Method and system for evaluating service life of lithium battery of engineering machinery and electronic equipment

Abstract

The invention belongs to the technical field of battery life evaluation, and relates to an engineering machinery lithium battery life evaluation method and system and electronic equipment, and the method comprises the steps: obtaining characteristic parameters and a life attenuation curve graph of an engineering machinery lithium battery; dividing attenuation sections according to the characteristic parameters and the life attenuation curve graph, and extracting common damage characteristics of the attenuation sections to obtain common damage factors of the attenuation sections; obtaining an ultra-large polarization stress factor, and determining a mapping relation between the ultra-large polarization stress and the damage factor; an equivalent fatigue life model is constructed according to the mapping relation and the common damage factors, then an equivalent fatigue life decline model is obtained, and a closed-loop fatigue life model is obtained according to the equivalent fatigue life decline model, the temperature and the charge state initial value through a weight coefficient method and parameter updating; based on a closed-loop fatigue life model, determining a battery life attenuation and demand value boundary curve according to a Pareto method; and obtaining a discharge boundary quantitative evaluation result. And scientific and rigorous technical support is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery life assessment, and relates to a method, system and electronic equipment for assessing the life of a lithium battery of an engineering machinery. Background Art

[0002] Under the macro background of "carbon peak" and "carbon neutrality", traditional fuel-powered construction machinery has serious pollution and high carbon emissions, which can no longer meet the strategic needs of green and low-carbon development, forcing the electrification of construction machinery construction operations. However, construction machinery construction operations require repeated shoveling, loading, transportation and other operations, and large changes in periodic loads are a significant feature of its operating conditions. The capacity of lithium batteries decays rapidly under high-pulse strong cycle discharge, resulting in a rapid decrease in vehicle operating capacity. Under heavy load impact loads such as lifting and shoveling of construction machinery and steep slope transportation, the instantaneous discharge rate of the battery system is as high as 10 C, which is several times or even more than ten times that of electric vehicles. The ultra-large current pulse discharge causes ultra-large polarization inside the battery, accelerates the battery life decline, and significantly reduces the durability of construction machinery. However, due to the lack of ultra-large polarization discharge construction machinery lithium battery life assessment means, it is impossible to effectively trace the decline process of construction machinery lithium batteries, nor is it possible to accurately explain their decline mechanism, resulting in the contradiction between the high power demand and durability operation of construction machinery, which restricts the development of electric construction machinery. Summary of the invention

[0003] The purpose of the present invention is to provide a method, system and electronic equipment for evaluating the life of engineering machinery lithium batteries, so as to solve the technical problem in the prior art that there is a lack of ultra-large polarization discharge engineering machinery lithium battery life evaluation means and it is impossible to effectively trace the decline process of engineering machinery lithium batteries and accurately explain their decline mechanism.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present application discloses a method for evaluating the life of a lithium battery of an engineering machinery, comprising: Obtain characteristic parameters of engineering machinery lithium batteries and life attenuation curves of engineering machinery lithium batteries; According to the characteristic parameters and the life decay curve, the decay sections are divided into slow decay section, buffer decay section and plunge decay section; based on the internal evolution mechanism of the engineering machinery lithium battery - each decay section is analyzed to obtain the common damage characteristics of each decay section, and the common damage factors of each decay section are obtained by extracting the common damage characteristics of each decay section; Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; An equivalent fatigue life model is constructed according to the mapping relationship and the common damage factor, and the equivalent fatigue life model is solved by using asymptotic approximation theory to obtain an equivalent fatigue life decay model; According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, the weight coefficient method is adopted to establish an adaptive fatigue life model. According to the adaptive fatigue life model, the closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method. Multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0005] Preferably, the obtaining of characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery specifically includes the following steps: S101: Analyze the energy demand of the lithium battery system of pure electric engineering machinery with large load impact, and use the power matching method to quantitatively approximate the ultra-large polarization discharge parameters; S102: According to the ultra-large polarization discharge parameters, a parallel aging experiment is used to perform high pulse strong cycle discharge aging experiments on the engineering machinery lithium batteries of the same batch and specification at different pulse rates and different pulse times to obtain the characteristic parameters of the engineering machinery lithium batteries and the life attenuation curve of the engineering machinery lithium batteries.

[0006] Preferably, the attenuation segments are divided according to the characteristic parameters and the life attenuation curve diagram to obtain the slow attenuation segment, the buffer attenuation segment and the dive attenuation segment; based on the internal evolution mechanism of the engineering machinery lithium battery - each attenuation segment is analyzed to obtain the common damage characteristics of each attenuation segment, and the common damage characteristics of each attenuation segment are extracted to obtain the common damage factor of each attenuation segment, which specifically includes the following steps: S201: using a data characteristic analysis method combined with a mathematical analytical solution method for a decay curve to identify a life decay curve diagram, and obtaining a first inflection point and a second inflection point of battery decay under ultra-large polarization discharge; S202: dividing the life decay curve into a slow decay section, a buffer decay section and a dive decay section according to the first inflection point and the second inflection point of battery decay under ultra-large polarization discharge; S203: Use non-destructive analysis methods to determine the key influencing factors of the slow decay section, buffer decay section and dive decay section of lithium batteries under ultra-large polarization; S204: Based on the key influencing factors, the battery after the parallel aging experiment is disassembled in combination with the microscopic analysis method, and the battery material characterization analysis method is used to deeply study the battery degradation mechanism under ultra-large polarization to determine the common aging mechanism of the first inflection point and the second inflection point; S205: According to the degradation mechanism of lithium batteries under ultra-large polarization, the variation law of ultra-large polarization current over time is analyzed from the time domain, and the relationship between the key factors of ultra-large polarization and battery aging is decoupled by combining the frequency domain impedance analysis method; S206: Starting from the factors that affect the discharge rate and discharge time of super-large polarization, single factor analysis and multi-factor analysis are used to determine the conditions for the occurrence of super-large polarization and the evolution law of the decay in each stage; S207: According to the occurrence conditions of ultra-large polarization and the evolution law of decay in each stage, a multi-level common damage feature analysis method is used to qualitatively give physical interpretation to the features and quantitatively extract the common damage features of each stage.

[0007] Preferably, the method of obtaining the ultra-large polarization stress factor of the engineering machinery lithium battery uses the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay segment and the subduction decay segment to obtain a mapping relationship between the ultra-large polarization stress and the damage factor, specifically including the following steps: S301: Based on the ultra-large discharge rate and instantaneous pulse time, the ultra-large polarization stress factor is obtained through sampling test; S302: Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and the mapping relationship between the ultra-large polarization stress and the damage factor is fitted.

[0008] Preferably, the equivalent fatigue life model is constructed according to the mapping relationship and the common damage factor, and the equivalent fatigue life model is solved by asymptotic approximation theory to obtain the equivalent fatigue life decay model; specifically, the following steps are included: S401: Aiming at the common damage factors of the slow decay section and the plunge decay section, the fatigue decay theory is adopted to construct the relationship between the decay life of lithium batteries and the common damage factors.

[0009] S402: Based on the relationship between life and common damage factor, a mapping relationship between ultra-large polarization stress and damage factor is introduced to obtain a relationship between ultra-large polarization stress factor, common damage factor and life.

[0010] S403: Asymptotic approximation theory is used to solve the relationship between the super-large polarization stress factor, the common damage factor and the life span, and an equivalent fatigue degradation model of the engineering machinery lithium battery is obtained.

[0011] Preferably, the method of using a weight coefficient method according to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge to establish an adaptive fatigue life model, and according to the adaptive fatigue life model, by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, to obtain a closed-loop fatigue life model; specifically includes the following steps: S501: Based on the equivalent fatigue decay model, combined with the initial values ​​of temperature and state of charge, a weight coefficient method is used to construct an adaptive fatigue decay model of initial values ​​of temperature and state of charge; S502: Based on the adaptive fatigue decay model, combined with the influence of different temperature conditions and different initial charge states on ultra-large polarization discharge, the weight coefficient parameters of the damage factor, the temperature of the engineering machinery lithium battery and the initial value of the charge state in the equivalent fatigue life decay model are updated to obtain a closed-loop equivalent fatigue decay model.

[0012] Preferably, based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; the battery life attenuation and demand value boundary curve are optimized by multiple objectives to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary, and the specific steps are as follows: S601: Based on the closed-loop fatigue life model, a large load impact load is used to quantify the demand value of lithium batteries, and common damage characteristics are used to quantify battery life attenuation. The battery life attenuation and demand value boundary curve is obtained based on the Pareto method; S602: Based on the battery life attenuation and demand value boundary curve, multi-objective optimization is performed using battery life attenuation and demand value to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary.

[0013] In a second aspect, the present application provides a system for evaluating the life of a lithium battery for construction machinery, comprising: An acquisition unit, used to acquire characteristic parameters of the engineering machinery lithium battery and a life attenuation curve of the engineering machinery lithium battery; The extraction unit is used to divide the attenuation segment according to the characteristic parameters and the life attenuation curve diagram to obtain the slow attenuation segment, the buffer attenuation segment and the dive attenuation segment; based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each attenuation segment to obtain the common damage characteristics of each attenuation segment, extract the common damage characteristics of each attenuation segment to obtain the common damage factor of each attenuation segment; A mapping unit is used to obtain the ultra-large polarization stress factor of the lithium battery of engineering machinery. The Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section to obtain the mapping relationship between the ultra-large polarization stress and the damage factor. A model building unit, used to build an equivalent fatigue life model according to the mapping relationship and the common damage factor, and solve the equivalent fatigue life model using asymptotic approximation theory to obtain an equivalent fatigue life decay model; A model updating unit is used to establish an adaptive fatigue life model by using a weight coefficient method according to an equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, and to obtain a closed-loop fatigue life model by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge according to the adaptive fatigue life model; The evaluation unit is used to determine the battery life attenuation and demand value boundary curve based on the closed-loop fatigue life model and the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary.

[0014] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above-mentioned methods for evaluating the life of a lithium battery for construction machinery when executing the computer program.

[0015] In a fourth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any of the above-mentioned methods for evaluating the life of a lithium battery of an engineering machinery are implemented.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Aiming at the coupling relationship between the internal mechanism of lithium battery degradation in engineering machinery and the external conditions, the present invention proposes to clarify the coupling relationship between the ultra-large polarization stress factor and the common damage characteristics of each stage based on the Miller linear damage accumulation criterion; for the problem of cyclic operation of large-load impact load, the present invention proposes a research idea of ​​fatigue hypothesis, and establishes an equivalent fatigue life model based on the conditions, internal mechanism and external characteristics; quantifies the life attenuation by common damage characteristics, quantifies the demand value by large-load impact load, and proposes to obtain the boundary curve of life attenuation and demand value based on the Pareto method, which provides technical support for the layout and optimization design of lithium battery systems in engineering machinery.

[0017] The present invention uses parallel aging experiments and multi-dimensional mechanism analysis methods to solve the contradiction between high-power demand and durability operation of engineering machinery with drastic changes in periodic loads, reveals the degradation mechanism of ultra-large polarization discharge lithium iron phosphate batteries, establishes an equivalent fatigue life model that integrates ultra-large polarization conditions and internal damage factors, and proposes an ultra-large polarization discharge quantitative evaluation method with multi-objective optimization of life / demand value, thereby ensuring the durability of engineering machinery lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 is a flow chart of the method of the present invention; Figure 2 is a flow chart of a method according to an embodiment of the present invention; Figure 3 This is a design concept diagram of the engineering machinery lithium battery life assessment method of the present invention; Figure 4 This is a life attenuation curve diagram of the engineering machinery lithium battery of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 The present application discloses a method for evaluating the life of a lithium battery for construction machinery, comprising: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S6: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0027] In view of the coupling relationship between the internal mechanism of lithium battery degradation in construction machinery and the external conditions, it is proposed to clarify the coupling relationship between the ultra-large polarization stress factor and the common damage characteristics of each stage based on the Miller linear damage accumulation criterion; for the problem of high-load impact load cyclic operation, a research idea of ​​fatigue hypothesis is proposed, and an equivalent fatigue life model based on occurrence conditions, internal mechanism and external characteristics is established; the life attenuation is quantified by common damage characteristics, and the demand value is quantified by high-load impact load, and it is proposed to obtain the battery life attenuation and demand value boundary curve based on the Pareto method, which provides technical support for the layout and optimization design of lithium battery systems in construction machinery.

[0028] In some embodiments, the obtaining of characteristic parameters of a construction machinery lithium battery and a life attenuation curve of a construction machinery lithium battery specifically includes the following steps: S101: Analyze the energy demand of the lithium battery system of pure electric engineering machinery with large impact loads, and use the power matching method to quantitatively approximate the ultra-large polarization discharge parameters (discharge rate, pulse time); S102: According to the ultra-large polarization discharge parameters, a parallel aging experiment is used to perform high pulse strong cycle discharge aging experiments on the engineering machinery lithium batteries of the same batch and specification at different pulse rates and different pulse times to obtain the characteristic parameters of the engineering machinery lithium batteries and the life attenuation curve of the engineering machinery lithium batteries.

[0029] Specifically, six groups of lithium iron phosphate batteries of the same batch and specification were subjected to high-pulse strong cycle discharge aging experiments at pulse rates of 4C, 6C, 8C, and 10C and pulse times of 4s, 6s, 8s, and 10s, respectively, to obtain the life decay curve diagram, current, voltage, temperature, and time characteristic data under ultra-large polarization discharge.

[0030] See also Figure 4 , is the life decay curve under ultra-large polarization discharge. According to the lithium battery decay curve under large load impact load of construction machinery, it is divided into slow decay area, buffer decay area and subduction decay area. The transition point from slow decay area to buffer decay area is the first inflection point, and the transition point from buffer decay area to subduction decay area is the second inflection point. The decay curve of construction machinery lithium battery is divided into three stages through the first and second inflection points. Through time domain, frequency domain and electrochemical mechanism analysis, the common damage characteristics of each stage are obtained, and the equivalent fatigue decay model of construction machinery lithium battery is established based on Miller criterion.

[0031] In some embodiments, a method for evaluating the life of a lithium battery for construction machinery includes: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S201: using a data characteristic analysis method combined with a mathematical analytical solution method for a decay curve to identify a life decay curve diagram, and obtaining a first inflection point and a second inflection point of battery decay under ultra-large polarization discharge; S202: dividing the life decay curve into a slow decay section, a buffer decay section and a dive decay section according to the first inflection point and the second inflection point of battery decay under ultra-large polarization discharge; S203: Use non-destructive analysis methods to determine the key influencing factors of the slow decay section, buffer decay section and dive decay section of lithium batteries under ultra-large polarization; S204: Based on the key influencing factors, the battery after the parallel aging experiment is disassembled in combination with the microscopic analysis method, and the battery material characterization analysis method is used to deeply study the battery degradation mechanism under ultra-large polarization to determine the common aging mechanism of the first inflection point and the second inflection point; S205: According to the degradation mechanism of lithium batteries under ultra-large polarization, the variation law of ultra-large polarization current over time is analyzed from the time domain, and the relationship between the key factors of ultra-large polarization and battery aging is decoupled by combining the frequency domain impedance analysis method; S206: Starting from the factors that affect the discharge rate and discharge time of super-large polarization, single factor analysis and multi-factor analysis are used to determine the conditions for the occurrence of super-large polarization and the evolution law of the decay in each stage; S207: According to the occurrence conditions of ultra-large polarization and the evolution law of decay in each stage, a multi-level common damage feature analysis method is used to qualitatively give physical interpretation to the features and quantitatively extract the common damage features of each stage.

[0032] S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S6: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0033] In some embodiments, a method for evaluating the life of a lithium battery for construction machinery includes: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S301: Based on the ultra-large discharge rate and instantaneous pulse time, the ultra-large polarization stress factor is obtained through sampling test; S302: Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and the mapping relationship between the ultra-large polarization stress and the damage factor is fitted.

[0034] S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S6: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0035] In some embodiments, a method for evaluating the life of a lithium battery for construction machinery includes: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S401: Aiming at the common damage factors of the slow decay section and the plunge decay section, the fatigue decay theory is adopted to construct the relationship between the decay life of lithium batteries and the common damage factors.

[0036] S402: Based on the relationship between life and common damage factor, a mapping relationship between ultra-large polarization stress and damage factor is introduced to obtain a relationship between ultra-large polarization stress factor, common damage factor and life.

[0037] S403: Asymptotic approximation theory is used to solve the relationship between the super-large polarization stress factor, the common damage factor and the life span, and an equivalent fatigue degradation model of the engineering machinery lithium battery is obtained.

[0038] S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S6: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0039] In some embodiments, a method for evaluating the life of a lithium battery for construction machinery includes: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S501: Based on the equivalent fatigue decay model, combined with the initial values ​​of temperature and state of charge, a weight coefficient method is used to construct an adaptive fatigue decay model of initial values ​​of temperature and state of charge; S502: Based on the adaptive fatigue decay model, combined with the influence of different temperature conditions and different initial charge states on ultra-large polarization discharge, the closed-loop equivalent fatigue decay model is obtained by updating the damage factor and weight coefficient parameters.

[0040] In some embodiments, see Figure 2 , a method for evaluating the life of a lithium battery for construction machinery, comprising: S1: Obtain characteristic parameters of the engineering machinery lithium battery and the life attenuation curve of the engineering machinery lithium battery; S2: Divide the decay segments according to the characteristic parameters and the life decay curve to obtain the slow decay segment, buffer decay segment and dive decay segment; Based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each decay segment, obtain the common damage characteristics of each decay segment, extract the common damage characteristics of each decay segment to obtain the common damage factor of each decay segment; S3: Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; S4: constructing an equivalent fatigue life model according to the mapping relationship and the common damage factor, solving the equivalent fatigue life model by using asymptotic approximation theory, and obtaining an equivalent fatigue life decay model; S5: According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, a weight coefficient method is used to establish an adaptive fatigue life model. According to the adaptive fatigue life model, a closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; S6: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

[0041] S601: Based on the closed-loop fatigue life model, a large load impact load is used to quantify the demand value of lithium batteries, and common damage characteristics are used to quantify battery life attenuation. The battery life attenuation and demand value boundary curve is obtained based on the Pareto method; S602: Based on the battery life attenuation and demand value boundary curve, multi-objective optimization is performed using battery life attenuation and demand value to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary, thereby sacrificing a small amount of demand value and significantly improving the battery life value.

[0042] In some embodiments, see Figure 3, starting from the construction needs of pure electric engineering machinery with large changes in periodic loads, the design of the life assessment method of lithium batteries for engineering machinery is carried out. It mainly includes three steps: aging and decline experiment of lithium batteries for engineering machinery, fatigue life model of lithium batteries, and life assessment and system of lithium batteries. In the first part, starting from the high pulse and strong cycle power curve of engineering machinery, the ultra-large polarization discharge parameters are quantified to obtain the high pulse and strong cycle discharge parameters (pulse time, pulse rate) of the aging experiment of lithium batteries for engineering machinery; secondly, six groups of parallel aging experiments are carried out to obtain the decline curve of lithium batteries for engineering machinery; finally, the first and second inflection points of battery decline are identified by combining the data characteristic analysis method with the mathematical analytical solution method of the decline curve. In the second part, firstly, according to the three-stage decline area of ​​lithium batteries for engineering machinery divided in the first part, the damage characteristics of each stage of battery decline are analyzed from the time domain, frequency domain, and electrochemical level, and the common damage characteristics of each stage are extracted; secondly, the ultra-large polarization discharge sampling experiment of engineering machinery is designed, and the corresponding relationship between the damage factor and the discharge stress factor is obtained based on the Miller criterion assumption of the evolution law of damage characteristics. Finally, based on the three damage factors, the functional relationship between the life decay and damage factors of lithium batteries for construction machinery is established, and the fatigue life model is solved by the asymptotic approximation theory. In the third part, based on the functional relationship of energy demand under large load impact load conditions of construction machinery and the functional relationship of life decay, the minimum objective function of demand and life value is proposed, and the intelligent algorithm is used to find the optimal solution to identify the discharge boundary of lithium batteries for construction machinery. Secondly, considering the battery operating temperature, SOC initial value, etc., an adaptive weight coefficient is proposed to update the life fatigue model, quantify the life according to the damage characteristics, quantify the demand according to the impact load, and draw the Pareto boundary curve of life and demand, so as to sacrifice a small amount of demand value and significantly improve the life value; finally, a lithium battery hardware-in-the-loop experimental platform is built using xPC Target hardware host, Freescale chip controller, CAN communication back to the host and other equipment to verify the effectiveness of the proposed construction machinery lithium battery life evaluation method and system, and achieve the goal of applicability and durability of construction machinery lithium batteries.

[0043] The present application also discloses a system for evaluating the life of a lithium battery for construction machinery, comprising: An acquisition unit, used to acquire characteristic parameters of the engineering machinery lithium battery and a life attenuation curve of the engineering machinery lithium battery; The extraction unit is used to divide the attenuation segment according to the characteristic parameters and the life attenuation curve diagram to obtain the slow attenuation segment, the buffer attenuation segment and the dive attenuation segment; based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each attenuation segment to obtain the common damage characteristics of each attenuation segment, extract the common damage characteristics of each attenuation segment to obtain the common damage factor of each attenuation segment; A mapping unit is used to obtain the ultra-large polarization stress factor of the lithium battery of engineering machinery. The Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section to obtain the mapping relationship between the ultra-large polarization stress and the damage factor. A model building unit, used to build an equivalent fatigue life model according to the mapping relationship and the common damage factor, and solve the equivalent fatigue life model using asymptotic approximation theory to obtain an equivalent fatigue life decay model; A model updating unit is used to establish an adaptive fatigue life model by using a weight coefficient method according to an equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, and to obtain a closed-loop fatigue life model by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge according to the adaptive fatigue life model; The evaluation unit is used to draw a Pareto boundary curve based on a closed-loop fatigue life model according to battery life attenuation and demand value; multi-objective optimization of the Pareto boundary curve is performed based on battery life and demand value to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary.

[0044] The present application also discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of any of the above-mentioned methods for evaluating the life of a lithium battery for construction machinery are implemented.

[0045] The present application also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any of the above-mentioned methods for evaluating the life of a lithium battery of an engineering machinery are implemented.

[0046] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0047] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0048] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0049] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the life of a lithium battery for construction machinery, characterized in that: include: Obtain characteristic parameters of engineering machinery lithium batteries and life attenuation curves of engineering machinery lithium batteries; According to the characteristic parameters and the life decay curve, the decay sections are divided into slow decay section, buffer decay section and plunge decay section; based on the internal evolution mechanism of the engineering machinery lithium battery - each decay section is analyzed to obtain the common damage characteristics of each decay section, and the common damage factors of each decay section are obtained by extracting the common damage characteristics of each decay section; Obtain the ultra-large polarization stress factor of the engineering machinery lithium battery, use the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and obtain the mapping relationship between the ultra-large polarization stress and the damage factor; An equivalent fatigue life model is constructed according to the mapping relationship and the common damage factor, and the equivalent fatigue life model is solved by using asymptotic approximation theory to obtain an equivalent fatigue life decay model; According to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, the weight coefficient method is adopted to establish an adaptive fatigue life model. According to the adaptive fatigue life model, the closed-loop fatigue life model is obtained by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge; Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method. Multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary.

2. A method for evaluating the life of a lithium battery for construction machinery according to claim 1, characterized in that: The method of obtaining characteristic parameters of a construction machinery lithium battery and a life attenuation curve of a construction machinery lithium battery specifically includes the following steps: S101: Analyze the energy demand of the lithium battery system of pure electric engineering machinery with large load impact, and use the power matching method to quantitatively approximate the ultra-large polarization discharge parameters; S102: According to the ultra-large polarization discharge parameters, a parallel aging experiment is used to perform high pulse strong cycle discharge aging experiments on the engineering machinery lithium batteries of the same batch and specification at different pulse rates and different pulse times to obtain the characteristic parameters of the engineering machinery lithium batteries and the life attenuation curve of the engineering machinery lithium batteries.

3. A method for evaluating the life of a construction machinery lithium battery according to claim 2, characterized in that: According to the characteristic parameters and the life decay curve, the decay sections are divided into slow decay sections, buffer decay sections and dive decay sections; based on the internal evolution mechanism of the engineering machinery lithium battery, each decay section is analyzed to obtain the common damage characteristics of each decay section, and the common damage factors of each decay section are obtained by extracting the common damage characteristics of each decay section, which specifically includes the following steps: S201: using a data characteristic analysis method combined with a mathematical analytical solution method for a decay curve to identify a life decay curve diagram, and obtaining a first inflection point and a second inflection point of battery decay under ultra-large polarization discharge; S202: dividing the life decay curve into a slow decay section, a buffer decay section and a dive decay section according to the first inflection point and the second inflection point of battery decay under ultra-large polarization discharge; S203: Use non-destructive analysis methods to determine the key influencing factors of the slow decay section, buffer decay section and dive decay section of lithium batteries under ultra-large polarization; S204: Based on the key influencing factors, the battery after the parallel aging experiment is disassembled in combination with the microscopic analysis method, and the battery material characterization analysis method is used to deeply study the battery degradation mechanism under ultra-large polarization to determine the common aging mechanism of the first inflection point and the second inflection point; S205: According to the degradation mechanism of lithium batteries under ultra-large polarization, the variation law of ultra-large polarization current over time is analyzed from the time domain, and the relationship between the key factors of ultra-large polarization and battery aging is decoupled by combining the frequency domain impedance analysis method; S206: Starting from the factors that affect the discharge rate and discharge time of super-large polarization, single factor analysis and multi-factor analysis are used to determine the conditions for the occurrence of super-large polarization and the evolution law of the decay in each stage; S207: According to the occurrence conditions of ultra-large polarization and the evolution law of decay in each stage, a multi-level common damage feature analysis method is used to qualitatively give physical interpretation to the features and quantitatively extract the common damage features of each stage.

4. The method for evaluating the life of a construction machinery lithium battery according to claim 1, characterized in that: The method of obtaining the ultra-large polarization stress factor of the engineering machinery lithium battery uses the Miller linear damage accumulation criterion to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section to obtain the mapping relationship between the ultra-large polarization stress and the damage factor, and specifically includes the following steps: S301: Based on the ultra-large discharge rate and instantaneous pulse time, the ultra-large polarization stress factor is obtained through sampling test; S302: Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section, and the mapping relationship between the ultra-large polarization stress and the damage factor is fitted.

5. The method for evaluating the life of a lithium battery for construction machinery according to claim 1, characterized in that: The equivalent fatigue life model is constructed according to the mapping relationship and the common damage factor, and the equivalent fatigue life model is solved by asymptotic approximation theory to obtain the equivalent fatigue life decay model; specifically, the following steps are included: S401: Based on the common damage factors of the slow decay stage and the plunge decay stage, the fatigue decay theory is used to construct the relationship between the lithium battery decay life and the common damage factors; S402: Based on the relationship between life and common damage factor, a mapping relationship between ultra-large polarization stress and damage factor is introduced to obtain a relationship between ultra-large polarization stress factor, common damage factor and life; S403: Asymptotic approximation theory is used to solve the relationship between the super-large polarization stress factor, the common damage factor and the life span, and an equivalent fatigue degradation model of the engineering machinery lithium battery is obtained.

6. The method for evaluating the life of a lithium battery for construction machinery according to claim 1, characterized in that: The method adopts a weight coefficient method according to the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge to establish an adaptive fatigue life model, and obtains a closed-loop fatigue life model by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge according to the adaptive fatigue life model; specifically includes the following steps: S501: Based on the equivalent fatigue decay model, combined with the initial values ​​of temperature and state of charge, a weight coefficient method is used to construct an adaptive fatigue decay model of initial values ​​of temperature and state of charge; S502: Based on the adaptive fatigue decay model, combined with the influence of different temperature conditions and different initial charge states on ultra-large polarization discharge, the weight coefficient parameters of the damage factor, the temperature of the engineering machinery lithium battery and the initial value of the charge state in the equivalent fatigue life decay model are updated to obtain a closed-loop equivalent fatigue decay model.

7. The method for evaluating the life of a lithium battery for construction machinery according to claim 1, characterized in that: Based on the closed-loop fatigue life model, the battery life attenuation and demand value boundary curve are determined according to the Pareto method; the battery life attenuation and demand value boundary curve are optimized by multiple objectives to obtain the quantitative evaluation result of the ultra-large polarization discharge boundary. The specific steps are as follows: S601: Based on the closed-loop fatigue life model, a large load impact load is used to quantify the demand value of lithium batteries, and common damage characteristics are used to quantify battery life attenuation. The battery life attenuation and demand value boundary curve is obtained based on the Pareto method; S602: Based on the battery life attenuation and demand value boundary curve, multi-objective optimization is performed using battery life attenuation and demand value to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary.

8. A construction machinery lithium battery life assessment system, characterized in that: include: An acquisition unit, used to acquire characteristic parameters of the engineering machinery lithium battery and a life attenuation curve of the engineering machinery lithium battery; The extraction unit is used to divide the attenuation segment according to the characteristic parameters and the life attenuation curve diagram to obtain the slow attenuation segment, the buffer attenuation segment and the dive attenuation segment; based on the internal evolution mechanism of the engineering machinery lithium battery - analyze each attenuation segment to obtain the common damage characteristics of each attenuation segment, extract the common damage characteristics of each attenuation segment to obtain the common damage factor of each attenuation segment; A mapping unit is used to obtain the ultra-large polarization stress factor of the lithium battery of engineering machinery. The Miller linear damage accumulation criterion is used to decouple the ultra-large polarization stress factor from the common damage factor of the slow decay section and the subduction decay section to obtain the mapping relationship between the ultra-large polarization stress and the damage factor. A model building unit, used to build an equivalent fatigue life model according to the mapping relationship and the common damage factor, and solve the equivalent fatigue life model using asymptotic approximation theory to obtain an equivalent fatigue life decay model; A model updating unit is used to establish an adaptive fatigue life model by using a weight coefficient method according to an equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge, and to obtain a closed-loop fatigue life model by updating the weight coefficient parameters of the damage factor in the equivalent fatigue life decay model, the temperature of the engineering machinery lithium battery and the initial value of the state of charge according to the adaptive fatigue life model; The evaluation unit is used to determine the battery life attenuation and demand value boundary curve based on the closed-loop fatigue life model and the Pareto method; multi-objective optimization is performed on the battery life attenuation and demand value boundary curve to obtain a quantitative evaluation result of the ultra-large polarization discharge boundary.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for evaluating the life of a lithium battery of an engineering machinery as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for evaluating the life of a lithium battery of an engineering machinery according to any one of claims 1 to 7 are implemented.

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