CN110794315B

CN110794315B - Method for detecting electric quantity of rechargeable battery

Info

Publication number: CN110794315B
Application number: CN201911003256.7A
Authority: CN
Inventors: 刘浩宇; 林宗严; 林东晓
Original assignee: Xiamen Yealink Network Technology Co Ltd
Current assignee: Xiamen Yealink Network Technology Co Ltd
Priority date: 2019-08-06
Filing date: 2019-10-22
Publication date: 2022-07-12
Anticipated expiration: 2039-10-22
Also published as: CN110794315A

Abstract

The invention discloses a method for detecting the electric quantity of a rechargeable battery, and belongs to the field of battery electric quantity detection methods. The invention provides a method for detecting the electric quantity of a rechargeable battery, aiming at the problems of inaccurate detection error of the electric quantity of the battery under a charging state, complex structure of a high-precision detection tool, complex calculation and high cost in the prior art. The invention is convenient to realize, does not need to additionally increase a monitoring load part and a hardware part, and has low cost, short development time and wide application scene; on the premise of not increasing the electricity meter, the calculation module and the calculation amount are reduced, the logic control is simple, the implementation is convenient, the detection effect is improved relative to the precision of the schemes of the same type, and the error is controlled within 10%.

Description

Method for detecting electric quantity of rechargeable battery

Technical Field

The invention relates to the field of battery electric quantity detection methods, in particular to a method for detecting the electric quantity of a rechargeable battery.

Background

Along with cell-phone, intelligence dress, electronic equipment such as computer is more and more popularized, and the battery becomes indispensable component in people's schedule life, and the accurate representation of battery electric quantity has also become an important performance index of electronic equipment because the electric quantity of battery is along with discharge time constantly changes, and has very big relevance with the load.

Measuring battery capacity is typically a measure of battery voltage. The charger detects a battery voltage during charging, and when the voltage reaches a predetermined voltage value, it is determined that the battery is fully charged. Generally, the charging capacity detection state is estimated by prompting charging or applying current and other charging capacities, and the error is large, so that a virtual height deviating from 30% or more is generated. On the premise of not using a high-price electricity meter, the battery voltage is high in the charging state during electricity detection, so that the electricity measurement of the battery is inaccurate, and the state error of pure analog electricity collection is large.

Chinese patent application, application No. 201310590560.2, published 2014, 9/3, discloses a system for measuring the amount of electricity in a battery, the system comprising: battery voltage acquisition module and microprocessor module. The input end of the battery voltage acquisition module is connected with the battery and is used for acquiring the terminal voltage of the battery. The microprocessor module is connected with the output end of the battery voltage acquisition module and used for receiving the terminal voltage of the battery and estimating the residual electric quantity of the battery. The micro-control processor module estimates the open-circuit voltage of the battery according to the terminal voltage of the battery and a built-in battery model, and then calculates the remaining electric quantity of the battery according to the SOC-OCV relation of a typical lithium ion battery. Through the mode, the battery power metering system can keep the accuracy of the power metering of the battery, and can be arranged inside or outside the battery. In the invention, the open circuit detection is to estimate the open circuit voltage of the battery, the actual voltage is not the actual voltage of the open circuit state of the battery, and the estimated value is inaccurate due to the dynamic output load. In addition, the battery model used by the method needs to additionally increase resistance overhead in an output circuit, the input impedance is increased, voltage measurement needs to be realized on hardware, and if the current output is large, the consumption is additionally increased.

Disclosure of Invention

1. Technical problem to be solved

The invention provides a method for detecting the electric quantity of a rechargeable battery, which can realize the monitoring and detection of the electric quantity in a charging state, play the role of prompting the electric quantity, control the error within 10 percent, avoid additionally increasing a monitoring load, and has the advantages of low cost, few modules, low calculation amount, short development time and wide application scene.

2. Technical scheme

The purpose of the invention is realized by the following technical scheme.

A method for detecting the electric quantity of a rechargeable battery comprises the following steps that hardware is connected with an I/O port of a main controller MCU through a USB, the hardware detects the voltage of the battery during working and the open-circuit voltage of the battery after power failure, differential pressure operation, load operation or digital-to-analog conversion are carried out on different types of voltages obtained according to detection, and the actual electric quantity of the battery is judged. To implement voltage detection in a charged state and abnormal state handling, a battery characteristic curve is analyzed, intermittent voltage rise determination is used, and charging enable is turned off within a variable time. The charging enable is closed in the charging process through a short time, so that after the battery voltage is recovered to a discharging state, the battery voltage is tested, after a certain time interval, the battery voltage is detected again, and through voltage drop, the current voltage and the like can calculate real-time voltage to obtain a relatively accurate electric quantity value. The detection mode is simple to implement, few in detection modules, low in cost, small in calculated amount and simple in logic, the error rate of measurement is controlled within 10%, the electric quantity value can be synchronously prompted in the charging process, the voltage of the battery can be tracked in real time, and the voltage can not cause sudden change when the charging state is pulled out. The power supply acquisition scheme of the invention controls the charging on-off enabling by software, directly converts to obtain the actual voltage on the premise of not increasing extra current-limiting current, and avoids extra consumption generated when the current is too large by voltage measurement realized by hardware.

Furthermore, the main controller MCU detects the connection condition by collecting the I/O port level change condition, and further obtains the voltage under different states. In the charging process, the plug-in effect is judged by monitoring the insertion of the USB port, the voltage conversion is rapidly carried out, and the real electric quantity of the battery is obtained. The I/O port of the main controller MCU judges different insertion effects by utilizing the switching effect of the triode, when the signal is at low level, the circuit is connected, and when the signal is at high level, the circuit is in an open circuit state. The detection voltage of the battery connection condition is judged according to the level change condition of the I/O port, the battery open-circuit voltage obtained by conversion after the battery is opened is the actual acquisition voltage, and the actual value is converted through the output voltage, so that the data is more accurate.

Furthermore, in the charging state, the method for determining the electric quantity of the battery comprises the steps of firstly obtaining an estimated voltage deviation value, and secondly performing differential pressure operation and load operation to obtain an output electric quantity value. Firstly obtaining an electric quantity value in the charging process, secondly obtaining the electric quantity value in the power-off process, then carrying out differential pressure operation to calculate the estimated voltage loaded voltage, secondly calculating the outer end equivalent impedance through load operation, finally obtaining the output actual electric quantity value according to the differential pressure operation and load operation results, and finally recovering the charging state. And in the charging process, the insertion effect is judged by monitoring the insertion of the USB port, the voltage conversion is quickly carried out, and the real capacity of the battery is obtained.

Furthermore, the battery is pulled out in the charging process, and the battery electric quantity judging method is to obtain the open-circuit electric quantity values of the battery twice, and respectively carry out load calculation to obtain the output electric quantity value. The method comprises the steps that in the charging process, the power-off state electric quantity is obtained firstly in the pulling-out state, the outer end equivalent impedance is calculated through load operation conducted on the power-off state electric quantity, then the secondary power-off electric quantity is obtained, load operation is conducted again according to the secondary power-off electric quantity, and the output actual electric quantity value is obtained according to the calculation results of the two times of load operation. When the battery is pulled out in the charging process, the battery voltage can be kept at a higher voltage for a period of time, and meanwhile, the battery load is increased, and a certain electric quantity drop can be generated. Therefore, after the voltage drop difference and the load are comprehensively calculated, the estimated capacity of the battery which is relatively reliable can be obtained and used for detecting the voltage of the battery.

Furthermore, in the non-charging process, the battery capacity determining method is to obtain two open-circuit capacity values of the battery, and perform analog-to-digital conversion respectively to obtain the battery capacity. The method comprises the steps of obtaining a power-off electric quantity value in an uncharged state, obtaining a voltage value through analog-to-digital conversion according to the obtained electric quantity value, then obtaining a secondary power-off electric quantity value, performing analog-to-digital conversion again according to the secondary obtained electric quantity value, directly carrying out secondary operation for eliminating jitter, collecting the electric quantity values twice, and averaging to obtain an output electric quantity value. Because the application load of the battery can be dynamically changed, the battery voltage can fluctuate under different applications, and after the battery voltage within a period of time is subjected to balanced operation, a stable difference value is obtained to estimate U_ADAnd if the difference between the expected operation and the actual operation is smaller, the electric quantity is judged to be reliable, so that the detection accuracy is improved.

Further, estimateAnd the voltage deviation value is obtained by simulating a battery electric quantity curve table according to the two time voltages obtained by the hardware. The hardware acquires voltages at two moments and acquires a predicted voltage deviation value through a simulation battery electric quantity curve table. At t₁Constantly acquiring voltage U₁After a certain time interval, at t₂Constantly acquiring voltage U₂Obtaining the estimated voltage deviation value U through simulating the battery electric quantity curve table_offset，

Δ t is t₂And t₁Difference between two moments, U_TThe real-time voltage collected at the current moment.

Furthermore, the voltage difference operation is to calculate the estimated voltage loaded actual voltage U by using the voltage after power failure and the estimated deviation value_real，U_real＝U_T-U_Offset. According to the method, the voltage difference operation is carried out according to the two time voltages acquired by the hardware, the estimated voltage deviation value is acquired, the calculation process is simple, other software assistance is not needed, the calculation cost is low, and the detection precision is improved compared with that of a similar method because the battery electric quantity is acquired according to different states of the battery.

Further, the load operation is to calculate the output current according to the voltage and the equivalent internal resistance, so as to obtain the outer end equivalent impedance R_out，

R_batThe load operation of the invention does not need to additionally increase a monitoring load part for the equivalent internal resistance of the battery, and has low cost and low power consumption.

Further, digital-to-analog operation is the basic operation to convert the A/D value into a voltage value,

the A/D value is obtained from an ADC module which integrates 10 bits in the chip, and 10-bit ADC value is collected in a register and the maximum value is 2¹⁰I.e. 1024, N_adFor sampled A/D valuesAnd U_vddThe power supply voltage multiplication result.

Furthermore, the simulated battery electric quantity curve table is obtained according to the charging and discharging time of different batteries, the average state is obtained by measuring a plurality of groups of states, and the accuracy of the simulated battery electric quantity curve is ensured by measuring data for a plurality of times.

The battery electric quantity detection method is low in cost, compared with a high-precision battery electric quantity detection tool, the battery electric quantity detection method is few in calculation module and few in auxiliary measurement tool, a load monitoring part and a hardware part do not need to be additionally arranged, electric quantity of the battery in different states only needs to be acquired, corresponding differential pressure operation, load operation or digital-analog operation is carried out, requirements on hardware and software in the detection process are low, system development time is short, and application scenes are quite wide. The algorithm is simple, the calculation logic is simple, the calculation amount is low, and the power consumption is small in the application process; aiming at the detection application of the battery electric quantity, under the conditions of simple algorithm, low calculated amount, low power consumption and low cost, the detection effect of the invention is improved relative to the precision of the same type of scheme, the error is below 4% in the slow charging state, the error in the fast charging state is about 8% and the total data calculation error is controlled within 10% according to the inconsistency of the fast charging performance and the slow charging performance.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

the invention judges the electric quantity of the battery through discontinuous voltage lifting, closes the charging enable within variable time, is convenient to realize the detection process, only needs to detect the voltage values under different states and carry out corresponding calculation, does not need to additionally increase a monitoring load part and a hardware part, saves the detection cost, has short system development time and has very wide application scenes; under the premise that the electricity meter is not additionally used in the detection process, the electricity detection logic is simple to control and convenient to implement, the electricity value is synchronously prompted in the charging process, the voltage of the battery is tracked in real time, and the voltage cannot cause sudden change when the charging state is extracted. The detection effect of the invention is improved compared with the precision of the same type of scheme, the error is below 4% under the slow charging state, the error is about 8% under the fast charging state, and the total data calculation error is controlled within 10% according to the inconsistency of the fast charging and slow charging performances.

Drawings

FIG. 1 is a schematic flow diagram of the present invention;

Detailed Description

The invention is described in detail below with reference to the drawings and specific examples.

Example 1

To implement voltage detection in a charged state and abnormal state handling, a battery characteristic curve is analyzed, intermittent voltage rise determination is used, and charging enable is turned off within a variable time. The charging enable is closed in a charging process in a short time, so that after the battery voltage is recovered to a discharging state, the battery voltage is tested, the battery voltage is detected again after a certain time interval according to a battery simulation electric quantity curve, the real-time voltage can be calculated through voltage drop, a relatively accurate electric quantity value is obtained, and the battery simulation electric quantity curve table is obtained according to the test. At t₁Constantly acquiring voltage U₁After a time Δ t, t₂Constantly acquiring voltage U₂Obtaining the estimated voltage deviation value U through simulating the battery electric quantity curve table_offsetThe simulated battery electric quantity curve table is obtained according to the charge-discharge time tested by different batteries, the average state is obtained by measuring a plurality of groups of states,

U_Tis the real-time voltage collected at the present moment. After the estimated voltage deviation value is obtained, the estimated voltage deviation value is subtracted from the voltage after power failure, and differential pressure operation is carried out to obtain the estimated voltage loaded actual voltage U_real。

In the charging process, judging the insertion effect by monitoring the insertion of the USB port, and quickly performing voltage conversion to obtain the real capacity of the battery; using hardware USB detection to connect the USB with an I/O port of a main controller MCU, and detecting the connection by the MCU main controller through acquiring the level change state of the I/O port; by using the switching effect of the triode, when the signal is at low level, the circuit is connected, and when the signal is at high level, the circuit is in an open circuit state.

The method for judging the electric quantity of the battery in the charging process comprises the following steps: charging → obtaining electric quantity value → power cut-off → obtaining electric quantity value → differential pressure operation → load operation → output electric quantity → recovery charging. Wherein the voltage difference operation is to use the voltage after power failure to subtract the voltage estimated deviation value to obtain the estimated voltage loaded actual voltage U_real，U_real＝U_T-U_Offset. The load carrying calculation is to obtain output current by dividing the acquired voltage by the equivalent internal resistance of the battery so as to obtain the equivalent impedance R of the outer end_out，

R_batIs the equivalent internal resistance of the battery.

Through conversion of a battery conversion discharge curve, actual values obtained through data supplement in different scenes are compared with errors of discharge time acquired by a battery, values between conversion voltage and actual measurement voltage are shown in a table 1, and the errors are far smaller than the virtual height of the prior art, which is more than 30% of errors caused by inaccurate battery electric quantity detection in a charging state. Different error values of the charging state during testing can be obtained through analysis of the testing result, algorithms of the battery electric quantity detection method are consistent, the quick-charging result and the slow-charging result are different in performance, error data can be guaranteed to be below 4% in the slow-charging state, and the error of the quick-charging state can reach 7% -8%. The detection method is simple, the process is convenient to realize, only voltage values in different states need to be detected and corresponding calculation is carried out, a monitoring load part and a hardware part do not need to be additionally arranged, the detection cost is saved, the system development time is short, and the application scenes are very wide; the power supply acquisition scheme of the invention controls the charging on-off enabling through software, and directly converts to obtain the actual voltage on the premise of not increasing extra current-limiting current, thereby avoiding extra consumption generated when the current is too large by voltage measurement realized by hardware; on the premise of not increasing the use of an electricity meter in the detection process, the electricity quantity detection logic is simple to control and convenient to implement, the electricity quantity value is synchronously prompted in the charging process, the voltage of the battery is tracked in real time, and the voltage is prevented from causing sudden change when the charging state is pulled out.

TABLE 1

Serial number	Scaling voltage	Measured voltage	Actual error	Serial number	Scaling voltage	Measured voltage	Actual error
								1	3.5261	3.5411	-0.42％	14	3.9206	3.9923	-1.80％
2	3.6496	3.783	-3.53％	15	3.96	4.0042	-1.10％
								3	3.6561	3.7229	-1.79％	16	4.0721	4.1257	-1.30％
4	3.6948	3.7597	-1.73％	17	4.089	4.1365	-1.15％
								5	3.7141	3.784	-1.85％	18	4.1212	4.1731	-1.24％
6	3.7464	3.8144	-1.78％	19	4.147	4.1958	-1.16％
								7	3.7787	3.8477	-1.79％	20	4.1993	4.2291	-0.70％
8	3.7916	3.8412	-1.29％	21	4.1993	4.2251	-0.61％
								9	3.7916	3.8612	-1.80％	22	4.2187	4.2483	-0.70％
10	3.798	3.8659	-1.76％	23	4.2316	4.2536	-0.52％
								11	3.8238	3.8922	-1.76％	24	4.238	4.2719	-0.79％
12	3.8561	3.9247	-1.75％	25	4.3219	4.3528	-0.71％
								13	3.869	3.9399	-1.80％

Example 2

This embodiment is the same as embodiment 1 except for the method of detecting the amount of electricity of the battery pulled out during the charging process. The battery voltage can be kept at a higher battery voltage within a period of time by pulling out the battery in the charging process, and meanwhile, the battery load is increased, so that certain electric quantity can be generated to drop, and the accuracy of voltage detection is reduced. Therefore, after the voltage drop difference is calculated through the pressure difference and the comprehensive load operation is carried out, the estimated electric quantity of the battery which is relatively reliable can be obtained.

The method for judging the electric quantity of the battery pulled out in the charging process comprises the following steps: charging → power off → obtaining of electric quantity value → load operation → obtaining of secondary electric quantity → secondary load operation → output of electric quantity, the load operation is the same as the algorithm in embodiment 1, and the offset parameter is different because the power-off load is different from the power-on load by default, when there is power on, the offset of the load is increased according to the current estimated voltage offset value, and the offset parameter is decreased according to the low load in standby. And secondary load operation is used during calculation, the two load operation methods are consistent, and the secondary operation increases the reliability of the operation.

Example 3

This example is the same as example 1, except that the amount of electricity is detected during non-charging. The application load of the battery can be dynamically changed, the battery voltage can fluctuate under different applications, stable difference value estimation is obtained after battery voltage equalization operation within a period of time, reliable electric quantity is judged if the expected difference value and the actual operation difference value are small, the operation is judged to be an abnormal result when the error is large, abnormal counting is added, and if abnormality occurs for more than five times continuously, the difference value is averaged and superposed on the existing reference for maintaining environment change, so that the detection accuracy is improved.

The method for judging the electric quantity of the battery in the uncharged process comprises the following steps: power-off → obtaining electric quantity value → operation → obtaining electric quantity value → secondary operation → outputting electric quantity, operation as basic operation, converting A/D value into voltage value,

calculation result U_ADThe method of the secondary operation is consistent with that of the actual voltage, the secondary operation is directly used for eliminating the jitter, the actual result is acquired, the electric quantity values calculated twice are averaged, the A/D value is acquired from a 10-bit ADC module integrated in the chip, the acquired value of 10-bit ADC in a register is 2 to the maximum¹⁰I.e. 1024, N_adIs the sampled A/D value and U_vddPower supplyThe result of the voltage multiplication.

The invention and its embodiments have been described above schematically, without limitation, and the invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The representation in the drawings is only one of the embodiments of the invention, the actual construction is not limited thereto, and any reference signs in the claims shall not limit the claims concerned. Therefore, if a person skilled in the art receives the teachings of the present invention, without inventive design, a similar structure and an embodiment to the above technical solution should be covered by the protection scope of the present patent. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Several of the elements recited in the product claims may also be implemented by one element in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A method for detecting the electric quantity of a rechargeable battery comprises the following steps that hardware is connected with an I/O port of a main controller MCU through a USB, and the hardware detects the voltage of the battery during working and the open-circuit voltage of the battery after power failure;

in the charging state, the method for judging the battery electric quantity comprises the steps of firstly obtaining a predicted voltage deviation value, secondly carrying out differential pressure operation and load operation to obtain an output electric quantity value, and obtaining a predicted voltage deviation value U through a simulated battery electric quantity curve table_offset，

Δ t is t₂And t₁Difference between two moments, U_TFor the real-time voltage, U, of the acquisition at the present moment₁Is t₁The voltage, U, is collected at all times₂Is t₂Acquiring voltage at any moment; calculating to obtain estimated voltage loaded actual voltage U by using the voltage after power failure and the estimated deviation value_real，U_real＝U_T-U_OffsetRoot of Chinese characterCalculating the output current according to the actual voltage and the equivalent internal resistance to obtain the outer end equivalent impedance R_out，

R_batIs the equivalent internal resistance of the cell;

the battery is pulled out in the charging process, the battery electric quantity judging method comprises the steps of obtaining two times of battery open-circuit electric quantity values, respectively carrying out load calculation, carrying out load calculation through the electric quantity in a power-off state to calculate the outer end equivalent impedance, then obtaining the secondary power-off electric quantity, carrying out load calculation again according to the secondary power-off electric quantity, obtaining an output actual electric quantity value according to the two times of load calculation results, and obtaining an output electric quantity value;

in the non-charging process, the battery capacity judging method includes obtaining two open-circuit battery capacity values, performing A/D conversion to obtain battery capacity, converting A/D value into voltage value by D/A operation,

the A/D value is taken from an ADC module with 10 bits integrated in a chip, N_adIs the sampled A/D value and U_vddThe power supply voltage multiplication result;

and performing differential pressure operation, load operation or digital-to-analog conversion on the voltages of different types obtained by detection to judge the actual battery electric quantity.

2. The method for detecting the electric quantity of the rechargeable battery according to claim 1, wherein the main controller MCU detects the connection condition by collecting the level change condition of the I/O port, and further obtains the voltages in different states.

3. The method according to claim 2, wherein the simulated battery power curve is obtained according to different battery test charging and discharging times.