CN112083341A - Method for accurately calculating percentage of remaining electric quantity of battery of Internet of things equipment - Google Patents
Method for accurately calculating percentage of remaining electric quantity of battery of Internet of things equipment Download PDFInfo
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention provides a method for accurately calculating the percentage of the remaining electric quantity of a battery of equipment of the Internet of things, which comprises the following steps: s1, formulating various equipment operation modes and establishing a temperature-battery voltage curve; s2, electrifying the equipment for the first time, taking the temperature as a constant to obtain the battery electric quantity percentage, and obtaining the current battery electric quantity by using a simplified coulomb method; and S3, calibrating the battery capacity and the current battery capacity under different environmental temperatures, and performing secondary calibration through the sampling voltage to obtain the percentage of the remaining battery capacity after calibration. The invention ensures that the percentage of the remaining electric quantity displayed on the user display end is stably reduced without increasing the equipment cost obviously, and the phenomena of electric quantity reverse rise, electric quantity jump, unbalance of electric quantity and use time and the like can not occur.
Description
Technical Field
The invention relates to the technical field of battery percentage calculation, in particular to a method for accurately calculating the percentage of the remaining electric quantity of a battery of equipment of the Internet of things.
Background
With the continuous development of the technology of the internet of things, the demand of the equipment of the internet of things is increasing. Due to installation environment limitations and market requirements, most internet of things devices (hereinafter referred to as devices) have to be powered by batteries. Usually, both the device administrator and the user need to pay attention to the remaining capacity percentage of the device in real time so that they can replace the battery in time to ensure the normal operation of the device. Inaccurate calculation of the residual electric quantity of the battery can affect the judgment of a device administrator and a user, the battery cannot be replaced timely due to the fact that the electric quantity is high enough to affect normal work of the device, the calculated residual electric quantity is low, 0% of the electric quantity of the device can work normally, and user experience is seriously affected. The quantity of the internet of things equipment is large, the requirements on cost management and control and low power consumption are high, and part of equipment can be kept to work continuously for years or decades by using batteries, so that a complex sampling circuit or a complex algorithm is not suitable.
Due to the characteristic that the battery voltage decreases as the battery level decreases, it is possible to approximate the way of calculating the battery level. However, the battery voltage is influenced by a lot of external interference factors, mainly including:
1) under the condition of the same residual capacity of the same battery, the voltage value can change along with the load size. In the no-load condition, the voltage is highest.
2) Under the condition of the same residual capacity of the same battery, the voltage value can change along with the temperature of the environment. The higher the ambient temperature, the higher the voltage, and the lower the ambient temperature, the lower the voltage.
3) The discharge characteristic curves may also be inconsistent for different types of batteries.
4) For rechargeable batteries, cycling of charge and discharge also changes the battery discharge characteristic.
The percentage calculation scheme of the remaining power used in the industry of the Internet of things at present comprises the following steps:
1) the MCU selects and collects the battery voltage uniformly under the condition of closing all the peripheral equipment, ensures that the loads are kept as consistent as possible, then collects the battery voltage for multiple times, performs certain filtering processing on the collected voltage value, then obtains the average value of the voltage, and then calculates the percentage of electric quantity according to a voltage-discharge time curve.
2) The initial value of the battery electric quantity estimates the battery electric quantity according to the sampling voltage, estimates the discharge current of the equipment, and calculates the discharge quantity according to the discharge time and the discharge current, thereby calculating and obtaining the current electric quantity, SOCc＝SOCl-I*Δt。SOCCRepresenting the current amount of electricity, SOC1Represents the last calculated charge, I represents the estimated discharge current, and Δ t represents the duration at which the discharge current I is maintained.
3) The net charge number, i.e. the remaining capacity, is obtained by integrating the charge flowing into/out of the battery by measuring it using coulometry.
4) And establishing a specific function fitting battery discharge curve, collecting battery voltage, estimating the electric quantity of the battery according to the fitting curve, and correcting the electric quantity through a mathematical model.
5) And establishing a huge battery discharge curve library, comparing discharge curves in the curve library by a certain algorithm according to the sampled voltage value, and determining a most similar discharge curve so as to obtain the electric quantity of the battery.
The prior art has the following defects:
1) the current voltage of the battery is directly collected, the battery electric quantity is obtained according to the battery discharge curve through a certain filtering mode, the mode is simple in calculation, extra devices do not need to be added, the universality is good, and the calculation accuracy of the battery electric quantity cannot be guaranteed when the load and the ambient temperature change.
2) The internet of things equipment generally has low power consumption requirements, the battery power accuracy of calculation can be improved by using the current to calculate the power, but the circuit sampling current needs to be increased, and the MCU is required to keep working all the time, so that the equipment cost and the power consumption are increased.
3) By using the method of eliminating the power consumption in the estimation time period, the estimated discharge current has an error, the error is accumulated along with the calculation times, and the battery power accuracy of the calculation cannot be ensured after the battery is used for a period of time.
4) A specific function is selected to fit a discharge curve, and then an algorithm for correcting the electric quantity is performed through a mathematical model, so that the problem of measurement accuracy caused by load change can be solved, but the calculation error of the environmental temperature change on the electric quantity of the battery cannot be guaranteed.
5) By using the method of comparing the sampled battery voltage with the discharge curve library, the storage space of the MCU is occupied, the calculation amount is large, and the influence of load and temperature change on the battery voltage cannot be solved.
Disclosure of Invention
The invention solves the problem that the residual electric quantity calculation precision of the battery is influenced due to the fact that the voltage of the battery of the Internet of things equipment is changed under the simultaneous action of load change and environmental temperature change, and provides the method for accurately calculating the residual electric quantity percentage of the battery of the Internet of things equipment.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a method for accurately calculating the percentage of the remaining electric quantity of a battery of equipment of the Internet of things comprises the following steps:
s1, formulating various equipment operation modes and establishing a temperature-battery voltage curve;
s2, electrifying the equipment for the first time, taking the temperature as a constant to obtain the battery electric quantity percentage, and obtaining the current battery electric quantity by using a simplified coulomb method;
and S3, calibrating the battery capacity and the current battery capacity under different environmental temperatures, and performing secondary calibration through sampling voltage to obtain the percentage of the battery residual capacity after calibration.
According to the characteristic parameters of the battery, the influence of battery load, environmental temperature and voltage sampling errors on battery electric quantity calculation is comprehensively considered, a complex multivariate function mathematical model is decomposed into a plurality of simple unitary functions, the consumed electric quantity is calculated by using a simplified coulomb method, the battery capacity and the current battery electric quantity under different environmental temperatures are calibrated by using the mathematical model, and then secondary calibration is carried out by sampling voltage, so that a fitted discharge curve approaches to an actual discharge curve through each calculation. The battery power calculated by the method dynamically changes according to the characteristic change of the new battery and the old battery, so that the calculated battery power percentage is more accurate.
Preferably, the step S1 specifically includes:
s101, making various equipment operation modes and estimating current;
s102, fitting a temperature-battery total capacity curve according to temperature and discharge capacity scatter data;
s103, decomposing a plurality of characteristic curves with different temperatures into a plurality of linear functions of battery voltage and battery electric quantity percentage according to a slope change rule;
and S104, fitting the temperature-battery voltage by taking the battery electric quantity percentage boundary value as a constant.
Preferably, the step S2 specifically includes:
s201, electrifying equipment for the first time, and sampling a voltage value and an environment temperature;
s202, calculating battery voltage according to a temperature-battery voltage curve of the battery electric quantity percentage boundary value;
s203, fitting a battery voltage-battery power percentage curve by taking the temperature as a constant, and obtaining the battery power percentage according to the voltage;
and S204, acquiring the total capacity of the battery according to the temperature-total capacity curve of the battery, and acquiring the current electric quantity of the battery according to the electric quantity percentage of the battery.
Preferably, the step S3 specifically includes:
s301, switching the operation modes;
s302, calculating the electric quantity consumed by the last operation mode;
s303, obtaining the current battery electric quantity, and calculating the current battery electric quantity percentage according to the total battery capacity;
s304, acquiring the current temperature, and calibrating the total capacity of the battery according to the temperature;
s305, keeping the current battery power percentage unchanged, and calculating the current battery power of temperature calibration;
s306, acquiring the current battery voltage, and calibrating the current battery capacity and the total battery capacity according to the battery voltage;
and S307, looping the step S301 to the step S306 to obtain the calibrated remaining capacity percentage of the battery.
Preferably, the step S102 includes a step of fitting an ambient temperature-total battery capacity curve function according to a plurality of sets of data of temperature and discharge capacity
SOC0(T)＝a0+a1T+a2T2
SOC0Representing the total capacity of the battery, T representing the ambient temperature, a0，a1，a2Is a constant;
the step S103 includes decomposing a plurality of characteristic curves at different temperatures into n sections of linear functions according to the change rule of the slope,
represents the temperature TmBattery voltage and battery charge percentage function, SOCP represents temperature TmPercentage of battery charge at b0，Λ，bk1，ΛbnIs a constant value of p1，Λ，pk，ΛpnIndicating a battery charge percentage boundary value;
said step S104 includes adding p1，Λ，pk，ΛpnSubstitution temperature TmThe battery voltage and battery capacity percentage function at the temperature T is obtainedmLower p1，Λ，pk，ΛpnCorresponding battery voltage value, p1，Λ，pk，ΛpnAs a constant, temperature TmAnd battery voltage
As an independent variable, a set of discrete values is obtained,
pkcorresponding set
according toSet PkFitting a linear function curve
Λ
Λ
Preferably, the step S201 specifically includes performing battery voltage sampling and temperature measurement under the condition that the device is powered on for the first time and the peripheral is turned off to obtain the current battery voltage UcAmbient temperature Tc；
Step S202 specifically includes setting T ═ TcTo obtain
Temperature TcAs a constant, percentage of battery charge pkAnd battery voltage
Performing piecewise linear function fitting as an independent variable to obtain the temperature TcDischarge curve of the following functional expression
u represents the battery voltage, SOCPcWhich represents the percentage of charge of the battery,
the step S203 specifically includes converting the current battery voltage UcSubstituting the function to obtain the current battery power percentage SOCPc(Uc)；
Step S204 specifically includes setting T ═ TcObtaining the total battery capacity SOC at the current temperature0(Tc)；
Calculating the current battery electric quantity SOCc(Tc)＝SOC0(Tc)×SOCPc(Uc)。
Preferably, the step S301 specifically includes: when the running mode of the equipment is changed, the current environmental temperature and the current battery voltage U are obtainedc1；
The steps S302 and S303 specifically include: calculating the power consumed by the last operation mode, wherein the power consumed by the last operation mode is Δ SOC ═ i × t, where i represents the average current of the last operation mode, and t represents the duration in the operation mode; calculating the battery capacity by current theory:
SOCc1＝SOCc-ΔSOC，
current battery power percentage: SOCPc1＝SOCc1÷SOC0(Tc)。
Preferably, the step S304 specifically includes: let T be Tc1To obtain Tc1Total battery capacity SOC at temperature0(Tc1)；
The step S305 specifically includes: calculating Tc1The current battery charge at the temperature of the battery,
let Uc＝Uc1，Tc＝Tc1Obtaining the percentage SOCP of the battery electric quantity calculated according to the battery voltageU；
The step S306 specifically includes: theoretical calculation of percentage of battery charge SOCPc1Error value SOCP of single electric quantity percentage calculated with battery voltageerr＝SOCPc1-SOCPu
Set allowable error value SOCPstd-err(ii) a If error value SOCPerr＞SOCPstd-errCalibration compensation is required, and the current battery capacity after calibration is as follows:
battery total capacity SOC corresponding to calibrated current temperaturecorrect0＝SOC÷SOCPc1(ii) a The calculation of the percentage of the electric quantity of the battery is finished, and the percentage of the electric quantity of the battery is SOCPc1。
Preferably, the step S307 specifically includes: the SOC is controlled by switching the running mode of the equipment oncec＝SOCcorrectC，SOC0＝SOCcorrect0Step S301 to step S306 are repeated.
The invention has the following beneficial effects: the invention comprehensively considers the influence of battery load, environment temperature and voltage sampling error on the battery electric quantity calculation, and the calculated battery electric quantity dynamically changes according to the actual condition of the battery, so that the battery electric quantity calculation is more accurate. The invention does not need to add extra circuit design, occupies less resources and effectively reduces the equipment cost. The invention converts the complex relation of battery load, environment temperature and voltage into a plurality of simple mathematical models, and occupies little MCU resource. The invention uses a simplified coulometer method to calculate the battery electric quantity, and uses the environment temperature and the battery voltage to carry out secondary calibration on the battery electric quantity respectively, and the battery electric quantity dynamically changes to approach the battery discharge curve of the real environment.
Drawings
FIG. 1 is a flowchart of the present embodiment;
FIG. 2 is a graph showing the relationship between the ambient temperature and the total capacity of the battery in the present embodiment;
FIG. 3 is a graph showing the relationship between the ambient temperature and the total capacity of the battery in the present embodiment;
FIG. 4 is a temperature characteristic curve in the present embodiment;
fig. 5 is a 50 Ω load temperature characteristic curve in the present embodiment;
FIG. 6 is a graph of the relationship between temperature and cell voltage in the present embodiment;
FIG. 7 is a 10 ℃ characteristic curve in the present example.
Detailed Description
Example (b):
the embodiment provides a method for accurately calculating the percentage of the remaining capacity of a battery of equipment of the internet of things, which comprises the following steps:
s1, formulating various equipment operation modes and establishing a temperature-battery voltage curve;
step S1 specifically includes:
s101, making various equipment operation modes and estimating current;
s102, fitting a temperature-battery total capacity curve according to temperature and discharge capacity scatter data;
s103, decomposing a plurality of characteristic curves with different temperatures into a plurality of linear functions of battery voltage and battery electric quantity percentage according to a slope change rule;
and S104, fitting the temperature-battery voltage by taking the battery electric quantity percentage boundary value as a constant.
Step S103 comprises decomposing a plurality of characteristic curves at different temperatures into n sections of linear functions according to the change rule of the slope,
represents the temperature TmBattery voltage and battery charge percentage function, SOCP represents temperature TmPercentage of battery charge at b0，Λ，bk1，ΛbnIs a constant value of p1，Λ，pk，ΛpnIndicating a battery charge percentage boundary value;
step S104 includes adding p1，Λ，pk，ΛpnSubstitution temperature TmThe battery voltage and battery power percentage function at the time of the battery discharge are obtainedmLower p1，Λ，pk，ΛpnCorresponding battery voltage value, p1，Λ，pk，ΛpnAs a constant, temperature TmAnd battery voltage
As an argument, a discrete set is obtained,
pkcorresponding set
according to the set PkFitting a linear function curve
Λ
Λ
S2, electrifying the equipment for the first time, taking the temperature as a constant to obtain the battery electric quantity percentage, and obtaining the current battery electric quantity by using a simplified coulomb method;
step S2 specifically includes:
s201, electrifying equipment for the first time, and sampling a voltage value and an environment temperature;
s202, calculating battery voltage according to a temperature-battery voltage curve of the battery electric quantity percentage boundary value;
s203, fitting a battery voltage-battery power percentage curve by taking the temperature as a constant, and obtaining the battery power percentage according to the voltage;
and S204, acquiring the total capacity of the battery according to the temperature-total capacity curve of the battery, and acquiring the current electric quantity of the battery according to the electric quantity percentage of the battery.
Step S201 specifically includes first powering on the device, and performing battery voltage sampling and temperature measurement under the condition that the peripheral is turned off to obtain the current battery voltage UcAmbient temperature Tc；
Step S202 specifically includes making T ═ TcTo obtain
Temperature TcAs a constant, percentage of battery charge pkAnd battery voltage
Performing piecewise linear function fitting as an independent variable to obtain the temperature TcDischarge curve of the following functional expression
u represents the battery voltage, SOCPcWhich represents the percentage of charge of the battery,
step S203 specifically includes converting the current battery voltage UcSubstituting the function to obtain the current battery power percentage SOCPc(Uc)；
Step S204 specifically includes setting T ═ TcObtaining the total battery capacity SOC at the current temperature0(Tc)；
Calculating the current battery electric quantity SOCc(Tc)＝SOC0(Tc)×SOCPc(Uc)。
And S3, calibrating the battery capacity and the current battery capacity under different environmental temperatures, and performing secondary calibration through sampling voltage to obtain the percentage of the battery residual capacity after calibration.
Step S3 specifically includes:
s301, switching the operation modes;
s302, calculating the electric quantity consumed by the last operation mode;
s303, obtaining the current battery electric quantity, and calculating the current battery electric quantity percentage according to the total battery capacity;
s304, acquiring the current temperature, and calibrating the total capacity of the battery according to the temperature;
s305, keeping the current battery power percentage unchanged, and calculating the current battery power of temperature calibration;
s306, acquiring the current battery voltage, and calibrating the current battery capacity and the total battery capacity according to the battery voltage;
and S307, looping the step S301 to the step S306 to obtain the calibrated remaining capacity percentage of the battery.
Step S102 includes fitting an ambient temperature-total battery capacity curve function according to multiple sets of data of temperature and discharge capacity
SOC0(T)＝a0+a1T+a2T2
SOC0Representing the total capacity of the battery, T representing the ambient temperature, a0，a1，a2Is a constant;
step S301 specifically includes: when the running mode of the equipment is changed, the current environmental temperature and the current battery voltage U are obtainedc1；
Step S302 and step S303 specifically include: calculating the power consumed by the last operation mode, wherein the power consumed by the last operation mode is Δ SOC ═ i × t, where i represents the average current of the last operation mode, and t represents the duration in the operation mode; calculating the battery capacity by current theory:
SOCc1＝SOCc-ΔSOC，
current battery power percentage: SOCPc1＝SOCc1÷SOC0(Tc)。
Step (ii) ofS304 specifically includes: let T be Tc1To obtain Tc1Total battery capacity SOC at temperature0(Tc1)；
Step S305 specifically includes: calculating Tc1The current battery charge at the temperature of the battery,
let Uc＝Uc1，Tc＝Tc1Obtaining the percentage SOCP of the battery electric quantity calculated according to the battery voltageU；
Step S306 specifically includes: theoretical calculation of percentage of battery charge SOCPc1Error value SOCP of single electric quantity percentage calculated with battery voltageerr＝SOCPc1-SOCPu
Set allowable error value SOCPstd-err(ii) a If error value SOCPerr＞SOCPstd-errCalibration compensation is required, and the current battery capacity after calibration is as follows:
battery total capacity SOC corresponding to calibrated current temperaturecorrect0＝SOC÷SOCPc1(ii) a The calculation of the percentage of the electric quantity of the battery is finished, and the percentage of the electric quantity of the battery is SOCPc1。
Step S307 specifically includes: the SOC is ordered every time the running mode of the equipment is switchedc＝SOCcorrectC，SOC0＝SOCcorrect0Step S301 to step S306 are repeated.
The specific implementation process is as follows:
1) the basic characteristics and typical characteristics of the battery were obtained from a data manual provided by the battery manufacturer, as shown in the basic characteristic table of Table 2-1 and the typical characteristic table of Table 2-2.
TABLE 2-1 basic Property Table
TABLE 2-2 typical characteristics Table
2) Three sets of data (-20, 1200), (23, 1900), (60, 1800) of ambient temperature and discharge capacity were obtained according to 5.4 in the exemplary characteristics table of table 2-2, with reference to fig. 2.
3) According to the relation graph of the environmental temperature and the total capacity of the battery, curve fitting is carried out on the data source by using a least square method, referring to the graph 3, and the expression of the fitted curve is
SOC0(T)＝-0.2373T2+16.991T+1634.7
4) According to the temperature characteristic curve provided by the battery manufacturer, referring to fig. 4, the characteristic curves at 4 different temperatures are respectively decomposed into four sections of linear functions according to the change rule of the slope, which are shown in the table 2-3 of the relationship table between the battery voltage and the electric quantity.
TABLE 2-3 relationship table of battery voltage and electric quantity
5) And obtaining a temperature characteristic curve after piecewise fitting according to the relation table of the battery voltage and the electric quantity in the tables 2-3, and referring to the figure 5.
6) According to fig. 5, the temperature and battery voltage relationship curves at 100%, 95%, 40%, 10% charge, respectively, are fitted, referring to fig. 6.
U100(T)＝0.0056T+2.7754
U95(T)＝0.0055T+2.5882
U40(T)＝0.0054T+2.4598
U10(T)＝0.004T+2.2268
7) First sampling battery voltage U under the condition that peripheral equipment is not started after equipment is powered oncAnd measuring the ambient temperature at that time to obtain TcSuppose Uc＝2.75V，Tc＝10(℃)。
8) Let T c10 (. degree. C.) to give TcVoltage value U corresponding to 100% electric quantity at temperature100(Tc) Voltage value U corresponding to 2.831(V) and 95% of electric quantity95(Tc) Voltage value U corresponding to 2.614(V) and 40% of electric quantity40(Tc) 2.514(V), voltage value U corresponding to 10% electric quantity10(Tc)＝2.267(V)。
9) According to point (100, U)100(Tc))、(95，U95(Tc))、(40，U40(Tc))、(10，U10(Tc))、 (0，U0(Tc) Namely (100, 2.831), (95, 2.614), (40, 2.514), (10, 2.267) and (0, 2) to obtain TcTemperature profile at temperature, see fig. 7.
The corresponding function of fig. 7 is:
changing U to UcSubstituting 2.75(V) to obtain the current battery capacity percentage SOCPc＝98.13(％)
10) Changing T to TcSubstituting 10 (deg.C) to obtain the total battery capacity SOC at the current temperature0＝1781(mA·h)＝6411168(mA·s)
11) Current battery power
SOCc＝SOC0*SOCPc＝6411168*0.9813≈6291279(mA·s)
12) When the running mode of the equipment is changed, the current environment temperature T is obtainedc1Current battery voltage Uc1。
13) The amount of power consumed for the last operational mode. Let T bec1When the average current i is 2(mA) and the duration t is 3600(s) in the last operation mode is-10 (deg.c), the power consumption Δ SOC of the last operation mode is i × t 2 × 3600 7200(mA · s), and the current theory calculates the battery power SOCc1＝SOCc- Δ SOC 6291279-Volume percent SOCPc1＝SOCc1÷SOC0＝6284079÷6411168≈98.02(％)
14) Calculating the current ambient temperature Tc1Total battery capacity at-10 (. degree. C.)
SOC0(Tc1)≈1441(mA·h)＝5187600(mA·s)
15) Calibrating Tc1Current battery charge at-10 (deg.c),
16) assume the currently sampled battery voltage Uc12.6(V), let Uc＝Uc1＝2.6(V)， Tc＝Tc1And (4) executing the steps (8) and (9) to obtain the battery capacity percentage SOCP calculated according to the battery voltageU＝96.80(％)。
17) Theoretical calculation of percentage of battery charge SOCPc1Error value SOCP of single electric quantity percentage calculated with battery voltageerr＝SOCPc1-SOCPu＝0.9802-0.9680＝1.22(％)
18) Assuming a set allowable error value SOCPstd-err1 (%). Because of the error value SOCPerr＞SOCPstd-errThe current battery capacity after calibration needs to be compensated
Total capacity of battery corresponding to current temperature after calibration
SOCcorrect0＝SOC÷SOCPc1＝5148155÷0.9802≈5252147(mA·s)
19) The calculation of the percentage of the electric quantity of the battery is finished, and the percentage of the electric quantity of the battery is SOCPc1＝98.02(％)。
20) The SOC is ordered every time the running mode of the equipment is switchedc＝SOCcorrectC， SOC0＝SOCcorrect0And (4) repeating the steps (12) to (19).
According to the characteristic parameters of the battery, the influence of battery load, environmental temperature and voltage sampling errors on battery electric quantity calculation is comprehensively considered, a complex multivariate function mathematical model is decomposed into a plurality of simple unitary functions, the consumed electric quantity is calculated by using a simplified coulomb method, the battery capacity and the current battery electric quantity under different environmental temperatures are calibrated by using the mathematical model, and then secondary calibration is carried out by sampling voltage, so that a fitted discharge curve approaches to an actual discharge curve through each calculation. The battery power calculated by the method dynamically changes according to the characteristic change of the new battery and the old battery, so that the calculated battery power percentage is more accurate.
The invention has the following beneficial effects: the invention comprehensively considers the influence of battery load, environment temperature and voltage sampling error on the battery electric quantity calculation, and the calculated battery electric quantity dynamically changes according to the actual condition of the battery, so that the battery electric quantity calculation is more accurate. The invention does not need to add extra circuit design, occupies less resources and effectively reduces the equipment cost. The invention converts the complex relation of battery load, environment temperature and voltage into a plurality of simple mathematical models, and occupies little MCU resource. The invention uses a simplified coulometer method to calculate the battery electric quantity, and uses the environment temperature and the battery voltage to carry out secondary calibration on the battery electric quantity respectively, and the battery electric quantity dynamically changes to approach the battery discharge curve of the real environment.
Claims (9)
1. A method for accurately calculating the percentage of the remaining electric quantity of a battery of equipment of the Internet of things is characterized by comprising the following steps:
s1, formulating various equipment operation modes and establishing a temperature-battery voltage curve;
s2, electrifying the equipment for the first time, taking the temperature as a constant to obtain the battery electric quantity percentage, and obtaining the current battery electric quantity by using a simplified coulomb method;
and S3, calibrating the battery capacity and the current battery capacity under different environmental temperatures, and performing secondary calibration through the sampling voltage to obtain the percentage of the remaining battery capacity after calibration.
2. The method of claim 1, wherein the step S1 specifically includes:
s101, making various equipment operation modes and estimating current;
s102, fitting a temperature-battery total capacity curve according to temperature and discharge capacity scatter data;
s103, decomposing a plurality of characteristic curves with different temperatures into a plurality of linear functions of battery voltage and battery electric quantity percentage according to a slope change rule;
and S104, fitting the temperature-battery voltage by taking the battery electric quantity percentage boundary value as a constant.
3. The method of claim 2, wherein the step S2 specifically includes:
s201, electrifying equipment for the first time, and sampling a voltage value and an environment temperature;
s202, calculating the battery voltage according to a temperature-battery voltage curve of the battery electric quantity percentage boundary value;
s203, fitting a battery voltage-battery power percentage curve by taking the temperature as a constant, and obtaining the battery power percentage according to the voltage;
and S204, acquiring the total capacity of the battery according to the temperature-total capacity curve of the battery, and acquiring the current electric quantity of the battery according to the electric quantity percentage of the battery.
4. The method of claim 3, wherein the step S3 specifically includes:
s301, switching the operation modes;
s302, calculating the electric quantity consumed by the last operation mode;
s303, obtaining the current battery capacity, and calculating the current battery capacity percentage according to the total capacity of the battery;
s304, acquiring the current temperature, and calibrating the total capacity of the battery according to the temperature;
s305, keeping the current battery power percentage unchanged, and calculating the current battery power of temperature calibration;
s306, acquiring the current battery voltage, and calibrating the current battery capacity and the total battery capacity according to the battery voltage;
and S307, looping the step S301 to the step S306 to obtain the calibrated remaining capacity percentage of the battery.
5. The method as claimed in claim 2, wherein the percentage of the remaining battery capacity of the IOT device is calculated,
step S102 includes fitting an ambient temperature-total battery capacity curve function according to a plurality of groups of data of temperature and discharge capacity
SOC0(T)＝a0+a1T+a2T2
SOC0Representing the total capacity of the battery, T representing the ambient temperature, a0，a1，a2Is a constant;
the step S103 includes decomposing a plurality of characteristic curves at different temperatures into n sections of linear functions according to the change rule of the slope,
represents the temperature TmBattery voltage and battery charge percentage function, SOCP represents temperature TmPercentage of battery charge at b0，Λ，bk1，ΛbnIs a constant value of p1，Λ，pk，ΛpnIndicating a battery charge percentage boundary value;
said step S104 includes adding p1，Λ，pk，ΛpnSubstitution temperature TmThe battery voltage and battery power percentage function at the time of the temperature T is obtainedmLower p1，Λ，pk，ΛpnCorresponding battery voltage value, p1，Λ，pk，ΛpnAs a constant, temperature TmAnd battery powerPress and press
As an argument, a discrete set is obtained,
pkcorresponding set
according to the set PkFitting a linear function curve
6. The method as claimed in claim 5, wherein the percentage of the remaining battery capacity of the IOT device is calculated,
step S201 specifically includes first powering on the device, and performing battery voltage sampling and temperature measurement under the condition that the peripheral is turned off to obtain the current battery voltage UcAmbient temperature Tc；
Step S202 specifically includes setting T ═ TcTo obtain
Temperature TcAs a constant, percentage of battery charge pkAnd battery voltage
Performing piecewise linear function fitting as an independent variable to obtain the temperature TcDischarge curve of the following functional expression
u represents the battery voltage, SOCPcWhich represents the percentage of charge of the battery,
the step S203 specifically includes converting the current battery voltage UcSubstituting the function to obtain the current battery power percentage SOCPc(Uc)；
Step S204 specifically includes setting T ═ TcObtaining the total battery capacity SOC at the current temperature0(Tc)；
Calculating the current battery electric quantity SOCc(Tc)＝SOC0(Tc)×SOCPc(Uc)。
7. The method as claimed in claim 6, wherein the percentage of the remaining battery capacity of the IOT device is calculated,
the step S301 specifically includes: when the running mode of the equipment is changed, the current environmental temperature and the current battery voltage U are obtainedc1；
The steps S302 and S303 specifically include: calculating the power consumed by the last operation mode, wherein the power consumed by the last operation mode is Δ SOC ═ i × t, where i represents the average current of the last operation mode, and t represents the duration in the operation mode; calculating the battery capacity by current theory:
SOCc1＝SOCc-ΔSOC，
current battery power percentage: SOCPc1＝SOCc1÷SOC0(Tc)。
8. The method as claimed in claim 7, wherein the percentage of the remaining battery capacity of the IOT device is calculated,
the step S304 specifically includes: let T be Tc1To obtain Tc1Total battery capacity SOC at temperature0(Tc1)；
The step S305 specifically includes: calculating Tc1The current battery charge at the temperature of the battery,
let Uc＝Uc1，Tc＝Tc1Obtaining the percentage SOCP of the battery electric quantity calculated according to the battery voltageU；
The step S306 specifically includes: theoretical calculation of percentage of battery charge SOCPc1Error value SOCP of single electric quantity percentage calculated with battery voltageerr＝SOCPc1-SOCPu
Set allowable error value SOCPstd-err(ii) a If error value SOCPerr＞SOCPstd-errCalibration compensation is required, and the current battery capacity after calibration is as follows:
battery total capacity SOC corresponding to calibrated current temperaturecorrect0＝SOC÷SOCPc1(ii) a The calculation of the percentage of the electric quantity of the battery is finished, and the percentage of the electric quantity of the battery is SOCPc1。
9. The method of claim 8, wherein the step S307 specifically includes: the SOC is ordered every time the running mode of the equipment is switchedc＝SOCcorrectC，SOC0＝SOCcorrect0Step S301 to step S306 are repeated.
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