CN102854394A - System for estimating health state of lithium ion battery and method for estimating health state of lithium ion battery by using same - Google Patents

Abstract

The invention discloses a lithium-ion battery health state estimation system and a method for estimating the lithium-ion battery health state using the system, wherein the lithium-ion battery health state estimation system includes a single-chip microcomputer central control module, an AC pulse output module for outputting AC pulses, and a battery module and a display module, the single-chip central control module is respectively connected with the AC pulse output module, the battery module and the display module, the AC pulse output module is connected with the battery module, and the battery module is a lithium-ion power battery. The lithium-ion battery health state estimation system of the present invention has a simple structure, is specially aimed at lithium-ion batteries, and can accurately and quickly measure the actual internal resistance of the lithium-ion power battery and the impedance of each internal chemical component and determine the actual state of the lithium-ion battery.

Description

Lithium-ion battery state of health estimation system and method for estimating state of health of lithium-ion battery using the system

technical field

The invention relates to an estimation system, in particular to a lithium ion battery health state estimation system. the

The invention also relates to a method for estimating the state of health of the lithium-ion battery by using the above system. the

Background technique

Since the International Electrotechnical Association (IEEE1118-1996) established a standard for battery maintenance to predict battery life by regularly testing internal resistance, the China Post and Telecommunications Industry Product Quality Supervision and Inspection Center of the Ministry of Information Industry of China has also supplemented the internal resistance specification to YD/799-2002 . With the development of the domestic economy and the popularization of social information, the number of battery packs used in communication power supply, network energy supply, power unit, power generation and distribution, and various industries has increased sharply. As the last link of the backup power supply, accurate understanding of the online quality status of the battery is not only an important guarantee and basis for the battery to provide stable backup support, but also conducive to the optimization and integration of battery resources. the

Lithium-ion power batteries will gradually age with the increase of use time and cycle times. The main reasons for the aging are due to the oxidation of electrode current collectors, decomposition of electrolytes, and shedding of active materials, which cause the batteries to fail to maintain good power output. By estimating the state of health of the battery, it provides a basis for battery maintenance and replacement. the

The International Electrotechnical Association (IEEE1118-1996) stipulates that when the capacity of the battery drops to 80% of the nominal capacity of the battery, it is a backward battery, and the battery needs to be replaced. The state of health is represented by SOH, and the calculation formula is SOH = (current capacity - standard Said capacity)/Nominal capacity. the

Due to the time-consuming capacity test method, the International Electrotechnical Association (IEEE1118-2005) stipulates that obvious changes in the internal resistance of the battery mean that the performance of the battery has deteriorated. Its calculation formula is SOH=(current dynamic internal resistance value-initial internal resistance value)/initial internal resistance value. the

At present, the main test methods and systems for battery health status include the following:

(1) Internal resistance test method. The correlation between internal resistance and capacity is: when the internal resistance of the battery is greater than 25% of the initial value (base value), the battery will fail the capacity test. When the internal resistance of the battery is greater than 2 times the initial value, the capacity of the battery will be below 80% of its rated capacity. Based on this, the battery internal resistance tester mainly adopts the internationally popular different frequency method (AC test method) for testing, by adding a specific AC signal (I) to the battery, and then using a high-performance band-pass filter to detect the internal resistance of the battery. The pressure drop (U), R=U/I. The internal resistance method is convenient for testing, regardless of whether the battery is fully charged or not. It can be tested online or offline. The test speed is fast and it is suitable for large-scale testing. the

However, the relationship parameters between internal resistance and capacity obtained by this method are based on lead-acid batteries, not for lithium-ion power batteries, and the test parameters are not suitable for lithium-ion power batteries. The internal resistance test method only obtains the resistance between the metal conductors of the battery's internal current collector, and cannot obtain the resistance between the actual current collector and the active material material inside the lithium-ion power battery, and the resistance between the active material material and the electrolyte. The resistance value, the resistance value between the electrolyte and the diaphragm, and the migration resistance of lithium ions during the working process of the electrolyte. Therefore, this method cannot accurately measure the actual internal resistance of the lithium-ion power battery. the

(2) Actual capacity test method. The actual capacity of the storage battery is calculated by the time (T) required for the storage battery to be discharged to the minimum allowable voltage of the storage battery by a certain current (I). Q=I*T. The health status of the battery is estimated by the ratio of the actual capacity of the battery to the initial capacity. This method can only be tested offline, and it takes a lot of work to remove the battery; during the test, the battery to be tested must first be fully charged before the discharge test can be started, and the charging and discharging process requires a lot of time. This method is not suitable for online measurement of the state of health of lithium-ion power batteries, and it is not suitable for rapid measurement. the

Contents of the invention

The present invention is completed in order to solve the deficiencies in the prior art. The purpose of the present invention is to provide a simple structure, specifically for lithium-ion batteries, which can accurately and quickly measure the actual internal resistance and internal chemical components of lithium-ion power batteries online. A lithium-ion battery state-of-health estimation system that determines the impedance of the lithium-ion battery and determines the actual condition of the lithium-ion battery. the

The lithium-ion battery health state estimation system of the present invention comprises a single-chip central control module, an AC pulse output module for outputting AC pulses, a battery module and a display module, and the single-chip central control module is connected with the AC pulse output module, the battery module and the display module respectively connected, the AC pulse output module is connected to the battery module, and the battery module is a lithium-ion power battery. the

Lithium-ion battery state of health estimation system of the present invention can also be:

The AC pulse output module respectively outputs AC pulse signals of two frequencies to the battery modules connected to it.

The AC pulse output module outputs AC pulse signals at frequencies of 5963 Hz and 3 Hz to the battery modules connected to it respectively. the

The single-chip central control module includes a data receiving part, a data analysis part, a data processing part and a result sending part, and the data receiving part is connected with the battery module to receive the response signal data made by the battery module to the AC pulse signal output by the AC pulse , the data analysis part is connected with the data receiving part for analyzing the received response signal data, the data processing part is connected with the data analysis part for processing the analyzed response signal data, and the result is sent The part is respectively connected with the data processing part and the display module for displaying the result of data processing in the display module. the

The AC pulse output module includes a high-speed DA data conversion part, a high-frequency operational amplifier and a high-frequency triode, the high frequency is above 6MHz, and the high-speed DA data conversion part is connected to the output end of the single-chip central control module, The high-speed DA data conversion part is respectively connected with a high-frequency operational amplifier and a high-frequency triode. the

The single-chip central control module is a PIC high-frequency single-chip microcomputer, and the battery module is connected with the data receiving part of the single-chip central control module. the

The display module is a liquid crystal display or an LED indicator light, and the display module is connected with the result sending part of the central control module of the single-chip microcomputer. the

The lithium-ion battery health state estimation system of the present invention comprises a single-chip central control module, an AC pulse output module for outputting AC pulses, a battery module and a display module, and the single-chip central control module is connected with the AC pulse output module, the battery module and the display module respectively connected, the AC pulse output module is connected to the battery module, and the battery module is a lithium-ion power battery. In this way, when in use, the single-chip central control module controls the AC pulse output module to output AC pulse signals of different frequencies to the battery module, and the battery module makes different response signals to different AC pulse signals, and these different response signals are sent to the single-chip central control module , the single-chip central control module receives, analyzes and processes the above-mentioned response signal data to obtain an estimated health status of the lithium-ion battery and sends it to the display module for display. Therefore, compared with the prior art, the advantage is that the structure is simple, it is specially for lithium-ion batteries, and it can accurately and quickly measure the actual internal resistance of lithium-ion power batteries and the impedance of various internal chemical components and determine the actual status of lithium-ion batteries. the

Another object of the present invention is to provide a method for estimating the state of health of a lithium-ion battery using the above-mentioned system for estimating the state of health of a lithium-ion battery. This method starts with the estimation from the bottom-level electrochemical information of the lithium-ion battery, which is closer to the actual condition of the battery, and can be quickly measured and estimated online. the

The method for estimating the state of health of the lithium ion battery using the state of health estimation system of the lithium ion battery of the present invention comprises the following steps:

A. The battery module is installed in the lithium-ion battery state of health estimation system, and it is connected with the single-chip central control module and the battery module respectively;

B. The single-chip central control module controls the AC pulse output module to output 5963Hz and 3Hz AC pulse signals to the battery module;

C. The battery module responds to the AC pulse signal in step B and transmits the response signal data to the single-chip central control module, and the single-chip central control module receives the response signal data and analyzes the response signal measured at 5963Hz, and passes Process to get the estimated value of the battery health state;

D. The single-chip central control module sends the processed result to the display module connected to it to display the estimated value of the battery health status. the

The method for estimating the health state of the lithium ion battery using the health state estimation system of the lithium ion battery of the present invention can quickly measure online and obtain the real and actual health state of the lithium ion battery through the above steps, and the accuracy of the result is high. the

Description of drawings

Fig. 1 is a schematic diagram of an embodiment of a system for estimating the state of health of a lithium-ion battery according to the present invention. the

Fig. 2 is an equivalent circuit diagram of the internal impedance of the lithium-ion battery of the embodiment of the system for estimating the state of health of the lithium-ion battery of the present invention. the

Description of figure number

1...Single-chip central control module 2...AC pulse output module

3...battery module 4...display module

Detailed ways

The system for estimating the state of health of a lithium-ion battery and the method for estimating the state of health of a lithium-ion battery using the system of the present invention will be further described in detail below with reference to FIGS. 1 to 2 of the accompanying drawings. the

The lithium-ion battery health state estimation system of the present invention, please refer to Fig. 1 to Fig. 2, comprises single-chip microcomputer central control module 1, the AC pulse output module 2 of outputting AC pulse, battery module 3 and display module 4, described single-chip microcomputer central control module 1 is respectively connected to the AC pulse output module 2, the battery module 3 and the display module 4, the AC pulse output module 2 is connected to the battery module 3, and the battery module 3 is a lithium-ion power battery. In this way, during use, the single-chip central control module 1 controls the AC pulse output module 2 to output AC pulse signals of different frequencies to the battery module 3, and the battery module 3 makes different response signals to different AC pulse signals, and these different response signals are sent to The single-chip central control module 1, the single-chip central control module 1 receives, analyzes and processes the above-mentioned response signal data to obtain an estimated health status of the lithium-ion battery and sends it to the display module 4 for display. The principle of the present invention is: the lithium-ion power battery is the battery module 3, and its function is equivalent to an electrolytic cell during use. When AC impedance measurement is performed on the battery module 3 , when AC pulses of different frequencies pass through the electrolytic cell (battery module 3 ), each component inside the electrolytic cell (battery module 3 ) will produce different responses to the alternating current. Since the electrode is polarized by a small-amplitude symmetrical alternating current, when the frequency is high enough, the duration of each half cycle is very short, which will not cause serious concentration polarization and surface state changes. Moreover, anodic processes and cathodic processes alternately appear on the electrodes, even if the measurement signal acts on the electrolytic cell (battery module 3 ) for a long time, it will not lead to the cumulative development of the current phase of polarization. Therefore, when AC pulse currents of different frequencies pass through the interior of the lithium-ion battery as the battery module 3, between the positive electrode current collector and the active material material, between the active material material and the electrolyte, between the electrolyte and the diaphragm, and between the electrolyte and the negative electrode material Different responses can be measured between the negative electrode material and the negative electrode current collector, and the different response signals are sent to the single-chip central control module 1, and the single-chip central control module 1 analyzes the impedance of each component inside the battery. The simplified circuit diagram of the lithium-ion battery (battery module 3) is analyzed as shown in Figure 2. In Figure 2, Rct represents the charge transfer resistance, which is proportional to the negative number of the electron transfer speed. The faster the transfer speed, the lower the resistance. Cd stands for electric double layer capacitance. Rs represents the solution resistance. Zw represents the Warburg impedance, the resistance that limits the mass transfer process. According to a large amount of experimental data, during the aging process of the lithium-ion power battery (battery module 3), the loss degree of the lithium-ion power battery can be estimated through the change of Rct and Rs. The experimental data shows that when the AC pulse signal of 5963Hz is output, the Rs of the lithium-ion power battery can be obtained, and when the AC pulse signal of 3Hz is output, the value obtained by subtracting the value of Rs can obtain the value of Rct. Therefore, compared with the prior art, the advantage is that the structure is simple, it is specially for lithium-ion batteries, and it can accurately and quickly measure the actual internal resistance of lithium-ion power batteries and the impedance of various internal chemical components and determine the actual status of lithium-ion batteries. the

Specific analysis of the present invention has the following advantages and effects compared with the prior art: penetrate into the interior of the lithium-ion battery, and estimate the health status of the lithium-ion battery from the bottom electrochemical information of the battery module 3, that is, the lithium-ion battery. The existing battery internal resistance measurement method only obtains the resistance of the internal conductor of the battery, but cannot obtain the impedance of each chemical component inside the battery. The present invention outputs different AC pulse signals through the AC impedance measurement method, and analyzes and obtains the impedance of each chemical component inside the battery, so that the value estimated by the estimation system is closer to the real working battery and more in line with the actual battery. the

The lithium-ion battery health state estimation system of the present invention, please refer to Fig. 1 to Fig. 2, on the basis of the previous technical solution, specifically, the AC pulse output module 2 can output two kinds of frequency AC to the battery module 3 connected to it. Pulse signal. The advantage of this is: two AC pulse signals of different frequencies are output, and Rs and Rct are selected as estimated parameters to ensure the accuracy of the system in estimating the health status of the lithium-ion battery. Through the analysis of a large number of experimental data obtained by testing the complex internal chemical system of the battery, the two eigenvalues of Rs and Rct are selected as the parameters for the estimation of the state of health of the lithium-ion power battery. Through the formula, the Rs parameter and the Rct parameter are independent and interact with each other in the estimation process, and the estimation results are divided into 5 levels, so that the estimation results are more accurate and the estimation error is reduced. A further preferred technical solution is that the AC pulse output module 2 respectively outputs AC pulse signals at frequencies of 5963 Hz and 3 Hz to the battery modules 3 connected thereto. The high-frequency AC pulse signal obtains the electron transfer impedance of the lithium-ion battery, and the low-frequency AC pulse signal obtains the mass transfer impedance of the lithium-ion battery. According to the statistics of the experimental data, in the high frequency of 5963Hz, The starting point of Rs can be obtained. In the low frequency of 3Hz, the node of the value of Rs+Rct can be obtained. After data processing, the value of Rct can be obtained. A further preferred technical solution is: the single-chip central control module 1 includes a data receiving part, a data analysis part, a data processing part and a result sending part, and the data receiving part is connected with the battery module 3 for receiving the AC pulse of the battery module 3. The response signal data made by the output AC pulse signal, the data analysis part is connected with the data receiving part for analyzing the received response signal data, and the data processing part is connected with the data analysis part for analyzing The response signal data is processed, and the result sending part is respectively connected with the data processing part and the display module 4 for displaying the result of the data processing in the display module 4 . In this way, it is ensured that the single-chip central control module 1 can receive, analyze and process the response signal data sent by the battery module 3, so as to estimate the health status of the tested lithium-ion battery. A further preferred technical solution is that on the basis of the previous technical solution, the AC pulse output module 2 includes a high-speed DA data conversion part, a high-frequency operational amplifier and a high-frequency triode, the high frequency is above 6MHz, and the high-speed The DA data conversion part is connected with the output end of the single-chip central control module 1, and the high-speed DA data conversion part is respectively connected with a high-frequency operational amplifier and a high-frequency triode. The advantage of this is that the DA data conversion part is controlled by the single-chip central control module 1 to output AC pulses of different frequencies to the battery module 3 in real time, and the response signal is input to the single-chip central control module 1 for real-time estimation, and the obtained estimated value is transmitted to the display module 4 in real time Display, to achieve real-time online estimation and rapid measurement of the state of health of lithium-ion batteries. It can also be that the single-chip central control module 1 is a PIC high-frequency single-chip microcomputer, and the battery module 3 is connected to the data receiving part of the single-chip central control module 1 . PIC high-frequency single-chip microcomputer can control high-speed DA, and perform timely data processing on the high-frequency response signal obtained from the test to prevent data processing lag. Other high-frequency series single-chip microcomputers can also be used. The advantage of using PIC high-frequency single-chip microcomputer is that the data processing speed is fast, and there is no problem in controlling high-speed DA. In addition, the display module 4 may also be a liquid crystal display or an LED indicator light, and the display module 4 is connected to the result sending part of the single-chip central control module 1 . the

The present invention also protects the method for estimating the state of health of lithium-ion batteries using the above-mentioned state of health estimation system for lithium-ion batteries, including the following steps:

A, the battery module 3 is installed in the lithium-ion battery state of health estimation system, and it is connected with the single-chip central control module 1 and the battery module 3 respectively;

B. The single-chip central control module 1 controls the AC pulse output module 2 to output 5963Hz and 3Hz AC pulse signals to the battery module 3;

C. The battery module 3 responds to the AC pulse signal in step B and transmits the response signal data to the single-chip central control module 1, and the single-chip central control module 1 receives the response signal data and analyzes the response measured at 5963Hz The signal is processed to obtain an estimated value of the battery health state;

D. The single-chip central control module 1 sends the processed result to the display module 4 connected to it to display the estimated value of the battery health status.

The method for estimating the health state of the lithium ion battery using the health state estimation system of the lithium ion battery of the present invention can quickly measure online and obtain the real and actual health state of the lithium ion battery through the above steps, and the accuracy of the result is high. the

The method for estimating the state of health of a lithium-ion battery using the state-of-health estimation system of the lithium-ion battery of the present invention can also be that the data analysis and processing process in the C step is: the response signal measured at 5963 Hz, on the basis of the previous technical solution, The Rs impedance inside the lithium-ion battery is obtained by processing, and the response signal measured at 3Hz is obtained by subtracting the value of Rs from the value obtained by processing to obtain the Rct inside the lithium-ion battery. The Rs value measured for the first installation and use of the lithium-ion power battery is used as the initial value of the lithium-ion power battery Rs, expressed as _Rs , and the Rct value measured for the first installation and use of the lithium-ion power battery is used as the lithium-ion power battery Rs value. The Rct initial value of the power battery, expressed in Rct _initial . Then use the following calculation formula to calculate:

X indicates the estimated value of the battery health status, 0-1 indicates the battery health status is excellent, 1-2 indicates the battery health status is good, 2-3 indicates the battery health status is medium, 3-4 indicates the battery health status is poor, and slight damage has occurred, 4-5 indicates that the battery health is poor and moderate damage has occurred, and above 5 indicates that the battery health is very poor and the battery needs to be replaced. the

The advantages of the method for estimating the state of health of the lithium ion battery using the state of health estimation system of the lithium ion battery of the present invention are:

(1) Penetrate into the interior of the lithium-ion battery, and estimate the health status of the lithium-ion battery from the battery module 3, that is, the bottom-level electrochemical information of the lithium-ion battery. The existing battery internal resistance measurement method only obtains the resistance of the internal conductor of the battery, but cannot obtain the impedance of each chemical component inside the battery. Through the measurement method of AC impedance, different AC pulse signals are output, and the impedance of each chemical component inside the battery is analyzed, so that the estimation method is closer to the real working battery and more in line with the actual battery. the

(2) Output two AC pulse signals with different frequencies, and select Rs and Rct as estimated parameters. Through the analysis of a large number of experimental data obtained by testing the complex internal chemical system of the battery, the two eigenvalues of Rs and Rct are selected as the parameters for the estimation of the state of health of the lithium-ion power battery. pass

The formula makes the two parameters Rs and Rct independent and influence each other in the estimation process, divides the estimation results into 5 levels, makes the estimation results more accurate and reduces the estimation error. the

(3) Real-time online estimation and rapid measurement of the health status of lithium-ion power batteries. The DA data conversion is controlled by the single-chip central control module 1 to output AC pulses of different frequencies in real time to the battery module 3, and the battery module 3 outputs a response signal and sends the response signal to the single-chip central control module 1 for real-time estimation, and the obtained estimated value is real-time It is transmitted to the display module 4 for display, so as to realize real-time online estimation and fast measurement of the health status. the

The above only illustrates several specific embodiments of the present invention, but it cannot be regarded as the scope of protection of the present invention. Any equivalent change or modification or proportional amplification or reduction made according to the design spirit of the present invention shall be considered to fall within the protection scope of the present invention. the

Claims (9)

1. Lithium ion battery state of health estimation system, it is characterized in that: comprise single-chip microcomputer central control module, the AC pulse output module of output AC pulse, battery module and display module, described single-chip microcomputer central control module is connected with AC pulse output module, battery module respectively It is connected with the display module, and the AC pulse output module is connected with the battery module, and the battery module is a lithium-ion power battery. 2. The lithium-ion battery state of health estimation system according to claim 1, wherein the AC pulse output module outputs AC pulse signals of two frequencies to the battery modules connected to it respectively. 3. The lithium-ion battery health state estimation system according to claim 2, wherein the AC pulse output module outputs AC pulse signals at frequencies of 5963 Hz and 3 Hz to the battery modules connected thereto. 4. Lithium-ion battery state of health estimation system according to claim 3, is characterized in that: described single-chip microcomputer central control module comprises data receiving part, data analyzing part, data processing part and result sending part, and described data receiving part and The battery module is connected to receive the response signal data made by the battery module for the AC pulse signal output by the AC pulse, the data analysis part is connected to the data receiving part for analyzing the received response signal data, and the data processing part is connected to the The data analysis part is connected to process the analyzed response signal data, and the result sending part is respectively connected to the data processing part and the display module to display the data processing result in the display module. 5. The lithium-ion battery state of health estimation system according to claim 4, characterized in that: the AC pulse output module includes a high-speed DA data conversion part, a high-frequency operational amplifier and a high-frequency triode, and the high frequency is a frequency between Above 6 MHz, the high-speed DA data conversion part is connected to the output end of the single-chip central control module, and the high-speed DA data conversion part is connected to a high-frequency operational amplifier and a high-frequency transistor respectively. 6. Lithium-ion battery state of health estimation system according to claim 4, is characterized in that: the central control module of the single-chip microcomputer is a PIC high single-frequency chip microcomputer, and the data receiving part of the battery module and the central control module of the single-chip microcomputer connect. 7. The lithium-ion battery health status estimation system according to claim 4, characterized in that: the display module is a liquid crystal display or an LED indicator light, and the display module is connected to the result sending part of the central control module of the single-chip microcomputer . 8. The method for estimating the state of health of a lithium ion battery using the state of health estimation system for a lithium ion battery according to any one of claims 1 to 7, characterized in that: comprising the following steps: A, the battery module is installed in the lithium-ion battery state of health estimation system, and it is connected with the central control module of the single-chip microcomputer and the battery module respectively; B. The single-chip central control module controls the AC pulse output module to output 5963Hz and 3Hz AC pulse signals to the battery module; C. The battery module responds to the AC pulse signal in step B and transmits the response signal data to the single-chip central control module, and the single-chip central control module receives the response signal data and analyzes the response signal measured at 5963Hz, and passes Process to obtain an estimate of the battery state of health; D. The single-chip central control module sends the processed result to the display module connected to it to display the estimated value of the battery health status. 9. The method for estimating the state of health of a lithium-ion battery using a state-of-health estimation system for a lithium-ion battery according to claim 8, characterized in that: the data analysis and processing process in step C is: the response signal measured at 5963Hz, The Rs impedance inside the lithium-ion battery is obtained by processing, and the response signal measured at 3Hz is obtained by subtracting the value of Rs from the value obtained by processing to obtain the Rct inside the lithium-ion battery. The Rs value measured for the first installation and use of the lithium-ion power battery is used as the initial value of the lithium-ion power battery Rs, expressed as _Rs , and the Rct value measured for the first installation and use of the lithium-ion power battery is used as the lithium-ion power battery Rs value. The Rct initial value of the power battery, expressed in Rct _initial . Then use the following calculation formula to calculate: X indicates the estimated value of the battery health status, 0-1 indicates the battery health status is excellent, 1-2 indicates the battery health status is good, 2-3 indicates the battery health status is medium, 3-4 indicates the battery health status is poor, and slight damage has occurred, 4-5 indicates that the battery health is poor and moderate damage has occurred, and above 5 indicates that the battery health is very poor and the battery needs to be replaced.

Images