Cell voltage estimation method in failure mode of cell voltage acquisition circuit

Abstract

The invention discloses a cell voltage estimation method in a failure mode of a cell voltage acquisition circuit, and relates to the technical field of power batteries, and the method comprises the following steps: a control program takes a moment when the failure of the cell voltage acquisition circuit of a power battery is detected as an initial moment; acquiring the current electric core charge quantity of the power battery at any time step length from the initial moment; acquiring an open-circuit voltage of the power battery cell based on the current cell charge quantity and a preset mapping relation; obtaining an equivalent cell circuit model of the power battery based on the use condition data of the power battery and the battery performance test data; based on the equivalent cell circuit model, ohmic internal resistance partial voltage of the ohmic internal resistance and polarization partial voltage of the RC circuit are obtained; acquiring the cell voltage of the power battery; therefore, on the premise of not introducing hardware elements, when the battery cell voltage acquisition circuit of the power battery suddenly fails, the battery cell voltage of the power battery can be quickly obtained at low cost.

Description

Technical Field

[0001] The present invention relates to a method for estimating a cell voltage in a cell voltage acquisition circuit failure mode in the technical field of automotive power batteries, and in particular to a method for estimating a cell voltage in a cell voltage acquisition circuit failure mode, and also to a device for estimating a cell voltage in a cell voltage acquisition circuit failure mode using the method. Background Art

[0002] At present, measures to deal with cell voltage failure use redundant hardware design or inference through other hardware sampling circuits. For example, an additional set of backup cell voltage acquisition circuits is added, or a module voltage sampling circuit is added to reversely infer the cell voltage of the failed cell.

[0003] However, introducing redundant hardware design will add two types of costs. On the one hand, it will increase the cost of hardware elements such as analog-to-digital converters, filters, and voltage-divider resistors. On the other hand, it will also increase the cost of hardware redesign.

[0004] Therefore, there is an urgent need for a method for quickly and inexpensively acquiring the cell voltage of a power battery when a cell voltage acquisition circuit of the power battery suddenly fails. Summary of the invention

[0005] In order to obtain the cell voltage of a power battery quickly and at low cost when a cell voltage acquisition circuit of the power battery suddenly fails, the present invention provides a method and device for estimating the cell voltage in a cell voltage acquisition circuit failure mode.

[0006] The present invention is implemented by the following technical scheme: a method for estimating cell voltage under a cell voltage acquisition circuit failure mode, comprising the following steps: taking the moment when the failure of the cell voltage acquisition circuit of the power battery is detected as the initial moment, obtaining the current cell charge and cell temperature of the power battery cell at any time step from the initial moment; obtaining the open circuit voltage of the power battery cell based on the current cell charge, the cell temperature and a preset mapping relationship; the preset mapping relationship is used to characterize the mapping relationship between the charge of the power battery cell and the open circuit voltage of the power battery cell; obtaining an equivalent cell circuit model of the power battery based on the operating condition data of the power battery and the battery performance test data; the equivalent cell circuit model includes an RC circuit composed of an ohmic internal resistance, a polarization internal resistance and a polarization capacitor, and a current source; based on the equivalent cell circuit model, obtaining the ohmic internal resistance divided voltage of the ohmic internal resistance and the polarization divided voltage of the RC circuit; obtaining the voltage of the power battery cell based on the open circuit voltage, the ohmic internal resistance divided voltage and the polarization divided voltage.

[0007] As a further improvement of the above scheme, the open circuit voltage of the power battery cell is obtained based on the current battery cell charge, the battery cell temperature and a preset mapping relationship, which previously includes the following steps: obtaining open circuit voltage test data of the battery cells in the power battery; taking the open circuit voltage of the power battery cell as the dependent variable, the current battery cell charge as the first independent variable, and the battery cell temperature as the second independent variable; based on the battery cell open circuit voltage test data, obtaining a preset mapping relationship between the dependent variable, the first independent variable and the second independent variable.

[0008] As a further improvement of the above scheme, the open circuit voltage of the power battery cell is obtained based on the current battery cell charge, the battery cell temperature and a preset mapping relationship, comprising the following steps: substituting the battery cell temperature and the current battery cell charge into the preset mapping relationship to obtain the open circuit voltage of the power battery cell.

[0009] As a further improvement of the above scheme, when the equivalent cell circuit model is a first-order equivalent circuit model, the equivalent cell circuit model of the power battery is obtained based on the operating condition data of the power battery and the battery performance test data, including the following steps: based on the operating condition data of the power battery, the number of charge and discharge cycles of the power battery cell is obtained; based on the battery performance test data, a first function expression of the resistance value of the ohmic internal resistance and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source and the number of charge and discharge cycles is fitted; based on the battery performance test data, a second function expression characterizing the mapping relationship between the resistance value of the polarization internal resistance and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source and the number of charge and discharge cycles is fitted; based on the battery performance test data, a third function expression characterizing the mapping relationship between the capacitance value of the polarization capacitor and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source and the number of charge and discharge cycles is fitted.

[0010] As a further improvement of the above scheme, the method of obtaining the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent battery cell circuit model includes the following steps: obtaining the effective current value and current direction output by the current source; obtaining the ohmic internal resistance voltage division of the ohmic internal resistance based on the effective current value and the resistance value of the ohmic internal resistance.

[0011] As a further improvement of the above scheme, the method of obtaining the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent battery cell circuit model also includes the following steps: obtaining the polarization voltage division of the RC circuit based on the second function expression and the third function expression.

[0012] As a further improvement of the above scheme, the obtaining of the cell voltage of the power battery based on the open circuit voltage, the ohmic internal resistance voltage division and the polarization voltage division includes the following steps: adding the open circuit voltage, the ohmic internal resistance voltage division and the polarization voltage division to obtain the voltage of the power battery cell at any time step from the initial moment.

[0013] The present invention also provides a cell voltage estimation device in a cell voltage acquisition circuit failure mode, which applies any of the above-mentioned cell voltage estimation methods in a cell voltage acquisition circuit failure mode, and comprises:

[0014] A charge acquisition module, which is used to take the moment when the cell voltage acquisition circuit of the power battery is detected to fail as the initial moment, and acquire the current cell charge of the power battery cell at any time step from the initial moment;

[0015] An open circuit voltage acquisition module, which is used to acquire the open circuit voltage of the power battery cell based on the current battery cell charge and a preset mapping relationship; the preset mapping relationship is used to characterize the mapping relationship between the charge of the power battery cell and the open circuit voltage of the power battery cell;

[0016] An equivalent model acquisition module, which is used to acquire an equivalent cell circuit model of the power battery based on the operating condition data of the power battery and the battery performance test data; the equivalent cell circuit model includes an RC circuit composed of an ohmic internal resistance, a polarization internal resistance and a polarization capacitor, and a current source;

[0017] A voltage division acquisition module, which is used to obtain the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent cell circuit model;

[0018] A comprehensive voltage acquisition module is used to acquire the voltage of the power battery cell based on the open circuit voltage, the ohmic internal resistance partial voltage and the polarization partial voltage.

[0019] Compared with the existing method for estimating the cell voltage under the failure mode of the cell voltage acquisition circuit, the method and device for estimating the cell voltage under the failure mode of the cell voltage acquisition circuit of the present invention have the following beneficial effects: the control program takes the moment when the failure of the cell voltage acquisition circuit of the power battery is detected as the initial moment, and obtains the current cell charge of the power battery cell at any time step from the initial moment; based on the current cell charge, the cell temperature and the preset mapping relationship, the open circuit voltage of the power battery cell is obtained; based on the operating condition data of the power battery and the battery performance test data, the equivalent cell circuit model of the power battery is obtained; based on the equivalent cell circuit model, the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit are obtained; based on the open circuit voltage, the ohmic internal resistance voltage division and the polarization voltage division, the cell voltage of the power battery is obtained; through the above method, without introducing hardware elements and hardware design costs, when dealing with the sudden failure of the cell voltage acquisition circuit of the power battery, the cell voltage of the power battery can be obtained quickly and at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flowchart of a method for estimating a cell voltage in a cell voltage acquisition circuit failure mode according to an embodiment of the present invention.

[0021] Figure 2 The figure is a flow chart of the method for obtaining the open circuit voltage according to an embodiment of the present invention.

[0022] Figure 3 The present invention is a flowchart of the method for obtaining the equivalent model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] See also Figure 1 In an embodiment of the present application, a method for estimating a cell voltage in a cell voltage acquisition circuit failure mode is proposed, and the method comprises the following steps:

[0025] S101, taking the moment when the cell voltage acquisition circuit of the power battery is detected to fail as the initial moment, obtaining the current cell charge of the power battery cell at any time step from the initial moment;

[0026] Specifically, when the control program detects that there is a collection fault in the power battery cell voltage collection circuit, it is determined that the power battery cell voltage collection circuit has failed, and the moment when the failure of the power battery cell voltage collection circuit is detected is taken as the initial moment. When it is necessary to obtain the voltage of the power battery cell at the initial moment and any moment after the initial moment, the current cell charge of the power battery cell at any time step from the initial moment is first obtained.

[0027] S102, obtaining an open circuit voltage of a power battery cell based on a current battery cell charge, a battery cell temperature, and a preset mapping relationship;

[0028] The preset mapping relationship is used to characterize the mapping relationship between the current cell charge of the power battery cell and the open circuit voltage of the power battery cell.

[0029] Based on the current battery cell charge, battery cell temperature and a preset mapping table, the open circuit voltage of the power battery cell is obtained, which includes the following steps: obtaining the open circuit voltage test data of the battery cell in the power battery; taking the battery cell open circuit voltage as the dependent variable, the current battery cell charge as the first independent variable, and the temperature of the power battery as the second independent variable; based on the battery cell open circuit voltage test data, obtaining the preset mapping relationship between the dependent variable, the first independent variable and the second independent variable.

[0030] Specifically, after the control program obtains the real-time temperature of the power battery cell, it substitutes the real-time temperature and the current charge of the cell into the preset mapping relationship to obtain the open circuit voltage of the power battery cell.

[0031] S103, obtaining an equivalent cell circuit model of the power battery based on the usage condition data of the power battery and the battery performance test data;

[0032] Among them, the operating condition data includes calendar life data and cycle life data, and the cycle life data includes the number of times the power battery can be charged and discharged in a cycle; the calendar life data refers to the life of the power battery when it is left under a certain power level and temperature conditions.

[0033] Specifically, the control program obtains the number of charge and discharge cycles of the power battery based on the operating condition data of the power battery; based on the battery performance test data, fits a first function expression of the resistance value of the ohmic internal resistance of the power battery cell and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles; based on the battery performance test data, fits a second function expression of the resistance value of the polarization internal resistance of the power battery cell and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles; based on the battery performance test data, fits a third function expression of the capacitance value of the polarization capacitance of the power battery cell and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles; finally, based on the first function expression of the ohmic internal resistance, the second function expression of the polarization internal resistance, and the third function expression of the polarization capacitance, the equivalent cell circuit model of the power battery is obtained.

[0034] S104. Based on the equivalent cell circuit model, obtain the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit.

[0035] Specifically, the control program obtains the effective current value and current direction output by the current source, obtains the ohmic internal resistance voltage division of the ohmic internal resistance based on the effective current value and the resistance value of the ohmic internal resistance, and obtains the polarization voltage division of the RC circuit based on the second function expression and the third function expression.

[0036] S105 . Obtain the cell voltage of the power battery based on the open circuit voltage, the ohmic internal resistance voltage division, and the polarization voltage division.

[0037] In the present application, the control program takes the moment when the failure of the power battery cell voltage acquisition circuit is detected as the initial moment, obtains the current cell charge of the power battery cell at any time step from the initial moment; obtains the open circuit voltage of the power battery cell based on the current cell charge and the preset mapping relationship; obtains the equivalent cell circuit model of the power battery based on the power battery usage condition data and the battery performance test data; obtains the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent cell circuit model; obtains the cell voltage of the power battery based on the open circuit voltage, the ohmic internal resistance voltage division and the polarization voltage division; through the above method, without introducing hardware elements and increasing the hardware design cost, when dealing with the sudden failure of the power battery cell voltage acquisition circuit, the voltage of the power battery cell can be obtained quickly and at low cost.

[0038] In an application embodiment, please refer to Figure 2 , step S2 comprises:

[0039] S201, obtaining open circuit voltage test data of power battery cells;

[0040] S202, taking the open circuit voltage of the battery cell as the dependent variable, the current charge of the battery cell as the first independent variable, and the temperature of the battery cell as the second independent variable;

[0041] S203: Based on the cell open circuit voltage test data, obtain a preset mapping relationship between the dependent variable, the first independent variable, and the second independent variable.

[0042] The preset mapping relationship can be expressed as U cell =f(SOC,T), where U cell It represents the open circuit voltage of the battery cell, SOC represents the current charge of the battery cell, and T represents the battery cell temperature.

[0043] In an embodiment of the present application, the mapping relationship between the current charge of the power battery cell and the open circuit voltage of the power battery cell is obtained by using the open circuit voltage test data of the power battery cell, so that the open circuit voltage of the power battery cell can be more accurately obtained according to the current charge of the power battery cell.

[0044] In an application embodiment, please refer to Figure 3 , step S3 comprises:

[0045] S301, obtaining the number of charge and discharge cycles of the power battery cell based on the usage condition data of the power battery;

[0046] S302, based on the battery performance test data, fitting a first function expression of the resistance value of the ohmic internal resistance and the current battery cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles;

[0047] The first function expression can be R0=f R0 (SOC,T,I,N c ), R0 represents the ohmic internal resistance, I represents the effective current value of the current source, N c It is the number of charge and discharge cycles of the power battery.

[0048] S303, based on the battery performance test data, fitting a second function expression of the polarization internal resistance, the current battery cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles;

[0049] The second function expression can be R1=f R1 (SOC,T,I,N c ), R1 represents the polarization internal resistance, I represents the effective current value of the current source, N c It is the number of charge and discharge cycles of the power battery.

[0050] S304, based on the battery performance test data, fitting a third function expression of the capacitance value of the polarized capacitor and the current cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles.

[0051] Among them, the third function expression can be C1=f C1 (SOC,T,I,N c ), C1 represents the polarized capacitance, I represents the effective current value of the current source, N c It is the number of charge and discharge cycles of the power battery.

[0052] In an embodiment of the present application, the number of charge and discharge cycles of the power battery is obtained based on the operating condition data of the power battery, and then based on the battery performance test data, the functional expressions of the polarization internal resistance and polarization capacitance can be fitted offline, providing a basis for the next step of accurately obtaining the polarization voltage division of the RC circuit.

[0053] It can be understood that in order to further improve the accuracy of the equivalent cell circuit model, the equivalent cell circuit model acquired offline can be updated online based on the actual operating condition collection data, wherein the actual operating condition collection data includes the real-time current value acquired at the current moment; specifically, the control program obtains the real-time current value according to the current acquisition device, obtains the significant step condition window according to the real-time current value, and calculates the ratio of the voltage drop and the current difference within a unit time step when the power battery cell is in the significant step condition, as the updated value of the ohmic internal resistance R0.

[0054] In other embodiments, it is also possible to select an operating condition window that can simultaneously reflect the ohmic characteristics and polarization characteristics of the battery, perform Laplace transform on the output and input of the equivalent battery cell circuit model to obtain the S-domain transfer function, and then use Z transform to obtain the transfer function in the Z domain, and perform online identification of R0, R1 and C1 based on the recursive least squares method to obtain the online updated values ​​of the ohmic internal resistance R0, the polarization internal resistance R1 and the polarization capacitance C1.

[0055] In one embodiment of the application, step S4 includes the following steps:

[0056] Specifically, the control program can obtain the polarization voltage division of the RC circuit according to the recursive formula, the second function expression and the third function expression. The recursive formula can be expressed as:

[0057]

[0058] Among them, U 1st (n) represents the polarization partial pressure of the RC network at the current moment, n represents the time step from the initial moment when the failure of the cell voltage acquisition circuit of the power battery is detected, U 1st(n-1) represents the polarization voltage at the previous time step of the current moment, C1(n) represents the polarization capacitance at the current moment, I(n) represents the current value at the current moment, and R1(n) represents the polarization internal resistance at the current moment.

[0059] It should be noted that the cell voltage error predicted based on the equivalent cell circuit model is different from the cell voltage error collected based on the cell voltage collection circuit. In order to better protect the power battery cells, it is necessary to update the overvoltage threshold and undervoltage threshold of the power battery cells. The expressions of the overvoltage threshold and undervoltage threshold are as follows:

[0060] λ cal =g(λ i ,λ m ,λ u )

[0061]

[0062] Among them, λ u is the voltage error collected by the cell voltage collection circuit, λ i The current error based on circuit acquisition is, m is the calculation error of the equivalent cell circuit model, λ cal is the voltage error predicted based on the equivalent cell circuit model, U ov_cal Indicates the overvoltage threshold, U uv_cal Indicates the undervoltage threshold.

[0063] Therefore, considering different factors of cell voltage error estimation based on the model and correcting the overvoltage threshold and undervoltage threshold can better protect the cells of the power battery.

[0064] In the application embodiment, according to the recursive formula of polarization voltage division, the second function expression for characterizing polarization internal resistance and the third function expression for characterizing polarization capacitance, the polarization voltage division of the RC circuit can be accurately obtained, and the cell voltage of the power battery finally obtained is also more accurate.

[0065] This embodiment provides a cell voltage estimation device in a cell voltage acquisition circuit failure mode, and a cell voltage estimation method in a cell voltage acquisition circuit failure mode of the device, which includes:

[0066] A charge acquisition module, which is used to take the moment when the cell voltage acquisition circuit of the power battery is detected to fail as the initial moment, and acquire the current cell charge and cell temperature of the power battery cell at any time step from the initial moment;

[0067] An open circuit voltage acquisition module, which is used to acquire the open circuit voltage of the power battery cell based on the current battery cell charge, the battery cell temperature and a preset mapping relationship; the preset mapping relationship is used to characterize the mapping relationship between the charge of the power battery cell and the open circuit voltage of the power battery cell;

[0068] An equivalent model acquisition module, which is used to acquire an equivalent cell circuit model of the power battery based on the operating condition data of the power battery and the battery performance test data; the equivalent cell circuit model includes an RC circuit composed of an ohmic internal resistance, a polarization internal resistance and a polarization capacitor, and a current source;

[0069] A voltage division acquisition module, which is used to obtain the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent cell circuit model;

[0070] A comprehensive voltage acquisition module is used to acquire the voltage of the power battery cell based on the open circuit voltage, the ohmic internal resistance partial voltage and the polarization partial voltage.

[0071] Compared with the prior art, the advantages of the cell voltage estimation device in the cell voltage acquisition circuit failure mode are the same as those of the cell voltage estimation method in the cell voltage acquisition circuit failure mode in Example 1, which will not be elaborated here.

[0072] In one embodiment of the application, a computer terminal is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The steps of the method for estimating the cell voltage in the failure mode of the cell voltage acquisition circuit are implemented when the processor executes the program. When the method is applied, it can be applied in the form of software, such as being designed as an independently running program and installed on a computer terminal, which can be a computer, a smart phone, a control system, and other Internet of Things devices. The method can also be designed as an embedded running program and installed on a computer terminal, such as a single-chip microcomputer.

[0073] In one application embodiment, this embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by the processor, the steps of the method for estimating the cell voltage in the failure mode of the cell voltage acquisition circuit are implemented. When the method is applied, it can be applied in the form of software, such as a program designed to be independently run by a computer-readable storage medium. The computer-readable storage medium can be a U disk, designed as a U shield, and the U disk is designed to start the program of the entire method through an external trigger.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating a cell voltage in a cell voltage acquisition circuit failure mode, characterized in that: The method comprises the following steps: Taking the moment when the cell voltage acquisition circuit of the power battery is detected to fail as the initial moment, obtaining the current cell charge and cell temperature of the power battery cell at any time step from the initial moment; Based on the current battery cell charge, the battery cell temperature and a preset mapping relationship, the open circuit voltage of the power battery cell is acquired; the preset mapping relationship is used to characterize the mapping relationship between the charge of the power battery cell and the open circuit voltage of the power battery cell; Based on the operating condition data of the power battery and the battery performance test data, an equivalent cell circuit model of the power battery is obtained; the equivalent cell circuit model includes an RC circuit composed of an ohmic internal resistance, a polarization internal resistance and a polarization capacitor, and a current source; Based on the equivalent cell circuit model, obtaining the ohmic internal resistance partial pressure of the ohmic internal resistance and the polarization partial pressure of the RC circuit; The voltage of the power battery cell is obtained based on the open circuit voltage, the ohmic internal resistance partial voltage and the polarization partial voltage.

2. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 1, characterized in that: The step of obtaining the open circuit voltage of the power battery cell based on the current battery cell charge, the battery cell temperature and a preset mapping relationship comprises the following steps: Obtaining open circuit voltage test data of the battery cells in the power battery; Taking the open circuit voltage of the power battery cell as the dependent variable, the current charge of the cell as the first independent variable, and the cell temperature as the second independent variable; Based on the cell open circuit voltage test data, a preset mapping relationship among the dependent variable, the first independent variable and the second independent variable is obtained.

3. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 2, characterized in that: The step of obtaining the open circuit voltage of the power battery cell based on the current battery cell charge, the battery cell temperature and a preset mapping relationship comprises the following steps: The battery cell temperature and the current battery cell charge are substituted into the preset mapping relationship to obtain the open circuit voltage of the power battery cell.

4. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 1, characterized in that: When the equivalent cell circuit model is a first-order equivalent circuit model, the step of obtaining the equivalent cell circuit model of the power battery based on the usage condition data of the power battery and the battery performance test data comprises the following steps: Based on the operating condition data of the power battery, the number of charge and discharge cycles of the power battery cell is obtained; Based on the battery performance test data, a first function expression is fitted between the resistance value of the ohmic internal resistance and the current battery cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles; Based on the battery performance test data, a second function expression is fitted to characterize the mapping relationship between the resistance value of the polarization internal resistance and the current battery cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles; Based on the battery performance test data, a third function expression is fitted to characterize the mapping relationship between the capacitance value of the polarization capacitor and the current battery cell charge, the real-time temperature of the power battery cell, the effective current value of the current source, and the number of charge and discharge cycles.

5. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 4, characterized in that: The step of obtaining the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent cell circuit model comprises the following steps: Obtaining an effective current value and a current direction output by the current source; Based on the effective current value and the resistance value of the ohmic internal resistor, an ohmic internal resistance divided voltage of the ohmic internal resistor is obtained.

6. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 4, characterized in that: The step of obtaining the ohmic internal resistance partial pressure of the ohmic internal resistance and the polarization partial pressure of the RC circuit based on the equivalent cell circuit model further includes the following steps: Based on the second function expression and the third function expression, the polarization voltage division of the RC circuit is obtained.

7. The method for estimating cell voltage in a cell voltage acquisition circuit failure mode according to claim 1, characterized in that: The step of obtaining the cell voltage of the power battery based on the open circuit voltage, the ohmic internal resistance partial voltage, and the polarization partial voltage comprises the following steps: The open circuit voltage, the ohmic internal resistance partial voltage and the polarization partial voltage are added together to obtain the voltage of the power battery cell at any time step from the initial moment.

8. A cell voltage estimation device in a cell voltage acquisition circuit failure mode, the device comprising: A charge acquisition module, which is used to take the moment when the cell voltage acquisition circuit of the power battery is detected to fail as the initial moment, and acquire the current cell charge and cell temperature of the power battery cell at any time step from the initial moment; An open circuit voltage acquisition module, which is used to acquire the open circuit voltage of the power battery cell based on the current battery cell charge, the battery cell temperature and a preset mapping relationship; the preset mapping relationship is used to characterize the mapping relationship between the charge of the power battery cell and the open circuit voltage of the power battery cell; An equivalent model acquisition module, which is used to acquire an equivalent cell circuit model of the power battery based on the operating condition data of the power battery and the battery performance test data; the equivalent cell circuit model includes an RC circuit composed of an ohmic internal resistance, a polarization internal resistance and a polarization capacitor, and a current source; A voltage division acquisition module, which is used to obtain the ohmic internal resistance voltage division of the ohmic internal resistance and the polarization voltage division of the RC circuit based on the equivalent cell circuit model; A comprehensive voltage acquisition module is used to acquire the voltage of the power battery cell based on the open circuit voltage, the ohmic internal resistance partial voltage and the polarization partial voltage.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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