A control method for over-temperature control protection

Abstract

The application relates to the technical field of electric vehicle charging control, and discloses a control method for over-temperature control protection, which comprises the following steps: first, a thermal-electric coupling dynamic model representing the dynamic correlation among charging current, contact resistance and interface temperature of a charging interface is established; subsequently, an active excitation signal is superimposed on a basic charging current instruction to apply a dynamic current disturbance to the charging interface, and temperature response data and current data of the charging interface under the action of the active excitation signal are collected; then, online parameter identification is performed on the thermal-electric coupling dynamic model based on the temperature response data and the current data. By superimposing an active high-frequency micro-disturbance signal on the basic charging current instruction, the application artificially constructs a continuous excitation condition required by system identification, so that the dynamic change of internal physical parameters of the charging interface can be accurately captured through a mathematical model while the current output is stable.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging control technology, and in particular to a control method for over-temperature control and protection. Background Technology

[0002] With the popularization of high-power fast charging technology for new energy vehicles, the charging interface, as a key hub for power transmission, is carrying an increasingly higher current density and facing increasingly severe thermal stress challenges. During long-term plugging and unplugging, the contact pair between the charging gun head and the socket will inevitably experience mechanical wear, plating peeling, and oxidation corrosion, leading to a gradual increase in contact resistance. Under continuous high-current charging conditions, the deteriorated contact resistance will generate excessive Joule heat. If the heat cannot be dissipated in time, it can easily cause serious safety accidents such as plug burning or even the entire vehicle burning.

[0003] Currently, over-temperature protection for charging interfaces mainly relies on physical detection using negative temperature coefficient (NTC) thermistors or thermocouples embedded inside the plug. Existing mainstream control strategies typically employ logic judgment based on absolute temperature thresholds: when the temperature collected by the sensor exceeds a preset safety value (e.g., 85°C), a relay is triggered to disconnect the charging circuit; or a current derating strategy is adopted, which reduces the charging current linearly or in a stepped curve according to the temperature rise, in an attempt to maintain thermal balance.

[0004] However, the aforementioned passive defense technology based on direct temperature measurement has significant limitations in practical applications. Firstly, due to limitations in packaging processes and electrical insulation requirements, temperature sensors often cannot directly contact the core heating point of the conductive terminal. There is an inevitable thermal resistance and thermal capacitance between the sensor and the heat source, resulting in a significant physical lag in temperature conduction. When the sensor detects an over-temperature signal, the contact center is often already at an extremely high temperature, or even irreversible material damage has occurred. This lag in thermal response means that the protection action always lags behind the occurrence of the fault.

[0005] Secondly, existing temperature threshold control methods cannot identify the physical nature of plug aging through the surface temperature. Temperature is the result of the combined effects of ambient temperature, heat dissipation conditions, and contact resistance heating. In low-temperature environments or under strong heat dissipation conditions (such as outdoor charging in winter), even if the contact resistance of the plug increases abnormally due to severe wear, the absolute temperature measured by the sensor may still be within a safe range due to the strong cooling effect of the environment. This can cause the charging pile to misjudge the system health and continue to output a large current. This state not only exacerbates the hidden losses of the plug, but also instantly triggers thermal runaway once the environmental conditions change or the heat accumulation exceeds the critical point. In addition, existing technologies lack the ability to predict the evolution trend of contact resistance throughout its entire life cycle. They rely solely on simple logical judgments based on transient temperature values, which cannot construct a dynamic system stability boundary and make it difficult to effectively identify and actively intervene in the early stages of a fault. Therefore, this invention designs an over-temperature control and protection method based on the problems mentioned above. Summary of the Invention

[0006] The purpose of this invention is to provide a control method for over-temperature control and protection, which solves the problems of the lag in existing charging over-temperature protection technology due to its reliance on passive detection by temperature sensors, and the inability to effectively identify the deterioration of plug contact resistance in low temperature or strong heat dissipation environments, thus causing the plug to operate with defects and leading to the risk of burn-out.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a control method for over-temperature control and protection, comprising the following steps:

[0008] S1. First, establish a dynamic model of thermo-electric coupling that characterizes the dynamic relationship between charging current, contact resistance and interface temperature of the charging interface.

[0009] S2. Subsequently, an active excitation signal is superimposed on the basic charging current command to apply dynamic current disturbance to the charging interface, and the temperature response data and current data of the charging interface under the action of the active excitation signal are collected.

[0010] S3. Then, based on the temperature response data and the current data, online parameter identification is performed on the thermo-electric coupling dynamic model to decouple and estimate the contact resistance value of the charging interface in real time.

[0011] S4. Construct an energy function characterizing the system risk energy based on the contact resistance value and the interface temperature, and define a safe operating manifold based on the stability boundary of the energy function;

[0012] S5. Monitor in real time the position and changing trend of the system state characterized by the energy function in the safe working manifold, and dynamically adjust the charging current or cut off the charging circuit according to the monitoring results.

[0013] Preferably, the establishment of the thermo-electric coupling dynamic model characterizing the dynamic relationship between charging current, contact resistance, and interface temperature of the charging interface in step S1 specifically includes:

[0014] Construct the thermal-electric coupling dynamic model in the form of a discretized difference equation;

[0015] The thermo-electric coupling dynamic model takes the current interface temperature as the output and a data vector containing the squared terms of the interface temperature and the current data from the previous moment as the input.

[0016] The thermal-electric coupling dynamic model includes a set of parameters to be identified, and the parameters in the set of parameters to be identified represent the thermal inertia of the charging interface, the thermal resistance of the ambient heat dissipation, and the contact resistance value, respectively.

[0017] Preferably, the superposition of the active excitation signal on the basic charging current command in step S2 specifically refers to:

[0018] The active excitation signal is configured as a high-frequency sinusoidal micro-perturbation signal;

[0019] The frequency of the active excitation signal is set higher than the ambient heat dissipation thermal response cutoff frequency of the charging interface, so that the temperature response data caused by the active excitation signal is mainly dominated by the change in the contact resistance value.

[0020] By superimposing the active excitation signal, the data input to the thermo-electric coupling dynamic model is made to satisfy the continuous excitation condition.

[0021] Preferably, step S3 involves online parameter identification of the thermo-electric coupling dynamic model, specifically including:

[0022] Construct an observation vector containing the temperature response data and the current data at historical moments;

[0023] The covariance matrix of the thermo-electric coupling dynamic model is updated in real time based on the observation vector using the recursive least squares algorithm with forgetting factor.

[0024] Based on the updated covariance matrix and prediction error, the estimated values ​​of the parameter set to be identified are recursively calculated and updated.

[0025] Preferably, the decoupling and real-time estimation of the contact resistance value of the charging interface specifically includes:

[0026] Based on the physical mapping relationship of the thermal-electric coupling dynamic model, a first parameter term representing the input thermal gain and a second parameter term representing the autoregressive coefficient are separated from the estimated values ​​of the parameter set to be identified.

[0027] By performing algebraic operations using the first and second parameter terms, the contact resistance value, after eliminating the influence of ambient temperature, is obtained.

[0028] Preferably, the step of constructing the energy function characterizing the system risk energy based on the contact resistance value and the interface temperature specifically involves:

[0029] Construct the Lyapunov generalized energy function, the value of which consists of a weighted sum of squares of two parts:

[0030] The first part is the square of the temperature deviation between the interface temperature and the preset safe temperature;

[0031] The second part is the square of the impedance deviation between the contact resistance value and the nominal contact resistance value.

[0032] Preferably, the definition of the safe working manifold based on the stability boundary of the energy function specifically includes:

[0033] The safe working manifold is defined as a state space constrained by the value of the energy function and its first-order differential rate of change.

[0034] A risk energy threshold is set. When the value of the energy function is less than the risk energy threshold and the first-order difference rate of change of the energy function is less than or equal to zero, the system state is determined to be in the stable region of the safe working manifold.

[0035] Preferably, the step of dynamically adjusting the charging current based on the monitoring results specifically includes:

[0036] The first-order difference rate of change of the energy function is calculated in real time;

[0037] When the value of the energy function is detected to be within a preset safe range, but the first-order difference rate of change is greater than zero, it is determined that the system state has a risk of divergence.

[0038] Based on the Lyapunov stability constraint that makes the first-order differential rate of change less than zero at the next time step, the maximum allowable current value is calculated, and the charging current is limited to the maximum allowable current value.

[0039] Preferably, the calculation of the maximum allowable current value specifically involves:

[0040] Based on the aforementioned thermo-electric coupling dynamic model, the upper limit of the current required to bring the interface temperature to converge to the target trajectory is derived in reverse, thereby forcing the system state to return to the stable region of the safe operating manifold.

[0041] Preferably, the step of cutting off the charging circuit based on the monitoring results specifically includes:

[0042] When the value of the energy function is detected to exceed the preset risk energy threshold, it is determined that the system state has escaped the safe operating flow; the output of the charging current is immediately terminated, and a fault signal of abnormal contact impedance is issued.

[0043] In summary, the present invention has at least one of the following beneficial technical effects:

[0044] 1. This invention artificially constructs the continuous excitation conditions required for system identification by superimposing an active high-frequency micro-perturbation signal on the basic charging current command, ensuring that while the current output is stable, the dynamic changes of the internal physical parameters of the charging interface can still be accurately captured through mathematical models.

[0045] 2. By utilizing the frequency domain characteristics difference between the fast heat generation response of contact resistance under high-frequency excitation signals and the slow heat dissipation response of the environment, this invention can eliminate the masking effect of low temperature environment or strong air cooling on temperature monitoring, thereby accurately identifying the true degree of contact resistance degradation caused by wear or oxidation, and avoiding the risk of burn-out caused by continuous high current operation of plugs in a faulty state of low temperature but high impedance.

[0046] 3. This invention establishes a multi-dimensional system safety evaluation system by constructing a Lyapunov generalized energy function that includes temperature deviation energy and impedance degradation energy. This breaks through the limitations of traditional single temperature threshold protection and can identify potential hazards in the early stage when the temperature has not yet reached the alarm red line but the risk energy has already accumulated. This effectively eliminates the safety blind spot caused by the thermal conduction hysteresis of physical sensors.

[0047] 4. This invention defines a safe working manifold based on the energy function and its first-order differential rate of change, setting a strict dynamic stability boundary for the charging process, ensuring that the system state is always constrained within a mathematically provable convergence region; once the system state shows a tendency to escape the manifold (i.e. risk divergence), the protection logic can be triggered immediately, significantly improving the intrinsic safety level in high-power charging scenarios.

[0048] 5. This invention achieves smooth adaptive derating control by deriving the maximum allowable current in reverse based on Lyapunov stability derivative constraints. When a slight decrease in contact performance is detected, the current is automatically calculated and limited to maintain the thermal balance of the contact point, rather than directly triggering a fault shutdown. This ensures that the equipment does not overheat and become damaged, thus maintaining the continuity of charging to the greatest extent possible. Attached Figure Description

[0049] Figure 1 This is one of the schematic diagrams of the method flow of the present invention;

[0050] Figure 2 This is a second schematic diagram of the method flow of the present invention;

[0051] Figure 3 This is the third schematic diagram of the method flow of the present invention;

[0052] Figure 4 This is the fourth schematic diagram of the method flow of the present invention;

[0053] Figure 5 This is the fifth schematic diagram of the method flow of the present invention;

[0054] Figure 6 This is the sixth schematic diagram of the method flow of the present invention. Detailed Implementation

[0055] The following is in conjunction with the appendix Figure 1 -Appendix Figure 6 The present invention will be further described in detail below.

[0056] This invention provides a control method for over-temperature control and protection, comprising the following steps:

[0057] S1. First, establish a thermo-electric coupling dynamic model characterizing the dynamic relationship between charging current, contact resistance, and interface temperature of the charging interface. Specifically, this involves constructing a discretized difference equation form of the thermo-electric coupling dynamic model. The thermo-electric coupling dynamic model uses the current interface temperature as the output and a data vector containing the squared terms of the interface temperature and current data from the previous time step as the input. The thermo-electric coupling dynamic model includes a set of parameters to be identified, where the parameters represent the thermal inertia of the charging interface, the ambient thermal resistance, and the contact resistance value, respectively.

[0058] Specifically, this step aims to build a mathematical model that can describe the physical and thermal characteristics of the charging interface, serving as the basis for subsequent control algorithms.

[0059] Physical modeling: The metal contact points of the charging gun head or socket are considered as a lumped-parameter thermal system. The heat source of this system mainly comes from the Joule heat generated when current flows through the contact resistance. The system's heat dissipation occurs through cable conduction and environmental convection. Based on the law of conservation of energy, the differential equation for heat balance over continuous time is established:

[0060] ;

[0061] in: Real-time temperature at the contact point; : Load current flowing through the contact point; Contact resistance, a parameter that varies with plug wear, oxidation, and temperature, is a key physical quantity monitored in this invention. Equivalent thermal resistance of the contact point to the environment; : Equivalent heat capacity at the contact point; Ambient temperature;

[0062] Model Discretization: To facilitate implementation in a digital microprocessor, the forward Euler method is used to discretize the above differential equations, with the sampling period set to [value missing]. The discretized difference equation model is obtained by rearranging the equations:

[0063] ;

[0064] The model establishes the temperature at the current moment. Temperature compared to the previous moment and the square term of the current The linear regression relationship between them, where, This represents the system modeling error and noise. The parameter vector to be identified has the following correspondence with the physical parameters:

[0065] ;

[0066] ;

[0067] .

[0068] S2. Subsequently, an active excitation signal is superimposed on the basic charging current command to apply dynamic current perturbation to the charging interface, and temperature response data and current data of the charging interface under the action of the active excitation signal are collected. Specifically, superimposing the active excitation signal on the basic charging current command involves: configuring the active excitation signal as a high-frequency sinusoidal micro-perturbation signal; setting the frequency of the active excitation signal to be higher than the environmental heat dissipation thermal response cutoff frequency of the charging interface, so that the temperature response data caused by the active excitation signal is mainly dominated by the change in the contact resistance value; and superimposing the active excitation signal to ensure that the data input to the thermo-electric coupling dynamic model meets the continuous excitation condition.

[0069] Specifically, this step aims to address the problem of insufficient system excitation under constant current charging and ensure the convergence of parameter identification;

[0070] Excitation generation: The base charging current requested by the battery management system (BMS). Above this, a sinusoidal disturbance signal with a specific frequency and a small amplitude is superimposed, and the final current command output by the controller is determined. for:

[0071] ;

[0072] in, The injection amplitude should be small enough (e.g., 1% to 5% of the base current) to avoid affecting battery life and charging efficiency.

[0073] Frequency selection: Injection frequency The choice is crucial, due to contact resistance The heat generated is directly applied to the metal at the contact point, resulting in a rapid thermal response; while the thermal resistance of the environmental heat dissipation path is... and heat capacity The resulting thermal inertia is relatively large, exhibiting low-pass filtering characteristics, therefore, it is set... Higher than the system's ambient thermal response cutoff frequency (i.e. At this frequency, the fluctuation component in the temperature response is mainly dominated by the change in contact resistance, thus separating the influence of contact resistance from the heat dissipation of the environment in the frequency domain, satisfying the "continuous excitation condition" for system identification.

[0074] S3. Then, based on the temperature response data and the current data, online parameter identification is performed on the thermo-electric coupling dynamic model to decouple and estimate the contact resistance value of the charging interface in real time. Specifically, online parameter identification of the thermo-electric coupling dynamic model includes: constructing an observation vector containing historical temperature response data and current data; using a recursive least squares algorithm with a forgetting factor to update the covariance matrix of the thermo-electric coupling dynamic model in real time based on the observation vector; and recursively calculating and updating the estimated values ​​of the parameter set to be identified based on the updated covariance matrix and the prediction error. Specifically, decoupling and estimating the contact resistance value of the charging interface in real time includes: separating a first parameter term representing the input thermal gain and a second parameter term representing the autoregressive coefficient from the estimated values ​​of the parameter set to be identified according to the physical mapping relationship of the thermo-electric coupling dynamic model; and performing algebraic operations using the first and second parameter terms to inversely solve for the contact resistance value after eliminating the influence of ambient temperature.

[0075] Specifically, this step uses a recursive algorithm to invert the contact resistance in real time, thereby realizing virtual sensing;

[0076] Constructing the observation vector: Defining the time step Data observation vector :

[0077] ;

[0078] Recursive Least Squares (FF-RLS) operation: The recursive least squares method with a forgetting factor is used to update the parameter estimates in real time. The specific process is as follows:

[0079] Calculate the gain matrix :

[0080] ;

[0081] in Let covariance matrix be the variance matrix. Forgetting factor This is used to adjust the algorithm's tracking speed of time-varying parameter characteristics and update parameter estimates. :

[0082] ;

[0083] Update covariance matrix :

[0084] ;

[0085] Parameter decoupling and impedance calculation: obtaining parameter estimates and Then, combine the preset or slowly estimated system thermal resistance The contact resistance is then calculated by inversely solving the physical mapping relationship from step S1. :

[0086] ;

[0087] This calculation process eliminated the environmental temperature variable. The interference was eliminated, and the pure physical quantification of the plug contact performance was achieved.

[0088] S4. Construct an energy function characterizing the system risk energy based on the contact resistance value and the interface temperature, and define a safe operating manifold based on the stability boundary of the energy function. Specifically, constructing the energy function characterizing the system risk energy based on the contact resistance value and the interface temperature involves: constructing a Lyapunov generalized energy function, the value of which consists of a weighted sum of squares of two parts: the first part is the square of the temperature deviation between the interface temperature and the preset safe temperature; the second part is the square of the impedance deviation between the contact resistance value and the nominal contact resistance value. Defining the safe operating manifold based on the stability boundary of the energy function involves: defining the safe operating manifold as a state space constrained by the value of the energy function and its first-order differential rate of change; setting a risk energy threshold; when the value of the energy function is less than the risk energy threshold, and the first-order differential rate of change of the energy function is less than or equal to zero, it is determined that the system state is located in the stable region of the safe operating manifold.

[0089] Specifically, first construct the energy function:

[0090] Define the Lyapunov generalized energy function The function consists of two weighted sums of squares, representing the risk of heat accumulation and the risk of aging, respectively:

[0091] ;

[0092] in: : The preset optimal safe operating temperature; The nominal contact resistance of the plug in its brand new condition; : Weighting coefficient, used to balance the contribution of temperature deviation and resistance aging to system risk;

[0093] Define a safe manifold:

[0094] Define the system's safe workflow The state space region is constrained by the energy function and its derivative:

[0095] ;

[0096] in The maximum permissible risk energy threshold is defined as follows: the system is considered safe only when the system state is within this manifold, i.e., the risk energy is low and shows a convergent trend.

[0097] S5. Real-time monitoring of the position and trend of the system state characterized by the energy function within the safe working manifold, and dynamic adjustment of the charging current or disconnection of the charging circuit based on the monitoring results. The dynamic adjustment of the charging current based on the monitoring results specifically includes: real-time calculation of the first-order differential rate of change of the energy function; when the value of the energy function is within a preset safe range, but the first-order differential rate of change is greater than zero, determining that the system state has a risk of divergence; calculating the maximum allowable current value based on the Lyapunov stability constraint condition that makes the first-order differential rate of change less than zero at the next moment, and limiting the charging current within the maximum allowable current value. The calculation of the maximum allowable current value specifically involves: based on the thermo-electric coupling dynamic model, deriving the upper limit of the current required to converge the interface temperature to the target trajectory, thereby forcing the system state to return to the stable region of the safe working manifold. The disconnection of the charging circuit based on the monitoring results specifically involves: when the value of the energy function exceeds a preset risk energy threshold, determining that the system state has escaped the safe working manifold; immediately terminating the output of the charging current and issuing a fault signal indicating abnormal contact impedance.

[0098] Specifically, this step executes specific control actions based on the Lyapunov stability criterion;

[0099] Calculation of the rate of change: Real-time calculation of the first-order difference rate of change of the energy function:

[0100] ;

[0101] Tiered control strategy: Stable region (no intervention required): If and This indicates that the system is operating smoothly and maintaining the current charging state;

[0102] Warning zone (reduction limit): If but This indicates that although the temperature is not currently too high, risk energy is accumulating (divergent trend) due to factors such as increased contact resistance. Therefore, it is necessary to force the temperature to rise at the next moment. Based on model predictions, the maximum allowable current is calculated by reverse calculation. :

[0103] ;

[0104] in To achieve the target temperature trajectory point where the energy function decreases, the controller limits the charging current to... Within this range, the system trajectory is forced to return to stability; danger zone (fault disconnection): if This indicates that the system state has escaped from a safe state and there is a risk of thermal runaway. The controller immediately cuts off the charging circuit and reports an abnormal contact impedance fault to prevent plug burning.

[0105] In summary, this invention provides a control method for over-temperature control and protection. By superimposing an active high-frequency micro-perturbation signal on the basic charging current command, the continuous excitation conditions required for system identification are artificially constructed. This overcomes the technical problem of the covariance matrix diverging and model parameters becoming unsolvable in the parameter identification algorithm due to the near-zero rate of change of current under conventional constant current charging conditions. It ensures that while the current output is stable, the dynamic changes of the internal physical parameters of the charging interface can still be accurately captured through the mathematical model. Furthermore, by utilizing the difference in frequency domain characteristics between the fast heat generation response of contact resistance and the slow heat dissipation response of the environment under high-frequency excitation signals, the contact resistance and ambient temperature are decoupled during the parameter identification process. This eliminates the masking effect of low temperature environment or strong air cooling on temperature monitoring, thereby accurately identifying the true degree of contact resistance degradation caused by wear or oxidation. This avoids the risk of burn-out caused by continuous high-current operation of the plug under faulty conditions of low temperature but high impedance.

[0106] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A control method for over-temperature control and protection, characterized in that, Includes the following steps: S1. First, establish a dynamic model of thermo-electric coupling that characterizes the dynamic relationship between charging current, contact resistance and interface temperature of the charging interface. S2. Subsequently, an active excitation signal is superimposed on the basic charging current command to apply dynamic current disturbance to the charging interface, and the temperature response data and current data of the charging interface under the action of the active excitation signal are collected. S3. Then, based on the temperature response data and the current data, online parameter identification is performed on the thermo-electric coupling dynamic model to decouple and estimate the contact resistance value of the charging interface in real time. S4. Construct an energy function characterizing the system risk energy based on the contact resistance value and the interface temperature, and define a safe operating manifold based on the stability boundary of the energy function; S5. Monitor in real time the position and changing trend of the system state characterized by the energy function in the safe working manifold, and dynamically adjust the charging current or cut off the charging circuit according to the monitoring results.

2. The control method for over-temperature control and protection according to claim 1, characterized in that, The establishment of a thermo-electric coupling dynamic model characterizing the dynamic relationship between charging current, contact resistance, and interface temperature of the charging interface in step S1 specifically involves: Construct the thermal-electric coupling dynamic model in the form of a discretized difference equation; The thermo-electric coupling dynamic model takes the current interface temperature as the output and a data vector containing the squared terms of the interface temperature and the current data from the previous moment as the input. The thermal-electric coupling dynamic model includes a set of parameters to be identified, and the parameters in the set of parameters to be identified represent the thermal inertia of the charging interface, the thermal resistance of the ambient heat dissipation, and the contact resistance value, respectively.

3. The control method for over-temperature control and protection according to claim 1, characterized in that, The step S2, which involves superimposing an active excitation signal on the basic charging current command, specifically refers to: The active excitation signal is configured as a high-frequency sinusoidal micro-perturbation signal; The frequency of the active excitation signal is set higher than the ambient heat dissipation thermal response cutoff frequency of the charging interface, so that the temperature response data caused by the active excitation signal is mainly dominated by the change in the contact resistance value. By superimposing the active excitation signal, the data input to the thermo-electric coupling dynamic model is made to satisfy the continuous excitation condition.

4. The over-temperature control and protection method according to claim 1, characterized in that, Step S3 involves online parameter identification of the thermo-electric coupling dynamic model, specifically including: Construct an observation vector containing the temperature response data and the current data at historical moments; The covariance matrix of the thermo-electric coupling dynamic model is updated in real time based on the observation vector using the recursive least squares algorithm with forgetting factor. Based on the updated covariance matrix and prediction error, the estimated values ​​of the parameter set to be identified are recursively calculated and updated.

5. The over-temperature control and protection method according to claim 4, characterized in that, The process of decoupling and real-time estimation of the contact resistance value of the charging interface specifically includes: Based on the physical mapping relationship of the thermal-electric coupling dynamic model, a first parameter term representing the input thermal gain and a second parameter term representing the autoregressive coefficient are separated from the estimated values ​​of the parameter set to be identified. By performing algebraic operations using the first and second parameter terms, the contact resistance value, after eliminating the influence of ambient temperature, is obtained.

6. The control method for over-temperature control and protection according to claim 1, characterized in that, The energy function that characterizes the system risk energy based on the contact resistance value and the interface temperature is specifically as follows: Construct the Lyapunov generalized energy function, the value of which consists of a weighted sum of squares of two parts: The first part is the square of the temperature deviation between the interface temperature and the preset safe temperature; The second part is the square of the impedance deviation between the contact resistance value and the nominal contact resistance value.

7. The over-temperature control and protection method according to claim 6, characterized in that, The stability boundary defined based on the energy function defines the safe operating manifold, specifically as follows: The safe working manifold is defined as a state space constrained by the value of the energy function and its first-order differential rate of change. A risk energy threshold is set. When the value of the energy function is less than the risk energy threshold and the first-order difference rate of change of the energy function is less than or equal to zero, the system state is determined to be in the stable region of the safe working manifold.

8. The control method for over-temperature control and protection according to claim 1, characterized in that, The step of dynamically adjusting the charging current based on the monitoring results specifically includes: The first-order difference rate of change of the energy function is calculated in real time; When the value of the energy function is detected to be within a preset safe range, but the first-order difference rate of change is greater than zero, it is determined that the system state has a risk of divergence. Based on the Lyapunov stability constraint that makes the first-order differential rate of change less than zero at the next time step, the maximum allowable current value is calculated, and the charging current is limited to the maximum allowable current value.

9. The control method for over-temperature control and protection according to claim 8, characterized in that, The calculation of the maximum allowable current value is specifically as follows: Based on the aforementioned thermo-electric coupling dynamic model, the upper limit of the current required to bring the interface temperature to converge to the target trajectory is derived in reverse, thereby forcing the system state to return to the stable region of the safe operating manifold.

10. The control method for over-temperature control and protection according to claim 1, characterized in that, The step of cutting off the charging circuit based on the monitoring results specifically involves: When the value of the energy function is detected to exceed the preset risk energy threshold, it is determined that the system state has escaped the safe operating flow; the output of the charging current is immediately terminated, and a fault signal of abnormal contact impedance is issued.

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