CN116879760A

CN116879760A - Historical overcharge fault diagnosis method and device for retired power battery

Info

Publication number: CN116879760A
Application number: CN202311140207.4A
Authority: CN
Inventors: 郑伟鹏; 丁柏栋; 李艳芹; 叶利强; 傅婷婷; 胡银平
Original assignee: Shenzhen Jiecheng Nickel Cobalt New Energy Technology Co ltd
Current assignee: Shenzhen Jiecheng Nickel Cobalt New Energy Technology Co ltd
Priority date: 2023-09-06
Filing date: 2023-09-06
Publication date: 2023-10-13
Anticipated expiration: 2043-09-06
Also published as: CN116879760B

Abstract

The invention relates to the field of battery overcharge, and discloses a historical overcharge fault diagnosis method and device for retired power batteries, wherein the method comprises the following steps: calculating the charging speed of the retired power battery, and analyzing whether the charging time of the retired power battery is abnormal or not; constructing a charging process model of the retired power battery, calculating the charging multiplying power of the retired power battery, and carrying out model adjustment on the charging process model; calculating a battery voltage of the retired power battery, and identifying a first historical overcharge fault of the retired power battery; acquiring temperature data before echelon utilization, constructing a temperature curve of the temperature data, identifying a first temperature maximum value of the temperature curve, performing curve adjustment on the temperature curve, and identifying a second temperature maximum value of the adjustment curve; identifying a second historical overcharge fault using the first temperature maxima and the second temperature maxima; a final overcharge fault of the retired power cell is determined. The invention can diagnose whether the history of the retired power battery has overcharge faults.

Description

Historical overcharge fault diagnosis method and device for retired power battery

Technical Field

The invention relates to the field of battery overcharge, in particular to a method and a device for diagnosing historical overcharge faults of retired power batteries.

Background

At present, fault detection of the retired power battery is an indispensable link when the retired power battery is used in a cascade, and often comprises two aspects of appearance defect detection and internal defect detection of the retired power battery, but the defect detection of the retired power battery with overcharging faults and capacity meeting the use condition is lacking, because the retired power battery with the capacity meeting the use condition can still be used continuously, and the overcharging faults are the problem that the retired power battery is gradually developed after being put into use.

In practice, the historical usage condition data of the retired battery cannot be obtained under most conditions, so that whether the history of the retired power battery has an overcharge fault or not cannot be judged by utilizing the historical data, hidden danger exists when the battery is used in a gradient manner, and therefore, the requirement for diagnosing whether the retired power battery has the history overcharge fault or not is urgent.

Disclosure of Invention

In order to solve the problems, the invention provides a method and a device for diagnosing historical overcharge faults of a retired power battery, which can diagnose whether the historical overcharge faults of the retired power battery exist.

In a first aspect, the present invention provides a method for diagnosing an overcharge fault of a retired power battery, comprising:

Collecting battery capacity and charging current of a retired power battery, calculating the charging speed of the retired power battery based on the battery capacity and the charging current, and analyzing whether the charging time of the retired power battery is abnormal or not by utilizing the charging speed;

when the charging time of the retired power battery is abnormal, a charging process model of the retired power battery is built based on the lithium ion concentration of the retired power battery, the charging multiplying power of the retired power battery is calculated based on the charging current, and the charging process model is subjected to model adjustment by utilizing the charging multiplying power to obtain an adjustment model;

calculating the battery voltage of the retired power battery by using the adjustment model, and judging whether the retired power battery has a first historical overcharge fault by using the battery voltage;

if the temperature data exists, acquiring the acquired temperature data of the retired power battery, constructing a temperature curve of the temperature data, identifying a first temperature maximum value in the temperature curve, performing curve adjustment on the temperature curve to obtain an adjustment curve, and identifying a second temperature maximum value in the adjustment curve;

judging whether the retired power battery has a second historical overcharge fault or not by utilizing the first temperature maximum value and the second temperature maximum value according to the temperature curve and the adjustment curve;

And determining a final historical overcharge fault of the retired power battery by utilizing the first historical overcharge fault and the second historical overcharge fault.

In a possible implementation manner of the first aspect, the calculating, based on the battery capacity and the charging current, a charging speed of the retired power battery includes:

based on the battery capacity and the charging current, calculating a charging speed of the retired power battery using the following formula:

wherein ,represents the charging speed at time t +.>Represents the charging current at time t +.>The battery capacity at time t is shown.

In a possible implementation manner of the first aspect, the analyzing, with the charging speed, whether a charging time of the retired power battery is abnormal includes:

calculating the historical charging speed of the retired power battery by using the following formula:

wherein ,representing the historical charging speed,/->Representing the battery remaining capacity of the retired power battery at the end of charging,/for the battery>Representing the battery remaining capacity of the retired power battery at the beginning of charging +.>Representing the surplus capacity of said retired power cell from +.>Fill to->Is a total length of time of (2);

calculating the current charging time corresponding to the charging speed by using the following formula:

wherein ,representing the current charging time,/or->Represents the charging speed at time t +.>Representing the battery remaining capacity of the retired power battery at the end of charging,/for the battery>Representing the battery remaining capacity of the retired power battery at the beginning of charging +.>Indicating the moment of the retired power battery at the beginning of charging +.>Indicating the moment when the charging of the retired power battery is terminated;

based on the current charging time, a speed average value of the charging speed is calculated using the following formula:

wherein ,representing the speed average,/->Representing the current charging time,/or->The charging speed at time t is represented;

when the absolute value of the difference between the historical charging speed and the speed average value is larger than a preset difference value, judging that the charging time of the retired power battery is abnormal;

and when the absolute value of the difference between the historical charging speed and the speed average value is not larger than the preset difference value, judging that the charging time of the retired power battery is not abnormal.

In one possible implementation manner of the first aspect, the constructing a charging process model of the retired power battery based on a lithium ion concentration of the retired power battery includes:

Based on the lithium ion concentration of the retired power battery, the solid phase potential of the retired power battery is calculated using the following formula:

wherein ,represents the positive potential of the solid phase potential, < >>Represents the negative electrode potential among the solid phase potentials,represents the potential of the positive electrode at a reference temperature equal to 298.15K and with an open circuit, +.>Represents the potential of the negative electrode at a reference temperature equal to 298.15K and with the circuit open,/for>Represents the solid-phase lithium ion concentration inside the particles of the positive electrode,/->Represents the solid-phase lithium ion concentration inside the particles of the negative electrode,/->Represents the maximum solid-phase lithium ion concentration of the positive electrode, < >>Represents the maximum solid-phase lithium ion concentration of the negative electrode, < >>//>Represents the ratio of solid-phase lithium ions intercalated in the positive electrode to full-scale solid-phase lithium ions intercalated in the positive electrode, +.>//>Represents the ratio of the solid-phase lithium ion intercalated by the negative electrode to the full-scale solid-phase lithium ion intercalated by the negative electrode, +.>Represents solid phase lithium ion concentration, ">Indicating solid phase,/->Representing the positive pole of the retired power battery, < >>Negative pole of the retired power battery, < >>Abbreviations, i.e., reference symbols, representing Reference;

based on the solid phase potential, a charging process model of the retired power battery is constructed using the following formula:

wherein ,representing the charging process model,/->Represents the positive potential of the solid phase potential, < >>Represents the negative potential of the solid phase potential, < >>Indicating overvoltage of positive electrode, +.>Indicating the overvoltage of the negative electrode,represents the liquid phase potential of the positive electrode, +.>Represents the liquid phase potential of the negative electrode, +.>Represents the coordinates of the positive electrode in the horizontal direction, +.>Represents the coordinates of the negative electrode in the horizontal direction, +.>Representing the liquid phase.

In a possible implementation manner of the first aspect, the calculating, based on the charging current, a charging rate of the retired power battery includes:

based on the charging current, the charging rate of the retired power battery is calculated using the following formula:

wherein ,represents the charge rate of the positive electrode in the charge rates,/->Represents the charge rate of the negative electrode in the charge rates,/->Representing the charging current, +.>Indicate time of day->Represents the positive electrode capacity of the battery, < >>The negative electrode capacity of the battery is represented.

In a possible implementation manner of the first aspect, the performing model adjustment on the charging process model by using the charging multiplying power to obtain an adjustment model includes:

based on the charging rate, the potential of the solid phase in the charging process model is adjusted by using the following formula to obtain an adjusted potential:

wherein ,represents the positive potential in the adjustment potential, < >>Represents the negative electrode potential in the adjustment potential,represents the potential of the positive electrode at a reference temperature equal to 298.15K and with an open circuit, +.>Represents the potential of the negative electrode at a reference temperature equal to 298.15K and with the circuit open,/for>Represents the solid-phase lithium ion concentration inside the particles of the positive electrode,/->Represents the solid-phase lithium ion concentration inside the particles of the negative electrode,/->Represents the maximum solid-phase lithium ion concentration of the positive electrode, < >>Represents the maximum solid-phase lithium ion concentration of the negative electrode, < >>//>Represents the ratio of solid-phase lithium ions intercalated in the positive electrode to full-scale solid-phase lithium ions intercalated in the positive electrode, +.>//>Represents the ratio of the solid-phase lithium ion intercalated by the negative electrode to the full-scale solid-phase lithium ion intercalated by the negative electrode, +.>Represents solid phase lithium ion concentration, ">Indicating solid phase,/->Representing the positive pole of the retired power battery, < >>Negative pole of the retired power battery, < >>Abbreviations indicating Reference, i.e. Reference symbols, ">Represents the charge rate of the positive electrode in the charge rates,/->Representing a charging rate of the negative electrode among the charging rates;

the tuning model is constructed using the tuning potentials.

In one possible implementation manner of the first aspect, the identifying, with the battery voltage, a first historical overcharge fault of the retired power battery includes:

Acquiring positive electrode capacity and negative electrode capacity corresponding to the battery voltage;

constructing a voltage-positive electrode curve between the battery voltage and the positive electrode capacity, and constructing a voltage-negative electrode curve between the battery voltage and the negative electrode capacity;

identifying a voltage curve trend, an anode curve trend and a cathode curve trend of the battery when the voltage of the battery is larger than a preset standard voltage from the voltage-anode curve and the voltage-cathode curve;

and identifying a first historical overcharge fault of the retired power battery by utilizing the voltage curve trend, the positive curve trend and the negative curve trend.

In a possible implementation manner of the first aspect, the identifying a first temperature maximum in the temperature curve includes:

constructing a curve function of the temperature curve;

the function derivative of the curve function is calculated using the following formula:

wherein ,representing the first derivative of said curve function at the x-coordinate of said function derivatives,/->Representing the second derivative of said curve function to the left of the x-coordinate of said function derivatives, a +.>Representing the third derivative of the function derivative of the curve function on the right side of the x-coordinate, x representing the time in the temperature curve, f (x) representing the temperature value corresponding to the x-time coordinate in the temperature curve,/- >Representing the difference between the nearest time coordinate to the x time coordinate and the x time coordinate, +.>Representing a temperature value corresponding to a nearest time coordinate at the x time coordinate;

and when the first derivative of the function derivatives accords with a preset threshold, the second derivative of the function derivatives is larger than the preset threshold, and the third derivative of the function derivatives is smaller than the preset threshold, taking the temperature value corresponding to the function derivatives as the first temperature maximum value.

In a possible implementation manner of the first aspect, the identifying, according to the temperature curve and the adjustment curve, the second historical overcharge fault of the retired power battery using the first temperature maximum and the second temperature maximum includes:

inquiring a first time corresponding to the first temperature maximum value in the temperature curve when the first temperature maximum value is the temperature maximum value in the temperature curve, and inquiring a second time corresponding to the second temperature maximum value in the adjustment curve;

and when the first time is consistent with the second time, taking the first temperature maximum value as an abnormal temperature of the retired power battery, and taking the abnormal temperature as the second historical overcharge fault.

In a second aspect, the present invention provides a retired power battery overcharge fault diagnosis device, comprising:

the time analysis module is used for collecting battery capacity and charging current of the retired power battery, calculating the charging speed of the retired power battery based on the battery capacity and the charging current, and analyzing whether the charging time of the retired power battery is abnormal or not by utilizing the charging speed;

the model adjustment module is used for constructing a charging process model of the retired power battery based on the lithium ion concentration of the retired power battery when the charging time of the retired power battery is abnormal, calculating the charging multiplying power of the retired power battery based on the charging current, and performing model adjustment on the charging process model by utilizing the charging multiplying power to obtain an adjustment model;

the first fault identification module is used for calculating the battery voltage of the retired power battery by using the adjustment model, and judging whether a first historical overcharge fault exists in the retired power battery by using the battery voltage;

the second temperature identification module is used for acquiring the acquired temperature data of the retired power battery, constructing a temperature curve of the temperature data, identifying a first temperature maximum value in the temperature curve, performing curve adjustment on the temperature curve to obtain an adjustment curve, and identifying a second temperature maximum value in the adjustment curve;

The second fault identification module is used for judging whether the retired power battery has a second historical overcharge fault or not by utilizing the first temperature maximum value and the second temperature maximum value according to the temperature curve and the adjustment curve;

and the final fault determining module is used for determining the final historical overcharge fault of the retired power battery by utilizing the first historical overcharge fault and the second historical overcharge fault.

Compared with the prior art, the technical principle and beneficial effect of this scheme lie in:

according to the embodiment of the invention, firstly, the charge speed of the retired power battery is calculated based on the capacity of the battery and the charge current, so that when the charge speed is slower than the prior art, the internal temperature of the battery is increased based on the principle that the overcharge can lead to the reduction of the battery charge, and therefore the performance and the service life of the battery are affected, furthermore, the embodiment of the invention judges whether the retired power battery possibly has overcharge faults by analyzing whether the charge time of the retired power battery is abnormal or not by utilizing the charge speed, and is used for judging whether the retired power battery has the possibility of overcharge faults or not, and the embodiment of the invention judges whether the charge process model of the retired power battery is formed by constructing a charge process model of the retired power battery based on the lithium ion change in the charge process of the retired power battery into a mathematical model related to the voltage change or not, and further judges whether the charge rate of the retired power battery is charged as initial solid-phase lithium ion charge rate and the full-phase lithium ion battery charge level loss in the charge process of the retired power battery are larger than the initial charge rate by utilizing the charge current, namely, if the invention is further judges whether the charge process of the retired power battery has the abnormal temperature is larger than the maximum temperature, and is more than the threshold value in the threshold value, and the invention is further, and whether the abnormal temperature is possible is judged by determining whether the abnormal temperature is higher or not, and the temperature is possible or not, according to the embodiment of the invention, whether the retired power battery has a second historical overcharge fault or not is judged by utilizing the first temperature maximum value and the second temperature maximum value according to the temperature curve and the adjustment curve, and then the first historical overcharge fault and the second historical overcharge fault are combined to determine the final historical overcharge fault. Therefore, the method and the device for diagnosing the historical overcharge fault of the retired power battery can accurately diagnose whether the historical overcharge fault exists in the retired power battery.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.

FIG. 1 is a schematic flow chart of a method for diagnosing historical overcharge failure of a retired power battery according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of coordinates of a positive electrode and a negative electrode in a horizontal direction of a historical overcharge fault diagnosis method for a retired power battery according to one embodiment of the present invention;

FIG. 3 is a schematic diagram of a voltage-negative curve and a voltage-positive curve of a method for diagnosing historical overcharge failure of a retired power battery according to one embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an adjustment curve of a historical overcharge fault diagnosis method for a retired power battery according to one embodiment of the present invention;

FIG. 5 is a schematic block diagram of a historical overcharge fault diagnosis device for retired power cells according to one embodiment of the present invention;

fig. 6 is a schematic diagram of an internal structure of an electronic device for implementing a method for diagnosing historical overcharge failure of a retired power battery according to an embodiment of the present invention.

Detailed Description

It should be understood that the detailed description is presented by way of example only and is not intended to limit the invention.

The embodiment of the invention provides a historical overcharge fault diagnosis method for a retired power battery, and an execution subject of the overcharge fault diagnosis method during echelon utilization of the retired power battery comprises, but is not limited to, at least one of a server, a terminal and the like which can be configured to execute the method provided by the embodiment of the invention. In other words, the retired power battery history overcharge fault diagnosis method may be performed by software or hardware installed in a terminal device or a server device, and the software may be a blockchain platform. The service end includes but is not limited to: a single server, a server cluster, a cloud server or a cloud server cluster, and the like. The server may be an independent server, or may be a cloud server that provides cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (Content Delivery Network, CDN), and basic cloud computing services such as big data and artificial intelligence platforms.

Referring to fig. 1, a flow chart of a method for diagnosing historical overcharge failure of a retired power battery according to an embodiment of the invention is shown. The method for diagnosing historical overcharge faults of the retired power battery shown in FIG. 1 comprises the following steps:

s1, collecting battery capacity and charging current of a retired power battery, calculating the charging speed of the retired power battery based on the battery capacity and the charging current, and analyzing whether the charging time of the retired power battery is abnormal or not by utilizing the charging speed.

According to the embodiment of the invention, the battery capacity and the charging current of the retired power battery before the power battery is utilized in a gradient manner are collected, so that the battery capacity and the charging current are utilized to calculate how much electricity can be charged into the retired power battery per hour.

The retired power battery refers to a power lithium ion battery carried by a new energy automobile, and it is required to say that when the battery capacity of the power lithium ion battery carried by the new energy automobile is attenuated by about 20% compared with the battery capacity of a factory, the power requirement of large-sized objects such as the new energy automobile cannot be met again, the power lithium ion battery at the moment becomes the retired battery, but the retired battery does not refer to a battery which cannot be used continuously, and because the retired battery still has 70% -80% of battery capacity, the power requirement of a plurality of small and medium electric appliances can still be met, and before the retired battery is put into use again, related fault detection needs to be carried out on the retired battery, so that the battery can enter into cascade utilization, and further, the cascade utilization refers to the process of carrying out necessary inspection detection, classification, battery repair or recombination on the waste power battery into a cascade product, so that the retired battery can be applied to other fields; the battery capacity refers to the remaining battery capacity, which represents the current charge amount that the battery can store, usually in ampere hours (Ah); the charging current is the current charged by overcharging the retired power battery in the process of overcharging fault detection before the retired power battery is utilized in a gradient manner. It should be noted that, when the battery is charged, the charging process is continued after the battery reaches a full charge state, and after the battery is charged to a certain extent, lithium ions in the electrolyte can start to form lithium metal on the surface of the graphite electrode, which can cause the internal temperature of the battery to rise, and further cause phenomena of thermal runaway, explosion and the like, and the overcharge modes comprise constant current variable voltage and constant voltage variable current modes.

Further, according to the embodiment of the invention, the charging speed of the retired power battery is calculated based on the battery capacity and the charging current, so that when the charging speed is slower than the previous charging speed, the possibility of overcharge faults of the retired power battery is judged based on the principle that the internal temperature of the battery is increased due to overcharge, so that the performance and the service life of the battery are affected and the battery is slower to charge.

The charging speed refers to the speed of how much electricity the retired power battery is charged per hour.

In an embodiment of the present invention, the charging speed of the retired power battery is calculated based on the battery capacity and the charging current by using the following formula:

Further, the embodiment of the invention analyzes whether the charging time of the retired power battery is abnormal by utilizing the charging speed so as to judge whether the retired battery has the possibility of overcharge fault.

In an embodiment of the present invention, the analyzing whether the charging time of the retired power battery is abnormal using the charging speed includes: calculating the historical charging speed of the retired power battery by using the following formula:

when the absolute value of the difference between the historical charging speed and the speed average value is larger than a preset difference value, judging that the charging time of the retired power battery is abnormal; and when the absolute value of the difference between the historical charging speed and the speed average value is not larger than the preset difference value, judging that the charging time of the retired power battery is not abnormal.

The preset difference may be set to 10 according to practical situations, for example, the historical charging speeds all float between 20 and 30, and the average speed is 40.

S2, when the charging time of the retired power battery is abnormal, a charging process model of the retired power battery is built based on the lithium ion concentration of the retired power battery, the charging multiplying power of the retired power battery is calculated based on the charging current, and the charging multiplying power is utilized to carry out model adjustment on the charging process model, so that an adjustment model is obtained.

According to the embodiment of the invention, the charging process model of the retired power battery is constructed based on the lithium ion concentration of the retired power battery, so that the lithium ion change of the retired power battery in the charging process is converted into a mathematical model related to the voltage change.

The lithium ion concentration comprises the lithium ion concentration of a positive electrode and the lithium ion concentration of a negative electrode in the retired power battery, and the measurement of the lithium ion concentration is realized through X-rays.

In an embodiment of the present invention, the constructing a charging process model of the retired power battery based on the lithium ion concentration of the retired power battery includes: based on the lithium ion concentration of the retired power battery, the solid phase potential of the retired power battery is calculated using the following formula:

wherein ,representing the charging process model,/->Represents the positive potential of the solid phase potential, < >>Represents the negative potential of the solid phase potential, < > >Indicating overvoltage of positive electrode, +.>Indicating the overvoltage of the negative electrode,represents the liquid phase potential of the positive electrode, +.>Represents the liquid phase potential of the negative electrode, +.>Represents the coordinates of the positive electrode in the horizontal direction, +.>Represents the coordinates of the negative electrode in the horizontal direction, +.>Representing the liquid phase.

It should be noted that, the internal structure of the retired power battery, i.e. the lithium ion battery, includes a positive electrode, a diaphragm, a negative electrode, and an electrolyte, and when the battery is charged, lithium ions are separated from the positive electrode and are inserted into the negative electrode, and based on the internal structure of the lithium ion battery and the change of the lithium ions in the charging process, the following will be explained: the solid phase is a phase composed of solid, namely a phase on the positive electrode and the negative electrode, the liquid phase is a phase composed of liquid, namely a phase in the electrolyte, further, the solid-phase lithium ions are lithium ions which are inserted into the positive electrode and the negative electrode, when the liquid-phase lithium ions are lithium ions which are diffused in the electrolyte when the lithium ions are separated from the positive electrode and are inserted into the negative electrode and pass through the electrolyte, the overvoltage is a voltage exceeding the normal working voltage, further, the lithium ions are diffused in the horizontal direction from the positive electrode to the negative electrode when the lithium ions are separated from the positive electrode and are inserted into the negative electrode, and finally, the fully-inserted solid-phase lithium ions are lithium ions which are inserted into the positive electrode and the negative electrode when the battery leaves the factory, namely when the battery capacity is 100%.

Referring to fig. 2, a schematic diagram of coordinates of a positive electrode and a negative electrode in a horizontal direction of a historical overcharge fault diagnosis method for a retired power battery according to an embodiment of the invention is shown in fig. 1.

Further, the embodiment of the invention calculates the charging multiplying power of the retired power battery based on the charging current, so as to use the charging multiplying power as the loss generated in the battery charging process by taking the initial ratio of the intercalated solid-phase lithium ions to the intercalated full-scale solid-phase lithium ions.

In an embodiment of the present invention, based on the charging current, the charging rate of the retired power battery is calculated using the following formula:

In an embodiment of the present invention, the performing model adjustment on the charging process model by using the charging rate to obtain an adjustment model includes: based on the charging rate, the potential of the solid phase in the charging process model is adjusted by using the following formula to obtain an adjusted potential:

the tuning model is constructed using the tuning potentials.

And S3, calculating the battery voltage of the retired power battery by using the adjustment model, judging whether the retired power battery has a first historical overcharge fault by using the battery voltage, if so, entering S4, and if not, judging that the retired power battery has no historical overcharge fault.

According to the embodiment of the invention, the battery voltage of the retired power battery is calculated by using the adjustment model, so that the voltage change under the premise that the lithium ions of the positive electrode and the negative electrode of the lithium ion battery are changed is calculated by using the standard model, namely, the relationship between the lithium ion change and the voltage change of the positive electrode and the negative electrode is improved, and the adaptability of the voltage abnormality identification is improved.

Wherein, the battery voltage refers to the terminal voltage of the battery.

Optionally, the process of calculating the battery voltage of the retired power battery using the adjustment model is: and selecting different lithium ion concentrations, and substituting the different lithium ion concentrations into the formula of the adjustment model, so that a plurality of different battery voltages corresponding to the different lithium ion concentrations are calculated by using the formula of the adjustment model.

Further, the embodiment of the invention identifies the first historical overcharge fault of the retired power battery by using the battery voltage, so as to calculate the voltage change of the retired power battery in the historical process by using the adjustment model, thereby judging whether the retired power battery is overcharged in the historical time.

In one embodiment of the present invention, the identifying a first historical overcharge fault of the retired power battery using the battery voltage includes: acquiring positive electrode capacity and negative electrode capacity corresponding to the battery voltage; constructing a voltage-positive electrode curve between the battery voltage and the positive electrode capacity, and constructing a voltage-negative electrode curve between the battery voltage and the negative electrode capacity; identifying a voltage curve trend, an anode curve trend and a cathode curve trend of the battery when the voltage of the battery is larger than a preset standard voltage from the voltage-anode curve and the voltage-cathode curve; and identifying whether the retired power battery has a first historical overcharge fault by utilizing the voltage curve trend, the positive curve trend and the negative curve trend, if so, further judging is needed, and if not, judging that the historical overcharge fault does not exist.

Referring to fig. 3, a schematic diagram of a voltage-negative curve and a voltage-positive curve of the method for diagnosing an overcharge fault of a retired power battery according to an embodiment of the invention is shown in fig. 1. In fig. 3, when the anode capacity gradually decreases, since it is known based on the adjustment model that the anode capacity is proportional to the anode potential, the anode potential also gradually decreases, and as the anode potential decreases, the voltage gradually stops changing, which means that the change in voltage is mainly affected by the anode capacity, while the influence of the cathode capacity is small, and therefore, whether or not voltage abnormality occurs can be recognized by the change in the anode capacity, and as the anode active material decays, the voltage gradually disappears, based on which it can be inferred that an overcharge failure occurs at this time, because the anode surface adsorbs too many lithium ions at the time of the overcharge failure, and the structure of the anode changes, that is, the anode active material decays.

S4, acquiring temperature data of the retired power battery, constructing a temperature curve of the temperature data, identifying a first temperature maximum value in the temperature curve, performing curve adjustment on the temperature curve to obtain an adjustment curve, and identifying a second temperature maximum value in the adjustment curve.

According to the embodiment of the invention, the temperature data of the retired power battery is acquired, namely the temperature data of the retired power battery in the charging process is acquired, so that whether the temperature of the retired power battery is abnormal or not is judged. The anomaly indicates that an overcharge failure may have occurred before. During charging, the battery generates heat, and thus overcharge tends to cause the temperature of the battery to rise. By monitoring the temperature data of retired batteries, it can be observed whether frequent or excessive temperature fluctuations exist, thereby diagnosing whether the battery has been subjected to an overcharge condition.

Wherein the temperature data records a temperature change value per unit time.

Further, the embodiment of the invention is used for observing the change of temperature with time by constructing a temperature curve of the temperature data.

Wherein the temperature curve refers to a curve with time on the abscissa and temperature on the ordinate.

Further, the embodiment of the invention recognizes the first maximum temperature value in the temperature curve to be used for recognizing whether the abnormal temperature possibly exists in the temperature curve, namely, when the first maximum temperature value occurs, the abnormal temperature possibly occurs, but since the fixed temperature threshold is not available, whether the abnormal temperature occurs cannot be recognized at this time because the maximum temperature value is larger than the temperature threshold.

In an embodiment of the invention, the identifying the first temperature maximum in the temperature curve includes: constructing a curve function of the temperature curve; the function derivative of the curve function is calculated using the following formula:

wherein ,representing the first derivative of said curve function at the x-coordinate of said function derivatives,/->Representing the second derivative of said curve function to the left of the x-coordinate of said function derivatives, a +.>Representing the third derivative of the function derivative of the curve function on the right side of the x-coordinate, x representing the time in the temperature curve, f (x) representing the temperature value corresponding to the x-time coordinate in the temperature curve,/->Representing the difference between the nearest time coordinate to the x time coordinate and the x time coordinate, +.>Representing a temperature value corresponding to a nearest time coordinate at the x time coordinate;

Wherein the preset threshold is set to 0 because, when the first derivative is 0, it indicates that f (x) has an extremum.

Further, in the embodiment of the invention, the temperature curve is adjusted to be used for observing the change of the temperature curve when the battery is subjected to multiple overcharging and thermal runaway under the same environment, so as to distinguish whether the first temperature maximum value can be used for representing whether the temperature is abnormal or not, namely, whether the time of occurrence of the temperature maximum value in the temperature curve when the battery is subjected to multiple overcharging and thermal runaway in the historical time is consistent or not under the scenes of the same charging multiplying power, the environment temperature and the health state, and if the time of occurrence of the temperature maximum value is consistent, the temperature maximum value can be used as a sign of the representative temperature abnormality.

Optionally, the curve adjustment is performed on the temperature curve: under the scenes of the same charging multiplying power, the same environment temperature and the same health state, the battery is subjected to temperature during thermal runaway caused by repeated overcharging in the historical time, temperature curves during the thermal runaway are constructed, namely, under the scenes of the same charging multiplying power, the same environment temperature and the same health state, the retired power battery is subjected to repeated overcharging, and the temperature of each overcharging is generated into the temperature curves, so that a plurality of temperature curves are finally generated.

Referring to fig. 4, a schematic diagram of an adjustment curve of a historical overcharge fault diagnosis method for a retired power battery according to an embodiment of the invention is shown in fig. 1. In fig. 4, the first and second temperature maxima occur at a time point between 2500s and 3000s, that is, at about 2750 s.

Further, the embodiment of the invention is used for detecting whether the time of occurrence of the temperature maximum value of the adjustment curve is consistent with the time of occurrence of the temperature maximum value of the temperature curve or not by identifying the second temperature maximum value in the adjustment curve, and if so, the temperature maximum value can be used for representing that the temperature at the moment is abnormal.

In an embodiment of the present invention, the principle of identifying the second temperature maximum in the adjustment curve is similar to the principle of identifying the first temperature maximum in the temperature curve, and will not be further described herein.

And S5, judging whether the retired power battery has a second historical overcharge fault or not by utilizing the first temperature maximum value and the second temperature maximum value according to the temperature curve and the adjustment curve.

According to the embodiment of the invention, whether the retired power battery has a second historical overcharge fault or not is judged by utilizing the first temperature maximum value and the second temperature maximum value according to the temperature curve and the adjustment curve.

In an embodiment of the present invention, the identifying the second historical overcharge fault of the retired power battery according to the temperature curve and the adjustment curve by using the first temperature maximum and the second temperature maximum includes: inquiring a first time corresponding to the first temperature maximum value in the temperature curve when the first temperature maximum value is the temperature maximum value in the temperature curve, and inquiring a second time corresponding to the second temperature maximum value in the adjustment curve; and when the first time is consistent with the second time, taking the first temperature maximum value as an abnormal temperature of the retired power battery, and determining the second historical overcharge fault based on the abnormal temperature.

S6, determining the final historical overcharge fault of the retired power battery by utilizing the first historical overcharge fault and the second historical overcharge fault.

Optionally, the determining the final overcharge fault of the retired power battery using the first historical overcharge fault and the second historical overcharge fault includes: determining that the retired power battery has a historical overcharge fault when the first historical overcharge fault is present and the second historical overcharge fault is present.

It can be seen that the embodiment of the present invention firstly calculates the charging speed of the retired power battery based on the battery capacity and the charging current, so as to influence the performance and the service life of the battery due to the fact that the internal temperature of the battery is increased due to overcharge when the charging speed is slower than before, and further determines whether the retired power battery is likely to have overcharge fault by analyzing whether the charging time of the retired power battery is abnormal or not by using the charging speed, and further determines whether the retired power battery is likely to have overcharge fault by using the charging speed, further determines whether the overcharge history is further improved by using the temperature of the retired power battery to have a history of the invention by using the temperature of the retired power battery to be greater than the full-charge history of the battery, and further determines whether the invention is likely to have overcharge history by using the temperature of the retired power battery when the overcharge history is further adjusted by using the temperature of the invention, in order to identify whether an abnormal temperature may exist in the temperature curve, that is, when a first temperature maximum value occurs, it is stated that the temperature may be abnormal, but because there is no fixed temperature threshold, it cannot be distinguished whether the temperature abnormality occurs at this time because the temperature maximum value is greater than the temperature threshold. Therefore, the method for diagnosing the overcharge fault of the retired power battery provided by the embodiment of the invention can diagnose whether the history has the overcharge fault or not.

As shown in FIG. 5, the invention is a functional block diagram of an overcharge fault diagnosis device for the echelon utilization of the retired power battery.

The overcharge fault diagnosis device 500 for the step-by-step use of the retired power battery of the present invention may be installed in an electronic device. Depending on the functions implemented, the device for diagnosing overcharge faults during echelon use of the retired power battery may include a time analysis module 501, a model adjustment module 502, a first fault identification module 503, a second temperature identification module 504, a second fault identification module 505, and a final fault determination module 506. The module of the invention, which may also be referred to as a unit, refers to a series of computer program segments, which are stored in the memory of the electronic device, capable of being executed by the processor of the electronic device and of performing a fixed function.

In the embodiment of the present invention, the functions of each module/unit are as follows:

the time analysis module 501 is configured to collect a battery capacity and a charging current of the retired power battery before the retired power battery is utilized in a cascade, calculate a charging speed of the retired power battery based on the battery capacity and the charging current, and analyze whether a charging time of the retired power battery is abnormal according to the charging speed;

The model adjustment module 502 is configured to construct a charging process model of the retired power battery based on a lithium ion concentration of the retired power battery when a charging time of the retired power battery is abnormal, calculate a charging rate of the retired power battery based on the charging current, and perform model adjustment on the charging process model by using the charging rate to obtain an adjustment model;

the first fault identification module 503 is configured to calculate a battery voltage of the retired power battery using the adjustment model, and identify a first historical overcharge fault of the retired power battery using the battery voltage;

the second temperature identifying module 504 is configured to collect temperature data of the retired power battery before echelon utilization, construct a temperature curve of the temperature data, identify a first temperature maximum value in the temperature curve, perform curve adjustment on the temperature curve to obtain an adjustment curve, and identify a second temperature maximum value in the adjustment curve;

the second fault identification module 505 is configured to identify a second historical overcharge fault of the retired power battery according to the temperature curve and the adjustment curve, using the first temperature maximum and the second temperature maximum;

The final fault determination module 506 is configured to determine a final overcharge fault of the retired power battery using the first historical overcharge fault and the second historical overcharge fault.

In detail, the modules in the device 500 for diagnosing overcharge failure during cascade use of a retired power battery in the embodiment of the present invention use the same technical means as the method for diagnosing overcharge failure during cascade use of a retired power battery described in fig. 1 to 4, and can produce the same technical effects, which are not repeated here.

Fig. 6 is a schematic structural diagram of an electronic device according to the present invention, which implements an overcharge fault diagnosis method for a step-by-step use of a retired power battery.

The electronic device may include a processor 60, a memory 61, a communication bus 62, and a communication interface 63, and may also include a computer program stored in the memory 61 and executable on the processor 60, such as an overcharge fault diagnosis program when the retired power battery is used in a cascade.

The processor 60 may be formed by an integrated circuit in some embodiments, for example, a single packaged integrated circuit, or may be formed by a plurality of integrated circuits packaged with the same function or different functions, including one or more central processing units (Central Processing unit, CPU), a microprocessor, a digital processing chip, a graphics processor, a combination of various control chips, and the like. The processor 60 is a Control Unit (Control Unit) of the electronic device, connects various parts of the entire electronic device using various interfaces and lines, executes or executes programs or modules stored in the memory 61 (for example, an overcharge failure diagnosis program when the retired power battery is used in a cascade, etc.), and invokes data stored in the memory 61 to perform various functions of the electronic device and process data.

The memory 61 includes at least one type of readable storage media including flash memory, a removable hard disk, a multimedia card, a card memory (e.g., SD or DX memory, etc.), magnetic memory, magnetic disk, optical disk, etc. The memory 61 may in some embodiments be an internal storage unit of the electronic device, such as a mobile hard disk of the electronic device. The memory 61 may also be an external storage device of the electronic device in other embodiments, such as a plug-in mobile hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) or the like. Further, the memory 61 may also include both an internal storage unit and an external storage device of the electronic device. The memory 61 may be used not only for storing application software installed in the electronic device and various types of data, such as codes of database-configured connection programs, but also for temporarily storing data that has been output or is to be output.

The communication bus 62 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus, or an extended industry standard architecture (extended industry standard architecture, EISA) bus, among others. The bus may be classified as an address bus, a data bus, a control bus, etc. The bus is arranged to enable a connection communication between the memory 61 and at least one processor 60 etc.

The communication interface 63 is used for communication between the electronic device 6 and other devices, including a network interface and a user interface. Optionally, the network interface may include a wired interface and/or a wireless interface (e.g., WI-FI interface, bluetooth interface, etc.), typically used to establish a communication connection between the electronic device and other electronic devices. The user interface may be a Display (Display), an input unit such as a Keyboard (Keyboard), or alternatively a standard wired interface, a wireless interface. Alternatively, in some embodiments, the display may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch, or the like. The display may also be referred to as a display screen or display unit, as appropriate, for displaying information processed in the electronic device and for displaying a visual user interface.

Fig. 6 shows only an electronic device with components, and it will be understood by those skilled in the art that the structure shown in fig. 6 is not limiting of the electronic device and may include fewer or more components than shown, or may combine certain components, or a different arrangement of components.

For example, although not shown, the electronic device may further include a power source (such as a battery) for supplying power to the respective components, and the power source may be logically connected to the at least one processor 60 through a power management device, so that functions of charge management, discharge management, and power consumption management are implemented through the power management device. The power supply may also include one or more of any of a direct current or alternating current power supply, recharging device, power failure detection circuit, power converter or inverter, power status indicator, etc. The electronic device may further include various sensors, bluetooth modules, wi-Fi modules, etc., which are not described herein.

It should be understood that the embodiments described are for illustrative purposes only and are not limited in scope by this configuration.

The database-configured connection program stored by the memory 61 in the electronic device is a combination of a plurality of computer programs, which when run in the processor 60, can implement:

collecting battery capacity and charging current of the retired power battery before gradient utilization, calculating the charging speed of the retired power battery based on the battery capacity and the charging current, and analyzing whether the charging time of the retired power battery is abnormal or not by utilizing the charging speed;

calculating a battery voltage of the retired power battery using the adjustment model, and identifying a first historical overcharge fault of the retired power battery using the battery voltage;

acquiring temperature data of the retired power battery before echelon utilization, constructing a temperature curve of the temperature data, identifying a first temperature maximum value in the temperature curve, performing curve adjustment on the temperature curve to obtain an adjustment curve, and identifying a second temperature maximum value in the adjustment curve;

identifying a second historical overcharge fault of the retired power battery using the first temperature maximum and the second temperature maximum according to the temperature curve and the adjustment curve;

and determining a final overcharge fault of the retired power battery by utilizing the first historical overcharge fault and the second historical overcharge fault.

In particular, the specific implementation method of the processor 60 on the computer program may refer to the description of the relevant steps in the corresponding embodiment of fig. 1, which is not repeated herein.

Further, the electronic device integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a non-volatile computer readable storage medium. The storage medium may be volatile or nonvolatile. For example, the computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM).

The present invention also provides a storage medium storing a computer program which, when executed by a processor of an electronic device, can implement:

In the several embodiments provided in the present invention, it should be understood that the disclosed apparatus, device and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be other manners of division when actually implemented.

The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical units, may be located in one place, or may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional module in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units can be realized in a form of hardware or a form of hardware and a form of software functional modules.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference signs in the claims shall not be construed as limiting the claim concerned.

It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for diagnosing historical overcharge faults of a retired power battery, the method comprising:

2. The method of claim 1, wherein the calculating a charge rate of the retired power battery based on the battery capacity and the charge current comprises:

3. The method of claim 1, wherein said analyzing whether the charge time of the retired power battery is abnormal using the charge speed comprises:

4. The method of claim 1, wherein constructing a model of a charging process of the retired power battery based on lithium ion concentration of the retired power battery comprises:

wherein ,represents the positive potential of the solid phase potential, < >>Represents the negative potential of the solid phase potential, < >>Represents the potential of the positive electrode at a reference temperature equal to 298.15K and with an open circuit, +.>Represents the potential of the negative electrode at a reference temperature equal to 298.15K and with the circuit open,/for >Represents the solid-phase lithium ion concentration inside the particles of the positive electrode,/->Represents the solid-phase lithium ion concentration inside the particles of the negative electrode,/->Represents the maximum solid-phase lithium ion concentration of the positive electrode, < >>Represents the maximum solid-phase lithium ion concentration of the negative electrode, < >>//>Represents the ratio of solid-phase lithium ions intercalated in the positive electrode to full-scale solid-phase lithium ions intercalated in the positive electrode, +.>//>Represents the ratio of the solid-phase lithium ion intercalated by the negative electrode to the full-scale solid-phase lithium ion intercalated by the negative electrode, +.>Represents solid phase lithium ion concentration, ">Indicating solid phase,/->Representing the positive pole of the retired power battery, < >>Negative pole of the retired power battery, < >>Abbreviations, i.e., reference symbols, representing Reference;

wherein ,representing the charging process model,/->Represents the positive potential of the solid phase potential, < >>Represents the negative potential of the solid phase potential, < >>Indicating overvoltage of positive electrode, +.>Indicating the overvoltage of the negative electrode, +.>Represents the liquid phase potential of the positive electrode, +.>Represents the liquid phase potential of the negative electrode, +.>Represents the coordinates of the positive electrode in the horizontal direction, +.>Represents the coordinates of the negative electrode in the horizontal direction, +. >Representing the liquid phase.

5. The method of claim 1, wherein the calculating a charge rate of the retired power battery based on the charge current comprises:

6. The method of claim 1, wherein the model tuning the charging process model using the charging rate to obtain a tuning model comprises:

wherein ,represents the positive potential in the adjustment potential, < >>Represents the negative potential of the regulated potentials, < >>Represents the potential of the positive electrode at a reference temperature equal to 298.15K and with an open circuit, +.>Represents the potential of the negative electrode at a reference temperature equal to 298.15K and with the circuit open,/for >Represents the solid-phase lithium ion concentration inside the particles of the positive electrode,/->Represents the solid-phase lithium ion concentration inside the particles of the negative electrode,/->Represents the maximum solid-phase lithium ion concentration of the positive electrode, < >>Represents the maximum solid-phase lithium ion concentration of the negative electrode, < >>//>Represents the ratio of solid-phase lithium ions intercalated in the positive electrode to full-scale solid-phase lithium ions intercalated in the positive electrode, +.>//>Represents the ratio of the solid-phase lithium ion intercalated by the negative electrode to the full-scale solid-phase lithium ion intercalated by the negative electrode, +.>Represents solid phase lithium ion concentration, ">Indicating solid phase,/->Representing the positive pole of the retired power battery, < >>Negative pole of the retired power battery, < >>Abbreviations indicating Reference, i.e. Reference symbols, ">Represents the charge rate of the positive electrode in the charge rates,/->Representing a charging rate of the negative electrode among the charging rates;

the tuning model is constructed using the tuning potentials.

7. The method of claim 1, wherein said utilizing said battery voltage to determine whether said retired power battery has a first historical overcharge fault comprises:

and identifying whether the retired power battery has a first historical overcharge fault by utilizing the voltage curve trend, the positive curve trend and the negative curve trend.

8. The method of claim 1, wherein said identifying a first temperature maximum in said temperature profile comprises:

constructing a curve function of the temperature curve;

9. The method of claim 1, wherein said determining whether a second historical overcharge fault exists with said retired power cell based on said temperature profile and said tuning profile using said first temperature maximum and said second temperature maximum comprises:

and when the first time is consistent with the second time, taking the first temperature maximum value as an abnormal temperature of the retired power battery, and determining the second historical overcharge fault based on the abnormal temperature.

10. An apparatus for diagnosing an overcharge fault of a retired power battery, said apparatus comprising: