WO2018090678A1 - 一种监测锂离子电池荷电状态和健康状态的方法及其装置 - Google Patents

一种监测锂离子电池荷电状态和健康状态的方法及其装置 Download PDF

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WO2018090678A1
WO2018090678A1 PCT/CN2017/096345 CN2017096345W WO2018090678A1 WO 2018090678 A1 WO2018090678 A1 WO 2018090678A1 CN 2017096345 W CN2017096345 W CN 2017096345W WO 2018090678 A1 WO2018090678 A1 WO 2018090678A1
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state
lithium ion
ion battery
charge
battery
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PCT/CN2017/096345
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English (en)
French (fr)
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沈越
邓哲
黄云辉
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华中科技大学
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Priority to US16/083,318 priority Critical patent/US10663525B2/en
Priority to JP2018530878A priority patent/JP2018537682A/ja
Publication of WO2018090678A1 publication Critical patent/WO2018090678A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3828—Arrangements for monitoring battery or accumulator variables, e.g. SoC using current integration
    • G01R31/3832—Arrangements for monitoring battery or accumulator variables, e.g. SoC using current integration without measurement of battery voltage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/11—Analysing solids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/12—Analysing solids by measuring frequency or resonance of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
    • G01N29/4427—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with stored values, e.g. threshold values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/48—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by amplitude comparison
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392—Determining battery ageing or deterioration, e.g. state of health
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/488—Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4278—Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention belongs to the technical field of batteries, and particularly relates to a monitoring method and device for charging state and health state of a battery.
  • the state of charge of the battery also called the remaining capacity, represents the ratio of the remaining capacity of the battery after a period of use or long-term suspension to its fully charged state, referred to as SOC.
  • SOC the state of charge of the battery and its measurable characteristics such as current and voltage are a very complicated nonlinear relationship, and it is difficult to directly measure with the battery environment and life, so how to accurately charge the battery
  • the measurement of the state is an international problem.
  • the health of the battery is a quality factor compared to its ideal state, referred to as SOH.
  • SOH quality factor
  • the health status of the battery decreases as the time and number of uses increases.
  • we set a threshold for battery health When the battery health is below this threshold, it means the battery is not suitable for further use. Since there is no specific physical quantity in the health status of the battery, the industry has different methods for how to establish the health status of the battery.
  • the battery internal resistance, capacity, voltage, self-discharge speed, charging capacity, charge and discharge ring are used. Changes in the number of electrical parameters to establish the health of the battery.
  • the battery may have health problems such as flatulence, leakage, etc. due to abnormal use such as overcharge, overheating, short circuit, mechanical damage, etc. If not found in time, it may cause the battery to burn or even explode.
  • the state of charge of the battery cannot be directly measured. People usually measure the state of charge of the battery by measuring other physical quantities in both offline and online modes. In offline mode, the battery is charged and discharged at a constant rate to integrate the power. This mode is very accurate in estimating the state of charge of the battery but it takes a long time and the operation of the battery must be interrupted during the test. So people tend to measure online formula.
  • the current online measurement modes mainly include chemical method, voltage method, current integration method, internal resistance method, Kalman filter method, neural network method and the like to indirectly estimate the state of charge of the battery.
  • the chemical method is only applicable to batteries that can be exposed to the electrolyte.
  • a non-sealed lead-acid battery determines its state of charge by measuring the pH and density of the electrolyte.
  • the voltage method converts the voltage value into the state of charge of the battery by comparing the known charge and discharge voltage state of charge curve.
  • the voltage of the lithium ion battery tends to be relatively stable, and the amplitude varies little with the state of charge, and the battery The voltage is greatly affected by current, temperature, and lifetime, resulting in a very inaccurate state of charge measured by this method.
  • the voltage method can improve the accuracy by introducing current and temperature correction coefficients, but the accuracy is still not high.
  • the current integration method also known as the ampere-integral method or the coulomb count, calculates the state of charge of the battery by integrating the battery current over time.
  • This method lacks a reference point, and it is impossible to measure the capacity attenuation of the battery due to self-discharge, and the error is cumulative and gradually increases with time. Therefore, when this method is used, it is necessary to periodically recalibrate the state of charge of the battery, for example, to reset the state of charge of the battery to 100% after being fully charged.
  • the internal resistance method has the AC internal resistance and the DC internal resistance, and they are all closely related to the state of charge of the battery.
  • the battery AC impedance is a transfer function between the battery voltage and current. It is a complex variable that indicates the battery's resistance to AC. It should be measured with an AC impedance meter.
  • the AC impedance of the battery is greatly affected by temperature. It is controversial whether the battery is in an open state after standing or in the process of charging and discharging the battery.
  • the DC internal resistance indicates the resistance of the battery to DC power. In actual measurement, the battery is charged or discharged with constant current from the open state. The difference between the load voltage and the open circuit voltage divided by the current value is the DC internal resistance.
  • the DC internal resistance is obviously increased, which can be used to estimate the state of charge of the battery; the variation of the DC internal resistance of the nickel-hydrogen battery and the lithium-ion battery is different from that of the lead battery, and the application is less.
  • the core idea of the Kalman filter method is to make an optimal estimate of the state of the dynamic system in the sense of minimum variance.
  • the Kalman filter method treats the battery as a power system, and the state of charge of the battery is an internal state of the system.
  • the core of the estimated battery state of charge algorithm is a set including battery charging
  • the state estimation value and the recursive equation of the covariance matrix reflecting the estimation error, and the covariance matrix is used to give the estimation error range.
  • the method is applicable to various batteries, especially the estimation of the state of charge of a hybrid electric vehicle battery with relatively high battery current fluctuation. Compared with other methods, it not only gives an estimate of the state of charge of the battery, but also gives an estimation error of the state of charge of the battery.
  • the neural network method believes that the battery is a highly nonlinear system, and it is difficult to establish an accurate mathematical model during its charging and discharging process.
  • the neural network has the basic characteristics of nonlinearity, has parallel structure and learning ability. For external excitation, it can give corresponding output and can simulate the dynamic characteristics of the battery to estimate the state of charge of the battery.
  • the neural network method is applicable to various batteries. The disadvantage is that a large amount of reference data is required for training, and the estimation error is greatly affected by the training data and the training method.
  • the current battery state of charge and health state test methods are based on the measurement of electrical parameters such as current, voltage, impedance, etc., but because of the complex factors affecting the electrical parameters of the battery, it is not possible to obtain sufficiently reliable results.
  • the state of charge and the state of health can be measured by other battery characteristic parameters other than the electrical parameters, it is important to improve the accuracy of the state of charge measurement and promptly indicate the state of health.
  • the present invention provides a method for monitoring the state of charge and health of a lithium ion battery, the purpose of which is to establish a correspondence between the acoustic parameters and the state of charge and health of the lithium ion battery, respectively.
  • the relationship utilizes acoustic parameters to monitor the state of charge and health of the lithium ion battery, thereby solving the problem of poor reliability of monitoring lithium ion battery power and health status based on electrical parameters in the prior art.
  • a method for monitoring a state of charge and a state of health of a lithium ion battery is provided.
  • the acoustic wave is passed through various charged state lithium ion batteries under different charging and discharging current conditions to obtain acoustic parameters, thereby establishing acoustic parameters and lithium ion battery state of charge and health respectively.
  • Kang state corresponds to various charged state lithium ion batteries under different charging and discharging current conditions.
  • the state of charge and the state of health of the lithium ion battery are determined.
  • the acoustic parameters include: amplitude attenuation of the sound wave after propagation in the lithium ion battery, time of flight, and acoustic fingerprint
  • the flight time refers to the time of the sound wave from the ultrasonic signal source to the ultrasonic signal receiver.
  • the ultrasonic signal source and the ultrasonic signal receiver are both connected to the same lithium ion battery, and the acoustic fingerprint refers to a waveform after the sound wave passes through the lithium ion battery.
  • the ultrasonic wave of a specific frequency and amplitude passes through various charged state lithium ion batteries under different charging and discharging current conditions to obtain the amplitude attenuation degree of the ultrasonic wave of the specific frequency and amplitude, thereby establishing different charging and discharging.
  • the amplitude attenuation of the ultrasonic wave with the specific frequency and amplitude after passing through the lithium ion battery under different charging and discharging current conditions is monitored, and different charging and discharging current conditions are obtained according to the calibration map.
  • the principle of the above inventive concept is that for a certain battery, during the calibration process, the current, the state of charge, and the amplitude of the ultrasonic wave after passing through the battery are all known quantities that can be measured, and the study found that there is a relationship between the three. Objective correspondence. During the use of the battery, the state of charge is not directly available. According to the above method, the measured state of the current and the amplitude of the ultrasonic wave passing through the battery can be used to estimate the state of charge of the battery.
  • the amplitude of the ultrasonic wave after passing through the battery changes, which is the basis for the establishment of the above invention.
  • the reason is that under different charging states, the chemical composition of the positive and negative materials inside the lithium ion battery is different, and the particles of the positive and negative materials will change with the volume of the charging and discharging process, resulting in a change in the tightness of the internal particle packing of the electrode sheet.
  • the absorption rate of the acoustic energy of the battery as a whole changes, and the amplitude of the ultrasonic wave changes after passing through the battery.
  • the ultrasonic wave passes through various charged state lithium ion batteries under different charging and discharging current conditions to obtain the flight time, thereby establishing the flight time under different charging and discharging current conditions and the state of charge of the lithium ion battery.
  • obtaining a calibration map and then, during the use of the lithium ion battery, monitoring the flight time of the ultrasonic wave passing through the lithium ion battery under different charging and discharging current conditions, according to the calibration map, obtaining different charging and discharging current conditions, The correspondence between the ultrasonic flight time and the state of charge, and then the state of charge of the battery is determined.
  • the principle of the above inventive concept is that for a certain battery, during the calibration process, the current, the state of charge, and the flight time of the ultrasonic wave passing through the battery are all known quantities that can be measured, and the study finds that there is an objective relationship between the three. Correspondence. During the use of the battery, the state of charge is not directly available. According to the above method, the current and the time when the ultrasonic wave passes through the battery are measured, and the state of charge of the battery can be estimated.
  • the flight time of the ultrasonic wave passing through the battery changes, which is the basis for the establishment of the above invention.
  • the reason is that under different states of charge, the chemical composition of the positive and negative materials inside the lithium ion battery is different, and the particles of the positive and negative materials will change in volume with charge and discharge, resulting in a change in the tightness of particle packing inside the electrode sheet.
  • the average speed of sound inside the battery changes, which is manifested by the amplitude of the ultrasonic wave passing through the battery.
  • the ultrasonic wave of the specific frequency and amplitude is passed through the healthy lithium ion battery of various charged states under different charging and discharging current conditions to obtain the amplitude attenuation degree of the ultrasonic wave of the specific frequency and amplitude, thereby obtaining different charging.
  • the amplitude of the lithium ion battery in a healthy state under discharge current conditions, and then, the lithium ion battery of various states of charge under different charging and discharging current conditions with the ultrasonic wave of the specific frequency and amplitude is monitored through the lithium
  • the ultrasonic amplitude of the specific frequency and amplitude of the ion battery is abnormally reduced as compared with that under a healthy state lithium ion battery, it can be known that the lithium ion battery is in a poor health state.
  • a healthy lithium ion battery with various charged states under different charging and discharging current conditions is obtained by ultrasonic waves to obtain a flight time of a specific peak in the ultrasonic wave, thereby obtaining the specific peak under different charging and discharging current conditions.
  • Pass the flight time of a healthy lithium-ion battery pick up
  • the lithium-ion battery with various ultrasonic states in the condition that the ultrasonic waves pass through different charging and discharging currents increases the flight time of the specific peak passing through the lithium ion battery and the abnormal increase in the state of the lithium ion battery under the state of health.
  • the ultrasonic signal passing through the lithium ion battery is recorded by the ultrasonic through the healthy lithium ion battery of various charged states under different charging and discharging current conditions, and the reference acoustic fingerprint is obtained, and then the ultrasonic wave passes through different
  • the lithium ion battery of various states of charge under the condition of charge and discharge current obtains the detected acoustic fingerprint, and the health status of the lithium ion battery can be known when the detected acoustic fingerprint changes by more than the set limit compared with the reference acoustic fingerprint. Not good.
  • the principle of the above inventive concept is that for a certain battery, during the calibration process, the amplitude, waveform and flight time of the ultrasonic wave after passing through the battery are all known quantities that can be measured, and the deterioration of the health state of the battery causes the ultrasonic wave to pass through.
  • the amplitude, waveform and flight time of the battery vary greatly.
  • the health status of the battery does not directly correspond to the physical quantity, but can be reflected by the indirect amount.
  • the amplitude, waveform and flight time of the ultrasonic wave passing through the battery can be measured, which can indirectly reflect the change of the health state of the battery.
  • the amplitude, waveform and flight time of the ultrasonic wave pass through the battery greatly change, it can be advanced in advance. Early warning of batteries with poor health.
  • an apparatus for implementing the method as described above comprising an ultrasonic signal source and an ultrasonic signal receiver, the ultrasonic signal source and the ultrasonic signal receiver being respectively located at a lithium ion to be monitored On both sides of the battery, the ultrasonic signal source is used to transmit ultrasonic waves, and the ultrasonic signal receiver is used to receive and record the amplitude, time of flight, and acoustic fingerprint of the ultrasonic waves.
  • the invention adopts an ultrasonic method to measure the amplitude attenuation degree of the sound wave after propagating in the battery under different charging and discharging states and the flight time (the time when the sound wave is transmitted from the ultrasonic signal source to the ultrasonic signal receiver) from the acoustic angle and
  • the acoustic fingerprint (the waveform after the sound wave passes through the battery) measures the state of charge of the battery and monitors the health of the battery.
  • the invention can more directly obtain the change of the internal electrode during the charging and discharging process of the battery through the ultrasonic wave.
  • the method of the present invention can effectively measure the state of charge of the battery and monitor the health of the battery, and can be applied to various types of lithium batteries of various shapes, and has a good application prospect.
  • FIG. 1 is a schematic diagram of a device for detecting a state of charge and a state of health of a battery according to an embodiment of the present invention
  • Embodiment 2 is a waveform (acoustic fingerprint) of an ultrasonic pulse passing through a battery in a 50% state of charge in Embodiment 1 of the present invention
  • Embodiment 3 is a corresponding relationship between a peak value of an ultrasonic signal and a state of charge of a battery during discharge in Embodiment 1 of the present invention
  • Embodiment 6 is a correspondence relationship between an ultrasonic signal flight time and a battery state of charge in a charging process in Embodiment 1 of the present invention
  • FIG. 7 is a comparison diagram of an acoustic fingerprint of a battery in a state of poor health and an acoustic fingerprint of a battery in a normal state of health in an embodiment of the present invention.
  • the present invention proposes a new method for measuring the state of charge and health of the battery and establishes a corresponding device.
  • the method for monitoring the state of charge of the battery by the amplitude attenuation of the acoustic wave after passing through the lithium battery is: first, the calibration of the battery under different charging and discharging currents and different states of charge, the ultrasonic waves of a specific frequency and amplitude pass through the The amplitude after the battery establishes the corresponding relationship between the amplitude and current of the ultrasonic wave passing through the battery and the state of charge of the battery.
  • the amplitude of the ultrasonic wave of a specific frequency and amplitude after passing through the battery is monitored, and the corresponding relationship between the amplitude and the state of charge obtained at the current obtained during the calibration process is compared, thereby presuming the state of charge of the battery.
  • the method for monitoring the state of charge of the battery by the time of flight of the acoustic wave comprises: first, calibrating the flight time of the ultrasonic wave of the specific frequency and amplitude through the battery under different charging and discharging currents and different states of charge; Establishing a correspondence between the flight time of the ultrasonic wave passing through the battery and the current and the state of charge of the battery. Afterwards, during use, the ultrasonic wave of a specific frequency and amplitude is monitored through the battery or the time of flight, and the correspondence between the flight time and the state of charge of the acoustic wave obtained at the current obtained during the calibration process is compared, thereby presuming the charge of the battery. status.
  • the method for monitoring the health state of the battery by time of flight, amplitude and acoustic fingerprint is as follows: first, after the battery is calibrated under different charging and discharging currents and different charging states, ultrasonic waves of a specific frequency and amplitude pass through the battery. The amplitude, waveform and time of flight extract the amplitude, waveform and time of flight of the ultrasonic wave through the cell and the relative invariants of the corresponding current and state of charge of the battery.
  • the amplitude, waveform and time of flight of the ultrasonic wave of a specific frequency and amplitude after passing through the battery are monitored, and the amplitude of the current obtained during the calibration process is compared,
  • the relative invariant of the waveform or time of flight, the difference between the amplitude, waveform and flight time and the previously extracted invariant is used as an indicator of the health status of the battery.
  • the difference reaches a predetermined value, the battery health condition is determined to be poor and needs to be replaced.
  • the amplitude, waveform and flight time of the ultrasonic wave passing through the battery are all known quantities that can be measured, and the deterioration of the health state of the battery causes the ultrasonic wave to pass through the battery.
  • the health status of the battery does not directly correspond to the physical quantity, but can be reflected by the indirect amount.
  • the amplitude, waveform and flight time of the ultrasonic wave passing through the battery can be measured, which can indirectly reflect the change of the health state of the battery.
  • the amplitude, waveform and flight time of the ultrasonic wave pass through the battery greatly change, it can be advanced. Alerts on batteries that are not in good health.
  • the principle of the invention is that the charging and discharging process of the lithium ion battery is essentially the insertion and extraction of lithium ions between the positive and negative electrodes.
  • the positive and negative electrodes have different lithium contents in different pool states, so that the physical density such as electrode density, Young's modulus and crystal structure are different.
  • the changes in the acoustic parameters of the battery can directly reflect the physical changes of the internal electrodes of the battery. Therefore, the battery charge state and health state of the battery can be estimated by measuring changes in these acoustic parameters.
  • FIG. 1 is a schematic diagram of a device for detecting a state of charge and a state of health of a battery according to an embodiment of the present invention. As can be seen from the figure, it includes an ultrasonic signal source 1, a battery 2, and an ultrasonic signal receiver 3, and the battery 2 is a lithium ion battery to be monitored.
  • the ultrasonic signal source 1 and the ultrasonic signal receiver 3 are respectively located on two sides of a lithium ion 2 battery to be monitored, and the ultrasonic signal source is used to transmit ultrasonic waves, and the ultrasonic signal receiver is configured to receive and record the amplitude of the ultrasonic waves, Flight time and acoustic fingerprints.
  • the ultrasonic signal source and the ultrasonic signal receiver are respectively attached to the soft ternary material - graphite lithium ion
  • the upper and lower surfaces of the battery are similar to those shown in Figure 1.
  • An ultrasonic pulse signal is emitted by the ultrasonic signal source, and the ultrasonic signal passing through the battery is monitored by the ultrasonic signal receiver on the other side in the transmission mode.
  • the battery is charged and discharged with a battery tester at a current of 5 A, and the waveform (ie, acoustic fingerprint) of the ultrasonic pulse passing through the battery under different states of charge is recorded in real time, as shown in FIG. 2, and FIG. 2 is an embodiment of the present invention.
  • the ultrasonic pulse passes through the waveform (sound fingerprint) of the battery, and the information of the strongest peak amplitude and the flight time of the strongest peak ultrasonic wave is extracted from the acoustic fingerprint.
  • FIG. 3 is the same as the peak of the ultrasonic signal during discharge in the embodiment of the present invention.
  • the correspondence of the state of charge is as shown in FIG. 3, and FIG. 3 is the same as the peak of the ultrasonic signal during discharge in the embodiment of the present invention. The correspondence of the state of charge.
  • FIG. 4 is a peak of the ultrasonic signal during charging in the embodiment of the present invention. Correspondence of electrical states.
  • the lithium ion battery was normally cycled for 50 cycles between 2.8V and 4.2V, and the corresponding relationship between the strongest peak amplitude (amplitude attenuation degree) and the state of charge after the ultrasonic wave passed through the battery did not change significantly.
  • FIG. 5 is the correspondence between the flight time of the ultrasonic signal and the state of charge of the battery during the discharge process in the embodiment of the present invention.
  • Relationship, FIG. 6 is a correspondence relationship between the flight time of the ultrasonic signal and the state of charge of the battery during charging in the embodiment of the present invention. It can be seen from Fig. 5 and Fig. 6 that under a certain charge and discharge current, there is a certain correspondence between the flight time of the ultrasonic wave and the state of charge. In the subsequent battery use process, the current is charged and discharged with a current of 5 A, and the measurement is transparent. Ultrasonic over lithium ion battery The flight time of the wave, and then find the corresponding points in Fig. 5 and Fig. 6, respectively, and the state of charge of the battery can also be obtained.
  • Example 1 The battery in Example 1 was overcharged to 4.25 V and cycled for 5 cycles to damage the health of the battery to a certain extent, and the full charge capacity of the battery was reduced to 60% of the nominal capacity. Then, the device shown in Figure 1 was used to test the health. A battery with a damaged state.
  • the test found that the amplitude of the strongest peak transmitted through the ultrasound was reduced to one-fifth of that of a healthy battery. Therefore, it can be seen that during the use of the battery, it is found that the amplitude of the strongest peak transmitted through the ultrasonic wave is abnormally decreased, indicating that the battery is in a poor state of health.
  • Example 1 The battery in Example 1 was normally circulated for 500 cycles at a current of 5 A, the battery was aged, the state of health was destroyed to some extent, and the full charge capacity of the battery was reduced to 80% of the nominal capacity, and then tested by the apparatus shown in FIG. Aging battery.
  • FIG. 7 is a comparison of the acoustic fingerprint of the battery with poor health in the embodiment of the present invention and the acoustic fingerprint of the battery in the normal healthy state.
  • the solid line is the acoustic fingerprint under normal health condition of the battery
  • the dotted line is the acoustic fingerprint after the battery is aging.
  • the method of the present invention is different from the traditional measurement of the state of charge of the battery depending on the electrical parameters.
  • the present invention first uses ultrasonic means to measure the state of charge and health of the battery pool by measuring the change of the acoustic parameters of the battery.
  • the measurement process is not subject to many influencing factors like electrical parameters, and the test results are relatively accurate.

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Abstract

一种监测锂离子电池（2）荷电状态和健康状态的方法以及装置，首先，以声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池（2），以获得声学参数，进而建立声学参数分别与锂离子电池（2）荷电状态和健康状态的对应关系，接着，通过监测锂离子电池（2）的声学参数，再根据声学参数分别与锂离子电池（2）荷电状态和健康状态的对应关系，判断锂离子电池（2）的荷电状态和健康状态。基于锂离子电池（2）的声学参数的变化监测荷电状态与健康状态，提高了荷电状态的测量精度，能够及时提示健康状态。

Description

一种监测锂离子电池荷电状态和健康状态的方法及其装置 [技术领域]
本发明属于涉及电池技术领域，特别涉及电池荷电状态与健康状态的监测方法和装置。
[背景技术]
电池的荷电状态，也叫剩余电量，代表的是电池使用一段时间或长期搁置不用后的剩余容量与其完全充电状态的容量的比值，简称SOC。电池的荷电状态和其电流、电压等可测量特性之间是一种非常复杂的非线性关系，且随电池使用环境和寿命变化，很难直接测得，因此，如何准确地进行电池荷电状态的测量是一个国际性的难题。
电池的健康状态是电池同其理想状态相比较的一个品质因素，简称SOH。通常电池的健康状态随着使用时间与次数的增加而降低。通常，我们会给电池健康状态设定一个阈值，当电池健康状态低于此阈值即代表电池不适合再继续使用。由于电池的健康状态并不存在一个具体的对应的物理量，因此工业界对于如何确立电池健康状态的方法各不相同，通常采用电池内阻、容量、电压、自放电快慢、充电能力、充放电圈数等电学参数的变化来确立电池的健康状态。而在实际使用中，电池还会因为过充、过热、短路、机械破坏等非正常使用原因，出现胀气、漏夜等健康状态问题，如果不及时发现，可能导致电池燃烧甚至***。
电池的荷电状态无法被直接测量，人们通常通过离线和在线两种模式测量其他物理量对电池荷电状态进行估测。离线模式下，电池以恒定的速率充放电，对电量进行积分。这种模式能非常精确的估测电池荷电状态但耗时长且测试过程中电池的工作必须中断。因此人们倾向于在线测量的模 式。当前在线测量模式主要有化学法、电压法、电流积分法、内阻法、卡尔曼滤波法、神经网络法等间接估测电池荷电状态的方法。
化学法仅适用于能接触到电解液的电池，例如非密封式铅酸电池通过测定其电解液的PH值与密度来确定其荷电状态。
电压法通过对比已知的充放电电压荷电状态曲线，将电压值转换为电池的荷电态，然而锂离子电池的电压往往比较稳定，随荷电状态不同而变化的幅度很小，且电池电压受电流、温度、寿命的影响非常大，导致这种方法测得的荷电状态非常不准确。电压法可以通过引入电流、温度修正系数的方法提高精确度，但精确度依然不高。
电流积分法又称为安时积分法或库伦计数，通过将电池电流对时间进行积分来计算电池的荷电状态。这种方法缺乏参照点，无法测得电池因为自放电而产生的容量衰减，且其误差具有累积性，会随着时间的增加而逐渐增大。因此，采用这种方法时需要定期对电池荷电状态进行重新标定，例如在充满电后将电池荷电状态重新设为100％。
内阻法有交流内阻和直流内阻之分，它们都与电池荷电状态有密切关系。电池交流阻抗是电池电压与电流之间的传递函数，是一个复数变量，表示电池对交流电的反抗能力，要用交流阻抗仪来测量。电池交流阻抗受温度影响大，是在电池处于静置后的开路状态还是在电池充放电过程中进行交流阻抗测量，存在争议。直流内阻表示电池对直流电的反抗能力，在实际测量中，将电池从开路状态开始恒流充电或放电，相同时间内负载电压和开路电压的差值除以电流值就是直流内阻。对于铅蓄电池在放电后期，直流内阻明显增大，可用来估计电池荷电状态；镍氢电池和锂离子电池直流内阻变化规律与铅蓄电池不同，应用较少。
卡尔曼滤波法的核心思想是对动力***的状态做出最小方差意义上的最优估计。卡尔曼滤波法将电池被看成一个动力***，电池荷电状态是***的一个内部状态。估计电池荷电状态算法的核心，是一套包括电池荷电 状态估计值和反映估计误差的、协方差矩阵的递归方程，协方差矩阵用来给出估计误差范围。该方法适用于各种电池，尤其是电池电流波动比较剧烈的混合动力电动汽车电池的荷电状态的估计。相比于其他方法，它不仅给出了电池荷电状态的估计值，还给出了电池荷电状态的估计误差。
神经网络法认为，电池是高度非线性的***，在它充放电过程中很难建立准确的数学模型。神经网络具有非线性的基本特性，具有并行结构和学习能力，对于外部激励，能给出相应的输出，能够模拟电池动态特性，来估计电池荷电状态。神经网络法适用于各种电池，缺点是需要大量的参考数据进行训练，估计误差受训练数据和训练方法的影响很大。
总的来说，当前的电池的荷电状态与健康状态的测试方法都基于电流、电压、阻抗等电学参数的测量，却都因为电池的电学参数影响因素复杂，无法得到足够可信的结果。
因此，如果能通过电学参数以外的其他电池特性参数对荷电状态与健康状态进行测量，则对提高荷电状态测量精度、及时提示健康状态具有重要意义。
[发明内容]
针对现有技术的以上缺陷或改进需求，本发明提供了一种监测锂离子电池荷电状态和健康状态的方法，其目的在于，建立声学参数分别与锂离子电池荷电状态和健康状态的对应关系，进而利用声学参数监测锂离子电池的荷电状态和健康状态，由此解决现有技术中基于电学参数监测锂离子电池电量和健康状态结果可靠性不佳的问题。
为实现上述目的，按照本发明的一个方面，提供了一种监测锂离子电池荷电状态和健康状态的方法，
首先，以声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得声学参数，进而建立声学参数分别与锂离子电池荷电状态和健 康状态的对应关系，
接着，通过监测锂离子电池的声学参数，再根据所述的声学参数分别与锂离子电池荷电状态和健康状态的对应关系，判断锂离子电池的荷电状态和健康状态，
其中，所述声学参数包括：声波在锂离子电池中传播后的振幅衰减程度、飞行时间以及声指纹，所述飞行时间是指声波从超声信号源到超声信号接收器的用时。所述超声信号源和超声信号接收器均连接同一锂离子电池，所述声指纹是指声波穿过锂离子电池后的波形。
进一步的，首先，以特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得该特定频率与振幅的超声波的振幅衰减程度，进而建立不同充放电电流条件下的振幅衰减程度与锂离子电池荷电状态的对应关系，获得标定图谱，
接着，在锂离子电池的使用过程中，监测不同充放电电流条件下以该特定频率与振幅的超声波在穿过锂离子电池后的振幅衰减程度，根据所述标定图谱，获得不同充放电电流条件下，该特定频率与振幅的超声波振幅衰减程度与荷电状态的对应关系，进而判断出电池的荷电状态。
以上发明构思的原理在于：对于一个确定的电池，在标定过程中，电流、荷电状态、超声波穿过电池后的振幅均是可以测得的已知量，而研究发现这三者之间有客观的对应关系。在电池的使用过程中，荷电状态是无法直接得到的。按以上的方法，测得电流与超声波穿过电池后的振幅，就可以推测电池的荷电状态。
不同荷电状态下，超声波穿过电池后的振幅会发生变化，这是以上发明内容成立的基础。其原因在于不同荷电状态下，锂离子电池内部的正、负极材料化学组成是不同的，且正、负极材料颗粒会随着充放电过程发生体积变化，导致电极片内部颗粒堆积紧密程度改变，进而导致电池整体对声波能量的吸收率发生改变，表现为超声波穿过电池后的振幅会发生变化。
进一步的，首先，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得飞行时间，进而建立不同充放电电流条件下的飞行时间与锂离子电池荷电状态的对应关系，获得标定图谱，接着，在锂离子电池的使用过程中，监测不同充放电电流条件下超声波穿过锂离子电池的飞行时间，根据所述标定图谱，获得不同充放电电流条件下，该超声波飞行时间与荷电状态的对应关系，进而判断出电池的荷电状态。
以上发明构思的原理在于：对于一个确定的电池，在标定过程中，电流、荷电状态、超声波穿过电池的飞行时间均是可以测得的已知量，且研究发现三者之间有客观的对应关系。在电池的使用过程中，荷电状态是无法直接得到的。按以上的方法，测得电流与超声波穿过电池的时间，就可以推测电池的荷电状态。
不同荷电状态下，超声波穿过电池的飞行时间会发生变化，这是以上发明内容成立的基础。其原因在于，不同荷电状态下，锂离子电池内部的正、负极材料化学组成是不同的，且正、负极材料颗粒会随着充放电进行发生体积变化，导致电极片内部颗粒堆积紧密程度改变，进而导致电池内部的平均声速发生改变，表现为超声波穿过电池后的振幅会发生变化。
进一步的，首先，以特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，以获得该特定频率与振幅的超声波的振幅衰减程度，进而获得不同充放电电流条件下的在锂离子电池健康状态下的振幅，接着，以该特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，在监测到穿过锂离子电池的该特定频率与振幅的超声波振幅与健康状态锂离子电池下相比异常减小时，能获知锂离子电池健康状态不佳。
进一步的，首先，以超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，以获得该超声波中特定波峰的飞行时间，进而获得该特定波峰在不同充放电电流条件下穿过健康锂离子电池的飞行时间，接 着，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，在监测到穿过锂离子电池的所述特定波峰的飞行时间与健康状态锂离子电池下相比异常增加时，能获知锂离子电池健康状态不佳。
进一步的，首先，以超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，记录穿过锂离子电池后的超声波信号，获得参考声指纹，接着，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，获得检测声指纹，在所述检测声指纹与所述参考声指纹相比变化幅度超过设定限度时，能获知锂离子电池健康状态不佳。
以上发明构思的原理在于：对于一个确定的电池，在标定过程中，超声波穿过电池后的振幅、波形与飞行时间均是可以测得的已知量，电池健康状态的恶化会引起超声波穿过电池后的振幅、波形与飞行时间的巨大变化。电池的健康状态无直接对应物理量，但可以通过间接量来反映。按以上方法，测得超声波穿过电池后的振幅、波形与飞行时间，就可以间接反映电池健康状态的变化，当超声波穿过电池后的振幅、波形与飞行时间发生大幅度变化时可以提前对健康状态不佳的电池进行预警。
按照本发明的另一个方面，还提供一种实现如上所述方法的装置，其包括超声信号源和超声信号接收器，所述超声信号源和所述超声信号接收器分别位于待监测的锂离子电池两侧，所述超声信号源用于发射超声波，所述超声信号接收器用于接收并记录超声波的振幅、飞行时间以及声指纹。
总体而言，通过本发明所构思的以上技术方案与现有技术相比，能够取得下列有益效果：
本发明采用超声的方法，从声学角度通过测量不同充放电电流以及不同荷电状态下声波在电池中传播后的振幅衰减程度、飞行时间(声波从超声信号源到超声信号接收器的用时)以及声指纹(声波穿过电池后的波形)对电池的荷电状态进行测量并对电池的健康状态进行监测。
本发明通过超声能够更为直接的得到电池充放电过程中内部电极的变 化，从而从一个新的有别于电学参数测量的途径检测到电池荷电状态与健康状态的数据。实验证实，利用本发明的方法，能有效对电池荷电状态进行测量并对电池的健康状态进行监测，能够适用于各种形状各种类型的锂电池，具有良好的应用前景。
[附图说明]
图1是本发明实施例中电池荷电状态和健康状态的检测装置示意图；
图2是本发明实施例1中50％荷电状态下超声波脉冲穿过电池后的波形(声指纹)；
图3是本发明实施例1中放电过程中超声信号峰值同电池荷电状态的对应关系；
图4是本发明实施例1中充电过程中超声信号峰值同电池荷电状态的对应关系；
图5是本发明实施例1中放电过程中超声信号飞行时间同电池荷电状态的对应关系；
图6是本发明实施例1中充电过程中超声信号飞行时间同电池荷电状态的对应关系；
图7是本发明实施例中健康状态不佳的电池的声学指纹同正常健康状态电池声学指纹的对比图。
在所有的附图中，相同的附图标记自始至终表示相同元件或者结构，其中，
1-超声信号源  2-电池  3-超声信号接收器
[具体实施方式]
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此外，下面所描述的 本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
在大量的研究中发现，穿过锂离子电池的超声波衰减幅度随电池荷电状态的增加而减少，超声波的飞行时间随电池荷电态的增加而增加，同时对于同一电池，不同荷电状态下的波峰位置与波形相似(可以提取声指纹)。这就意味着我们可以利用超声的方式来对电池的荷电状态以及健康状态进行估测。因此，基于上述规律，本发明提出了一种全新的电池荷电状态和健康状态的测量方法并建立了相应装置。
本发明方法中，通过声波穿过锂电池后的振幅衰减程度监测电池荷电状态的方法在于：首先，标定电池在不同充放电电流以及不同荷电状态下，特定频率与振幅的超声波穿过该电池后的振幅，建立起超声波穿过该电池后的振幅与电流和电池荷电状态的对应关系。之后，在使用过程中，监测特定频率与振幅的超声波在穿过电池后的振幅，对比标定过程中得到的该电流下振幅与荷电状态的对应关系，进而推测电池的荷电状态。
本发明方法中，所述通过声波的飞行时间监测电池荷电状态的方法在于：首先，标定电池在不同充放电电流以及不同荷电状态下，特定频率与振幅的超声波穿过该电池的飞行时间，建立起超声波穿过该电池的飞行时间与电流和电池荷电状态的对应关系。之后，在使用过程中，监测特定频率与振幅的超声波在穿过电池的或飞行时间，对比标定过程中得到的该电流下声波的飞行时间与荷电状态的对应关系，进而推测电池的荷电状态。
本发明方法中，所述通过飞行时间、振幅以及声指纹监测电池健康状态的方法在于：首先，标定电池在不同充放电电流以及不同荷电状态下，特定频率与振幅的超声波穿过该电池后的振幅、波形与飞行时间，提取出超声波穿过该电池后的振幅、波形与飞行时间与对应电流和电池荷电状态的相对不变量。之后，在使用过程中，监测特定频率与振幅的超声波在穿过电池后的振幅、波形与飞行时间，对比标定过程中得到的该电流下振幅、 波形或飞行时间的相对不变量，以振幅、波形与飞行时间同之前提取出的不变量间的差异作为电池健康状态的指示参数，当差异达到预定值时认定电池健康状态不佳，需要更换。以上设计的原理在于：对于一个确定的电池，在标定过程中，超声波穿过电池后的振幅、波形与飞行时间均是可以测得的已知量，电池健康状态的恶化会引起超声波穿过电池后的振幅、波形与飞行时间的巨大变化。电池的健康状态无直接对应物理量，但可以通过间接量来反映。按我们的方法，测得超声波穿过电池后的振幅、波形与飞行时间，就可以间接反映电池健康状态的变化，当超声波穿过电池后的振幅、波形与飞行时间发生大幅度变化时可以提前对健康状态不佳的电池进行预警。
本发明的原理为：锂离子电池充放电过程本质是锂离子在正负极的嵌入与脱出。不同的池荷电状态下正负极拥有不同的锂含量，从而其电极密度、杨氏模量与晶体结构结构等物理量不同。而电池的声学参数(比如声波振幅衰减程度，声波飞行时间，穿过电池后的波峰形状)的变化，可以直接反映电池内部电极的物理变化。因此通过测量这些声学参数的变化能估测电池的池荷电状态与健康状态。
图1为本发明实施例中电池荷电状态和健康状态的检测装置示意图，由图可知，其包括超声信号源1、电池2以及超声信号接收器3，电池2为待监测的锂离子电池，所述超声信号源1和所述超声信号接收器3分别位于待监测的锂离子2电池两侧，所述超声信号源用于发射超声波，所述超声信号接收器用于接收并记录超声波的振幅、飞行时间以及声指纹。
更为详细地，为了更进一步说明本发明方法和装置，下面结合实施例更进一步阐述如下。
实施例1
将超声信号源和超声信号接收器分别贴在软包三元材料-石墨锂离子 电池(标称容量5000mAh，正常充放电区间为2.8-4.2V)的上下表面，类似如图1所示。由超声信号源发出一个超声脉冲信号，采用透过模式通过另一面的超声信号接收器监测穿过电池的超声信号。
用电池测试仪以5A电流对电池进行充放电，并实时记录不同荷电状态下超声波脉冲穿过该电池后的波形(也即声指纹)，如图2所示，图2是本发明实施例中50％荷电状态下超声波脉冲穿过电池后的波形(声指纹)，从声指纹中提取到最强峰振幅、最强峰超声波的飞行时间等信息。
放电过程中，超声波穿过该电池后的最强峰振幅(振幅衰减程度)与荷电状态的对应关系如附图3所示，图3是本发明实施例中放电过程中超声信号峰值同电池荷电状态的对应关系。
充电过程中，超声波穿过该电池后的最强峰振幅(振幅衰减程度)与荷电状态的对应关系如图4所示，图4是本发明实施例中充电过程中超声信号峰值同电池荷电状态的对应关系。
之后，锂离子电池在2.8V～4.2V之间正常循环50圈，超声波穿过该电池后的最强峰振幅(振幅衰减程度)与荷电状态的对应关系没有明显变化。
由图3、图4可知，在一定的充放电电流下，透过超声波的振幅随荷电状态呈单调变化，在后续电池使用过程中，以5A电流充、放电，同时测得透过超声波的最强峰振幅，然后在图3、图4中寻找对应的点，即可得到电池的荷电状态。
此外，依据同样发方法可知，超声波的飞行时间与荷电状态的对应关系如图5、图6所示，图5是本发明实施例中放电过程中超声信号飞行时间同电池荷电状态的对应关系，图6是本发明实施例中充电过程中超声信号飞行时间同电池荷电状态的对应关系。由图5和图6可知，在一定的充放电电流下，超声波的飞行时间与荷电状态的也存在一定的对应关系，在后续电池使用过程中，以5A电流充、放电，同时测得透过锂离子电池的超声 波的飞行时间，然后在图5、图6中分别寻找对应的点，也可以得到电池的荷电状态。
实施例2
将实施例1中的电池过充至4.25V，循环5圈，使电池的健康状态受到一定程度破坏，电池满充容量下降为标称容量的60％，之后用图1所示的装置测试健康状态受损的电池。
试验结果发现，透过超声波最强峰的振幅降低为健康电池的五分之一。因此可知，在电池使用过程中，发现透过超声波最强峰的振幅出现异常下降，则表明电池健康状态不佳。
实施例3
将实施例1中的电池在5A的电流下正常循环500圈，使电池老化，健康状态受到一定程度破坏，电池满充容量下降为标称容量的80％，之后用图1所示的装置测试老化的电池。
试验结果可知，透过超声波的波形(声指纹)发生了明显改变，如图7所示，图7是本发明实施例中健康状态不佳的电池的声学指纹同正常健康状态电池声学指纹的对比图。实线为电池正常健康状态下声指纹，虚线为电池老化后的声指纹，电池老化后健康状态不佳时，第四和第六波峰出现***且整体异常左移。所以，对比待检测电池的透过超声波波形与健康电池透过超声波波形，即可得待检测电池是否因为老化而健康状态不佳。
总而言之，本发明方法有别于传统的依赖于电学参数对电池荷电状态的测量，本发明首次运用超声的手段通过测量电池的声学参数变化来对电池池荷电状态与健康状态进行测量，其测量过程不会如同电学参数般受到诸多影响因素，检测结果相对比较准确。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已， 并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (7)

  1. 一种监测锂离子电池荷电状态和健康状态的方法，其特征在于，
    首先，以声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得声学参数，进而建立声学参数分别与锂离子电池荷电状态和健康状态的对应关系，
    接着，通过监测锂离子电池的声学参数，再根据所述的声学参数分别与锂离子电池荷电状态和健康状态的对应关系，判断锂离子电池的荷电状态和健康状态，
    其中，所述声学参数包括：声波在锂离子电池中传播后的振幅衰减程度、飞行时间以及声指纹，
    所述飞行时间是指声波从超声信号源到超声信号接收器的用时。所述超声信号源和超声信号接收器均连接同一锂离子电池，
    所述声指纹是指声波穿过锂离子电池后的波形。
  2. 如权利要求1所述的一种监测锂离子电池荷电状态和健康状态的方法，其特征在于，
    首先，以特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得该特定频率与振幅的超声波的振幅衰减程度，进而建立不同充放电电流条件下的振幅衰减程度与锂离子电池荷电状态的对应关系，获得标定图谱，
    接着，在锂离子电池的使用过程中，监测不同充放电电流条件下以该特定频率与振幅的超声波在穿过锂离子电池后的振幅衰减程度，根据所述标定图谱，获得不同充放电电流条件下，该特定频率与振幅的超声波振幅衰减程度与荷电状态的对应关系，进而判断出电池的荷电状态。
  3. 如权利要求1所述的一种监测锂离子电池荷电状态和健康状态的方 法，其特征在于，
    首先，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，以获得飞行时间，进而建立不同充放电电流条件下的飞行时间与锂离子电池荷电状态的对应关系，获得标定图谱，
    接着，在锂离子电池的使用过程中，监测不同充放电电流条件下超声波穿过锂离子电池的飞行时间，根据所述标定图谱，获得不同充放电电流条件下，该超声波飞行时间与荷电状态的对应关系，进而判断出电池的荷电状态。
  4. 如权利要求1所述的一种监测锂离子电池荷电状态和健康状态的方法，其特征在于，
    首先，以特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，以获得该特定频率与振幅的超声波的振幅衰减程度，进而获得不同充放电电流条件下的在锂离子电池健康状态下的振幅，
    接着，以该特定频率与振幅的超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，在监测到穿过锂离子电池的该特定频率与振幅的超声波振幅与健康状态锂离子电池下相比异常减小时，能获知锂离子电池健康状态不佳。
  5. 如权利要求1所述的一种监测锂离子电池荷电状态和健康状态的方法，其特征在于，
    首先，以超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，以获得该超声波中特定波峰的飞行时间，进而获得该特定波峰在不同充放电电流条件下穿过健康锂离子电池的飞行时间，
    接着，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，在监测到穿过锂离子电池的所述特定波峰的飞行时间与健康状态锂离子电池下相比异常增加时，能获知锂离子电池健康状态不佳。
  6. 如权利要求1所述的一种监测锂离子电池荷电状态和健康状态的方法，其特征在于，
    首先，以超声波穿过不同充放电电流条件下的各种荷电状态的健康锂离子电池，记录穿过锂离子电池后的超声波信号，获得参考声指纹，
    接着，以超声波穿过不同充放电电流条件下的各种荷电状态的锂离子电池，获得检测声指纹，在所述检测声指纹与所述参考声指纹相比变化幅度超过设定限度时，能获知锂离子电池健康状态不佳。
  7. 一种实现如权利要求1-6之一所述的方法的装置，其特征在于，其包括超声信号源和超声信号接收器，所述超声信号源和所述超声信号接收器分别位于待监测的锂离子电池两侧，
    所述超声信号源用于发射超声波，所述超声信号接收器用于接收并记录超声波的振幅、飞行时间以及声指纹。
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