CN112793461B - Battery management system, electric vehicle and initial state determination method of lithium battery - Google Patents
Battery management system, electric vehicle and initial state determination method of lithium battery Download PDFInfo
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 239
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 239
- 238000000034 method Methods 0.000 title claims abstract description 68
- 239000000178 monomer Substances 0.000 claims abstract description 85
- 230000008569 process Effects 0.000 claims abstract description 25
- 230000000630 rising effect Effects 0.000 claims abstract description 4
- 238000004891 communication Methods 0.000 claims description 14
- 238000007726 management method Methods 0.000 description 28
- 238000011084 recovery Methods 0.000 description 13
- 230000003068 static effect Effects 0.000 description 9
- 238000007599 discharging Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000005059 dormancy Effects 0.000 description 2
- 230000004622 sleep time Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000013024 troubleshooting Methods 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 230000036578 sleeping time Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Abstract
The invention provides a battery management system, an electric vehicle and a method for determining the initial state of a lithium battery, which comprises the steps of firstly powering on the electric vehicle, then recording the temperature of each lithium battery monomer at a corresponding moment through an upper computer or a whole vehicle controller, determining the rising value of the temperature of each lithium battery monomer in the previous operation process of the lithium battery in the electric vehicle as a first temperature difference of the lithium battery, determining the falling value of the current power-on moment of the electric vehicle relative to the temperature of each lithium battery monomer in the previous operation process as a second temperature difference of the lithium battery, if the first temperature difference is larger than the second temperature difference and the temperature of each lithium battery monomer at the current power-on moment is in a preset range and meets the preset range, judging that the lithium battery is in the initial state, determining whether the lithium battery is in the initial state or not through the temperature of each lithium battery monomer, solving the problem that the lithium battery without the real-time clock function cannot determine the initial state, the accuracy of battery state estimation of a lithium battery is improved.
Description
Technical Field
The invention belongs to the technical field of battery management, and particularly relates to a battery management system, an electric automobile and a method for determining an initial state of a lithium battery.
Background
In an electric automobile, a power battery is a very common energy storage element, and the performance of the power battery plays a decisive role in the performance of the whole automobile. In order to reasonably utilize the battery, prolong the service life of the battery and prolong the driving range of the vehicle, the state of the battery needs to be reasonably controlled, so that the estimation accuracy of the state of the battery is very important.
However, in a lithium battery without a real-time clock function, it is impossible to determine whether the lithium battery is in an initial state by determining whether a sleep time of the lithium battery before being powered on exceeds a specific time, which results in a low accuracy of estimating a battery state of the lithium battery.
Disclosure of Invention
In view of the above, the present invention provides a battery management system, an electric vehicle and an initial state determination method for a lithium battery, which are used for determining an initial state of the lithium battery, so as to improve accuracy of estimation of the battery state of the lithium battery.
The invention discloses a method for determining the initial state of a lithium battery, which is applied to a battery management system, and comprises the following steps:
powering on the electric automobile;
determining a first temperature difference and a second temperature difference of a lithium battery in the electric automobile; the first temperature difference is a rising value of the temperature of the lithium battery monomer in the previous operation process, the second temperature difference is a falling value of the current power-on moment to the temperature of the lithium battery monomer in the previous operation process, and the temperature of each lithium battery monomer is recorded by the upper computer or the whole vehicle controller at the corresponding moment;
judging whether the first temperature difference is larger than the second temperature difference and whether the temperature of the lithium battery monomer at the current power-on moment is within a preset range;
and if the first temperature difference is larger than the second temperature difference and the temperature of the single lithium battery at the current electrifying moment is within a preset range and simultaneously meets the preset range, judging that the lithium battery is in an initial state.
Optionally, determining a first temperature difference and a second temperature difference of a lithium battery in the electric vehicle includes:
acquiring the temperature of a lithium battery monomer at the current power-on moment, the temperature of the lithium battery monomer at the previous power-on moment and the temperature of the lithium battery monomer after preset time at the previous power-on moment;
using the formula Δ Trise＝(T1-T0) And Δ Tdrop＝|T2-T1Calculating the first temperature difference and the second temperature difference respectively;
wherein, Delta TriseIs said first temperature difference, Δ TdropIs said second temperature difference, T2The temperature of the lithium battery cell at the current power-on time,T1the temperature T of the lithium battery monomer after the preset time of the previous power-on moment0And the temperature of the lithium battery monomer at the previous power-on moment is obtained.
Optionally, the preset range is: (T)1-ΔT，T1)；
Wherein, T1And the delta T is the threshold value of the electric automobile for the temperature of the lithium battery monomer after the preset time of the previous power-on moment.
Optionally, the specific manner of obtaining the temperature of the lithium battery cell at the current power-on time, the temperature of the lithium battery cell at the previous power-on time, and the temperature of the lithium battery cell after the preset time of the previous power-on time is as follows: directly obtaining the data from the upper computer through communication, or obtaining the data from the whole vehicle controller through a Controller Area Network (CAN) bus;
the temperature of the lithium battery monomer at the current power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller at the current power-on moment, the temperature of the lithium battery monomer at the previous power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller at the previous power-on moment, and the temperature of the lithium battery monomer after the preset time at the previous power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller after the preset time at the previous power-on moment.
Optionally, after the electric vehicle is powered on, the method further includes:
reporting the temperature of the lithium battery monomer to the upper computer in real time through communication;
alternatively, the first and second electrodes may be,
and reporting the temperature of the lithium battery monomer to the vehicle Controller in real time through a Controller Area Network (CAN) bus.
Optionally, the preset time is greater than 30 minutes.
Optionally, after determining that the first temperature difference is greater than the second temperature difference and that the temperature of the lithium battery cell at the current power-on time is within a preset range and is simultaneously satisfied, the method further includes:
and if the first temperature difference is larger than the second temperature difference, and the temperature of the lithium battery monomer at the current electrifying moment is not simultaneously met within a preset range, judging that the lithium battery is not in the initial state.
A second aspect of the present invention discloses a battery management system, which is configured to execute the method for determining the initial state of the lithium battery according to any one of the first aspect of the present invention.
A third aspect of the invention discloses an electric vehicle, including: the battery management system comprises a lithium battery, a vehicle controller and the battery management system disclosed by the second aspect of the invention; wherein:
the vehicle control unit is in communication connection with the battery management system through a CAN bus;
the vehicle control unit is used for receiving the temperature of the lithium battery monomer reported by the battery management system in real time, and recording the power-on time and the temperature of the lithium battery monomer after the preset time of the power-on time after the electric vehicle is powered on every time.
According to the technical scheme, the method for determining the initial state of the lithium battery comprises the steps of firstly powering on an electric automobile, then recording the temperature of each lithium battery monomer at a corresponding moment through an upper computer or a whole vehicle controller, determining the rising value of the temperature of each lithium battery monomer in the previous operation process of the lithium battery in the electric automobile as a first temperature difference of the lithium battery, and determining the falling value of the current powering on moment of the electric automobile to the temperature of each lithium battery monomer in the previous operation process as a second temperature difference of the lithium battery; if the first temperature difference is larger than the second temperature difference, and the temperature of the lithium battery monomer at the current power-on moment is within a preset range, and the lithium battery monomer is satisfied, the lithium battery is judged to be in an initial state, so that whether the lithium battery is in the initial state or not is determined through the temperature of the lithium battery monomer, the problem that the initial state of the lithium battery cannot be determined without a real-time clock function is solved, the temperature of the lithium battery monomer directly affects the battery state of the lithium battery, the reliability of determining whether the lithium battery is in the initial state or not by utilizing the temperature of the lithium battery monomer is higher, and the accuracy of estimating the battery state of the lithium battery is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a method for determining an initial state of a lithium battery according to an embodiment of the present invention;
fig. 2 is a state transition diagram of a lithium battery provided in an embodiment of the present invention;
fig. 3 is a flowchart of another method for determining an initial state of a lithium battery according to an embodiment of the present invention;
fig. 4 is a flowchart of another method for determining an initial state of a lithium battery according to an embodiment of the present invention;
fig. 5 is a flowchart of another method for determining an initial state of a lithium battery according to an embodiment of the present invention;
fig. 6 is a flowchart of another method for determining an initial state of a lithium battery according to an embodiment of the present invention;
FIG. 7 is a diagram illustrating temperature variation of a lithium battery cell according to an embodiment of the present invention;
fig. 8 is a schematic diagram of an electric vehicle according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiment of the invention provides a method for determining an initial state of a lithium battery, which is applied to a battery management system and aims to solve the problem that the accuracy of estimating the battery state of the lithium battery is low because whether the lithium battery is in the initial state or not can not be determined by determining whether the sleep time of the lithium battery before the lithium battery is electrified exceeds a specific time or not without a real-time clock function.
The method for determining the initial state of the lithium battery, referring to fig. 1, includes:
s101, powering on the electric automobile.
Specifically, the electric vehicle is powered on by the engine ignition signal KL15, that is, the electric vehicle is in the RUN mode, in which a lithium battery in the electric vehicle is in a discharge mode and supplies electric energy to the electric vehicle to operate the electric vehicle.
The specific process of step S101 may be: the vehicle control unit judges whether a power-on request is received, and if the power-on request is received, the vehicle control unit controls a power-on relay of the electric vehicle to be closed so that a lithium battery in the electric vehicle supplies power to the electric vehicle.
Certainly, the process of powering on the electric vehicle is not limited to the above listed process, and other processes of powering on the electric vehicle are not described in detail herein, and for details, reference may be made to the prior art, and all of them are within the protection scope of the present application.
In practical applications, after step S101, the following steps may be included as shown in fig. 5: s301, reporting the temperature of the lithium battery monomer to an upper computer in real time through communication so that the upper computer can acquire the temperature of the lithium battery monomer and record the temperature.
Alternatively, after step S101, the following steps may be included as shown in fig. 6: s401, reporting the temperature of the lithium battery monomer to a vehicle control unit in real time through a CAN bus so that the vehicle control unit CAN acquire the temperature of the lithium battery monomer and record the temperature.
S102, determining a first temperature difference and a second temperature difference of a lithium battery in the electric automobile.
In the operation process of the electric automobile, the temperature of the single lithium battery gradually rises until the lithium battery is in a stable operation state, and when the lithium battery is in the stable state, the temperature of the single lithium battery floats within a specific temperature range. When the electric automobile is switched from the running state to the stop running state, the temperature of the lithium battery monomer is gradually reduced until the lithium battery is in the static state.
Specifically, the state of the lithium battery includes as shown in fig. 2: a quiescent state, a charge-discharge state, and a recovery state.
The mutual conversion relation among the static state, the charge-discharge state and the recovery state of the lithium battery is as follows: the charging and discharging state and the recovery state can be mutually converted, the recovery state can be converted into a static state, and the static state can be converted into the charging and discharging state.
The charge and discharge state refers to the state of charge and discharge of the lithium battery, in the process of the charge and discharge state, the temperature of the single lithium battery gradually rises until reaching a stable state, and after the lithium battery is in the stable state, the temperature of the single lithium battery is stabilized at a corresponding temperature.
The recovery state refers to a state after the lithium battery stops charging and discharging and before the lithium battery enters the static state, namely a transition stage of converting the charging and discharging state into the static state. During the state recovery process, the temperature of the lithium battery cell gradually decreases. The estimated value of the battery state in the recovery state is used as an initial value of the estimation of the battery state in the charge and discharge state, and the estimation of the battery state in the recovery state mainly considers the electric quantity change value of the lithium battery after the charge and discharge state is finished. Typically, the time elapsed for this recovery phase is 8 h.
The static state refers to a state in which the lithium battery is completely recovered after the charging and discharging of the lithium battery are stopped, i.e., the state is returned from the charging and discharging state to the recovery state and then to the static state, e.g., the state after the charging and discharging of the lithium battery are stopped and the stop time exceeds 8 hours. In the static state process, the temperature of the lithium battery monomer is stabilized at the corresponding temperature.
In the first temperature difference and the second temperature difference related to step S102, the first temperature difference is an increase value of the temperature of the lithium battery cell in the previous operation process, and the second temperature difference is a decrease value of the temperature of the lithium battery cell in the previous operation process at the current power-on time.
The temperature of each lithium battery monomer is recorded by the upper computer or the whole vehicle controller at a corresponding moment, and specifically, when the upper computer or the whole vehicle controller receives the temperature of each lithium battery monomer reported by the battery management system, the upper computer or the whole vehicle controller records the received temperature and corresponding time of each lithium battery monomer so as to be acquired by the battery management system when needed.
It should be noted that, when the electric vehicle is in the running process, the lithium battery in the electric vehicle is in the discharging state, and after the electric vehicle is powered off, when the electric vehicle is in the sleeping state, the lithium battery in the electric vehicle firstly enters the recovery state, until the sleeping time of the electric vehicle is longer than the time required for recovering the lithium battery, the lithium battery enters the resting state.
In practical applications, the step S102 may include the steps shown in fig. 3:
s201, obtaining the temperature of the lithium battery monomer at the current power-on moment, the temperature of the lithium battery monomer at the previous power-on moment and the temperature of the lithium battery monomer after the previous power-on preset time.
In practical application, the specific manner of obtaining the temperature of the lithium battery cell at the current power-on moment, the temperature of the lithium battery cell at the previous power-on moment and the temperature of the lithium battery cell after the preset time at the previous power-on moment is as follows: the method comprises the steps that communication is directly obtained from an upper computer, or the communication is obtained from a whole vehicle controller through a CAN bus, for example, the communication is obtained from the whole vehicle controller through the CAN bus in the running process of the electric vehicle; in the development and test stage or the overhaul and test stage of the electric automobile, the electric automobile is directly obtained from an upper computer through communication.
The temperature of the lithium battery monomer at the current power-on moment is as follows: and the upper computer or the whole vehicle controller records the temperature of the lithium battery monomer at the current power-on time. The temperature of the lithium battery monomer at the previous power-on time is as follows: and the upper computer or the whole vehicle controller records the temperature of the lithium battery monomer at the last power-on time. The temperature of the lithium battery monomer after the preset time at the previous power-on moment is as follows: and the upper computer or the whole vehicle controller records the temperature of the lithium battery monomer after the preset time at the last power-on moment.
S202, adopting a formula delta Trise＝(T1-T0) And Δ Tdrop＝|T2-T1And calculating to obtain a first temperature difference and a second temperature difference.
Wherein, Delta TriseIs the first temperature difference, Δ TdropIs the second temperature difference, T2Is the temperature T of the lithium battery cell at the current power-on time1The temperature T of the lithium battery monomer after the preset time for the previous power-on moment0The temperature of the lithium battery monomer at the previous power-on time.
In practical applications, the predetermined time may be 30 minutes, i.e. T1The temperature of the lithium battery cell 30 minutes after the power-on time. Of course, the preset time may have other values depending on the actual lithium battery, and all of them are within the protection scope of the present application.
S103, judging whether the first temperature difference is larger than the second temperature difference and whether the temperature of the lithium battery monomer at the current electrifying moment is within a preset range is met simultaneously.
In practical applications, the predetermined range may be (T)1-ΔT，T1) Wherein, T1The temperature of the lithium battery monomer after the preset time is set for the previous power-on, the delta T is the threshold of the electric vehicle, the electric vehicle adopts different lithium batteries, the threshold delta T is different, the specific value of the threshold delta T is determined according to the type of the actual lithium battery, and the specific values are not repeated one by one here and are all within the protection range of the application.
If the first temperature difference is greater than the second temperature difference, and the temperature of the lithium battery cell at the current power-on time is within the preset range and is simultaneously satisfied, step S104 is executed.
And S104, judging that the lithium battery is in an initial state.
It should be noted that, when the lithium battery just enters the recovery state, within a first period of time, for example, within 30 minutes, since the state of the lithium battery is not stable, the estimated related parameters are not accurate; as the time length of entering the recovery state is increased, the state of the lithium battery is gradually stabilized; after a certain period of time, for example, 30 minutes, the state of the lithium battery is stable, and the accuracy of each estimated value is high, which indicates that the lithium battery is in the initial state at this time.
The battery state estimation includes any one of: SOC estimation (State Of Charge) estimation, SOP (State Of Power) estimation, and SOH (State Of Health) estimation. Of course, the battery state estimation may also be other types of estimation, which are not described in detail herein and are within the scope of the present application.
In the running process of the electric automobile, the temperature of a single lithium battery is obtained from the whole automobile controller through the CAN bus, whether the lithium battery is in an initial state or not is judged through the method, a corresponding battery state estimation algorithm such as an open-circuit voltage method is executed, a battery state estimated value is obtained through calculation, and the estimated value is reported to the whole automobile controller through the CAN bus; the vehicle control unit can display information such as endurance mileage and the like through the instrument panel, so that a driver can know the battery state of the electric vehicle through the instrument panel. If the lithium battery is in the initial state, the accuracy that the driver knows the battery state of the electric automobile through the instrument panel is higher, the accuracy of the endurance mileage displayed on the instrument panel is higher, and the problem that the trip of the driver is inconvenient due to inaccurate estimated mileage is avoided.
In the development and test stage or the overhaul and test stage of the electric automobile, the temperature of the lithium battery monomer at each moment is directly read from the upper computer through communication, whether the lithium battery is in an initial state or not is judged through the method, a corresponding battery state estimation algorithm such as an open-circuit voltage method is executed, a battery state estimation value is obtained through calculation, and the estimation value is reported to the upper computer through communication; the upper computer displays the estimated value of the battery state, so that a worker can know the battery state of the electric automobile through the upper computer, and therefore testing or troubleshooting is carried out. If the lithium battery is in the initial state, the accuracy that the staff knows the battery state of electric automobile through the host computer is higher, is favorable to the staff to test or troubleshooting.
Alternatively, after step S103, if the first temperature difference is greater than the second temperature difference, and the temperature of the lithium battery cell at the current power-on time is not simultaneously satisfied within the preset range, as shown in fig. 4 (which is illustrated by taking fig. 1 as an example), step S106 may be further included.
And S106, judging that the lithium battery is not in the initial state.
And when the lithium battery is not in the initial state, executing a corresponding battery state estimation algorithm, such as a Kalman filtering method, and reporting the estimation value to the whole vehicle controller or the upper computer.
It should be noted that, because the internal structure of the lithium battery is complex, the state of charge of the lithium battery is affected by the discharge current, the internal temperature of the battery, self-discharge, aging, and other factors, so that the estimation of the battery state is difficult. Therefore, the initial state of the battery is determined, and the accuracy of the battery state estimation is greatly improved for the battery state estimation.
In this embodiment, if first temperature difference is greater than the second temperature difference, and, the lithium cell temperature at the moment of electrifying at present is in the default range, satisfy simultaneously, then judge that the lithium cell is in initial state, thereby confirm whether the lithium cell is in initial state through lithium cell temperature, the problem that the lithium cell that does not take the real-time clock function can't confirm its initial state is solved, and, lithium cell temperature direct influence the battery state of lithium cell, it is higher to utilize lithium cell temperature to confirm whether the lithium cell is in initial state's reliability, and then improve the accuracy of the battery state estimation of lithium cell.
Here, the method for determining the initial state of the lithium battery is illustrated in an actual application scenario, as follows:
as shown in fig. 7, three sets of lithium battery cell temperature data and three sets of time data are recorded to determine whether the electric vehicle is in the RUN mode after the KL15 is powered on, and whether the lithium battery is in the initial state.
(1) KL15 is electrified, the lithium battery is in a running state, and the upper computer or the vehicle control unit obtains the temperature T of the lithium battery monomer at the electrifying moment through the battery management system0And record T0Corresponding time t of0。
(2) After the lithium battery operates for a specific preset time, such as 30 minutes, the temperature of the lithium battery monomer gradually rises, and at this time, the upper computer or the vehicle control unit obtains the temperature T of the lithium battery monomer after the specific time through the battery management system1And record T1Corresponding time t of1。
(3) The KL15 is powered off, and the lithium battery enters a dormant state.
(4) After the dormancy time delta T, the KL15 is electrified again, the lithium battery is in the running state, and the upper computer or the vehicle controller obtains the monomer temperature T of the lithium battery at the moment of electrifying again through the battery management system2And record T2Corresponding time t2。
(5) The battery management system acquires the T through the upper computer or the whole vehicle controller0、T1、T2。
(6) Battery management system calculates Δ Trise＝(T1-T0)，ΔTdrop＝|T2-T1|。
(7) Battery management system determining delta Trise＞ΔTdrop、T2∈(T1-ΔT，T1) And t1-t0If the time is longer than the preset time, the conditions are met simultaneously.
Wherein, the Delta T is the threshold value of the electric automobile, the specific value of the Delta T is determined according to the type of the lithium battery,
(8) if Δ Trise＞ΔTdrop、T2∈(T1-ΔT，T1) And t1-t0If the preset time is longer than the preset time and the preset time is met, the battery management system judges that the dormancy time delta t is more than or equal to 30 minutes, and then the lithium battery can be judged to be in the initial state.
Since the temperature of the lithium battery monomer CAN be read through messages, any CAN tool CAN be used, and the specific CAN tool is not limited herein and is within the protection scope of the application.
Through comparing lithium cell monomer temperature under different moments to confirm whether the lithium cell is in initial condition, and, the instrument that reads the temperature is arbitrary CAN instrument, consequently it is more convenient to read the process, and then confirms whether the lithium cell is in initial condition simply, fast, high-efficiently.
An embodiment of the present invention provides a battery management system, where the battery management system is configured to execute the method for determining an initial state of a lithium battery according to any one of the above embodiments.
The battery management system is used for collecting lithium battery information such as the temperature of a lithium battery monomer, the current of a lithium battery and the voltage of the lithium battery, and also can be other information which are not described repeatedly one by one and are all within the protection range of the application, and then, the battery management system is also used for executing the method for determining the initial state of the lithium battery. The implementation process and principle of the method for determining the initial state of the lithium battery refer to any one of the above embodiments, and are not described in detail herein.
An embodiment of the present invention provides an electric vehicle, as shown in fig. 8, including: a lithium battery 10, a vehicle control unit 20, and the battery management system 30 according to the above embodiment; wherein:
the vehicle control unit 20 is in communication connection with the battery management system 30 through a CAN bus, and the vehicle control unit 20 is configured to receive the temperature of the lithium battery cell reported by the battery management system 30 in real time, and record the power-on time and the temperature of the lithium battery cell after a preset time of the power-on time after each power-on of the electric vehicle.
The operation of the battery management system 30 and the principle thereof are described in the above embodiments, and are not described in detail herein.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A method for determining an initial state of a lithium battery is applied to a battery management system, and comprises the following steps:
powering on the electric automobile;
determining a first temperature difference and a second temperature difference of a lithium battery in the electric automobile; the first temperature difference is a rising value of the temperature of the lithium battery monomer in the previous operation process, the second temperature difference is a falling value of the current power-on moment to the temperature of the lithium battery monomer in the previous operation process, and the temperature of each lithium battery monomer is recorded by the upper computer or the whole vehicle controller at the corresponding moment;
judging whether the first temperature difference is larger than the second temperature difference and whether the temperature of the lithium battery monomer at the current power-on moment is within a preset range;
and if the first temperature difference is larger than the second temperature difference and the temperature of the single lithium battery at the current electrifying moment is within a preset range and simultaneously meets the preset range, judging that the lithium battery is in an initial state.
2. The method of claim 1, wherein determining the first temperature difference and the second temperature difference of the lithium battery in the electric vehicle comprises:
acquiring the temperature of a lithium battery monomer at the current power-on moment, the temperature of the lithium battery monomer at the previous power-on moment and the temperature of the lithium battery monomer after preset time at the previous power-on moment;
using the formula Δ Trise＝(T1-T0) And Δ Tdrop＝|T2-T1Calculating the first temperature difference and the second temperature difference respectively;
wherein, Delta TriseIs said first temperature difference, Δ TdropIs said second temperature difference, T2The temperature T of the lithium battery cell at the current power-on moment1The temperature T of the lithium battery monomer after the preset time of the previous power-on moment0And the temperature of the lithium battery monomer at the previous power-on moment is obtained.
3. The initial state determination method of a lithium battery as claimed in claim 1The method is characterized in that the preset range is as follows: (T)1-ΔT，T1)；
Wherein, T1And the delta T is the threshold value of the electric automobile for the temperature of the lithium battery monomer after the preset time of the previous power-on moment.
4. The method for determining the initial state of the lithium battery as claimed in claim 2, wherein the specific manner of obtaining the temperature of the lithium battery cell at the current power-on time, the temperature of the lithium battery cell at the previous power-on time, and the temperature of the lithium battery cell after a preset time of the previous power-on time is as follows: directly obtaining the data from the upper computer through communication, or obtaining the data from the whole vehicle controller through a Controller Area Network (CAN) bus;
the temperature of the lithium battery monomer at the current power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller at the current power-on moment, the temperature of the lithium battery monomer at the previous power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller at the previous power-on moment, and the temperature of the lithium battery monomer after the preset time at the previous power-on moment is the temperature of the lithium battery monomer recorded by the upper computer or the whole vehicle controller after the preset time at the previous power-on moment.
5. The method for determining the initial state of the lithium battery as claimed in claim 4, wherein after the electric vehicle is powered on, the method further comprises:
reporting the temperature of the lithium battery monomer to the upper computer in real time through communication;
alternatively, the first and second electrodes may be,
and reporting the temperature of the lithium battery monomer to the vehicle control unit in real time through a CAN bus.
6. The method for determining an initial state of a lithium battery as claimed in any one of claims 2 to 5, wherein the preset time is more than 30 minutes.
7. The method for determining the initial state of the lithium battery according to claim 1, wherein after determining whether the first temperature difference is greater than the second temperature difference and the temperature of the lithium battery cell at the current power-on time is within a preset range, the method further comprises:
and if the first temperature difference is larger than the second temperature difference, and the temperature of the lithium battery monomer at the current electrifying moment is not simultaneously met within a preset range, judging that the lithium battery is not in the initial state.
8. A battery management system for performing the method for determining an initial state of a lithium battery according to any one of claims 1 to 7.
9. An electric vehicle, comprising: a lithium battery, a vehicle control unit, and the battery management system of claim 8; wherein:
the vehicle control unit is in communication connection with the battery management system through a CAN bus;
the vehicle control unit is used for receiving the temperature of the lithium battery monomer reported by the battery management system in real time, and recording the power-on time and the temperature of the lithium battery monomer after the preset time of the power-on time after the electric vehicle is powered on every time.
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