mSoC), the maximum temperature in the adjacent up-step charging interval, the current temperature T = T k + Δ mSoC does not exceed this maximum;
and 9, if the temperature does not exceed the maximum value, ending the charging until the battery is charged to SoC = 80%.
A third charging path:
Step 11, get/inputCharging MAP of battery, current SoC = SoC f Obtaining the maximum temperature value in the adjacent last charging interval, wherein the current temperature T = T k-1 +ΔT 2-f Equal to the maximum value;
step 12, record T = T k-1 +ΔT 2-f ,SoC=SoC f ,t=t 2-f Returning to the step 4;
step 13, step 11, when T = T k-1 +ΔT 2-f If not, returning to step 10.
In summary, in the method for optimizing low-temperature charging of a lithium battery in the above embodiment of the present invention, charging MAP is queried by obtaining a current temperature and a current state of charge to determine a current charging power at a current charging level and a current charging interval, a shortest charging time required before a state of charge reaches a lower limit of a state of charge of a next charging level is calculated according to the charging power, and an optimal heating rate is set according to the shortest charging time and a difference between the current temperature and a lower limit of a temperature of a next optimal charging interval, so that a temperature of a lithium battery system can preferentially reach the lower limit of the temperature of the next optimal charging interval before the current state of charge jumps, a charging path of the lithium battery system is mainly based on the maximum charging power as much as possible, and on the premise of ensuring safety, time required for charging is greatly reduced, and a technical problem that a lithium battery in the prior art has a long charging time at a low temperature is solved.
Example four
The present invention further provides a low-temperature charging optimization system for a lithium battery, as shown in fig. 3, the system includes:
the identification module 10 is configured to acquire a current temperature of the lithium battery system, and determine whether the current temperature is greater than or equal to a preset temperature threshold;
the obtaining module 20 is configured to query a charging MAP based on the current temperature and the current state of charge of the lithium battery system when the current temperature is greater than or equal to a preset temperature threshold, and determine a current charging level and a current charging interval where the lithium battery system is located, and current charging power of the current charging level and the current charging interval;
the calculation module 30 is configured to calculate, according to the charging power, a charging time required when the state of charge of the lithium battery system reaches an upper limit value of the state of charge of the current charging level;
the selecting module 40 is configured to determine an optimal heating rate under the current charging power according to the charging time and a difference between the current temperature and a temperature lower limit value of a next optimal charging interval;
and the execution module 50 is configured to charge the lithium battery system while heating according to the optimal heating rate and the current charging power.
Preferably, the system further comprises a first judging module, and the first judging module comprises:
the first judging unit is used for judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system and whether the current temperature reaches the rated temperature of the lithium battery system;
the first execution unit is used for inquiring charging MAP (MAP) based on the current temperature and the current charge state of the lithium battery system if the current charge state and the temperature do not reach the charge threshold and the rated temperature of the lithium battery system, re-determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval, and charging the lithium battery system while heating at the current charging power and the optimal heating rate;
and the second execution unit is used for stopping heating the lithium battery system and purely charging the lithium battery system with the current charging power if the current charge state does not reach the charge threshold value of the lithium battery system but the current temperature reaches the rated temperature of the lithium battery system.
Preferably, the system further includes a second determining module, where the second determining module includes:
a second judgment unit configured to judge whether the optimal heating rate is less than or equal to a heating rate threshold;
the third execution unit is used for executing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power when the optimal heating rate is less than or equal to a heating rate threshold value;
and the fourth execution unit is used for charging the lithium battery system while heating according to the heating rate threshold and the current charging power when the optimal heating rate is greater than the heating rate threshold.
Preferably, the second determining module further comprises:
the first calculation unit is used for calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charge level according to the current maximum heating rate and the current charging power;
the second calculation unit is used for calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
the comparison unit is used for comparing whether the temperature when the current charging power is completely charged is less than or equal to the lower temperature limit value of the next adjacent charging interval or not;
a fifth execution unit, configured to, when the temperature when the current charging power is completely charged is equal to the lower limit of the temperature of the next adjacent charging interval, reduce the current charging power to the lithium battery system to heat the lithium battery system while charging, so that the current temperature of the lithium battery system may reach the lower limit of the temperature of the next adjacent charging interval before the current state of charge reaches the upper limit of the state of charge of the current charging level;
and the sixth execution unit is used for executing the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power when the temperature of the current charging power after the charging is finished is smaller than the temperature lower limit value of the next adjacent charging interval.
Preferably, the identification module comprises:
and the heating module is used for heating the lithium battery system if the current temperature reaches the preset temperature threshold value.
In summary, in the low-temperature charging optimization system for a lithium battery in the above embodiments of the present invention, the charging MAP is queried by obtaining the current temperature and the state of charge to determine the current charging power at the current charging level and the current charging power in the current charging interval, the shortest charging time required before the state of charge reaches the lower limit of the state of charge of the next charging level is calculated according to the charging power, and an optimal heating rate is set according to the shortest charging time and the difference between the current temperature and the lower limit of the temperature in the next optimal charging interval, so that the temperature of the lithium battery system can preferentially reach the lower limit of the temperature in the next optimal charging interval before the current state of charge jumps, the charging path of the lithium battery system is mainly based on the maximum charging power as much as possible, the time required for charging is greatly reduced on the premise of ensuring safety, and the technical problem in the prior art that the charging time of the lithium battery is long in the low-temperature state is solved.
EXAMPLE five
The invention also provides a readable storage medium, on which a computer program is stored, which when executed by a processor implements the method for optimizing low-temperature charging of a lithium battery as described above.
The invention also provides a server, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the program to realize the low-temperature charging optimization method of the lithium battery.
Those of skill in the art will understand that the logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be viewed as implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following technologies, which are well known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, and these are all within the scope of protection of the present application. Therefore, the protection scope of the present patent application shall be subject to the appended claims.
Claims (7)
1. A low-temperature charging optimization method for a lithium battery is characterized by comprising the following steps:
step S101, acquiring the current temperature of a lithium battery system, and judging whether the current temperature is greater than or equal to a preset temperature threshold value;
step S102, if yes, inquiring a charging MAP based on the current temperature and the current charge state of the lithium battery system, and determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval;
step S103, calculating the charging time required when the charge state of the lithium battery system reaches the charge state upper limit value of the current charging level according to the charging power;
step S104, determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
step S105, charging while heating the lithium battery system according to the optimal heating rate and the current charging power;
wherein, the step of charging while heating the lithium battery system according to the optimal heating rate and the current charging power further comprises:
judging whether the optimal heating rate is smaller than or equal to a heating rate threshold value;
if so, performing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power;
if not, heating and charging the lithium battery system while heating according to the heating rate threshold and the current charging power;
if not, the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power further comprises the following steps:
according to the current heating rate threshold and the current charging power, calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charging level;
calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
comparing whether the temperature of the current charging power during the charging is less than or equal to the lower limit value of the temperature of the next adjacent charging interval or not;
when the temperature of the lithium battery system after the current charging power is completely charged is equal to the lower limit value of the temperature of the next adjacent charging interval, reducing the current charging power of the lithium battery system to heat the lithium battery system while charging so that the current temperature of the lithium battery system can reach the lower limit value of the temperature of the next adjacent charging interval before the current state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level;
and when the temperature of the lithium battery system is lower than the lower limit value of the temperature of the next adjacent charging interval when the current charging power is completely charged, executing the step of heating and charging the lithium battery system according to the heating rate threshold and the current charging power.
2. The method for optimizing low-temperature charging of a lithium battery according to claim 1, wherein after the step of charging the lithium battery system while heating according to the optimal heating rate and the current charging power, the method further comprises:
judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system or not and whether the current temperature reaches the rated temperature of the lithium battery system or not;
if the current charge state and the current temperature do not reach the charge threshold and the rated temperature of the lithium battery system, returning to the step S102;
and if the current charge state does not reach the charge threshold value of the lithium battery system, but the current temperature reaches the rated temperature of the lithium battery system, stopping heating the lithium battery system, and purely charging the lithium battery system by using the current charging power.
3. The method for optimizing the low-temperature charging of the lithium battery according to claim 1, wherein the step of obtaining the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold further comprises the steps of:
and if not, heating the lithium battery system until the current temperature reaches the preset temperature threshold.
4. The method as claimed in claim 1, wherein the optimal heating rate includes a heating rate of a heating fluid, a heat generation rate of a cell, and a heat dissipation rate of a battery system.
5. A lithium battery low temperature charge optimizing system, characterized by includes:
the identification module is used for acquiring the current temperature of the lithium battery system and judging whether the current temperature is greater than or equal to a preset temperature threshold value or not;
the acquisition module is used for inquiring charging MAP (MAP) based on the current temperature and the current charge state of the lithium battery system when the current temperature is greater than or equal to a preset temperature threshold value, and determining the current charging level and the current charging interval of the lithium battery system and the current charging power under the current charging level and the current charging interval;
the calculation module is used for calculating the charging time required when the state of charge of the lithium battery system reaches the upper limit value of the state of charge of the current charging level according to the charging power;
the selection module is used for determining the optimal heating rate under the current charging power according to the charging time and the difference value between the current temperature and the temperature lower limit value of the next optimal charging interval;
the execution module is used for charging the lithium battery system while heating according to the optimal heating rate and the current charging power;
the system further comprises a second judging module, wherein the second judging module comprises:
a second judgment unit configured to judge whether the optimal heating rate is less than or equal to a heating rate threshold;
the third execution unit is used for executing heating and charging while heating the lithium battery system according to the optimal heating rate and the current charging power when the optimal heating rate is less than or equal to a heating rate threshold value;
the fourth execution unit is used for charging the lithium battery system while heating according to the heating rate threshold and the current charging power when the optimal heating rate is greater than the heating rate threshold;
the second determination module further includes:
the first calculation unit is used for calculating the temperature rise of the lithium battery system when the current charge state of the lithium battery system reaches the charge state upper limit value of the current charge level according to the current heating rate threshold and the current charging power;
the second calculating unit is used for calculating the temperature of the lithium battery system when the lithium battery system is completely charged under the current charging power according to the temperature rise of the lithium battery system;
the comparison unit is used for comparing whether the temperature when the current charging power is completely charged is less than or equal to the lower temperature limit value of the next adjacent charging interval or not;
a fifth execution unit, configured to, when the temperature when the current charging power is completely charged is equal to the lower limit of the temperature of the next adjacent charging interval, reduce the current charging power to the lithium battery system to heat the lithium battery system while charging, so that the current temperature of the lithium battery system may reach the lower limit of the temperature of the next adjacent charging interval before the current state of charge reaches the upper limit of the state of charge of the current charging level;
and the sixth execution unit is used for executing the simultaneous heating and charging of the lithium battery system according to the heating rate threshold and the current charging power when the temperature of the current charging power after the charging is finished is smaller than the temperature lower limit value of the next adjacent charging interval.
6. The system for optimizing low-temperature charging of a lithium battery as claimed in claim 5, further comprising a first judging module, wherein the first judging module comprises:
the first judging unit is used for judging whether the current charge state of the lithium battery system reaches the charge threshold of the lithium battery system or not and whether the current temperature reaches the rated temperature of the lithium battery system or not;
the first execution unit is used for inquiring charging MAP (MAP) based on the current temperature and the current charge state of the lithium battery system if the current charge state and the temperature do not reach the charge threshold and the rated temperature of the lithium battery system, re-determining the current charging level and the current charging interval of the lithium battery system, and the current charging power under the current charging level and the current charging interval, and charging the lithium battery system while heating at the current charging power and the optimal heating rate;
and the second execution unit is used for stopping heating the lithium battery system and purely charging the lithium battery system with the current charging power if the current charge state does not reach the charge threshold value of the lithium battery system but the current temperature reaches the rated temperature of the lithium battery system.
7. A storage medium having stored thereon a computer program, characterized in that the program, when being executed by a processor, implements the method for optimizing low temperature charging of a lithium battery according to any one of claims 1 to 4.
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