CN110816366B - Temperature estimation method, system, medium and device suitable for inside of single battery - Google Patents
Temperature estimation method, system, medium and device suitable for inside of single battery Download PDFInfo
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- CN110816366B CN110816366B CN201911053761.2A CN201911053761A CN110816366B CN 110816366 B CN110816366 B CN 110816366B CN 201911053761 A CN201911053761 A CN 201911053761A CN 110816366 B CN110816366 B CN 110816366B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/24—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries
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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
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Abstract
The invention provides a temperature estimation method, a system, a medium and equipment suitable for the interior of a single battery, comprising the following steps: an electromotive force temperature coefficient obtaining step: voltage information, current information and battery surface temperature information are recorded at BMS time; a total resistance obtaining step: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any moment; acquiring ambient temperature: attaching a temperature sensor to the battery to acquire environmental temperature information; a total heat power obtaining step: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained; estimating the internal temperature of the battery: and acquiring estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environment temperature information and the total heat power information. The invention is beneficial to realizing the functions of the thermal management system of the battery, thereby improving the reliability and safety of the battery pack.
Description
Technical Field
The invention relates to the field of battery temperature acquisition, in particular to a method, a system, a medium and equipment for estimating the internal temperature of a single battery, and particularly relates to a method for estimating the internal temperature of a single lithium ion battery.
Background
In the use process of the battery of the electric automobile, accurate estimation of the temperature of the battery plays an important role in ensuring the normal work of the battery. For example, the temperature condition of the battery is monitored, so that whether the battery is in a normal working state can be known; the realization of the thermal management system function of the battery is also based on the accurate estimation of the battery temperature, and a corresponding thermal management strategy can be adopted under the condition of accurately estimating the battery temperature. Currently, the battery temperature is generally acquired by measuring with a temperature sensor, and mainly includes the following two types: one is the temperature measured with a battery surface temperature sensor; and in the other process of preparing the lithium ion battery, the temperature sensor probe is packaged in the battery to realize real-time temperature measurement in the battery. The temperature sensor is arranged on the surface of the battery during the temperature measurement of the lithium ion battery, and the acquisition value of the temperature sensor is used as the temperature of the battery. This method results in a large error between the battery surface temperature, not the battery internal temperature, and the battery internal temperature. In the preparation process of the lithium ion battery, the temperature sensor probe is packaged in the battery to realize real-time temperature measurement in the battery. The lithium ion battery is not popularized yet, and the lithium ion battery which is widely adopted is still a common lithium ion battery without a temperature sensor probe.
Patent document CN209200108U discloses a battery temperature collecting structure, which includes a battery pack formed by combining a plurality of batteries and a flexible circuit board arranged above the battery pack, wherein a plurality of temperature receiving areas are arranged at intervals on the edge of the flexible circuit board, a nickel sheet is arranged between the battery and the temperature receiving areas, and a temperature collecting plate capable of collecting the temperature on the nickel sheet and transmitting the temperature to the temperature receiving areas is arranged above the nickel sheet; above-mentioned temperature acquisition structure sets up the temperature acquisition board with the flexible circuit board intercommunication in the top of nickel piece for the collection of temperature can be close to the battery, reduces the temperature difference that leads to existence between the nickel piece both ends because of the loss of the temperature of nickel piece, and the normal operating of battery is guaranteed to the more accurate temperature that measures the battery, and then guarantees passenger's safety. This patent does not work well for internal temperature estimation in a single lithium ion battery.
Disclosure of Invention
In view of the defects in the prior art, an object of the present invention is to provide a method, a system, a medium, and an apparatus for estimating the temperature inside a single battery.
The invention provides a temperature estimation method applicable to the interior of a single battery, which is characterized by comprising the following steps: an electromotive force temperature coefficient obtaining step: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any time; a total resistance obtaining step: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any time; acquiring ambient temperature: attaching a temperature sensor to the battery to acquire environmental temperature information; a total heat power obtaining step: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained; estimating the internal temperature of the battery: and obtaining estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environmental temperature information and the total heat power information.
Preferably, the electromotive force temperature coefficient acquiring step includes: a temperature coefficient table making step: when charging and discharging the battery, the temperature value T with fixed temperature interval is taken 1 ，T 2 ，…，T i 823060, for example, the temperature interval DeltaT is taken i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages at two adjacent temperatures as a dependent variable and the temperature interval as an independent variable, and making a table; table look-up step: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
Preferably, the total resistance obtaining step includes: a current-time curve obtaining step: obtaining a current-time curve by adopting an HPPC (high Performance liquid chromatography) test method, and obtaining current-time curve information; evaluating the internal resistance of the battery: and according to the current-time curve information, solving the internal resistance of the battery according to the ratio of the voltage variation and the current variation of the battery, and acquiring the total resistance information of the battery.
Preferably, the total heat power obtaining step comprises: calculating the exothermic rate of reaction heat: obtaining reaction heat release rate information of the battery according to the reaction generated in the battery; calculating the heat release rate of polarized heat and ohmic heat: according to the polarization phenomenon and the current thermal effect in the charging and discharging process of the battery, the calculation formula of the polarization heat and ohmic heat release rate in the using process of the battery is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r o Ohmic internal resistance of the battery; r t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
and a merging calculation step: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat production power, q r Is the reaction heat exotherm rate of the cell, q p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
According to the invention, the temperature estimation system suitable for the interior of the single battery comprises: electromotive temperature coefficient acquisition module: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any moment; a total resistance acquisition module: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any moment; an ambient temperature acquisition module: attaching a temperature sensor to the battery to acquire environmental temperature information; the total heat power acquisition module: according to the current recorded by the BMS and the obtained total resistance, obtaining the total thermal power through a current thermal effect and obtaining the total thermal power information; a battery internal temperature estimation module: and acquiring estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environment temperature information and the total heat power information.
Preferably, the electromotive force temperature coefficient acquisition module includes: a temperature coefficient table making module: when charging and discharging the battery, the temperature value T with fixed temperature interval is taken 1 ，T 2 ，…，T i 8230e.g. by taking the temperature interval DeltaT i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages of two adjacent temperatures as a dependent variable, taking the temperature interval as an independent variable, and making a table; a table look-up module: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
Preferably, the total resistance obtaining module includes: a current-time curve acquisition module: obtaining a current-time curve by adopting an HPPC test system, and obtaining current-time curve information; the battery internal resistance evaluation module: and according to the current-time curve information, the internal resistance of the battery is calculated according to the ratio of the voltage variation and the current variation of the battery, and the total resistance information of the battery is obtained.
Preferably, the total heating power obtaining module comprises: a reaction heat release rate calculation module: obtaining reaction heat release rate information of the battery according to the reaction generated in the battery; the polarized heat and ohmic heat release rate calculation module comprises: according to the polarization phenomenon and the current thermal effect in the charging and discharging process of the battery, the calculation formula of the polarization heat and ohmic heat release rate in the using process of the battery is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r o Ohmic internal resistance of the battery; r t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
a merging calculation module: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat production power, q r Is the reaction heat exotherm rate, q, of the cell p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
According to the present invention, there is provided a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of a temperature estimation method applicable to the inside of a unit battery.
According to the present invention, there is provided a temperature estimation device adapted to be used inside a unit battery, comprising: a controller;
the controller includes a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of a temperature estimation method applicable to the inside of a unit cell; alternatively, the controller includes a temperature estimation system adapted to be internal to the battery cell.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, the internal temperature of the battery is estimated by modeling the internal temperature of the battery, so that the internal temperature of the battery is accurately reflected;
2. the invention can provide more reliable battery temperature values for the state calculation and fault diagnosis of the BMS;
3. the invention is beneficial to the realization of the heat management system function of the battery, thereby improving the reliability and the safety of the battery pack.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic flow chart of the method of the present invention.
FIG. 2 is a system framework diagram of the present invention.
FIG. 3 is a block diagram illustrating a method for estimating the internal temperature of a single lithium ion battery
FIG. 4 is a voltage-time curve diagram of a lithium ion battery
FIG. 5 is a pulse power test chart of a lithium ion battery
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will aid those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any manner. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
As shown in fig. 1 to 5, a method for estimating a temperature inside a battery cell according to the present invention includes: acquiring an electromotive force temperature coefficient: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any moment; a total resistance obtaining step: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any time; acquiring ambient temperature: attaching a temperature sensor to the battery to acquire environmental temperature information; a total heat power obtaining step: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained; estimating the internal temperature of the battery: and acquiring estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environment temperature information and the total heat power information.
There are two ways to obtain the temperature of the battery, the first way is to obtain the surface temperature of the battery through a temperature sensor and regard it as the internal temperature of the battery, and the disadvantage is that the precision is poor; the second method is to encapsulate the probe of the temperature sensor inside the battery for temperature measurement, but this method is costly and cannot ensure reliability. In order to solve the problem, the invention starts from a battery heat generation mechanism, establishes a battery thermal model based on the energy conservation law, and estimates the internal temperature of the battery by using the model, thereby achieving the purposes of improving the measurement precision of the internal temperature of the battery, reducing the measurement cost and ensuring the reliability of a battery system. The invention relates to the field of battery temperature acquisition of electric automobiles, in particular to a method for estimating the internal temperature of a single battery. Firstly, acquiring open-circuit voltage, battery current, battery electromotive force temperature coefficient and battery surface temperature at a certain moment; then determining the heat generation power of the battery at the moment according to the battery terminal voltage and the battery current at the moment; and finally estimating the internal temperature of the battery at the next moment according to the heat generation power of the battery, the electromotive force temperature coefficient and the surface temperature of the battery.
Preferably, the electromotive force temperature coefficient acquiring step includes: a temperature coefficient table making step: when charging and discharging the battery, taking a temperature value T with a fixed temperature interval 1 ，T 2 ，…，T i 8230e.g. by taking the temperature interval DeltaT i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages at two adjacent temperatures as a dependent variable and the temperature interval as an independent variable, and making a table; search ofThe following steps: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
Preferably, the total resistance obtaining step includes: a current-time curve obtaining step: obtaining a current-time curve by adopting an HPPC (high Performance liquid chromatography) test method, and obtaining current-time curve information; evaluating the internal resistance of the battery: and according to the current-time curve information, the internal resistance of the battery is calculated according to the ratio of the voltage variation and the current variation of the battery, and the total resistance information of the battery is obtained.
Preferably, the total heat power obtaining step comprises: calculating the exothermic rate of reaction heat: obtaining reaction heat release rate information of the battery according to the reaction generated in the battery; calculating the heat release rate of polarized heat and ohmic heat: according to the polarization phenomenon and the current thermal effect in the battery charging and discharging process, the calculation formula of the heat release rate of the polarization heat and the ohmic heat in the battery using process is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r is o Ohmic internal resistance of the battery; r is t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
and a merging calculation step: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat generation power, q r Is the reaction heat exotherm rate, q, of the cell p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
Specifically, in one embodiment, as shown in fig. 3, a method of estimating the internal temperature of a battery is as follows:
firstly, establishing a thermal model of the battery; regarding a single lithium ion battery as a system, the temperature of the system varies due to the amount of heat generated inside the system and the amount of heat exchange with the external environment. Lithium battery cell is in the use, because the thermal effect of electric current has heat to produce, and when the battery and external environment appear the difference in temperature when can appear the heat transfer phenomenon again, so according to energy balance have: net heat flow into the system + heat production from internal heat sources = internal energy increase. The thermal model of the battery can be expressed as follows:
obtaining a battery internal temperature recurrence formula by the discretized equation:
wherein, T k 、T k-1 Internal temperature of the battery at k and k-1, I k The current A and h at the moment k are convective heat transfer coefficients W/(m ^2℃) and R t,k Total resistance omega, C at time k p The specific heat capacity J/(kg. DEG C) of the lithium ion battery; m is the mass kg of a single battery; a is the surface area m of the battery 2 ；
The electromotive temperature coefficient at the moment k; t is amb At ambient temperature.
Therefore, when the internal temperature of the battery is estimated, the internal temperature T estimated before is utilized as long as the heat generation power q of the battery, the surface temperature of the battery, the current of the battery, the external environment temperature and the electromotive force temperature coefficient of the battery at the current moment are obtained k-1 The internal temperature T of the battery at the current moment can be determined according to a formula k 。
The battery temperature influence coefficient
The correlation with the ambient temperature is not large, and is preferably calculated by the following method:
in the range of the frequent operation of the battery,
the numerical value is small and has small variation, can be prepared by
Is approximately given, thereby having
Taking a series of temperature values T when charging and discharging the battery 1 ，T 2 ，…，T i 823080, the temperature interval is fixed, for example, the temperature interval DeltaT can be taken i ＝T i -T i-1 =0.5 ℃, and the open-circuit voltages U of the battery at different temperatures at different moments are respectively measured ocv Taking the difference value of the open-circuit voltages of two adjacent temperatures as a dependent variable and the temperature interval as an independent variable, and making delta U ocv A table of Δ T-k, wherein the temperature coefficient at the time k, k +1 is obtained by looking up the table
The total resistance of the cell can be measured experimentally. The total resistance comprises the polarization internal resistance and the ohm internal resistance of the battery, and the values can be measured by a general battery internal resistance test method, such as an HPPC method, an unbalanced bridge method and the like.
Preferably, the test is performed using the HPPC test. The internal resistance of the lithium battery mainly comprises two parts, wherein the ohmic resistance and the polarization internal resistance are basically stable and unchanged under the condition of constant temperature, and the polarization resistance can change along with factors influencing the polarization level.
The current-time curve is shown in fig. 5, operating according to the steps of the cell internal resistance measurement method HPPC. Discharging the battery at the time of t 0-t 1 by using the current of 120A; at the time of t 1-t 2, the battery is powered off and stands still; from time t2 to time t3, the battery is charged with a current of 100A. The internal resistance of the battery can be obtained by the ratio of the voltage variation and the current variation of the battery, and the specific calculation formula is as follows:
R o ＝(U B -U A )/I
R p ＝(U C -U B )/I
in the formula, R o Is the ohmic internal resistance of the battery, R p And I is the polarization internal resistance of the battery, and is charge-discharge current. The pulse discharging and charging time cannot be too long, so that the obvious influence of polarization internal resistance is avoided.
Ambient temperature T amb The value of (b) is measured by a temperature sensor, and it is generally considered that the ambient temperature does not change when the battery is charged and discharged.
Typically, C of ternary lithium batteries p The value range of (1) is 133-880J/(kg DEG C), and the convection coefficient h = 5-25W/(m 2K) of the naturally convected air.
A person skilled in the art may understand the method for estimating the temperature inside a single battery provided by the present invention as an embodiment of the system for estimating the temperature inside a single battery provided by the present invention. That is, the temperature estimation system adapted to the inside of the unit battery may be implemented by executing the flow of steps of the temperature estimation method adapted to the inside of the unit battery.
According to the present invention, there is provided a temperature estimation system for use inside a unit battery, comprising: electromotive temperature coefficient acquisition module: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any time; a total resistance obtaining module: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any time; an ambient temperature acquisition module: attaching a temperature sensor to the battery to acquire environmental temperature information; the total heat power acquisition module: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained; a battery internal temperature estimation module: and obtaining estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environmental temperature information and the total heat power information.
Preferably, the electromotive force temperature coefficient acquisition module includes: a temperature coefficient table making module: taking temperature interval when charging and discharging the batteryFixed temperature value T 1 ，T 2 ，…，T i 8230e.g. by taking the temperature interval DeltaT i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages of two adjacent temperatures as a dependent variable, taking the temperature interval as an independent variable, and making a table; a table look-up module: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
Preferably, the total resistance obtaining module includes: a current-time curve acquisition module: obtaining a current-time curve by adopting an HPPC test system, and obtaining current-time curve information; the battery internal resistance evaluation module: and according to the current-time curve information, the internal resistance of the battery is calculated according to the ratio of the voltage variation and the current variation of the battery, and the total resistance information of the battery is obtained.
Preferably, the total heating power obtaining module comprises: a reaction heat release rate calculation module: obtaining reaction heat release rate information of the battery according to the reaction generated in the battery; polarized heat and ohmic heat release rate calculation module: according to the polarization phenomenon and the current thermal effect in the battery charging and discharging process, the calculation formula of the heat release rate of the polarization heat and the ohmic heat in the battery using process is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r is o Ohmic internal resistance of the battery; r is t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
a merging calculation module: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat production power, q r Is the reaction heat exotherm rate of the cell, q p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
According to the present invention, there is provided a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of a temperature estimation method applicable to the inside of a unit battery.
According to the present invention, there is provided a temperature estimation device adapted to be used inside a unit battery, comprising: a controller;
the controller includes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a temperature estimation method applicable to the inside of a unit battery; alternatively, the controller includes a temperature estimation system adapted to be internal to the battery cell.
According to the invention, the internal temperature of the battery is estimated by modeling the internal temperature of the battery, so that the internal temperature of the battery is accurately reflected; the invention can provide more reliable battery temperature values for state calculation and fault diagnosis of the BMS; the invention is beneficial to the realization of the heat management system function of the battery, thereby improving the reliability and the safety of the battery pack.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the present invention can be regarded as a hardware component, and the devices, modules and units included therein for implementing various functions can also be regarded as structures within the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A method for estimating a temperature inside a battery cell, comprising:
acquiring an electromotive force temperature coefficient: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any time;
a total resistance obtaining step: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any time;
acquiring ambient temperature: attaching a temperature sensor to the battery to acquire environmental temperature information;
the total heat power acquisition step: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained;
estimating the internal temperature of the battery: acquiring estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environmental temperature information and the total heat power information;
in particular, the amount of the solvent to be used,
firstly, a battery thermal model is established, a single lithium ion battery is regarded as a system, the temperature change of the system is caused by the heat generation quantity inside the system and the heat exchange quantity with the external environment, the lithium ion battery generates heat due to the thermal effect of current in the use process, and the heat transfer phenomenon occurs when the temperature difference occurs between the battery and the external environment, so that the heat exchange system has the following advantages according to the energy balance: net heat flow into the system + heat production from internal heat sources = internal energy increase,
the thermal model of the battery is expressed by the following formula:
obtaining a battery internal temperature recurrence formula by the discretized equation:
wherein, T k 、T k-1 Internal temperature of the battery at k and k-1, I k The current A and h at the moment k are convective heat transfer coefficients W/(m ^2℃) and R t,k Total resistance omega, C at time k p The specific heat capacity of the lithium ion battery is J/(kg DEG C); m is the mass kg of a single battery; a is the cell surface area m 2 ；
The electromotive temperature coefficient at the moment k; t is amb Is ambient temperature.
2. The method for estimating the temperature inside a unit battery according to claim 1, wherein the electromotive temperature coefficient obtaining step includes:
a temperature coefficient table making step: when charging and discharging the battery, taking a temperature value T with a fixed temperature interval 1 ，T 2 ，…，T i 8230and taking the temperature interval delta T i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages of two adjacent temperatures as a dependent variable, taking the temperature interval as an independent variable, and making a table;
a table look-up step: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
3. The method for estimating the temperature inside a unit cell according to claim 1, wherein the total resistance obtaining step includes:
a current-time curve obtaining step: obtaining a current-time curve by adopting an HPPC (high Performance liquid chromatography) test method, and obtaining current-time curve information;
evaluating the internal resistance of the battery: and according to the current-time curve information, solving the internal resistance of the battery according to the ratio of the voltage variation and the current variation of the battery, and acquiring the total resistance information of the battery.
4. The method for estimating temperature inside a unit cell according to claim 1, wherein the total heat power obtaining step includes:
calculating the exothermic rate of reaction heat: acquiring the heat release rate information of the battery reaction heat according to the reaction generated in the battery;
and (3) calculating the rest heat release rates: according to the polarization phenomenon and the current thermal effect in the battery charging and discharging process, the calculation formula of the heat release rate of the polarization heat and the ohmic heat in the battery using process is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r o Ohmic internal resistance of the battery; r t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
and a merging calculation step: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat production power, q r Is the reaction heat exotherm rate of the cell, q p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
5. A temperature estimation system adapted for use inside a battery cell, comprising:
electromotive temperature coefficient acquisition module: acquiring electromotive force temperature coefficient information according to voltage information, current information and battery surface temperature information recorded by the BMS at any time;
a total resistance obtaining module: acquiring total battery resistance information according to voltage information and current information recorded by the BMS at any time;
an ambient temperature acquisition module: attaching a temperature sensor to the battery to acquire environmental temperature information;
the total heat power acquisition module: according to the current recorded by the BMS at any time and the obtained total resistance, total thermal power is obtained through the current thermal effect, and total thermal power information is obtained;
a battery internal temperature estimation module: obtaining the estimation result information of the internal temperature of the battery according to the electromotive force temperature coefficient information, the total resistance information of the battery, the environment temperature information and the total heat power information,
in particular, the amount of the solvent to be used,
firstly, establishing a battery thermal model, regarding a single lithium ion battery as a system, wherein the change of the system temperature is caused by the heat generation quantity inside the system and the heat exchange quantity with the external environment, and when the lithium ion battery is used, the heat transmission phenomenon can occur due to the heat generation of the thermal effect of the current and the temperature difference between the battery and the external environment, so that the battery thermal model has the following characteristics: net heat flow into the system + heat production from internal heat sources = internal energy increase,
the thermal model of the battery is expressed by the following formula:
obtaining a battery internal temperature recurrence formula by the discretized equation:
wherein, T k 、T k-1 Internal temperature of the battery at the time of k and k-1, I k The current A at the time of k, h is the convective heat transfer coefficient W/(m ^2 ·) DEG C, R t,k Total resistance omega, C at time k p The specific heat capacity of the lithium ion battery is J/(kg DEG C); m is the mass kg of a single cell; a is the surface area m of the battery 2 ；
The electromotive temperature coefficient at the moment k; t is amb At ambient temperature.
6. The temperature estimation system suitable for the inside of a unit battery according to claim 5, wherein the electromotive force temperature coefficient acquisition module includes:
a temperature coefficient table making module: when charging and discharging the battery, the temperature value T with fixed temperature interval is taken 1 ，T 2 ，…，T i 823060 the temperature interval Delta T is adopted i ＝T i -T i-1 =0.5 ℃; respectively measuring the open-circuit voltages of the battery at different temperatures at different moments, taking the difference value of the open-circuit voltages at two adjacent temperatures as a dependent variable and the temperature interval as an independent variable, and making a table;
a table look-up module: and looking up a table according to the temperature of the battery and the charging and discharging time information to obtain a temperature coefficient in a set time interval, and acquiring electromotive force temperature coefficient information.
7. The system of claim 5, wherein the total resistance obtaining module comprises:
the current-time curve acquisition module: obtaining a current-time curve by adopting an HPPC test system to obtain the current-time curve information;
the battery internal resistance evaluation module: and according to the current-time curve information, the internal resistance of the battery is calculated according to the ratio of the voltage variation and the current variation of the battery, and the total resistance information of the battery is obtained.
8. The system for estimating temperature inside single-cell according to claim 5, wherein the total heat power obtaining module comprises:
a reaction heat release rate calculation module: obtaining reaction heat release rate information of the battery according to the reaction generated in the battery;
and the other heat release rate calculation modules: according to the polarization phenomenon and the current thermal effect in the charging and discharging process of the battery, the calculation formula of the polarization heat and ohmic heat release rate in the using process of the battery is as follows:
q p ＝I 2 R p +I 2 R o ＝I 2 R t ；
wherein I is the battery current, R p Polarizing internal resistance of the battery; r is o Ohmic internal resistance of the battery; r is t Is the total internal resistance of the battery, q p The heat release rate of polarization heat and ohmic heat in the discharging process of the battery;
a merging calculation module: the total heat generation power is:
q＝q r +q p ；
wherein q is the total heat production power, q r Is the reaction heat exotherm rate of the cell, q p The heat release rate of the polarized heat and the ohmic heat in the discharging process of the battery.
9. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the method for estimating temperature inside a battery cell according to any one of claims 1 to 4.
10. A temperature estimation device adapted to be used inside a unit battery, comprising: a controller;
the controller comprises a computer readable storage medium of claim 9 storing a computer program which, when executed by a processor, implements the steps of the method of any one of claims 1 to 4 adapted for temperature estimation inside a single cell; alternatively, the controller comprises the temperature estimation system adapted for use inside a battery cell of any one of claims 5 to 8.
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