Lithium ion battery thermal runaway prevention and control method with high robustness

Abstract

The invention discloses a lithium ion battery thermal runaway prevention and control method with high robustness, which relates to the technical field of lithium batteries and comprises the following steps: establishing a lithium ion battery temperature error system model with high robustness, the lithium ion battery temperature which is not completely measurable in the thermal runaway process of the lithium ion battery with high robustness is estimated through a Luenberger observer, a switching boundary controller is designed to obtain an observation error model, and sufficient conditions for system stability are obtained through Lyapunov stability analysis. The observer gain and the boundary controller gain are obtained through MATLAB calculation processing, and the temperature in the thermal runaway process of the lithium ion battery is converged to the expected temperature through the Luenberger observer and the boundary controller. According to the method, the temperature in the thermal runaway process of the lithium ion battery can be accurately controlled in the presence of random disturbance, the adopted estimation method has good robustness and stability, the dynamic response and stability of the system are emphasized, and the cost can be minimized.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a method for preventing and controlling thermal runaway of lithium-ion batteries with strong robustness. Background Art

[0002] As an efficient electrochemical energy storage device, lithium-ion batteries play a vital role in modern electronic devices and electric vehicles. However, the thermal behavior of lithium-ion batteries during the charging and discharging process has a great impact on their performance and safety issues. The temperature changes rapidly and the heat generation peak is high during the charging process. Overdischarge may cause copper dendrites to deposit on the positive electrode. The dendrite growth may penetrate the diaphragm and cause internal short circuits. Therefore, factors such as overcharge, overdischarge and high temperature environment of lithium-ion batteries will cause thermal runaway of lithium-ion batteries, which may lead to serious consequences.

[0003] Traditional control methods for battery charging and discharging mainly rely on temperature monitoring and PID control algorithms. Temperature sensors installed inside and around the battery pack monitor the temperature changes of lithium-ion batteries in real time, and predict and evaluate the thermal behavior of the battery based on the PID control algorithm and preset models. Based on the prediction results, the PID controller adjusts the output of the cooling system in response to the deviation between the battery temperature and the set point, thereby maintaining the battery in a safe and efficient temperature range, ensuring battery performance and extending its service life.

[0004] Although these methods can reduce the temperature to a certain extent, they have many limitations. For example, there are random disturbances in the charging and discharging process of lithium-ion batteries that affect the temperature change rate of lithium-ion batteries, and the PID controller is not effective when dealing with nonlinear systems, making it difficult to achieve ideal control effects. In order to improve battery safety, extend battery life, focus on the dynamic response and stability of the system, and minimize costs while meeting performance requirements, it is necessary to establish a lithium-ion battery thermal runaway prevention and control method with strong robust performance. Summary of the invention

[0005] The present invention provides a lithium-ion battery thermal runaway prevention and control method with strong robustness, which can solve the above-mentioned problems.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for preventing and controlling thermal runaway of a lithium-ion battery with strong robustness, comprising the following steps:

[0008] Step 1, introducing random variables, and establishing a temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance according to the temperature system model of the thermal runaway process of lithium-ion batteries;

[0009] Step 2: Based on the temperature error system model of the thermal runaway process of the lithium-ion battery with strong robust performance, a Lumberg observer is constructed to estimate the incompletely measurable lithium-ion battery temperature in the thermal runaway process of the lithium-ion battery with strong robust performance, and a switching boundary controller is designed according to the estimated lithium-ion battery temperature to obtain an observation error system model;

[0010] Step 3: Perform Lyapunov stability analysis with reference to the temperature error system model and the observation error system model to obtain sufficient conditions for temperature stability during the thermal runaway process of the lithium-ion battery. Use MATLAB to solve the observer gain and boundary controller gain, and use the Lumberg observer and switching boundary controller to achieve the convergence of the lithium-ion battery temperature to the desired temperature.

[0011] As a further description of the above technical solution, in step 1, the temperature system model of the lithium-ion battery during thermal runaway is:

[0012]

[0013] The boundary conditions of the model are:

[0014]

[0015] The initial conditions of the model are:

[0016] T(x,0)=T0(x)

[0017] Where x represents the radius of the lithium-ion battery, t represents the thermal reaction time of the lithium-ion battery, T t (x, t) and T x (x, t) represent the first-order derivative of the lithium-ion battery temperature with respect to time and space, T xx (x, t) represents the second-order derivative of the lithium-ion battery temperature with respect to space; χ(T(x, t)) is a nonlinear function; α is a non-negative integer; ω(x, t) represents the external disturbance; y(x, t) represents the measurement output; T x (0,t) and T x (1,t) represent T x (x, t) is the value at x = 0 and x = 1; T ∞ represents the ambient temperature; T(1,t) represents the value of the internal temperature T(x,t) of the lithium-ion battery at x=1; T0(x) represents the initial temperature of the lithium-ion battery, k represents thermal conductivity; h represents the effective surface heat transfer coefficient.

[0018] As a further description of the above technical solution, it is assumed that the probability of a non-negative integer α is:

[0019]

[0020] Introducing random variables So the probability of the random variable β is

[0021]

[0022] The temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance is:

[0023]

[0024] The boundary conditions of the model are:

[0025]

[0026] The initial conditions of the model are:

[0027] T(x,0)=T0(x)

[0028] Among them, α (1) Indicates the case where α≠0, α (2) It shows the case where α=0.

[0029] As a further description of the above technical solution, the temperature error variable is defined as and boundary control input Among them, T d (x) represents the expected temperature range during thermal runaway of lithium-ion batteries, T d (1) represents T d (x) value at x=1;

[0030] Combined with the temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance, the temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance is obtained as follows:

[0031]

[0032] The boundary conditions of the model are:

[0033]

[0034] The initial conditions of the model are:

[0035] s(x,0)=s0(x)

[0036] Where s(1,t) represents the value of the temperature error s(x,t) at x=1, s t (x,t) and s x (x, t) represent the first-order derivative of s(x, t) with respect to time and space, s xx (x, t) represents the second-order derivative of s(x, t) with respect to space, s x (0,t) and sx (1,t) represent s respectively x The value of (x, t) at x = 0 and x = 1, s(x, 0) represents the initial temperature inside the lithium-ion battery, and its size is a function of s0(x).

[0037] As a further description of the above technical solution, step 2 specifically includes:

[0038] Step 2.1: Construct the Lumberg observer:

[0039]

[0040] in, represents the state of the observer; and express The boundary conditions satisfied by the estimator with respect to the first-order derivative in time and the second-order derivative in space are And the initial condition is represent The value at x=1; represent The value at time zero is represents the estimated value of χ(s(x,t)); L represents the observer gain, Measure output for the estimator;

[0041] Step 2.2, using the Lumberg observer to estimate the incompletely measurable lithium-ion battery temperature during the thermal runaway process of the lithium-ion battery with strong robust performance, the switching boundary controller is designed according to different working conditions as follows:

[0042]

[0043] Among them, u Δ (t) and They are the guaranteed performance controller and guaranteed cost controller to be designed respectively; And λ1+λ2=1; when λ1=1, the controller switches to the guaranteed performance controller mode, and when λ2=1, the controller switches to the guaranteed cost controller mode; the switching mechanism of the two controllers is:

[0044]

[0045] The guaranteed cost controller is designed as The guaranteed cost controller is designed as K1, K2 represent controller gains;

[0046] Step 2.3: Define the observation error variable Combined with the closed-loop system, the observation error system model is obtained:

[0047]

[0048] Among them, the observation error system model satisfies the boundary condition e x (0,t)=0 and e t (x,t) and e x (x, t) represent the first-order derivative of the observation error variable e(x, t) with respect to time and space, respectively. xx (x, t) represents the second-order derivative of e(x, t) with respect to space, e x (0,t) and e x (1,t) represent e x e(1,t) represents the value of (x,t) at x=0 and x=1, and e(1,t) represents the value of e(x,t) at x=1.

[0049] As a further description of the above technical solution, step 3 specifically includes:

[0050] Step 3.1, construct the following Lyapunov function:

[0051]

[0052] Where P σ and Q σ is a positive parameter; σ=1,2; dx represents the differential operator;

[0053] Step 3.2, derive the Lyapunov function and use the inequality technique to obtain:

[0054]

[0055] Where: η is a given exponential decay rate, γ and ω are given parameters greater than zero,

[0056] in s(x,t) represents the temperature error variable, s(1,t) represents the value of s(x,t) at x=1, ζ(x,t)=[e T (x,t),e T (1,t)] T , e(x,t) represents the estimated error variable, e(1,t) represents the value of e(x,t) at x=1, represent The nonlinear function of the matrix Ξ σ satisfy:

[0057]

[0058] In the formula: Definition symbol A, B, and C are matrices of appropriate dimensions, * indicates the symmetric terms of the matrix, B T represents the transpose of matrix B, and diag represents the diagonal matrix;

[0059]

[0060] E is a unit vector, Θ is a given positive parameter,

[0061] ι, κ, a, μ and γ are constants given and greater than zero;

[0062] Step 3.3: Obtain Ξ using inequality techniques σ <0, then bring ι, κ, a, μ and γ into Ξ σ In the expression of , the observer gain L and the switching boundary controller gain K1, K2 of the system are obtained by solving it through MATLAB;

[0063] Step 3.4, substitute the observer gain L into the Lumberg observer, substitute the switching boundary controller gains K1 and K2 into the boundary controller, and use the Lumberg observer and the switching boundary controller in the thermal runaway process of the lithium-ion battery with strong robust performance to observe and control the temperature of the lithium-ion battery.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] The present invention can accurately converge the temperature of a lithium-ion battery in thermal runaway to a desired temperature under different working conditions, and can accurately control the temperature of a lithium-ion battery in a thermal runaway process in the presence of random disturbances. The estimation method used in the present invention has good robustness and stability, can effectively ensure the reliability and safety of the battery, pays attention to the dynamic response and stability of the system, and minimizes the cost while meeting performance requirements.

[0066] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the embodiments of the present invention are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] 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.

[0068] Figure 1 It is a schematic diagram of the steps of a lithium-ion battery temperature fault detection method based on an intermittent bilateral estimator of the present invention;

[0069] Figure 2 is an open-loop evolution diagram of the temperature of the lithium-ion battery of the present invention;

[0070] Figure 3 is the observed error trajectory of the lithium-ion battery temperature;

[0071] Figure 4 is a closed-loop evolution diagram of the temperature of the lithium-ion battery of the present invention;

[0072] Figure 5 It is a temperature evolution diagram of a lithium-ion battery under the performance-guaranteed controller of the present invention;

[0073] Figure 6 This is a temperature evolution diagram of a lithium-ion battery under the cost-guaranteed controller of the present invention. DETAILED DESCRIPTION

[0074] 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 only part of the embodiments of the present invention, not all of the embodiments.

[0075] Please refer to Figure 1 The embodiment of the present invention provides a method for preventing and controlling thermal runaway of a lithium-ion battery with strong robustness, comprising the following steps:

[0076] Step 1: Based on the temperature system model of the lithium-ion battery in the thermal runaway process, a lithium-ion battery temperature error system model with strong robust performance is established.

[0077] The temperature system model expression during the thermal runaway process of lithium-ion batteries is as follows:

[0078]

[0079] The boundary conditions of the temperature system model during the thermal runaway of lithium-ion batteries are expressed as:

[0080]

[0081] The initial condition of the temperature system model during the thermal runaway of lithium-ion batteries is expressed as:

[0082] T(x,0)=T0(x) (3)

[0083] in:

[0084] x represents the radius of the lithium-ion battery, and t represents the thermal reaction time of the lithium-ion battery;

[0085] T(x,t) represents the temperature of the lithium-ion battery, T t (x, t) and Tx (x, t) represent the first-order derivative of the lithium-ion battery temperature with respect to time and space, T xx (x, t) represents the second-order derivative of the lithium-ion battery temperature with respect to space;

[0086] T(1,t) represents the value of the lithium-ion battery temperature T(x,t) at x=1;

[0087] T ∞ Represents the ambient temperature, its value is T ∞ =298.15K;

[0088] χ(T(x,t)) is a nonlinear function, which is expressed as χ(T(x,t))=k -1 I 2 R s (T(x,t),t);

[0089] ω(x, t) represents the external disturbance, and its value is ω(x, t) = sin(πt) / 0.61K;

[0090] α is a non-negative integer, k represents thermal conductivity, and its value is k = 0.61 W / (m·K);

[0091] I represents the battery output current, and its value is I=4A;

[0092] represents the internal resistance of the battery,

[0093] M(t) is a nonlinear function, and its expression is M(t)=90+sin(t).

[0094] Constant R s,ref =R s (T ref ,t)=15mΩ,T ref is a given reference temperature, which is taken as T ref =298.15K,

[0095] E a is the activation energy, which is taken as E a =33.8 kJ / mol, R is the universal gas constant, which is R=8.314 J / (mol·K);

[0096] y(x,t) represents the measured output, h represents the effective surface heat transfer coefficient, and its value is h=69.89W / (m 2 K), T ∞ (t) represents the ambient temperature; T x (0,t) and T x(1, t) represent the values ​​of the internal temperature T(x, t) of the lithium-ion battery at x = 0 and x = 1 respectively; T(x, 0) > 0 represents the initial temperature of thermal runaway of the lithium-ion battery, and its size is a function of T0(x).

[0097] Construct a mathematical model with strong robust performance, assuming that the probability of a non-negative integer α is:

[0098]

[0099] Introducing a random variable So the probability of the random variable β is

[0100]

[0101] The temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance is as follows:

[0102]

[0103] The boundary conditions of the temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance are expressed as follows:

[0104]

[0105] The initial conditions of the temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance are expressed as:

[0106] T(x,0)=T0(x) (6)

[0107] Among them, α (1) Indicates the case where α≠0, α (2) It shows the case where α=0.

[0108] In order to make the temperature of lithium-ion batteries reach the desired temperature T during thermal runaway d =298.15K. First, define the temperature error variable and boundary control input Then the error variable s(x, t) and the boundary control input u(t) are introduced into the system (4) to obtain the temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance:

[0109]

[0110] The boundary conditions of the temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance are expressed as:

[0111]

[0112] The initial condition of the temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance is expressed as:

[0113] s(x,0)=s0(x) (9)

[0114] Where s(1,t) represents the value of the temperature error s(x,t) at x=1, s t (x,t) and s x (x, t) represent the first-order derivative of s(x, t) with respect to time and space, s xx (x, t) represents the second-order derivative of s(x, t) with respect to space, s x (0,t) and s x (1,t) represent s respectively x The value of (x, t) at x = 0 and x = 1, s(x, 0) > 0 represents the initial temperature inside the lithium-ion battery, and its size is a function of s0(x).

[0115] Step 2: Using the measurement output obtained in formula (1), a Lumberg observer is constructed to estimate the incompletely measurable lithium-ion battery temperature during the thermal runaway process of the lithium-ion battery with strong robust performance. Then, a switching boundary controller is designed according to the estimated lithium-ion battery temperature, and the observation error system model is obtained, which is as follows:

[0116] Step 2.1: Construct the Lumberg observer as follows:

[0117]

[0118] in, represents the state of the observer; and express The boundary conditions satisfied by the estimator with respect to the first-order derivative in time and the second-order derivative in space are And the initial condition is represent The value at x=l; represent The value at time zero is represents the estimated value of χ(s(x,t)); L represents the observer gain, Measure the output for the estimator.

[0119] Step 2.2, using the Lumberg observer to estimate the incompletely measurable lithium-ion battery temperature during the thermal runaway process of the lithium-ion battery with strong robust performance, the switching boundary controller is designed according to different working conditions as follows:

[0120]

[0121] Among them, uΔ (t) and are the guaranteed cost controller and guaranteed cost controller to be designed, respectively, and the switching between them is determined by λ1 and λ2. And λ1+λ2=1. When λ1=1, the controller switches to the guaranteed performance controller mode, and when λ2=1, the controller switches to the guaranteed cost controller mode. The switching mechanism of the two controllers is:

[0122]

[0123] The guaranteed cost controller is designed as The guaranteed cost controller is designed as K1, K2 represent controller gains.

[0124] Step 2.3: Define the observation error variable Combined with the closed-loop system, the observation error system model is obtained:

[0125]

[0126] Among them, the observation error system model satisfies the boundary condition e x (0,t)=0 and e t (x,t) and e x (x, t) represent the first-order derivative of the observation error variable e(x, t) with respect to time and space, respectively. xx (x, t) represents the second-order derivative of e(x, t) with respect to space, e x (0,t) and e x (1,t) represent e x e(1,t) represents the value of (x,t) at x=0 and x=1, and e(1,t) represents the value of e(x,t) at x=1.

[0127] Step 3: Perform Lyapunov stability analysis with reference to the temperature error system model (7) and the observation error system model (13) to obtain sufficient conditions for temperature stability during the thermal runaway process of the lithium-ion battery. Use MATLAB to solve the observer gain and the boundary controller gain. Use the Lumberg observer (10) and the switching boundary controller (11) to achieve the convergence of the lithium-ion battery temperature to the desired temperature, thus completing the lithium-ion battery thermal runaway prevention and control with strong robustness, as follows:

[0128] Step 3.1, construct the following Lyapunov function:

[0129]

[0130] Where P σ and Q σ(σ=1,2) is a positive parameter, dx represents the differential operator;

[0131] Step 3.2, derive the Lyapunov function and use the inequality technique to obtain:

[0132]

[0133] Where:

[0134] η is a given exponential decay rate, γ and ω are given parameters greater than zero;

[0135]

[0136] in s(x,t) represents the temperature error variable, s(1,t) represents the value of s(x,t) at x=1, ζ(x,t)=[e T (x,t),e T (1,t)] T , e(x,t) represents the estimated error variable, e(1,t) represents the value of e(x,t) at x=1, represent The nonlinear function of ω(x, t) represents the external disturbance of the lithium-ion battery, and the matrix Ξ σ Satisfy the following formula:

[0137]

[0138] Where:

[0139] Defining symbols A, B, and C are matrices of appropriate dimensions, * indicates the symmetric terms of the matrix,

[0140] B T represents the transpose of matrix B, and diag represents the diagonal matrix;

[0141]

[0142]

[0143] σ=1,2, E is a unit vector, Θ is a given positive parameter,

[0144] ι, κ, a, μ and γ are given as constants greater than zero.

[0145] Step 3.3: Obtain Ξ using inequality techniques σ <0, then Established;

[0146] Then, by integration method, we can get:

[0147] Satisfied by this The sufficient condition for σ <0.

[0148] Therefore, according to the above analysis, the present invention obtains sufficient conditions for the temperature stability of the thermal runaway process of a lithium-ion battery with strong robust performance: σ When <0, the thermal runaway process of lithium-ion batteries satisfies the exponential input to state stability, that is, the temperature of the battery is stable within a bounded range at a convergence rate of η.

[0149] Then the given parameters ι = 1, κ = 2, a = 1, μ = 1 and γ = 1 are introduced into Ξ σ In the expression of , the system observer gain L = 1.95 and the switching boundary controller gain K1 = 1.23, K2 = 2.45 are obtained by solving it through MATLAB;

[0150] Step 3.4, substitute the observer gain L into the Lumberg observer, substitute the switching boundary controller gains K1 and K2 into the boundary controller, and use the Lumberg observer and the switching boundary controller in the thermal runaway process of the lithium-ion battery with strong robust performance to observe and control the temperature of the lithium-ion battery, thereby completing the thermal runaway prevention and control of the lithium-ion battery with strong robust performance of the present invention.

[0151] To illustrate the control effect of the scheme of the present invention in detail, the switching boundary control method of the lithium-ion battery thermal runaway process of the present invention is simulated in MATLAB. Through MATLAB simulation, the open-loop evolution of the lithium-ion battery temperature Figure 2 It shows that the temperature is rising sharply, so it is necessary to control the system. Further, in order to prove the rationality of the observer design, Figure 3 The observation error trajectory is given, which shows that the observation error converges to zero, that is, the observer design is reasonable. Further, the controller designed by the present invention acts on the boundary of the lithium-ion battery, and the closed-loop evolution of the lithium-ion battery temperature is Figure 4 It shows that the core temperature of the lithium-ion battery converges to the expected temperature of 313.15K, and the temperature at the boundary converges to the expected temperature of 298.15K. The designed boundary controller is effective. Figure 5 It shows that under different powers of lithium-ion batteries, the guaranteed cost controller can quickly converge the temperature to the desired temperature. Temperature evolution of lithium-ion batteries under guaranteed cost controller Figure 6 It shows that under different powers of lithium-ion batteries, the guaranteed cost controller can economically converge the temperature to the desired temperature. The Lumberg observer and boundary controller designed in the present invention are effective, that is, the prevention and control method of the thermal runaway process of lithium-ion batteries can be realized.

[0152] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preventing and controlling thermal runaway of a lithium-ion battery with strong robustness, characterized in that: The following steps are involved: Step 1, introducing random variables, and establishing a temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance according to the temperature system model of the thermal runaway process of lithium-ion batteries; Step 2: Based on the temperature error system model of the thermal runaway process of the lithium-ion battery with strong robust performance, a Lumberg observer is constructed to estimate the incompletely measurable lithium-ion battery temperature in the thermal runaway process of the lithium-ion battery with strong robust performance, and a switching boundary controller is designed according to the estimated lithium-ion battery temperature to obtain an observation error system model; Step 3: Perform Lyapunov stability analysis with reference to the temperature error system model and the observation error system model to obtain sufficient conditions for temperature stability during the thermal runaway process of the lithium-ion battery. Use MATLAB to solve the observer gain and boundary controller gain, and use the Lumberg observer and switching boundary controller to achieve the convergence of the lithium-ion battery temperature to the desired temperature.

2. The method for preventing and controlling thermal runaway of a lithium-ion battery according to claim 1, characterized in that: In step 1, the temperature system model of the lithium-ion battery during thermal runaway is: The boundary conditions of the model are: The initial conditions of the model are: T(x,0)=T0(x) Where x represents the radius of the lithium-ion battery, t represents the thermal reaction time of the lithium-ion battery, T t (x, t) and T x (x, t) represent the first-order derivative of the lithium-ion battery temperature with respect to time and space, T xx (x, t) represents the second-order derivative of the lithium-ion battery temperature with respect to space; χ(T(x, t)) is a nonlinear function; α is a non-negative integer; ω(x, t) represents the external disturbance; y(x, t) represents the measurement output; T x (0,t) and T x (1,t) represent T x (x, t) is the value at x = 0 and x = 1; T ∞ represents the ambient temperature; T(1,t) represents the value of the lithium-ion battery temperature T(x,t) at x=1; T0(x) represents the initial temperature of the lithium-ion battery, k represents the thermal conductivity; h represents the effective surface heat transfer coefficient; T(x,0) represents the initial temperature of the lithium-ion battery thermal runaway.

3. The method for preventing and controlling thermal runaway of a lithium-ion battery according to claim 2, characterized in that: Assume the probability of a non-negative integer α is: Introducing random variables So the probability of the random variable β is The temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance is: The boundary conditions of the model are: The initial conditions of the model are: T(x,0)=T0(x) Among them, α (1) Indicates the case where α≠0, α (2) It shows the case where α=0.

4. The method for preventing and controlling thermal runaway of a lithium-ion battery according to claim 3, characterized in that: Define the temperature error variable and boundary control input Among them, T d (x) represents the expected temperature range during thermal runaway of lithium-ion batteries, T d (1) represents T d (x) value at x=1; Combined with the temperature system model of the thermal runaway process of lithium-ion batteries with strong robust performance, the temperature error system model of the thermal runaway process of lithium-ion batteries with strong robust performance is obtained as follows: The boundary conditions of the model are: The initial conditions of the model are: s(x,0)=s0(x) Where s(1,t) represents the value of the temperature error s(x,t) at x=1, s t (x,t) and s x (x, t) represent the first-order derivative of s(x, t) with respect to time and space, s xx (x, t) represents the second-order derivative of s(x, t) with respect to space, s x (0,t) and s x (1,t) represent s respectively x The value of (x, t) at x = 0 and x = 1, s(x, 0) represents the initial temperature inside the lithium-ion battery, and its size is a function of s0(x).

5. The method for preventing and controlling thermal runaway of a lithium-ion battery according to claim 4, characterized in that: Step 2 specifically includes: Step 2.1: Construct the Lumberg observer: in, represents the state of the observer; and express The boundary conditions satisfied by the estimator with respect to the first-order derivative in time and the second-order derivative in space are And the initial condition is represent The value at x=l; represent The value at time zero is represents the estimated value of χ(s(x,t)); L represents the observer gain, Measure output for the estimator; Step 2.2, using the Lumberg observer to estimate the incompletely measurable lithium-ion battery temperature during the thermal runaway process of the lithium-ion battery with strong robust performance, the switching boundary controller is designed according to different working conditions as follows: Among them, u Δ (t) and They are the guaranteed performance controller and guaranteed cost controller to be designed respectively; And λ1+λ2=1; when λ1=1, the controller switches to the guaranteed performance controller mode, and when λ2=1, the controller switches to the guaranteed cost controller mode; the switching mechanism of the two controllers is: The guaranteed cost controller is designed as The guaranteed cost controller is designed as K1, K2 represent controller gains; Step 2.3: Define the observation error variable Combined with the closed-loop system, the observation error system model is obtained: Among them, the observation error system model satisfies the boundary condition e x (0,t)=0 and e t (x,t) and e x (x, t) represent the first-order derivative of the observation error variable e(x, t) with respect to time and space, respectively. xx (x, t) represents the second-order derivative of e(x, t) with respect to space, e x (0,t) and e x (1,t) represent e x e(1,t) represents the value of (x,t) at x=0 and x=1, and e(1,t) represents the value of e(x,t) at x=1.

6. The method for preventing and controlling thermal runaway of a lithium-ion battery according to claim 5, characterized in that: Step 3 specifically includes: Step 3.1, construct the following Lyapunov function: Where P σ and Q σ is a positive parameter; σ=1,2; dx represents the differential operator; Step 3.2, derive the Lyapunov function and use the inequality technique to obtain: Where: η is a given exponential decay rate, γ and ω are given parameters greater than zero, in s(x,t) represents the temperature error variable, s(1,t) represents the value of s(x,t) at x=1, ζ(x,t)=[e T (x,t),e T (1,t)] T , e(x,t) represents the estimated error variable, e(1,t) represents the value of e(x,t) at x=1, represent The nonlinear function of the matrix Ξ σ satisfy: In the formula: Definition symbol A, B, and C are matrices of appropriate dimensions, * indicates the symmetric terms of the matrix, B T represents the transpose of matrix B, and diag represents the diagonal matrix; E is a unit vector, Θ is a given positive parameter, ι, κ, a, μ and γ are constants given and greater than zero; Step 3.3: Obtain Ξ using inequality techniques σ <0, then bring ι, κ, a, μ and γ into Ξ σ In the expression of , the observer gain L and the switching boundary controller gain K1, K2 of the system are obtained by solving it through MATLAB; Step 3.4, substitute the observer gain L into the Lumberg observer, substitute the switching boundary controller gains K1 and K2 into the boundary controller, and use the Lumberg observer and the switching boundary controller in the thermal runaway process of the lithium-ion battery with strong robust performance to observe and control the temperature of the lithium-ion battery.

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